The Impact of Solar Air Collectors on Human Health, Maintenance of Buildings and Possible Energy Savings in Houses

The impact of Solar Air Collectors on human health, maintenance of buildings and possible energy savings in houses

Danish Technological Institute

Energy and Climate Division1

The impact of Solar Air Collectors on human health, maintenance of buildings and possible energy savings in houses

Søren Østergaard Jensen Lars Olsen Energy and Climate Division Danish Technological Institute

June 2012

2 Preface

The report concludes the work carried out in the project Solar air collector impact on the health of humans and on buildings, possible energy and maintenance savings in houses fi- nanced by Midtnet Journal no. 11.002 under the Central Denmark Region – Shanghai framework.

The aim of the work was to scientifically document the effect (related to energy, health and economy) of solar preheated ambient air injected into buildings under Chinese climate and structural conditions.

The following persons have participated in the project:

Søren Østergaard Jensen, Danish Technological Institute – project leader Lars Olsen, Danish Technological Institute Hans Jørgen Christensen, SolarVenti Enrique Martin, SolarVenti Alice Zhu, FocusChina Aps Lily Tao, FocusChina Aps

The work of the project has primarily been divided in the following way:

Danish Technological Institute – investigations on:

- humidity problems in Chinese homes and related health problems - documentation of efficiency and volume flow rates of the SolarVenti products - calculation of the drying and heating effect when supplying solar heated fresh air to Chinese homes

SolarVenti:

- SolarVenti collectors for tests at the Danish Technological Institute - comparative measurements with and without SolarVenti

FocusChina:

- contacts to institutions concerning humidity related health problems in Chinese homes - contacts regarding comparative measurements in Chinese homes - information on typical homes in China: floor plan, structural details, interior, etc.

The impact of Solar Air Collectors on human health, maintenance of buildings and possible energy savings in houses 1st printing, 1st edition, 2012 Danish Technological Institute Energy and Climate Division

ISBN: 87-7756-xxx-x ISSN: 1600-3780

3 Summary

Cold and damp conditions in buildings are normally considered as bad for both health and constructions. For this reason the Danish solar heating company SolarVenti invented an autonomous solar heating system which blows solar preheated air into the building during sunshine.

However, in order to be able to promote the system on especially the Chinese building marked there was need for documentation on:

- the health effect on drying out humid buildings - the magnitude of the problems with damp buildings in especially the Shanghai region - a more precise characterization of the SolarVenti system - the performance in real buildings

The health related problems regarding damp buildings is investigated in chapter 3 and it is documented that dampness causes health problems and that it is a major expense for the society worldwide. In chapter 2 it is documented that cold and humid buildings is a large problem in Chinese homes.

In chapter 4 the performance of the two SolarVenti systems SV14 and SV7 is documented based on measurements on a test rig at the Danish Technological Institute.

It was not possible to perform comparative tests in real buildings in China or Denmark. In- stead a series of tests were carried out in two containers in Denmark: one with and one without a SolarVenti system. The tests and the results are described in chapter 4. The comparative tests showed the large drying potential of the SolarVenti system, but cannot directly be transferred to buildings.

Instead of comparative tests in homes in Shanghai a simulation model was developed to represent the building, living and weather conditions in the Shanghai region. Parametric studies with the simulation model described in chapter 5 indicate that applying SolarVenti on homes in Shanghai will have a positive effect on the indoor air quality. The SolarVenti system is capable of both reducing the indoor relative humidity and increase the indoor air temperature. However, how much this will affect mould growth in actual cases is not possible to state. There is a need for comparative tests in real homes in Shanghai. The latter is the next logical step in introducing the SolarVenti system on the building marked in Shanghai.

4 List of contents

1. Introduction ...... 6

2. Temperature and humidity conditions in Chinese homes ...... 10 2.1. Conclusion ...... 14

3. Health problems related to humid homes ...... 15 3.1. Respiratory infections caused by dampness and mould in buildings ...... 15 3.1.1. Tuberculosis ...... 18 3.2. WHO guidelines ...... 18 3.3. Cost of respiratory illness ...... 22 3.4. Conclusions ...... 24

4. Characteristics of the SolarVenti system ...... 25 4.1. SV14 ...... 27 4.2. SV7 ...... 29 4.3. Normalized efficiency and volume flow rate ...... 30 4.3. Drying and heating capability ...... 32 4.4. Collectors for commercial use ...... 32

5. Comparative tests ...... 35 5.1. Conclusions ...... 38

6. Calculation of the heating and drying effect ...... 40 6.3. Discussion ...... 43

7. Conclusions ...... 44

8. References ...... 45

Appendix A Comparative tests in two 20’ containers ...... 48 Appendix B Materials of Building Construction in the Shanghai Area ...... 62 Appendix C Homes and interior in Shanghai ...... 68 Appendix D Information on a Chinese flat used in (Yoshino et al, 2006) ...... 74 Appendix E Description of the applied simulation model and the obtained simulation results ...... 76

5 1. Introduction

High relative humidity in buildings gives often raise to problems both with relation to health and the durability of the constructions of the building and the furniture within the building.

For this reason the Danish solar heating company SolarVenti (www.solarventi.com (English) or www.solarventi.cn (Chinese)) invented an autonomous solar heating system which blows solar preheated air into the building during sunshine. Figure 1.1 shows the principle of the solar heating system.

Figure 1.1 The principle of the SolarVenti collector when mounted on a house and being exposed to the sun.

The SolarVenti concept consists of a solar air collector with a build in pv-panel. The pv-panel is directly connected to the fan of the system. When the SolarVenti collector is hit by the sun the pc-panel produces electricity and the fans starts to draw air through the solar air collector. The air is heated by the sun when it passes the solar air collector. Due to the heating up of the air in the solar air collector the relative humidity of the air decreases. It is thus warm dry air which is blow into the building. Due to the dryness of the incoming air it is capable of evapo- rating humidity from the building constructions and furniture. When the air is exhausted from the building moisture is, therefore, removed from the building.

The efficiency of the system is further increased by two facts:

- ambient air is normally at a lower relative humidity during sunshine - sunshine coming in through the windows of the building helps to increase the temperature within the building and increases thus the removal of moisture from the building

The SolarVenti system is very popular for keeping Danish holidays houses dry during the winter, but are also used for other purposes as shown in figures 1.3-5.

For further information of the function of SolarVenti please see: http://www.solarventi.com/generelt/generelt.htm

Figure 1.2. SolarVenti mounted on a summer cottage in order to keep the cottage dry during the winter.

Figure 1.3. SolarVenti for conditioning of the fresh air to a kindergarten.

Figure 1.4. House where the air from SolarVenti heats and keeps the basement dry.

Figure 1.5 SolarVenti used to condition the fresh air to homes in Hungary.

Based on the response from the customers the concept works perfectly. The bed linen is no longer earthy, the salt is still dry and the smell is no longer moldy when a summer cottage is opened for the season. From Spanish apartments heated by gas burned directly in the rooms (which emits a lot of moisture) it is reported that repainting of the walls can be done less often when SolarVenti is used to heat and dehumidify the apartment.

However, the above statements are subjective impressions of the owners of SolarVenti. Alt- hough very important these statements are not sufficient when approaching larger investors. In this case there is need for a scientifically based evaluation of the performance of SolarVenti in order to get these investors interested in applying the technology.

This is the case when approaching the very large building sector in China. FocusChina has for SolarVenti prepared a marketing plan for the introduction of SolarVenti on the Chinese market (FocusChina, 2010). However, up till now without much success as there is a need for documentation on the performance and benefit of SolarVenti when utilized on Chinese buildings.

This is the reason why SolarVenti contacted the Danish Technological Institut. The Danish Technological Institute applied for funding from Midtnet (under the framework: Central Denmark Region – Shanghai) for documentation of the benefit of applying SolarVenti in homes in especially the Shanghai area.

The efficiency of the SolarVenti concept had earlier been documented in (Furbo and Schultz, 2007), (Fraunhofer, 2011), (Andersen, 2011) and (Lausen, 2011) – see chapter 4. In the first three references the efficiency of SolarVenti has been established as a function of the volume flow rate through the solar air collector. This is important as the efficiency of the collector is dependent on volume flow rate through the collector. However, although (Furbo and Schultz, 2007), (Fraunhofer, 2011) and (Andersen, 2011) realize the importance of measuring the efficiency at different flow rates none of them established a relationship between solar radiation and volume flow rate which is equal important as the fan is directly driven by this pv-panel and the volume flow rate thus changes with the level of solar radiation. This was done in (Jen- sen, 1994) for one of the first versions of SolarVenti – Sommerhuspakken (the summerhouse package), but as the volume flow rate is dependent on the chosen pv-panel, fan and the pres-

8 sure drop across the solar air collector the equation for the volume flow rate dependent on the solar radiation has to be established for each specific system. The efficiency and volume flow rate through two of the SolarVenti’s systems is documented in chapter 4.

There is further a need for investigation of the humidity problems in homes in the Shanghai area, - this is done in chapter 2, and the thereof related health problems. The latter is investigated in chapter 3.

Finally there is a need for documentation on how much SolaVenti is able to improve the quality of the indoor air. The results from comparative test are given in chapter 5 while the results from simulations are discussed in chapter 6.

9 2. Temperature and humidity conditions in Chinese homes

The budget of the project didn’t allow for performing measurements related to humidity problems in Chinese homes. Fortunately evaluation of measurements in this area is available in (Yoshino, H. et al, 2006) and (Zhang H. and Yoshino, H., 2010). The two papers describe the findings from measurements of indoor temperature and relative humidity in homes in the 9 cities shown in figure 2.1. The investigations were carried out as measurements in a limited number of homes in combination with questionnaires combined with liquid crystal thermome- ters in a larger number of homes in each city, - table 2.1 shows the number of houses for measurements and for questionnaire.

Figure 2.1. Cities where the indoor air and relative humidity has been measured in China (Zhang and Yoshino, 2010).

Table 2.1. Details on the measurements performed during the winter (Yoshino, H. et al, 2006).

Figure 2.1 shows that Shanghai, Changsha and Chongqing belongs to an area with similar weather conditions. The following will thus be concentrated on these three cities.

10 Figure 2.2 shows that the relative indoor humidity during the winter was measured to be above 70 % during 100 % of the time in Chongqing, during 70 % of the time in Changsha and during 50 % of the time in Shanghai. Figure 2.3 further show that the temperature in Chong- qing was measured to be below 14°C, between 3 and 20°C in Changsha, - but often below 10°C, and mainly between 10 and 17°C in Shanghai.

Figure 2.2. Cumulative frequency of the indoor relative humidity in houses of 9 Chinese cities (Zhang and Yoshino, 2010).

Figure 2.3. Temperature and humidity conditions in living rooms (between 20:00 and 22:00) (left) and in bedrooms (0:00-6:00) (right) during the winter (Zhang and Yoshino, 2010).

The high relative humidity below 10°C for Chongqing is explained in figure 2.4. In this example the indoor temperature and relative humidity follows nearly exactly the ambient conditions meaning that the heating is not turned on during the measurements and that there was a large air change rate with ambient.

Figure 2.4. The time variation of temperature and humidity in a home in Chongqing (Yoshino, et al, 2006).

Figure 2.5 shows an example of the measurements in a home in Changsha. It is seen that the temperature in the living room is raised during the afternoon and again in the evening. Mean- ing that the heating system is on during these two periods of the day – this is also seen in figure 2.6. The temperature of the bedroom increases a bit during the evening either due to start of a heating system or most probably due to heat from the living room. It is clearly seen how the heating decreases the relative humidity. The heating system was according to (Zhang, 2012) a split air-condition unit which was run in reverse during the winter – ie. as a heating system.

Figure 2.5. The time variation of temperature and humidity in a home in Changsha (Yoshino, et al, 2006).

12 An example for Shanghai is not shown in (Yoshino, et al, 2006), however, figure 2.6 shows that the heating system is mainly on during the early evening (17:00-21:00). Figure 2.7 shows the heating season for the 9 cities.

Figure 2.6. Operation ratio of the heating system during a winter day (Yoshino, et al, 2006).

Figure 2.7. Operation ration of the heating system during the heating season (Yoshino, et al, 2006).

(Zhang and Yoshino, 2010) concludes that: “A high or low humidity environment is related closely to not only many health problems, but also has great influence on the construction durability and energy consumption. It is very important to control humidity level, in order to achieve a healthy and comfortable indoor environment. However, various problems of the air humidity in inhabited dwellings are not yet taken serious consideration in China. Moreover, there is hardly any information available regarding the actual humidity environment in Chi- nese residential houses. For this reason, it is difficult to select appropriate moderate moisture strategies to maintain a harmonious indoor humidity level.

The current state of indoor humidity environment in the houses of 9 Chinese cities indicated that serious problems of high or low (the latter in Urumqi and Beijing with central heating

13 systems (ed.)) humidity generally exist in Chinese residential houses. The severe indoor humidity environment in the residential houses of China should be mitigated and controlled.”

Table 2.1 shows that the above measurements were carried out during 1998-2004. The above situation may have changed during the past 10 years due to the rapid development in China. (Zhu, 2012), however, states that it still is normal in Shanghai to only run the heating system in homes during the evening in order to save electricity to the individual heating system. It is also very common to leave windows open all day.

Table 2.2 shows the monthly sunshine hours for different cities in China compared with Co- penhagen (CPH). Shanghai has three times as many sunshine hours than Copenhagen during November, December, January and February and around twice as many during September, October, March and April. So if SolarVenti is capable of keeping a summer cottage dry during a Danish winter, SolarVenty should also be able to make an impact on the humidity level in homes in the Shanghai region. This is investigated in chapter 6.

Table 2.2. Monthly total number of sunshine hours in Chinese cities compared to Copenha- gen (FocusChina, 2010). * Copenhagen, Denmark.

2.1. Conclusion

The documents (Yoshino, H. et al, 2006) and (Zhang H. and Yoshino, H., 2010) show that there is sever problems with the indoor climate in homes in the Shanghai, Changsha and Chongqing region. High indoor relative humidity combined with low room temperatures has been reported. Conditions that may lead to health problems and problems with the durability of constructions.

The main problem is that the individual heating system is not run continuously during the heating season. The SolarVenti system may here help as it heats and drys out the apartment during the day. Heat will partly be stored in the constructions and furniture until the evening and the constructions and furniture will be dryer and thus be capable to absorbing moisture when the apartment is occupied leading to a lower mean relative humidity. This is further discussed in chapter 6.

14 3. Health problems related to humid homes

It is believe that most people instinctively know that cold damp conditions are bad for the health when exposed to it during long periods. However, (Arundel et al, 1986) states that before 1986: “Water vapor, usually measured as relative humidity or the percentage of water vapor held by the air compared to the saturation level, is not usually considered to be an indoor contaminant or a cause of health problems.”

(Arundel et al, 1986) performs a thorough investigation on all humidity related problems and concludes: “A review of the health effects of relative humidity in indoor environments suggests that relative humidity can affect the incidence of respiratory infections and allergies. Experimental studies on airborne-transmitted infectious bacteria and viruses have shown that the survival or infectivity of these organisms is minimized by exposure to relative humidities between 40 and 70%. Nine epidemiological studies examined the relationship between the number of respiratory infections or absenteeism and the relative humidity of the office, residence, or school. The incidence of absenteeism or respiratory infections was found to be lower among people working or living in environments with mid-range versus low or high relative humidities. The indoor size of allergenic mite and fungal populations is directly dependent upon the relative humidity. Mite populations are minimized when the relative humidity is below 50% and reach a maximum size at 80% relative humidity. Most species of fungi cannot grow unless the relative humidity exceeds 60%. Relative humidity also affects the rate of off- gassing of formaldehyde from indoor building materials, the rate of formation of acids and salts from sulfur and nitrogen dioxide, and the rate of formation of ozone. The influence of relative humidity on the abundance of allergens, pathogens, and noxious chemicals suggests that indoor relative humidity levels should be considered as a factor of indoor air quality. The majority of adverse health effects caused by relative humidity would be minimized by main- taining indoor levels between 40 and 60%. This would require humidification during winter in areas with cold winter climates. Humidification should preferably use evaporative or steam humidifiers, as cool mist humidifiers can disseminate aerosols contaminated with allergens.”

(Arundel et al, 1986) thus concludes that both too dry and too damp conditions are bad for the health and summarize the findings figure 3.1. The shape and height of the bars in the figure are only suggestive of an increase or a decrease in effect and do not represent quantitative data.

Figure 2.1 shows that bacteria, viruses, fungi, mites and chemicals at high humidity levels lead to allergic Rhinitis and Asthma but states that there were insufficient data to conclude about Respiratory infections at high humidity levels.

3.1. Respiratory infections caused by dampness and mould in buildings

Although (Arundel et al, 1986) could not conclude on respiratory infections cause by high humidity levels this has been concluded in many subsequent investigations and meta-analysis. In the following is given quotes from some of these investigations and meta-analysis.

(Fisk, Eliseeva and Mendels, 2010) defines Respiratory infections: “Respiratory (tract) infections are generally considered to include infections of the lower and upper respiratory tract, and otitis media. Lower respiratory tract infections include pneumonia, acute bronchitis, and acute exacerbation of chronic bronchitis. While acute bronchitis is generally caused by an

15 infection, chronic bronchitis is generally non-infectious in origin. Upper respiratory tract infections are acute infections of the nose, sinuses, and throat. Otitis media, an infection or inflammation of the middle ear often resulting from a prior upper respiratory tract infection, can be bacterial or viral in origin.”

Figure 3.1. Health related problems due to relative humidity (Arundel et al, 1986).

(Fisk, Eliseeva and Mendels, 2010) concludes: “Based on a proportion of damp/moldy housing in the population of 20-50%, and selected ORs (odds ratio (ed)) approximate ARPs (at- tributable risk proportion (ed)) would be: for acute bronchitis, 8-18%; for respiratory infections excluding common cold and nonspecific upper respiratory infections, 9-20%; and for respiratory infections in children or infants, 9-19%. Thus, if exposures related to residential dampness or mold directly caused respiratory infections, then preventing or remediating all this dampness and mold would reduce the prevalence of various respiratory infections by approximately 8-20%. Thus, this review provides evidence that preventing or remediating dampness and mold in residences, a very common condition, may substantially reduce the burden of respiratory infections. This could be one of the few available preventive environmental strategies for these common diseases, now considered mostly inevitable. In addition, most exacerbations of asthma have been shown to occur in the presence of viral respiratory infections, and hospitaliza- tions for severe exacerbations of asthma are strongly associated with viral infections. This agrees with the finding that dampness and mold in buildings are associated consistently with asthma exacerbation. Thus, reduction in viral respiratory infections may have important dual benefits. The results of these meta-analyses provide support for recommendations by the Institute of Medicine and WHO (see section 3.2 (ed)) to prevent building dampness and mold problems in

16 buildings, and to take corrective actions where such problems occur. Additional focused re- search is necessary to document whether these associations are causal, and to develop more objective assessment tools for dampness, mold, or various other microbiologic factors that correlate with human health effects.”

(Carter et al, 2003) writes: “Damp housing is usually associated with cold indoor temperatures and the two probably combine to produce ill health. Damp is caused by substandard construction and materials, inadequate heating systems and lack of ventilation. It provides ideal conditions for mould and the optimum relative humidity for growth is usually said to be 70 per cent. However, more important than average room conditions is the microenvironment of the surface on which the mould grows and mould may still be present in homes that have a relatively low humidity. Homes that are inadequately heated and insulated are more likely to have a higher humidity close to cold walls. Dampness also provides conditions favourable to bacteria and viruses. Mould and fungi both produce respiratory allergens that can lead to asthma, rhinitis and alveolitis. …. strong links have been found between damp mouldy housing and respiratory conditions (notably asthma) and skin problems. These links are independent of household income, smok- ing, unemployment and overcrowding. Evidence for health effects of damp and mould is strongest among children. It has been estimated that children living in damp mouldy homes are 1.5 to 3 times more prone to cough and wheeze than children in dry homes. One uncon- trolled study found that central heating reduced the proportion of unheated and damp homes from 92 per cent and 61 per cent to 14 per cent and 21 per cent respectively; respiratory symptoms and time lost from school with asthma were both significantly reduced.”

(Fisk, Lei-Gomez and Mendell, 2007) conclude in a meta-analyses that: ”The association of adverse health effects with dampness and mold in buildings has been the subject of much re- search. Most studies on this topic have found an increased risk of one or more adverse health effects in buildings with signs of dampness or visible mold. The Institute of Medicine (IOM) of the National Academy of Sciences recently completed a critical review (IOM, 2004) of this scientific literature. The IOM concluded that excessive indoor dampness is a public health problem, noted that dampness problems are common, and recommended corrective measures. While the IOM report summarized the main features and results of the reviewed studies, which included a broad range of health outcomes, it provided no quantitative summaries of the findings of these studies. This meta-analysis suggests that building dampness and mold are associated with increases of 30% to 50% in a variety of respiratory and asthma-related health outcomes, and the associations are statistically significant in nearly all cases. These results support a recommenda- tion to prevent building dampness and mold problems in buildings, and to take corrective actions where such problems occur.”

Shelter - the housing and homelessness charity organization states in the report: Chance of a lifetime. The impact of bad housing on children’s lives (Harker, 2006): “Damp and mould impact more strongly on children than adults. Reviews of the evidence in the UK and other countries have concluded that children living in damp, mouldy homes are between one and a half and three times more prone to coughing and wheezing – symptoms of asthma and other respiratory conditions – than children in dry homes. Such symptoms can lead to sleep loss, restrictions on children’s daily activities, and absence from school, all of which have long- term implications for a child’s personal development.”

17 (Kristensen and Larsen, 2007) states: ”Cold humid houses with draft with or without polluted air increase the risk for respiratory diseases and asthma.”

Only one reference concerning Chinese conditions have been found. (Sun et al, 2009) reports on the finding from a study at a University campus: “A cross-sectional study was carried out at Tianjin University campus, China, from February 1 to June 10, 2006, to survey the association between dampness in dorms, and allergy and airways infections among college students. The health and dampness conditions were self-reported by 3436 students living in 1511 dorm rooms located in 13 buildings on the campus. The buildings were selected according to their positions, construction periods and occupant densities. The symptoms involved wheezing, dry cough during night, rhinitis, eczema, cold/flu, ear inflammation, pneumonia and tuberculosis. The indoor moisture signs were mould/damp spots on walls, ceilings and floors; suspected or ever happened water damage; condensation on windowpane in winter and odours perceived by subjects themselves. There was a significant positive association between condensation and dry cough. Eczema was often reported in rooms with moisture problem. Dampness was a significant risk factor for common cold.”

3.1.1. Tuberculosis

Tuberculosis constitutes a special problem in China which also is related to humid and damp homes:

(Shen et al, 2009): “China reported the second-highest number of new TB cases (1.31 million) and the second-highest number of TB deaths (201,000 TB cases) in 2007, behind only India. Shanghai is a metropolitan area located on the east coast of China. Although the noti- fication rate of pulmonary TB in Shanghai (39.4/100 000 in 2000) was lower than the national rate (41.7/100 000 in 2000), mortality among TB patients in Shanghai (2.22/100 000 in 2000) was 56 times higher than the average national mortality rate among TB patients (0.04/100 000 in 2000). Of all of the notifiable communicable diseases in Shanghai, TB ranked first in terms of reported deaths in 2000.”

The homepage (TB Alert, 2012) gives the relationship between Tuberculosis and indoor climate conditions: “It is easier to get TB if you have no heating and live in damp, dark or dusty conditions. TB bacteria can live in damp and dusty air for longer. If it’s dark, TB bacteria don’t get killed by sunlight. TB bacteria hang around in the room if there is no fresh air.”

3.2. WHO guidelines

The seriousness of the problems with damp and mouldy homes is underlined by the fact that WHO has found it necessary to develop guidelines to prevent building dampness and mould problems in buildings.

The following is excerpts from (WHO, 2009):

“Healthy indoor air is recognized as a basic right. People spend a large part of their time each day indoors: in homes, offices, schools, health care facilities, or other private or public buildings. The quality of the air they breathe in those buildings is an important determinant of

18 their health and well-being. The inadequate control of indoor air quality therefore creates a considerable health burden.

Indoor air pollution – such as from dampness and mould, chemicals and other biological agents – is a major cause of morbidity and mortality worldwide.

Problems of indoor air quality are recognized as important risk factors for human health in both low-income and middle- and high-income countries. Indoor air is also important because populations spend a substantial fraction of time within buildings. In residences, day- care centers, retirement homes and other special environments, indoor air pollution affects population groups that are particularly vulnerable due to their health status or age. Microbi- al pollution involves hundreds of species of bacteria and fungi that grow indoors when sufficient moisture is available. Exposure to microbial contaminants is clinically associated with respiratory symptoms, allergies, asthma and immunological reactions.

The presence of many biological agents in the indoor environment is due to dampness and inadequate ventilation. Excess moisture on almost all indoor materials leads to growth of microbes, such as mould, fungi and bacteria, which subsequently emit spores, cells, fragments and volatile organic compounds into indoor air. Moreover, dampness initiates chemical or biological degradation of materials, which also pollutes indoor air. Dampness has therefore been suggested to be a strong, consistent indicator of risk of asthma and respiratory symptoms (e.g. cough and wheeze). The health risks of biological contaminants of indoor air could thus be addressed by considering dampness as the risk indicator.

The following is a summary of the conclusions on the work behind the WHO guidelines:

Sufficient epidemiological evidence is available from studies conducted in different countries and under different climatic conditions to show that the occupants of damp or mouldy buildings, both houses and public buildings, are at increased risk of respiratory symptoms, respiratory infections and exacerbation of asthma. Some evidence suggests increased risks of allergic rhinitis and asthma. Although few intervention studies were available, their results show that remediation of dampness can reduce adverse health outcomes. There is clinical evidence that exposure to mould and other dampness-related microbial agents increases the risks of rare conditions, such as hypersensitivity pneumonit- is, allergic alveolitis, chronic rhinosinusitis and allergic fungal sinusitis. Toxicological evidence obtained in vivo and in vitro supports these findings, showing the occurrence of diverse inflammatory and toxic responses after exposure to microorganisms isolated from damp buildings, including their spores, metabolites and com- ponents. While groups such as atopic and allergic people are particularly susceptible to biological and chemical agents in damp indoor environments, adverse health effects have also been found in nonatopic populations. The increasing prevalences of asthma and allergies in many countries increase the number of people susceptible to the effects of dampness and mould in buildings.

The conditions that contribute to the health risk were summarized as follows.

The prevalence of indoor dampness varies widely within and among countries, conti- nents and climate zones. It is estimated to affect 10–50% of indoor environments in

19 Europe, North America, Australia, India and Japan. In certain settings, such as river valleys and coastal areas, the conditions of dampness are substantially more severe than the national averages for such conditions. The amount of water on or in materials is the most important trigger of the growth of microorganisms, including fungi, actinomycetes and other bacteria. Microorganisms are ubiquitous. Microbes propagate rapidly wherever water is available. The dust and dirt normally present in most indoor spaces provide sufficient nu- trients to support extensive microbial growth. While mould can grow on all materials, selection of appropriate materials can prevent dirt accumulation, moisture penetration and mould growth. Microbial growth may result in greater numbers of spores, cell fragments, allergens, mycotoxins, endotoxins, β-glucans and volatile organic compounds in indoor air. The causative agents of adverse health effects have not been identified conclusively, but an excess level of any of these agents in the indoor environment is a potential health hazard. Microbial interactions and moisture-related physical and chemical emissions from building materials may also play a role in dampness-related health effects. Building standards and regulations with regard to comfort and health do not sufficiently emphasize requirements for preventing and controlling excess moisture and dampness. Apart from its entry during occasional events (such as water leaks, heavy rain and flooding), most moisture enters a building in incoming air, including that infiltrating through the building envelope or that resulting from the occupants’ activities. Allowing surfaces to become cooler than the surrounding air may result in unwanted condensation. Thermal bridges (such as metal window frames), inadequate insulation and unplanned air pathways, or cold water plumbing and cool parts of air- conditioning units can result in surface temperatures below the dew point of the air and in dampness.

On the basis of this review, the following guidelines were formulated.

Persistent dampness and microbial growth on interior surfaces and in building structures should be avoided or minimized, as they may lead to adverse health effects. Indicators of dampness and microbial growth include the presence of condensation on surfaces or in structures, visible mould, perceived mouldy odour and a history of water damage, leakage or penetration. Thorough inspection and, if necessary, appropriate measurements can be used to confirm indoor moisture and microbial growth. As the relations between dampness, microbial exposure and health effects cannot be quantified precisely, no quantitative health-based guideline values or thresholds can be recommended for acceptable levels of contamination with microorganisms. In- stead, it is recommended that dampness and mould-related problems be prevented. When they occur, they should be remediated because they increase the risk of hazard- ous exposure to microbes and chemicals. Well-designed, well-constructed, well-maintained building envelopes are critical to the prevention and control of excess moisture and microbial growth, as they prevent thermal bridges and the entry of liquid or vapour-phase water. Management of moisture requires proper control of temperatures and ventilation to avoid excess humidity, condensation on surfaces and excess moisture in materials. Ventilation should be dis- tributed effectively throughout spaces, and stagnant air zones should be avoided.

20 Building owners are responsible for providing a healthy workplace or living environment free of excess moisture and mould, by ensuring proper building construction and maintenance. The occupants are responsible for managing the use of water, heating, ventilation and appliances in a manner that does not lead to dampness and mould growth. Local recommendations for different climatic regions should be updated to control dampness-mediated microbial growth in buildings and to ensure desirable indoor air quality. Dampness and mould may be particularly prevalent in poorly maintained housing for low-income people. Remediation of the conditions that lead to adverse exposure should be given priority to prevent an additional contribution to poor health in populations who are already living with an increased burden of disease.

The guidelines are intended for worldwide use, to protect public health under various environmental, social and economic conditions, and to support the achievement of optimal indoor air quality. They focus on building characteristics that prevent the occurrence of adverse health effects associated with dampness or mould. The guidelines pertain to various levels of economic development and different climates, cover all relevant population groups and pro- pose feasible approaches for reducing health risks due to dampness and microbial contamination. Both private and public buildings (e.g. offices and nursing homes) are covered, as dampness and mould are risks everywhere. Settings in which there are particular production processes and hospitals with high-risk patients or sources of exposure to pathogens are not, however, considered.

Building dampness and its effect on indoor exposure to biological and non-biological pollu- tants (WHO, 2009)

A review of studies in several European countries, Canada and the United States in 2004 indicated that at least 20,% of buildings had one or more signs of dampness. This estimate agrees with those of a study of 16 190 people in Denmark, Estonia, Iceland, Norway and Sweden, which gave an overall prevalence of indoor dampness of 18%, with the lowest prevalence in Göteborg, Sweden (12.1%), and the highest in Tartu, Estonia (31.6%). Dampness was defined on the basis of self-reported indicators, such as water leakage or damage, bub- bles or discoloration of floor coverings, and visible mould growth indoors on walls, floors or ceilings. From several studies conducted in the United States it was estimated the prevalence of dampness or mould in houses to be approximately 50%.

Although few data are available for low-income countries, several studies suggest that indoor dampness is also common in other areas of the world. For example, a study of 4164 children in rural Taiwan, China, showed that 12.2% of the parents or guardians considered their dwelling to be damp, 30.1% reported the presence of visible mould inside the house in the past year, 43.4% reported the appearance of standing water, water damage or leaks, and 60% reported at least one of these occurrences. In a study in Singapore of 4759 children, the prevalence of dampness in the child’s bedroom was 5% and that of mould was 3%; the overall prevalence of mould and damp in the rest of the house was not given. About 11% of parents of 10 902 schoolchildren in a study in three cities in China (Beijing, Guangzhou and Hong Kong Special Administrative Region) reported mould on the ceilings and walls. In a study in Japan of the residents of 98 houses built within the past 4 years, condensation on window panes or walls was reported by the residents in 41.7% of all houses, and 15.6% had visible mould. Indoor damp was reported by 13% of 3368 adults living in Nikel in the Arctic area of the northern Russian Federation. A case-control study of asthma in the West Bank

21 and Gaza Strip, involving participants in villages, cities and refugee camps, showed that 62 of 110 dwellings (56%) had visible mould on the walls and ceilings. The prevalence of houses characterized as damp with visible mould was highest in the refugee camps, with an estimated 75% of houses affected. Another study in the West Bank in 188 randomly selected houses in the Al-Ama’ri refugee camp south of Ramallah City showed that 78.2% of the houses had damp problems, leaks or indoor mould.

As dampness is more likely to occur in houses that are overcrowded and lack appropriate heating, ventilation and insulation, the prevalence of indoor damp in low-income communities can be substantially higher than the national average. For example, in a study of 1954 young mothers in the United Kingdom, those who lived in owner-occupied or mortgaged accommodations (relatively affluent) reported damp (52%) and mould (24%) significantly less often than those who lived in council houses or rented accommodations (relatively deprived), 58% of whom reported damp and 56% of whom reported mould. Similarly, a study of 25 864 schoolchildren in eastern Germany showed that the children of parents with a low education- al level were 4.8 times more likely (95% confidence interval (CI), 3.4–5.4) to live in damp houses than those of parents with a high level of education. Children whose parents had re- ceived education at the intermediate level were 1.8 times as likely to live in a damp house (95% CI, 1.6–2.1).

Indoor damp is likely to remain an important issue in less affluent countries and neighbourhoods, particularly since an increasing shortage of affordable housing provides little incen- tive for landlords to improve rental accommodation. Similarly, the substantial costs involved in remediation may dissuade low-income home owners from improving substandard housing conditions. This will add to the already high burden of poor health in those communities.

The exact prevalence of home dampness cannot be established in the absence of a gold standard, but occupants’ and inspectors’ reports indicate that it is likely to be in the order of 10– 50% in the most affluent countries. Although the evidence is more limited for less affluent countries, the magnitude of the problem appears to be similar, the prevalence sometimes even exceeding 50% (e.g. in refugee camps in the West Bank and Gaza Strip, see above). As problems of damp are commonest in deprived neighbourhoods, a substantial proportion of that population is at risk of adverse health effects associated with damp indoor environments.”

3.3. Cost of respiratory illness

It is very difficult to determine the cost of the effect of cold and/or humid houses for the individual person and the society. This is a multi-million $ project with a duration of many years. Several institutions in China was contacted in order to verify if such an investigation had been carried out in China and also the International Centre for Indoor Environment and Energy at the Technological University of Denmark was contacted. There was no knowledge of such an investigation so it was concluded that it was not possible to obtain such data for Chinese conditions.

However, a study based on earlier studies has been carried out in USA (Fisk, 2000). The conclusion of this survey is given in the following.

22 “Population affected and Cost of Communicable Respiratory Illness Virtually everyone is affected by communicable respiratory illnesses. Averaging data from 1992 through 1994, the civilian non-institutional population experienced 43.3 common colds and 25.7 cases of influenza per 100 population, for a total of 0.69 illnesses per person per year.

The obvious costs of respiratory illness include health care expenses and the costs of absence from work. Additionally, respiratory illnesses may cause a performance decrement at work. Controlled experiments have shown that viral respiratory illnesses, even sub-clinical infections, can adversely affect performance on several computerized and paper-based tests that simulate work activities. The decrement in performance can start before the onset of symptoms and persist after symptoms are no longer evident.

Estimates of the productivity losses associated with respiratory illness are based on periods of absence from work and restricted activity days as defined in the National Health Interview Survey (U.S. Department of Health and Human Services, 1994). In the U.S., four common respiratory illnesses (common cold, influenza, pneumonia, and bronchitis) cause about 176 million days lost from work and an additional 121 million work days of substantially restricted activity. Assuming a 100% and 25% decrease in productivity on lost-work and restricted activity days, respectively, and a $39,200 average annual compensation, the annual value of lost work is approximately $34 billion. The annual health care costs for upper and lower respiratory tract infections total about $36 billion. Thus, the total annual cost of respiratory infections is approximately $70 billion. Neglected costs include the economic value of reduced housework and of absence from school.

Without being able to substantially change the building-related factors that influence disease transmission, we cannot realize these health care cost savings and productivity gains. A number of existing, relatively practical building technologies, such as increased ventilation, reduced air recirculation, improved filtration, ultraviolet disinfection of air, and reduced space sharing (e.g., shared office), and reduced occupant density have the theoretical potential of reducing inhalation exposures to infectious aerosols by more than a factor of two.

Investigations suggest that changes in building characteristics and ventilation could reduce indexes of respiratory illness by 15% (absence from school) to 76% (influenza in nursing homes), with the strongest study suggesting that a 33% reduction is possible. The amount of time spent in a building should influence the probability of disease transmission within the building. If efforts to reduce disease transmission were implemented primarily in commercial and institutional buildings that people occupy approximately 25% of the time, smaller reduc- tions in respiratory illness would be expected in the general population than indicated by the building-specific studies. To adjust the reported decreases in respiratory illness for time spent in buildings, we estimated the percentage of time that occupants spend in each type of building (100% of time in jails and nursing home, 66% in barracks and housing, and 25% in offices and schools) and assumed that the magnitude of the influence of a building factor on the incidence of respiratory illness varies linearly with time spent in the building. After this ad- justment the nine (applied (ed)) studies estimates of potential decreases in metrics for respiratory illness (some studies had multiple outcomes such as influenza and total respiratory infections), ranging from 9% to 41% with an average of 19%. Considering only the studies with explicit respiratory illness outcomes (i.e., excluding the study with an absence outcome) results in nine estimates of decreases in respiratory illness, adjusted for time in building, ranging from 9% to 41% with an average of 18%. The range is 9% to 20%, if the outlier value of

23 41% (illness in schools) is excluded. This narrower range is adopted, i.e., 9% to 20%, for the potential reduction in respiratory illness. With this estimate and 0.69 cases of common colds and influenza per person per year), approximately, 16 to 37 million cases of common cold or influenza would be avoided each year in the US. The corresponding range in the annual economic benefit is $6 billion to $14 billion.”

When only improving the indoor air quality in homes these savings will be less than the above stated $6 billion to $14 billion, however, still a potentially large saving.

The conditions in China and more specific in the Shanghai area are of course very much different from the conditions in USA. However, the above study indicates that there also could be large potential savings in China if the indoor air quality was improved in Chinese buildings.

3.4. Conclusions

In the above WHO guideline it is stated that: “… the relation between dampness, microbial exposure and health effects cannot be quantified precisely, …”. However, several studies try to quantify the problem: “…suggests that building dampness and mold are associated with increases of 30% to 50% in a variety of respiratory and asthma-related health outcomes, and the associations are statistically significant in nearly all cases.” and “…preventing or remediating all this dampness and mold would reduce the prevalence of various respiratory infections by approximately 8-20%.”

The magnitude of the problem is further underlined by the fact that WHO finds it necessary to develop guidelines to prevent building dampness and mould problems in buildings.

There is not much documentation on Chinese humidity problems in buildings but they are believed to be at least in the same order of magnitude as documented in studies and meta- analyses for other countries. This assumption is supported by the investigations summarized in chapter 2.

No socio-economic studies of the cost related to humidity related health problems in Chinese have been carried out. However, an investigation for USA indicates that the cost of humidity related health problems is very high. This is believed also to be true for China. Especially because damp conditions ease the spread of tuberculosis which is a very big problem in China having the second-highest number of TB death in the world.

Two of the recommendations given by the WHO guideline in order to decrease the humidity related health problems in buildings are: heating and ventilation. The SolarVenti concept is capable of doing both and may therefore be utilized as one of the means for obtaining less humid conditions in buildings.

24 4. Characteristics of the SolarVenti system

Figure 1.1 shows the principle of the SolarVenti concept. The concept is produced in five different sizes. The most important information on the five sizes is listed in table 4.1, while figures 4.1 shows examples of the five types mounted on buildings. For more information please see http://www.solarventi.com/produkter/modeller.htm.

Type Parameters SV2 SV3 SV7 SV14 SV30 Dimensions * External 524 x 704 x 1004 x 1974 x 3000 x height x width 524 x 524 x 704 x 704 x 1020 x x depth [mm] 55 55 55 55 75 Transparent 0.24 0.33 0.64 1.26 2.9 area [m²] Weight [kg] 4.9 5.5 9.5 14 29.1 Pv-panel Voltage [V] 12 12 12 12 12 Power [W] 1.9 6 12 12 18 Fan: Nominal 70 70 170 170 230 volume flow [m³/h] rate ** Typical [m³/h] 15-40 20-45 40-90 60-140 90-200 Recommended [m²] <15 <20 <40 <70 <140 room size ***

Table 4.1. The sizes of the different SolarVenti systems * the SolarVenti can be rotated so that one site both can be the width or the height ** the nominal volume flow rate is the free exhaust from the fan while the typical volume flow rate is when exposed to the pressure drop across the solar air collector *** the recommended room size is the floor area of the building which the So- larVenti system typically can keep dry during a Danish winter

The performance specifications given in table 4.1: Typical volume flow rate and Recom- mended room size is rules of thump based experience but does not really characterize the performance of the SolarVenti concept.

The way to characterize this type of solar heating system is by the:

- efficiency as a function of the volume flow rate through the solar air collector - the volume flow rate as a function of solar radiation hitting the solar air collector (Jensen, 1994).

The efficiency of SV14 has been measured as a function of the volume flow rate in (Fraunho- fer, 2011) and (Andersen, 2011), while the efficiency of SV7 has been measured at one flow rate in (Lausen, 2011). None of these documents deal with the solar radiation dependency of the volume flow rate, which is equally important to know as the volume flow rate dependent efficiency.

The reason for not dealing with the volume flow rate dependent on the solar radiation is that Fraunhofer ISE is interested in solar air collectors where the air is recirculated or the flow rate

25 is not dependent on the solar radiation. Fraunhofer is in charge of preparing an EN norm in this area (EN 12975). (Andersen, 2011) used SV14 as an test case for an external test rig which in capable of measuring the efficiency of solar air collectors with non-fluctuating volume flow rates. (Lausen, 2011) is a comparative test between SV7 and two other similar con- cepts from Dansolar and Scanheat.

SV2 SV3

SV7 SV14

SV30

Figure 4.1. Examples of the five types of SolarVenti mounted on buildings.

The present project ran simultaneously with a DANETV (http://www.etv-denmark.com/) project with the aim of Verification of Climate and Environmental Technologies. One of the

26 product types chosen for the development of a verification methodology was autonomous solar heating systems for drying/heating of buildings.

As the ETV verification methodology for autonomous solar heating systems also is developed at the Danish Technological Institute the ETV project was influenced by the present project to also measure the dependency of the volume flow rate on the solar radiation. Further will the simulation program described in chapter 6 be used to determine the drying and heating capacity in the ETV verification methodology. The ETV verification methodology is documented in (Jacobsen, 2012).

There is a growing marked for this type of solar heating system in Denmark and (Lausen, 2011) showed that there is large differences in the performance of these system. In order to be able to advise buyers of these systems the Danish Energy Agency asked the Danish Techno- logical Institute to perform comparative tests based on the ETV verification methodology.

Figure 4.2 show the SolarVenti SV14 and SV7 mounted at the test rig with space for seven systems.

Figure 4.2. The test rig for comparative test of up to seven systems at the Danish Techno- logical Institute. SV14 is the system is situated second from the right while SV7 is the system to the far left.

4.1. SV14

Figure 4.3 shows the efficiency for SolarVenti SV14 when using the ETV verification method compared with the efficiencies reported in (Fraunhofer, 2011) and (Andersen, 2011). It is seen that the ETV method gives almost exactly same results as (Fraunhofer, 2011) and (Andersen, 2011) which leads to the conclusion that the ETV verification methodology in this point is correct and further gives same results as the coming EN 12975 standard.

27 The efficiency based on the ETV method is in figure 4.3 only shown for volume flow rates between 60 and 125 m³/h as this was the flow rates measured at the test rig. Figure 4.4 show the volume flow rate of the SV14 as a function of the solar radiation hitting the solar air collector. At a flow rate around 300 m³/h there are both a blue and a red curve. This is due to the controller of the system; - the SV7 (see next section) was tested without the controller. The SV7 system started and stopped at a radiation level of 50 W/m² - see figure 4.6. The fan of the SV14 was allowed to start at a radiation level of 335 W/m² but stopped at a radiation level of 275 W/m².

Efficiency for SV14 0.8

0.7

0.6

0.5

0.4 (ETV, 2012) efficiency 0.3 (Fraunhofer, 2011) 0.2 (Andersen, 2011)

0.1

0 0 25 50 75 100 125 150 175 flow rate [m3/h]

Figure 4.3. The efficiency of SolarVenti SV14 compared with results reported in (Fraunho- fer, 2011) and (Andersen, 2011).

Flow rate through SV14 140

120

100

60 stop

flow rate[m3/h] 40 start

0 0 100 200 300 400 500 600 700 800 solar radiation [W/m2]

Figure 4.4. The volume flow rate through SolarVenti SV14 as a function of the solar radiation hitting the solar air collector.

28 The curves shown in figures 4.3-4 are regression lines based on measurements from one day with clear sky conditions.

The equations for the efficiency and volume flow rate found by the ETV method are:

efficiency = (-1.39744 + 0.776484·V + 6.64296·10-5V2 – 1.48815·10-5V3)/100 (4.1) where V is the volume flow rate [m³/h]:

volume flow rate = -115.21 + 0.947747·E – 1.34077·10-3E2 + 6.76175·10-7E3 (4.2) where E is the solar radiation [W/m²]. The fan starts at 335 [W/m²] and stops at 275 [W/m²]. The volume flow rate is constant 127 m³/h at solar radiation levels above 750 W/m².

4.2. SV7

Figure 4.5 and 4.6 shows the efficiency and the volume flow rate for SolarVenti SV7 when using the ETV verification method. The curves in figures 4.5-6 have a quite different shape than expected. It was expected that the curves would be similar to the curves shown for SV14 in figures 4.3-4. The reason for this is that may be that the curves in figures 4.5-6 still are preliminary and/or that the measurements was obtains for a lower max irradiation level as seen when comparing figure 4.6 with 4.4.

Efficiency for SV7 0.8

0.7

0.6

0.5

0.4 efficiency 0.3

0.2

0.1

0 0 25 50 75 100 125 150 175 flow rate [m3/h]

Figure 4.5. The efficiency of SolarVenti SV7.

29 Flow rate through SV7 140

120

100

60 flow flow rate [m3/h]

0 0 100 200 300 400 500 600 700 800 solar radiation [W/m2]

Figure 4.6. The volume flow rate through SolarVenti SV7 as a function of the solar radiation hitting the solar air collector.

The curves shown in figures 4.5-6 are regression lines based on measurements from one day with clear sky conditions.

The equations for the efficiency and volume flow rate found by the ETV method are:

efficiency = (3.96396·V – 0.141509·V2 + 2.5615·10-3V3 - 2.1966·10-5V4 + 7.3·10-7V5)/100 (4.3) where V is the volume flow rate [m³/h]:

volume flow rate = 9.22 + 0.1417·E (4.4) where E is the solar radiation [W/m²].

Care should be taken if using equation for extrapolating the efficiency above a volume flow rate of 90 m³/h and a volume flow rate above a solar radiation level of 600 W/m². This is discussed further in the following section 4.3.

4.3. Normalized efficiency and volume flow rate

Equation 4.1 cannot directly be compared with equation 4.3 and the same goes for equation 4.2 and 4.4 due to the different transparent areas – see table 4.1. However, the efficiencies and volume flow rates for the two systems can be compared, if figures 4.3-6 are normalized based on volume flow rate per m² collector area. This is done in figures 4.7-8.

30 Efficiency for SV7 and SV14 0.8

0.7

0.6

0.5

0.4

efficiency 0.3 SV7 0.2 SV12 (Lausen, 2011) 0.1

0 0 50 100 150 flow rate [m3/h/m2]

Figure 4.7. The efficiency of SolarVenti SV7, SV14 and SV7 as measured by (Lausen, 2011) as a function of the normalized volume flow rate.

Flow rate through SV7 and SV14 160

140

120

100

SV7 flow rate [m3/h/m2] rate flow 40 SV14 (Lausen, 2011) 20

0 0 100 200 300 400 500 600 700 800 solar radiation [W7m2]

Figure 4.8. The normalized volume flow rate of SolarVenti SV7, SV14 and SV7 as measured by (Lausen, 2011) as a function of the solar radiation.

Figure 4.7 shows a good agreement with equation 4.1 for SV14 and the findings in (Lausen, 2011). This was expected because the technology of SV7 and SV14 is identical the only difference being the size of the collector. However, the curve for SV7 shows a strange pattern

31 for flow rates between 50-140 m³/h/m². It is therefore believed that equation 4.3 needs further investigation and should not for the time being be applied.

Figure 4.8 also shows good agreement between SV14 and the findings in (Lausen, 2011). The large difference to the SV7 curve may be be explained by the fact that the solar cell panel of the SV7 tested in this project was different from the SV7 investigated in (Lausen, 2011). The pv-panel in (Lausen, 2011) and SV14 was based on thin film cells while the pv-panel in the here investigated SV7 was based on crystalline solar cells which normally are more efficient than thin film. And the SV7 in section 4.2 was tested without the controller which limit the power to the fan. So equation 4.4 may be correct, however, it should be used with care at solar radiation levels above 600 W/m², and only for application without controller.

4.4. Drying and heating capability

Based on equation 4.1-2 it is possible to calculate the annual drying and heating capability of the SolarVenti system as long as the ambient temperature, ambient relative humidity and the solar radiation (either as global and diffuse horizontal radiation or as direct and diffuse horizontal radiation) is known at hourly time steps.

Hour by hour the following calculations can be made:

based on the solar radiation -> the volume flow rate through the solar air collector based on the volume flow rate -> the efficiency of the solar air collector based on the efficiency and the solar radiation -> the heating power out of the solar air collector based on the heating power and the volume flow rate -> the temperature rise over the solar air collector based on the temperature rise over the solar air collector and the ambient temperature -> the outlet temperature of the solar air collector based on the outlet temperature of the collector, the ambient temperature and the ambient relative humidity -> the relative humidity of the outlet air

If the above calculations are combined with a model of a house it is possible to simulate how a SolarVenti system may increase the room temperature and decrease the relative humidity in the house as a function of time over the year. This is done in chapter 6.

4.5. Collectors for industrial use

The SolarVenti systems shown in the start of the present chapter are mainly for smaller buildings like homes and summerhouses. They are less applicable for large buildings like office buildings, factories, hospitals, etc. with a mechanical ventilation system.

For these buildings SolarVenti have developed a modulated solar collector (SV Industrial) which can be connected in order to create large collector areas as shown in figures 4.9-11.

Figure 4.9. Photos of the SV Industrial collector for larger buildings

Figure 4.10. Large collector area (93.5 m²) consisting of 50 connected SV Industrial collectors.

The dimensions of each module are:

External dimensions (l x h x d): 1975 x 1004 x 450 mm Transparent area: 1.87 m² Weight: 7 kg

The collector is expected soon to be tested at ISE Fraunhofer like the SV14 (Fraunhofer, 2011) has been, however, preliminary measurements indicate that the efficiency will be in the same order of magnitude as the SV14 collector.

The drying and heating capacity of this system will not be estimated in this report as a certi- fied efficiency equation not yet is available. Further, - the calculations carried out in chapter 6 on the drying and heating capacity of SV14 is not applicable for SV Industrial as this collector typically will be applied on different buildings than SV14 meaning that the conditions are different which is likely to influence the resulting heating up and drying out of the considered building.

Figure 4.11. The principle of SV Industrial.

34 5. Comparative tests

It was the intention to perform comparative test in a number of houses in Denmark and/or China where measurements in the houses with and without the SolarVenti system could be compared. However, the problem with performing comparative tests is that the houses and the use of them need to be identical or that the measurements needs to be carried out in a very large numbers of houses in order for the observed difference between houses with and without SolarVenti to be statistically significant. Investigations showed that this would not be possible in Denmark or in China.

Instead it was decided to perform comparative tests in two identical 20’ standard containers located at the manufacture SolarVenti – see figure 5.1.

The tests and the results of the tests are described in details in appendix A. One of the two containers was equipped with a SolarVenti system SV2 or SV7 – se figure 5.1 and figures 4 in appendix A - with a transparent collector area of respectively 0.24 and 0.64 m². The other container remained without modifications and acted as control container.

The dimensions of the containers were:

External: length x height x depth: 6058 x 2581 x 2438 mm Internal: length x height x depth: 5898 x 2393 x 2352 mm

This means that the internal volume due to the corrugated walls will be between 33 and 38 m³.

The containers were new with intact rubber sealing on the doors. The containers were equipped with ventilation holes at four locations. At each location there were a series of 9 holes each of a diameter of 9.5 mm. The location and ventilation holes are shown in figure 5.2. The 9 mm holes of each ventilation arrangement have a total opening area of 0.00064 m².

The air tightness was tested during a day with solar radiation around 710 W/m². The air speed into the container with SV7 was measured with open doors of the container, with closed doors and with closed doors and the ventilation holes closed with tape. The result was:

Open doors: 2.4-2.5 m/s Closed doors: 1-1.2 m/s and Closed doors and taped ventilation holes: 0 m/s

The experiment showed that the doors of the containers were well sealed and that there was a considerable pressure loss over the ventilation holes. The total area of the ventilation holes is only one fifth of the area of the outlet duct of the SV7.

The four series of ventilation holes will under Danish weather conditions (calulated based on (Stampe, 1982) and (Aggerholm and Grau, 2008)) lead to a mean air change rate in the order of 0.09 h-1. The above measured air speed of in mean 1.1 m/s with closed doors and open ventilation holes leads with a diameter of the duct of 0.125 m to a volume flow rate of in the order of 45 m³/h. This means that the SV container will have an air change rate of 1.3 h-1 or about 14 times higher than in the control container at clear sky conditions. The system was as in section 4.2 without controller, and as the 2,4-2,5 m/s equals the measured value in equation 4.2 at a solar radiation level at 710 W/m², equation 4.4 will be used in the following.

Figure 5.1. The comparative tests were performed in 20’ containers.

top corner

ventilation holes

SolarVenti the SV container seen from the top south

Figure 5.2. The ventilations holes of the container

37 If using the global solar radiation (on horizontal) shown in figure 14 in Appendix A and the volume flow rate equation from section 4.2 (equation 4.4), the mean air change rate of the SV container can be estimated. However, the SV7 was not horizontal but tilted in order to be per- pendicular to the sun at noon. For this reason the global solar radiation is enhanced by 27%. Based on this the air change rate of the SV container would have been around 0.57 h-1 (for the period shown in figure 14 Appendix A) or six times higher than in the control container.

The tests in appendix A show that the temperature insides the two containers were almost identical. This is because the containers are un-insulated: the U-value of the walls, floor and ceiling is thus high (= high heat transfer to ambient) and the walls and ceiling acts as simple solar collectors. Although the efficiency of the walls and ceiling as solar collectors is much lower than the efficiency of the SolarVenti collector the much larger area of the south wall and ceiling – 15.7 and 14.8 m² respectively – compared to the 0.64 m² of the SV7 collector makes the heat input to the containers from the walls and ceiling during sunshine much larger than from the SV7.

The two first tests in the containers were carried out with 15 dry pallets in each container. In the first of these two tests the performance of SV2 and SV4 was compared. The volume flow rate of SV2 is in the order of half the volume flow rate of SV7. SV2 decreased the relative humidity of the SV container to about 2 percent point lower than in the control container. SV7 increased this difference to around 5 percent point.

In the second test the SV7 manage to increase the difference between the two containers to nearly 15 percent point where it remained stable. It is assumed that the pallets at the end of the test couldn’t get any dryer.

A stress test with excess water in the containers was then carried out where a bucket with water and thin sheets of wet cardboard were located in the containers. The result of this test was also a difference of around 15 percent point at the end of the test. But while the relative humidity in the SV container decreased over the period there were a slight increase in the relative humidity in the control container. The water in the bucket was decreased in both containers: 5 liters in the control container and 9.5 liters in the SV container. As the evaporation in the control container occurred even with the very low air change rate is anticipated that this is partly due to the slight increase in relative humidity of the air in the container and partly an increase in the humidity of the pallets (this was not measured). However, twice as much water from the bucket was evaporated in the SV container compared to the control container. Fur- thermore, - when opening the containers there was a strong moldy smell in the control container, which was not detected in the SV container.

I addition to the above: the volume flow rate created by SV7 was only half the possible flow rate due to the too small ventilation holes in the SV container. In case of sufficiently large ventilation holes the difference in evaporated water in the stress test would have be considerably larger than the measured 4.5 liters. I.e. the SV7 didn’t show its real potential in the performed comparative tests.

5.1. Conclusion

The comparative tests in two standard containers show that SolarVenti has a drying effect. However, as the air temperature remained almost identical during all tests the drying effect in

38 the comparative tests are mostly based on the increase of the air change rate in the SV container. This is because the un-insulated walls and ceiling acts as solar collectors with a much higher heat input to the container than the applied SV2 and SV7. If the containers had been insulated both the temperature raise and the volume flow rate of the SolarVenti collectors would have contributed to the drying effect but the drying out would have been slower due to the lesser heat input.

The result from the comparative tests in containers cannot directly be transferred to buildings. However, some very important findings also relate to buildings:

- if a building already have a large heat input from windows facing the sun the drying effect of a SolarVenti system mostly rely on the increase in air change rate created by the SolarVenti system; - heat input from other sources when the fan of the SolarVenti system runs enhances the drying effect; - but the SolarVenti system needs to create a considerably larger air change rate than already present in the building in order to have a noticeable drying effect.

It is not possible based on the above comparative tests to determine the drying and heating effect in Chinese homes. This will be investigated using simulations in the following chapter.

39 6. Calculation of the heating and drying effect

It is as shown in section 4.4 rather simple to calculate the temperature and relative humidity of the air from the SolarVenti systems if the equations for the efficiency and volume flow rate are available. But it is a non-trivial task to determine how the air from a SolarVenti system will affect the indoor air in a building. This is very much dependent on the type of constructions of the building, the type of furniture, the area, orientation and type of windows, the air change rate not created by the SolarVenti system, the heating pattern in the building, humidity producing processes in the building (people, cooking, bathing, plants, etc.) and the actual weather conditions.

In order to be able to determine the heating and drying capability of a SolarVenti system there is a need for not only a model of the SolarVenti system but also a model of the house including equations for the energy and moisture flows in the building. Such a model was developed in (Furbo and Schultz, 2007) – see figure 6.1.

Figure 6.1. The energy and moisture flows in the model of (Furbo and Schultz, 2007).

The model was in (Furbo and Schultz, 2007) tested on a 75 m² Danish summerhouse under Danish weather conditions. The SolarVenti system applied was the SV30 hybrid liquid and solar air collector (http://www.solarventi.com/produkter/sider/sv30_H_side.htm). The efficiency as solar air collector is far lower than for the pure solar air collectors. And in (Furbo and Schultz, 2007) a linear dependency of the volume flow rate on the solar radiation was assumed. The results from (Furbo and Schultz, 2007) can thus not be used here but the model will in the following be modified to represent the weather conditions, building tradition and user pattern of the Shanghai region.

The model in (Furbo and Schultz, 2007) was developed to investigate the moisture conditions during the winter in unoccupied summer houses. The model included, therefore, not moisture production and heating in the building. As the present report deals with occupied homes the

40 model in (Furbo and Schultz, 2007) has been enhanced to also include moisture production and heating.

The developed model is described in details in Appendix E. Here are parametric studies with the model also carried out with from 0 to 10 SV14 applied on an 87 m² apartment located in the Shanghai region. The apartment was assumed to be inhabited with four people resulting in a moisture production in the apartment of 8.5 kg/day. Two different air change rates of the apartment (when the SV14s were not running) were investigated: 0.5 h-1 as considered in Denmark as a normal air change rate and 1.0 h-1 as stated in the Chinese Building Regulation. The apartment was heated according to the findings in figures 2.2-3 and 2.6-7, - i.e. heating in the period November to March (both months included) and only during the evening (18:00- 22:00).

Figures 6.2-3 summarize the findings from the parametric study, - also shown in figures 6.2-3. It was concluded that:

The sensitivity study show that applying a SolarVenti system on Chinese homes will have an impact on the indoor environment.

Based on figures 6.2.3 it can be summarized that the SV14 in the considered apartment is able during the winter (November 1th-March 15th) per applied SV14 (up to 3 systems) to:

- increase the mean indoor temperature by 0.27 K - increase the mean ventilation of the apartment by 12.5 m³/h - decrease the mean relative humidity of the indoor air by 1-1.6 % point (lowest for an infiltration of 1.0 h-1) - decrease the mean moisture content of the constructions/furniture by 0,1-0,18 kg (lowest for an infiltration of 1.0 h-1)

However, the hourly influence may be much higher when looking at figure E.4-E.13. For an air change rate of 0.5 h-1 and 3 SV14:

- increase of indoor air temperature of up to 2-3 K - almost doubling of the ventilation flow rate - decrease in indoor relative humility of up to 20 % point - reduction of the moisture content in constructions/furniture of up to 2 kg - heat input of up to 1500 W

This will have a large impact on the daily life in a home.

Figure 6.3 shows that one SV14 has a drying effect even if it is not able to raise the mean ventilation flow rate of the apartment.

It was not possible by the model to determine the reduction in mould growth. This is not only dependent on the indoor relative humidity and air temperature but also on the surface temperatures of the construction. The later may be low in Chinese homes due to the high U-value of the external constructions. For this reason: only a slight reduction in the indoor relative humidity may have a large reducing effect on mould growth and further the often more excessive drying out may also seriously reduce mould growth.

Figure 6.2. Relative humidity and the average room temperature in dependence of the number of SV14 modules used and the air change rate.

Figure 6.3. The average ventilation rate and the average moisture in the constructions in dependence of the number of SV14 modules used and the air change.

The applied model may be modified to simulate the indoor environment of any buildings under any climatic conditions. But it should be remembered that the model has not yet been validated based on real measured performance of the SolarVenti system. The next step forward

42 should, therefore, be to perform comparative tests as in chapter 5, however, in real inhabited homes.

6.1. Discussion

In Appendix E it is concluded that one SV14 will have a similar drying effect without increasing the mean air change rate of the apartment as SV14 number three which enhance the mean air change rate of the apartment. This is in contradiction with the conclusion reached from the comparative container test described in chapter 5: the SolarVenti system needs to create a considerably larger air change rate than already present in the building in order to have a noticeable drying effect.

However, there are large differences between applying the SolarVenti system on a container and in a closed down summerhouse during the winter in Denmark compared to applying it on a home in Shanghai:

- there is much more solar radiation on a south facing façade in Shanghai than in Denmark. Figure E.3 in Appendix E shows that there is sunny conditions nearly every day during the winter in Shanghai. This means that the SolarVenti system in Shanghai will provide a daily drying effect.

- an apartment needs a higher air change rate than a container or a closed down summerhouse. But at the same time there is a moisture production in the apartment due to cooking, bathing, cleaning, etc. This should worsen the conditions for the SolarVenti system, but the increased moisture production in an apartment together with the almost daily heat input from the SolarVenti system makes the heat input from the SolarVenti system very valuable even if the system doesn’t increase the mean air change rate of the apartment.

- the low indoor air temperatures during the day (see figure 2.5) together with a wish of a higher air temperature during the evening creates good conditions for the SolarVenti system.

- figure E.5 shows that a SolarVenti system often will create a bit higher indoor air temperature during the day, which may decrease the energy to the heating system of the apartment or if the power of the heating system is too low: increase the indoor air temperature a bit during the evening.

- although the indoor relative humidity in the apartment during the winter mainly stays below 80 % this will, due to the high U-values of the exterior surfaces, make perfect conditions for mould growth on cold surfaces. So even a slight reduction in the mean indoor relative humidity level may be an important improvement for the indoor air quality. This together with the fact that during daytime with solar radiation there is an excess drying effect on the constructions and furniture which last for a longer time than just the drying effect when the SolarVenti system is running.

The parametric studies with the simulation model indicate that applying SolarVenti on homes in Shanghai will have a positive effect on the indoor air quality. However, how much this will affect mould growth in actual cases is not possible to state. This should be measured in real homes with and without a SolarVenti system.

43 7. Conclusions

Many studies conclude that cold, damp conditions in buildings are bad for the health. This is underlined by the fact that WHO finds it necessary to develop guidelines to prevent building dampness and mould problems in buildings.

Besides documentation of the health problems related to cold, damp conditions in especially homes in the Shanghai area the main aims of the present project were to:

- characterize the SolarVenti system - perform comparative tests and - determine the benefit of applying SolarVenti systems on homes in the Shanghai area

The efficiency equation dependent on the volume flow rate and the equation for the volume flow rate dependent on the solar radiation have been established for SV14 and partly for SV7.

It was not possible to perform comparative tests in homes in Shanghai or in summerhouses in Denmark. Instead tests were carried out in containers in Denmark. The tests showed the large drying potential of the SolarVenti systems, but the tests couldn’t directly be transferred to buildings as the large un-insulated surfaces of the containers acted as larger solar collectors that the tested SV2 and SV7 systems.

In order to investigate the potential of applying SolarVenti on homes in Shanghai a model of a house with SolarVenti was further developed to represent the building, living and weather conditions in the Shanghai region. Parametric studies with the simulation model indicate that applying SolarVenti on homes in Shanghai will have a positive effect on the indoor air quality. The SolarVenti system is capable of both reducing the indoor relative humidity and increase the indoor air temperature. However, how much this will affect mould growth in actual cases is not possible to state. There is a need for comparative tests in real homes in Shanghai. The latter is the next logical step in introducing the SolarVenti system on the building marked in Shanghai.

44 8. References

Aggerholm, S. and Grau, K., 2008. The energy demand of buildings (in Danish). SBi guideline 213.

Andersen, E., 2011. Test rig for solar air collectors (in Danish). DTU Byg Report R 255. De- cember 2011.

Arundel, A. et al, 1986. Indirect Health Effects on Relative Humidity in Indoor Environments. Environment Health Perspectives vol. 65, pp. 351-361. Elsevier B.V.

Carter et al, 2003. Housing and health: building for the future. British Medical Association. http://www.bma.org.uk/images/Housinghealth_tcm41-146809.pdf

Dansk Standard, 2012. Calculation of effective heat capacity of buildings (in Danish). Draft. DS Information. 2012.

Fisk, W.J., 2000. Health and productivity gains from better indoor environments and their implications for the U.S. Lawrence Berkeley National Laboratory. http://escholarship.org/uc/item/6g82k2gv

Fisk, W.J, Lei-Gomez, Q. and Mark J Mendell, M.J., 2007. Meta-analyses of the associations of respiratory health effects with dampness and mold in homes. Indoor Air. 2007 Aug;17(4):284-96. http://www.iaqscience.lbl.gov/pdfs/mold-1.pdf

Fisk, W.J, Eliseeva, E.A and Mark J Mendell, M.J., 2010. Association of residential dampness and mold with respiratory tract infections and bronchitis: a meta-analysis. Environ Health. 2010; 9: 72. http://www.ehjournal.net/content/9/1/72.

FocusChina, 2010. Marketing plan – SolarVenti. July 2010.

Fraunhofer, 2011. Interner Zwischenbericht im Luko-E Projekt. Hierin werden die durch- geführten und geplanten Kollectorprüfungen am Solarventi SV14NS in Anlehnung an die ENM 12975 beschrieben (in German). Internal document Fraunhofer ISE report.

Furbo, S. and Schultz, J.M., 2007. Efficiency of air/liquid solar collector (in Danish). BYG•DTU report SR-07-07.

Harker, L, 2006). Chance of a lifetime. The impact of bad housing on children’s lives. Shelter - the housing and homelessness charity organization. September 2006. http://england.shelter.org.uk/__data/assets/pdf_file/0009/66429/Chance_of_a_Lifetime. pdf

IOM, 2004. Damp indoor spaces and health. Institute of Medicine, Washington, DC. National Academy Press.

Jacobsen, E.D.K, 2012. ETV Test Plan. J.no. 1201 – SolarVenti air heater. Danish Technolog- ical Institute.

45 Jensen, S.Ø., 1994. Test of the Summer House Package from Aidt Miljø. Thermal Insulation Laboratory, Technical University of Denmark. Report nr. 94-1. 1994.

Kristensen, J. and Larsen, J.E., 2007). Poverty, social exclusion and living conditions (in Dan- ish). Dansk Sociologi, vol. 4/18, 2007. http://boligforskning.dk/sites/default/files/artikel_dansk_sociologi.pdf

Lausen, C., 2011. Test for solar panels. Delta Report no. 201170064-6. November 2011.

Meteonorm, 2000. MeteoTest version 4.

Shen, X. et al, 2009) Deaths among tuberculosis cases in Shanghai, China: who is at risk? BMC Infectious Diseases journal, 2009, 9:95. http://www.biomedcentral.com/1471- 2334/9/95.

Stampe, O.B., 1982 Glent Ventilation (in Danish). Glent & Co.

Sun, Y. et al, 2009. Dampness in dorm rooms and its associations with allergy and airways infections among college students in China: a cross-sectional study. Indoor Air 2009; 19: 348–356. http://www.ncbi.nlm.nih.gov/pubmed/19627367

(TB Alert, 2012) is developed by TB Alert under the The Truth About TB programme for the Department of Health, UK. http://www.thetruthabouttb.org/am-i-at-risk/living- conditions

U.S Department of Health and Human Services, 1994. Vital and health statistics, current estimates from the national health interview survey, series 10. Data from the National Health Survey No. 189, DHHS Publication No. 94-1517.

Valbjørn, O., 2003. Investigation and evaluation of moisture and mould growth in buildings. (In Danish). By og Byg anvisning 204. Statens Byggeforskningsinstitut 2003.

WHO, 200). WHO guidelines for indoor air quality. Dampness and mould. ISBN: 978 92 890 41683. http://www.euro.who.int/__data/assets/pdf_file/0017/43325/E92645.pdf

Yoshino, H. et al, 2006. Indoor thermal environment and energy saving for urban residential buildings in China. Energy and Buildings 38 (2006) pp. 1308–1319. Elsevier B.V.

Zhang H. and Yoshino, H., 2010. Analysis of indoor humidity environment in Chinese residential buildings. Building and Environment 45 (2010) pp. 2132-2140.

Zhang, 2012. Mail correspondence with Huibo Zhang – author on (Yoshino, 2006 and Zhang and Yoshin0, 2010).

Zhu, A., 2012. Interview with Alice Zhu, FocusChina at Danish Technological Institut, Århus March 2, 2012.

Appendixes

47 48

49 50 51 52 53 54 55 56 57 58 59 60 61 Appendix B - Materials of Building Construction in the Shanghai Area

The following information of Chinese building constructions and materials has been collected by FocusChina.

1. Building materials of external wall

Along the development of energy-saving building construction in China in the past ten years, the external wall construction has changed a lot. More and more buildings use the hollow clay bricks(空心粘土砖), hollow blocks(空心砌块) and aerated concrete(充气混凝土) to instead of the solid clay bricks(实心粘土砖). And developing the insulation materials such as expanded polystyrene (EPS)[膨胀聚苯乙烯], Glass wool(玻璃棉) and expanded perlite (膨胀珍珠岩).

Hereby is the introduction and specification for several commonly used external wall materials in Shanghai area.

A. Perforated Concrete brick (混凝土多空砖) Since 1990, perforated concrete bricks have been applied widely in Shanghai area.

Table 1.1 Relative water content (RWC)[相对含水率] of perforated concrete bricks (%) Drying Shrinkage Ratio Relative water content (RWC) (干燥收缩率) Humid Middle Dry <0.030 45 40 35 0.030～0.045 40 35 30 Ps: Humid - means the area with the annually average humidity over than 75% Middle - means the area with the annually average humidity between 50%～75% Dry - means the area with the annually average humidity less than 50%

Table 1.2 Permeability resistance(抗渗性) of perforated concrete bricks (mm) Item name Standards Water level set-down (水面下降高度) Any of three bricks ≯ 10

Table 1.3 Specification of 240mm external wall of perforated concrete bricks Thermal Resistance R (热阻值) 0.56 m2·K/W Heat-transfer rate (传热系数) 1.79 W/(m2·K) Average sound transmission loss (平均 51 dB 隔声量)

B. Hollow concrete block (混凝土空心砌块) Hollow concrete blocks are commonly used in residential buildings now.

Table 1.4 Relative water content (RWC) of hollow concrete blocks (%) Area Humid Middle Dry Relative water content (RWC) 45 40 35 Ps: Humid - means the area with the annually average humidity over than 75% Middle - means the area with the annually average humidity between 50%～75% Dry - means the area with the annually average humidity less than 50%

Table 1.5 Permeability resistance of Hollow concrete brocks (mm) Item name Standards Water level set-down Any of three bricks ≯ 10

Table 1.6 Specification of Hollow concrete blocks with several common thicknesses Block Name Performance Index Referential Values 190mm hollow concrete block Weight ≈ 17kg (190mm 厚普通砌块) Thermal Resistance R=0.20 m2·K/W 90mm hollow concrete block Thermal Resistance R=0.14 m2·K/W (90mm 厚普通砌块) 90mm split decorative block Thermal Resistance R=0.12 m2·K/W (90mm 厚劈离装饰砌块)

C. Other materials

Except above two kinds of materials, there are so many different kinds of materials we are using now. For example, autoclaved aerated concrete blocks （蒸压加气混凝土砌块）, hollow clay blocks （空心粘土砌块）, cast- in-situ reinforced concrete（现浇钢筋混凝土）, clay unit masonry [各种砖（粘土砖；煤矸石砖；灰砂砖；空心砖等）], etc.

For the floors, the cast-in-situ reinforced concrete floor （现浇钢筋混凝土楼板）and pre- cast reinforced concrete slabs （钢筋混凝土预制板）are more commonly used than other kinds of floors.

Pre-cast reinforced concrete slabs are divided to several types based on its structure. They are solid slabs（实心板）, trough slabs（槽形板）and hollow slabs （空心板）.

Plasterboards（石膏板） and fiberboards（纤维板） are widely used in building decoration （建筑装饰）, for example to use it make a suspended ceiling （吊顶） and wall panel（墙板）. Thickness is around 9mm to 12mm for decoration in house.

Heat-transfer rate of plasterboard is 0.30 [W/(m2·K)] .

Table 1.7

63 Heat-transfer rate of fiberboard Type of board Density（密度） Heat-transfer rate [W/(m2·K)] Light fiberboard 200～400 0.035～0.056 Medium fiberboard 500～800 0.11～0.13 Hard fiberboard 800～1000 0.13～0.15

2. Building external thermal insulation system （建筑外墙保温系统）

Divided into four methods: 1. External wall of self-insulation system （外墙自保温系统） 2. Exterior wall external insulation system （外墙外保温系统） 3. Exterior wall inner insulation system （外墙内保温系统） 4. Exterior wall sandwich insulation system （外墙夹心保温系统---丹麦常用）

In china, exterior wall external insulation system （外墙外保温系统）is used more commonly. The materials of insulation layer are made of polystyrene board（聚苯板）, EPS board （膨胀聚苯板）and rock wools（岩棉）, etc.

Table 2.1 Main Properties Indexes of Polystyrene Board （聚苯板主要技术性能指标） Unit Index Density(kg/m3) [密度] 18~20 Compressive strength (MPa) [抗压强度] ≥0.15 Tensile strength (MPa) [抗拉强度] ≥0.118 Impact strength(MPa) 抗冲击强度] ≥0.29 Heat resistance (keeps the shape)℃ [耐 75 热性（不变形）] Cold resistance (keeps the shape)℃ [耐 -80 寒性（不变形）] Volumetric water absorption (24h)% [体积 ≤1 积水率] Heat-conductivity factor[W/(m﹒K)] [导热系 ≤0.04 数] Penetration of dampness [水分渗透] 0.38 Self-extinguishing(s) [自熄性] 2

Table 2.2

64 Main Properties Indexes of EPS Board （膨胀聚苯板主要性能指数） Test Unit Properties Index Heat-conductivity factor [W/(m﹒K)] [导热 ≤0.041 系数] Apparent density (kg/m3) [表面密度] 18.0~22.0 Tensile strength from the vertical direction of board surface(MPa) [垂直于板面 ≥0.10 方向的抗拉强度] Stability of measurement(%) [尺寸稳定性] ≤0.30

3．Specification of insulated composite walls （保温复合外墙性能参数）

Table 3.1 Thermal Insulation Property of Steel meshwork Polystyrene Board （钢丝网架聚苯保温板性能）

Thermal Insulation Property Thickness of Thickness of Index Composite wall heat insulat- Thickness of main mortar layer structure [复合 ing layer wall (mm) (mm) [砂 (mm) [保温层 Thermal Re- Heat-transfer 墙体构造] [主墙厚度] 浆面层厚度] sistance R rate K 厚度] (m2·k/W) [W/(m2﹒K)]

Solid Clay Brick 30 1.068 0.936 Wall, Steel mesh polystyrene Board, 40 240 25 1.267 0.789 Cement Mortar Rendering 50 1.465 0.628

30 0.864 1.157

40 160 25 1.062 0.941 Reinforced Con- crete Wall, Steel 50 1.261 0.793 mesh polystyrene Board, Cement 30 0.887 1.127 Mortar Rendering 40 160 25 1.085 0.921

50 1.284 0.799

30 1.186 0.843 Hollow Clay Brick Wall, Steel mesh polystyrene Board, 40 240 25 1.384 0.722 Cement Mortar Rendering 50 1.583 0.632

Table 3.2

65 Properties of Concrete Rockwool Composited Exterior Wall Boards （混凝土岩棉复合外墙板性能） Technical Properties Items Unit Index

Weight(kg/m2) [自重] 500~512 Average thermal resistance (m2﹒k/W) [平 0.99 均热阻值] Concrete Rockwool Composited Exterior Heat-transfer factor[W/(m2﹒k)] [传热系 1.01 wallboard [混凝土岩棉复数] 合墙板] Horizontal load(kN) [水平荷载]

Vertical load 106kN [垂直荷载 106kN 时] 77.8

Vertical load 440kN [垂直荷载 440kN 时] 11.7

Weight(kg/m2) 176~256

Average thermal resistance (m2﹒k/W) 1.702

Heat-transfer factor[W/(m2﹒k)] 0.593 Thin-walled Concrete Rockwool Composited Cracking load (kN) [开裂荷载] Exterior Wallboard 5-8-3 All-cut-off non-rib plate type [全切 Type ( Cold District) [薄 28.67~31.5 断型无肋板] 壁混凝土岩棉复合外墙板 rib plate type [带肋板型] 42.5~52.7 5-8-3 型（寒冷地区）] Failure load (kN) [破坏荷载]

All-cut-off non-rib plate type 46.67~72.67

rib plate type 62.24~64.94

Weight(kg/m2) 223

Average thermal resistance (m2﹒k/W) 1.92

Thin-walled Concrete Heat-transfer factor[W/(m2﹒k)] 0.52 Rockwool Composited Exterior Wallboard 5-10- Cracking load (kN) 3 Type ( Severe Cold Positive pressure(wind pressure) 44.33 District) [薄壁混凝土岩棉复合外墙板 5-10- Pounter pressure(lifting) 56.33 3 型（严寒地区）] Failure load (kN)

Positive pressure(wind pressure) 78.33

Pounter pressure(lifting) 105.13

Table 3.3

66 Thermal resistance of “Dryvit” Heat-preserving System with different layers compound wall structure (专威特体系与不同基层墙体复合的热阻值表) W all materials & Clay Lime- Steel reinforced Clay porous Cinder Thickness (mm) solid Concrete block sand concrete [钢 bricks [粘 bricks bricks [实 [混凝土砌块] bricks [炉渣砖] 筋混凝土] 土多孔砖] [灰砂砖] Thermal Resistance of 心粘土砖] Composite Wall(m2﹒K/W) 190 240 (single 140, 180, 250, 190 240 (triple 240 370 /double 240 370 190 240 160 200 300 (DM) (KP1) row of row of hole) Thickness of polystyrene hole)

30 1.18 1.34 0.97 0.99 1.03 1.22 1.30 1.06 1.17 1.11 1.22 1.12 1.18

40 1.43 1.58 1.21 1.23 1.27 1.45 1.54 1.30 1.41 1.34 1.46 1.36 1.42

50 1.66 1.82 1.44 1.47 1.51 1.69 1.78 1.53 1.64 1.58 1.70 1.60 1.66 Ps: “Dryvit” heat-preserving system is coming from “Dryvit” company in American, since 1997 it has become more and more popular in china. This system is composed of adhesives（胶粘剂), reinforced glass fiber net(增强玻纤网), EPS board (聚苯乙烯发泡板), and finish coat.(外饰面)

4. Paint

Commonly use synthetic resin emulsion coating(合成树脂乳液涂料) both for exterior walls and interior walls.

Before painting, one layer of plastering mortar （抹灰砂浆）is necessary to make the wall surface smooth, which is made of cement（水泥）， lime（石灰）or cement/lime based.

Table 4.1 Specification of plaster mortar with cement based (水泥抹面砂浆技术要点) Consistency （稠度） 100-120mm Bottom layer （底层） Sand (砂颗粒大小) 2.6mm Plaster mortar height （砂浆高 5-7mm 度) Consistency （稠度） 70-90mm Middle layer （中层） Sand (砂颗粒大小) 2.6mm Plaster mortar height (砂浆高度) 7-9mm Consistency （稠度） 70-80mm Surface （面层） Sand (砂颗粒大小) 1.2mm Plaster mortar height (砂浆高度) 5-8mm Ps：砂浆稠度=砂浆沉入度

67 Appendix C – Homes and interior in Shanghai

The following information on homes and the interior in Shanghai has been collected by Fo- cusChina.

In Shanghai China, most families living in a multi-story buildings or high-rise buildings, these apartments for one-family are around 100-120m2 of the floor area, family members are mainly 3 persons, parents with their kid. But we do not think they will become our sales target group in the nearly future. As we still have some difficult to fix the SolarVenti on a multi-story building and high-rise building.

Our target group would be the owners of a SINGLE HOUSE or TOWNHOUSE in Shanghai area. Along with economic development, a part of stable income and high income group raising their requirements of the residence; they are not content with apartment life, and looking for more natural and high quality living conditions.

The floor area of TOWNHOUSE is around 150-300m2; SINGLE HOUSE is around 250-500m2, the average floor area is about 220m2; the family members are normally 3 to 6 persons, these families might have one or two kids and live together with their grand-parents as well.

Villa homes trading volume in Shanghai area Year Build-up area (M2) Number of villas Data from 1992-2001 >7 million 15000 上海别墅策划全案 P.6 2002-2004 9.4 million 42700 中国别墅市场报告 2005 1.35 million 5364 2005 上海别墅市场分析报告 2006 1.14 million 5864 2006 年上海别墅市场分析 2007 1.67 million 7590 2007 年上海别墅市场报告 2008 1.21 million 5500 2008 年上海别墅市场年度回顾 2009 2.87 million 13067 2009 年上海别墅市场运行状况及 2010 年展望 2010 1.68 million 7625 2010 年上海别墅成交大回顾 As conservative estimate of the total Shanghai villa number is about 100,000 homes.

Hereby, I am going to introduce one typical Villa in Shanghai, which is called “Patio Villa Espana Ebtilo Devida”. The entire communi- ty including townhouses; overlay villas and sub-high-rise buildings, total building area is about 270,000 M2; total floor area is about 330,000 M2.

The number of villas 1st phase of the project: 683 homes 2nd phase of project: 256 homes

Materials of sub-high-rise apartments 1. Facade materials: Exterior wall paint and stone pain 2. Staircase flooring: Glass masonry flooring

68 3. Exterior wall insulation: EPS board, exterior wall external insulation system 4. Door of entrance: Insulated security door 5. Inner door: Hard Alloy Glass Door 6. Window: Thermal Insulation Al-Alloy profile + Hollow glass + LOW-E (Low emissivity) glass membrane. 7. Railing: Al-Alloy railing

Materials of townhouse: 1. Facade materials: Exterior wall paint, stone pain and a layer of rock be wounded in fight 2. Exterior wall insulation: EPS board, exterior wall external insulation system 3. Door of entrance: Insulated security door 4. Window: Thermal Insulation Al-Alloy profile + Hollow glass + LOW-E (Low emissivity) glass membrane. 5. Railing: Al-Alloy railing

Roof structure: 1. 40mm C20 fine aggregate concrete 2. 3mm SBS modified bitumen membrane 3. 30mm XPS board 4. 20mm 1:3 plaster mortar with cement based 5. At least 30mm sand haydite concrete 6. 1.5mm JSI cement based elastic waterproofing coating 7. Cast-in-situ reinforced concrete slab.

Exterior wall structure: 1. 25mm hanging marble 2. Light-gauge steel frame 3. 40mm EPS board with 1mm polymer mortar 4. 2mm interfacial waterproofing agent 5. 20mm 1:2.5 plaster mortar with cement based 6. Wall surface

The distance between two buildings is around 5-6m; and the height of a 3 story building is around 9-10m. (You can get some idea from the picture to the right).

The lay-out of a 3 story house Floor area: 253m2

Ground floor

Second floor

First floor

Second floor

Roof garden Basement

In Shanghai, we usually use air-condition to support the heating, and it is right the heating is typically started when there is activities in the building and stopped when the habitants sleep.

The windows are open in the morning when the habitants get up until they leave the house (it is around 6:00-8:00); as it is not safe to leave the window open when there is no person in the room. And when air- condition is opening, the windows are closed as well.

Bath-room and kitchen installed exhausting fans and after using, we will open the window to speed-up ventilation.

The most common floors material is solid wood; some are multi-ply parquet.

Most windows use single layer glass.

Properties of exterior wall paint

No Item Index Methods 1 Status in the vessel Evenly mixed, free from lumps Look 2 Construction Easy for construction, no sagging 3 Color and Appearance of Comply with the standard model and According to regulation paint its color ranges, painting surface flat GB1729-79 and smooth 4 Fineness(μm) ≯60 According to regulation GB1724-79 5 Dry time (h) Surface dry：≯2 According to regulation GB1728-79 Totally day：≯24

71 6 Hiding power (white & Emulsion paint: ≯200 According to regulation light color) (g/m2) GB1726-79 Solvent paint: ≯170 7 Solid content (%) ≮45 Rapid-bake test 8 Freeze-thaw stabilization No deterioration (-5±1)℃,16h; (23±1)℃,8h, (emulsion paint) Cycle number: 3 9 Water resistance Does not rise bubble, not peeling off, According to regulation allowing slight discoloration GB1733-79, (23±2)℃, dipping 96h 10 Alkali resistance Does not rise bubble, not peeling off, Reference test method for allowing slight discoloration water resistance, the spec- imen immersed in saturat- ed calcium hydroxide solution (23±2)℃, dipping 48h 11 Scrubbing resistance Emulsion paint: washing 1000 times, Washing apparatus test (0.5% soap solution) not see bottom (times) Solvent paint: washing 2000 times, not see bottom 12 Stain-resistance (white Emulsion paint: ≯ 50% 5 cycles, determination of & light color) reflection coefficient, cal- Solvent paint：≯ 30% culation of reflection coefficient the rate of decline 13 Weather resistance Does not rise bubble, not peeling off, According to regulation no cracks, discoloration and powder GB1865-80，GB1766-79 are not more than level2

Properties of interior wall paint

No Item Index Methods 1 Status in the vessel By mixing non-caking, precipitation Look and flocculation 2 Viscosity (Tu-4 Viscome- 40-80 According to regulation ter) ( s) GB1723-79 3 Color and Appearance of Comply with the standard model and According to regulation paint its color ranges, painting surface flat GB1729-79 and smooth 4 Fineness(μm) ≯ 80 According to regulation GB1724-79 5 附着力/ % 100 According to regulation GB1728-79 2 6 Hiding power (g/m ) ≯ 300 According to regulation GB1720-79

7 Water resistance Does not rise bubble, not removing According to regulation powder GB1733-79, (23±2)℃, dipping 24h 8 Alkali resistance Does not rise bubble, not removing Reference test method for powder water resistance, the spec- imen immersed in saturat- ed calcium hydroxide solution (23±2)℃, dipping 24h

72 9 Scrubbing resistance ≮100 times or ≮500 times Washing apparatus test (0.5% soap solution) (times) 10 Scuff resistance ≮ level1 Test by reciprocation washing and abrasion test machine

Furniture

73 Appendix D – Information on a Chinese flat used in (Yoshino et al, 2006)

The energy demand of an apartment located in Beijing and Shanghai has been investigated in (Yoshino, H. et al, 2006). The layout of the apartment is shown in figure D.1. Further information on the areas of the windows and the material of the constructions has been obtained via (Zhang, 2012).

The total floor area of the apartment is 87.2 m². The heating system is a small split air- condition unit situated in the living room. The air change rate in the apartment is 1 h-1 based on the requirement from the design code in China: Design Standard for Energy Efficiency of Residential Buildings in Hot Summer and Cold Winter Zone. The kitchen ventilation with 10 h-1 is achieved by exhaust ventilation for one hour three times a day.

The transparent area and location of the windows are shown in figure D.1. South facing windows are marked with red circles and highlighted with orange in the table.

3250 3000 1050 W3 Balcony W4 北ベランダ W4 location Width x Height Area W1 3.6m2 1200 2 W2 W1 1500x900mm 1.35m 2 W2 1500x1800mm 2.7m 2 Study Kitchen W 2800x1500mm 4.2m 3200 3 書斎台所 3200 2 2 10.4m2 9.6m Stairs W4 1000x1500mm 1.5m 階段室 2 W5 3600x1500mm 5.4m D2 D2

D1 1500

Next-door Living room D2 Next-door 隣戸 4400 居間隣戸 2 Bathroom 23.3m トイレ 2900 7.25m2 D2 D2 1450

Bedroom Child’s room 3900 3900 主寝室子供室 14.82m2 13.65m2 W2 Balcony W1 W4 南ベランダ W4 1200 4.56m2 W5 3800 3500

Figure D.1. Floor plan and windows of the apartment simulated in (Yoshino et al, 2006) - (Zhang, 2012).

Table D.1. Input to the simulations (Yoshino et al, 2006).

The thickness and materials of the external walls, internal walls, floor and ceiling are given in table D.2.

Item Thickness Thermal conductivity Material (mm) (kJ/mhK) External walls Lime mortar plaster 20 2.736 Brick 370 2.23 Mortar 20 3.348 Floor and ceiling Wooden flooring board 10 0.504 Mortar 20 3.348 Concrete 200 6.264 Lime mortar plaster 20 2.736 Internal walls Lime mortar plaster 20 2.736 Brick 240 2.23 Lime mortar plaster 20 2.736

Table D.2. Thickness and materials of the constructions (Zhang, 2012).

75 Appendix E – Description of the applied simulation model and the obtained simulation results

Introduction

The following work is a part of the work in the project: Solar Air collector impact on health of human and buildings, possible energy and maintenance savings in houses.

The Appendix describes the assumptions done in the calculations, the calculation principles, the input parameters and the results obtained followed by a discussion of the findings.

Background

The principle of the investigated solar heating system is to dry out the moisture in the buildings by a supply of solar heated ventilation air driven by a PV-operated ventilator. The simultaneousness of the ventilation and solar gains has an advantage due to the enhanced drying out of the building and due to the larger possible drying capacity of warm air compared to colder air.

The PV-operation implies that the ventilator runs when there is solar radiation and that there is no need for external electricity supply.

Description of building model

The result of a survey regarding information about typical buildings and constructions is given in Ap- pendix B and for one apartment in Appendix D. With this information it has been possible to develop a building model which represents and approximates the heat and mass flows in actual buildings. The model is assumed to provide a good estimate of the performance in practice. In the cases where the input parameters are with high uncertainty the performance is estimated with different values in order to find the sensitivity of changes in input parameters.

The building is selected to correspond to buildings in which there is expected to be a market for this type of systems. In the determination of the characteristics of the building the information given in Appendix C and D is applied. The apartment shown on figure D.1 is used as the basis for the calculation.

The building characteristics used for the evaluation of the drying effect of the solar air collector are:

Characteristics of the Building

Gross square area: 87.2 m2 Internal volume of building: 179 m3 Internal surface area of building: 380 m2 Weighted average U-value for constructions facing the exterior. 1.6 W/(m2 ∙ K) South facing window area: 6.75 m2 Reduction of transmitted solar radiation through south facing windows due to transmission losses through the glass, the frame area and shading from overhang, factor: 0.8 ∙ 0.8 ∙ 0.8: 0.51 Infiltration, with the SolarVenti system in operation: 0 h-1 *

76 Infiltration, without the SolarVenti sysetm in operation: 0.5 h-1 in base case. Also: 1.0 h-1 ** Infiltration is during three hours during the day (6.00-7.00, 12.00-13.00 and 18.00-19.00) enhanced (excess ventilation) due to cooking (10 h-h in the kitchen - see Appendix D) to: 1.1 h-1 *** Intermittent heating in the winter from 1. November to 31. Marts during the four hours 18:00 – 22:00 (see figure 2.6): 4000 W If the ambient temperature is lower than 5 °C then is the power of the heating system is increased from 4000 W to: 8000 W

* As the apartment is natural ventilated the volume air flow from the SV14s will replace this ventilation if higher than the normal infiltration/excess ventilation. If lower the heat input from the SV14 will be included but the infiltration will be as when the SV14 is not running ** The infiltration of the apartment is assumed to be either 0.5 or 1 h-1. 1 h-1 is the requirements of the Chinese building code (Appendix D) while 0.5 according to (Yoshino, 2006) will reduce the heating demand of the apartment by 13%. 0.5 h-1 is the requirement in the Danish Building code *** It is assumed that the kitchen is ventilated three times a day by 10 h-1 via exhaust ventilation. The 10 h-1 equals 1.0 h-1 for the whole apartment

Characteristics of the solar air collector

Type of solar collector SV14 Transparent area 1.26 m2 Number of SV14 modules 3 in base case. Varied from 1 to 10 Orientation of solar air collector South Slope of solar air collector Vertical 2 The ventilator starts at a solar irradiation of I0 = 355 W/m 2 The ventilator stops at a solar irradiation of I0 = 275 W/m 3 Maximum flow for ventilator Vmax = 127 m /h 2 Solar irradiation to obtain max air flow Imax = 750 W/m Volume flow of solar air collector Equation 4.2 Efficiency of air solar collector Equation 4.1

Assumptions for evaluations of the temperature and moisture balance

The evaluation is based on a simple model of the building as illustrated in figure E.2. The climate data used originates from Meteonorm for the Shanghai area (Meteonorm, 2000). The weather data represents hourly climatic data for a typical year. Below are the ambient temperature and the moisture content in the ambient air shown. In the summer time the temperatures is typically in the range of 20 °C to 35 °C.

Figure E.1. Ambient temperature and the moisture content in the ambient air for Shanghai.

The model used for the calculations is simplified by assuming there is no contact with the ground.

North

Figure E.2. Illustration of the building model used for evaluation of the drying out capacity of the solar air collector. The building in the calculations is assumed to be an apartment with only contact to the exterior via the south and north facade

78 The model calculates the temperatures, heat- and moisture flows for each hour of the year.

In the model is assumed that the constructions have a total efficient thermal capacity which can vary dependent on the constructions in the room. A measure for the average ability to store heat in the constructions is the thermal effusivity b for the surfaces.

A simplification is given which assumes that the temperature of the room is equivalent to the temperature of the active thermal capacity. For a given thermal effusivity b the energy stored in the constructions can be calculated as in (Furbo and Schultz, 2007).

Q(3600 s) = 1,13 · b · ΔT · (3600)0.5 where Q Stored energy after 1 hour (J/m2) b Thermal effusivity (J/(m2 · K · s0.5)) ΔT Momentary temperature increase (K)

Following examples of thermal effusivities b can be given (Dansk Standard, 2012) and the amount of heat per K stored in one hour can be calculated:

Wood: b =365 J/(m2 · K · s0.5), Q(3600 s) = 25 kJ/(m2 ∙ K)

Masonry (1500 kg/m3) b = 810 J/(m2 · K · s0.5), Q(3600 s) = 55 kJ/(m2 ∙ K)

Concrete (2000 kg/m3) b = 1690 J/(m2 · K · s0.5), Q(3600 s) = 114 kJ/(m2 ∙ K)

Then the active heat capacity for the building can be calculated by multiplying Q(3600 s) by the surface area of the active heat capacity. The active thermal mass is assumed to have the same temperature as the room temperature.

It is assumed that half of the thermal active area corresponds to wood and the other half corresponds to masonry. Therefore the average of these two types of surfaces is used in the calculations for the active thermal capacity: 25 + 55 = 40 kJ/(m2 ∙ K)

The building is assumed to be heated during four hours from 18.00 to 22.00 in the months from No- vember to March – see figure 2.7. The power of the heating system is increased to 8000 W when the ambient temperature is below 5 °C in order to avoid too low indoor air temperatures during these periods.

Moisture balance

The resulting moisture content in the room air is calculated as:

1. The moisture content at the end of a time step, assuming no moisture exchange with the surroundings:

Xi,new = ((Vol – qin ∙ τ) Xi,old + qin ∙ τ ∙ Xe) /Vol

where:

Xi,new Absolute moisture content in the room air (kg/kg)

79 Vol The internal volume of the building (m3) 3 qin Air change (m /s) τ Time step (s)

Xi,old Absolute moisture content at the start of the time step (kg/kg)

Xe Absolute moisture content of the exterior air (kg/kg)

2. The estimated moisture content is converted to a corresponding relative humidity of the room air:

ϕ1 = pd /ps = (101325 Xi,new /(Xi,new + 0,62198))/ exp(23.5771 – (4042.9 / (T - 37.58)))

where

ϕ1 Relative humidity of the room air (-)

pd Water vapour pressure of indoor air (Pa)

ps Saturation water vapour pressure of indoor air (Pa) T Indoor air temperature (K)

The atmospheric pressure is assumed to be constant 101325 Pa.

3. The moisture accumulation is simplified to be equivalent to moisture sorption in wood. One simplification is that the moisture content in wood is linearly dependent of the relative humidity of the room air:

Mwood = 0.22 ∙ ϕ1

where:

Mwood Moisture content of wood (kg/kg)

4. The moisture balance can be calculated by following the equation:

(ϕnew - ϕend, previous)∙ 0.22 ∙ Mwood = ((ϕnew - ϕ1)∙ (Vol ∙ρ)room air

where :

Mwood Moisture content of wood (kg/kg) ϕ Relative humidity (-) 3 ρroom air Density of room air (kg/m )

In this equation the ϕnew is estimated.

The calculation is analogue to the calculation of the heat balance. The moisture effusivity for wood is app. 4 x 10-7 kg/(Pa ∙ m2 · s0.5). It is calculated how much moisture that can be absorbed during one hour, if the relative humidity is increased by 1 % at the surface of the material. This gives an active moisture capacity of 2.7 x 10-7 kg/( m2 · Pa). This corresponds to that a layer of 1 mm of the inner part of the wall is contributing actively in the moisture exchange in a time step of 1 hour.

The area of the moisture active mass is assumed to be half of the interior surface area of walls, floors and ceilings. Many parts of the furniture, textiles and paper as books will also take part in the moisture absorption process. This assumption is, therefore, regarded as appropriate.

80 The choice of moisture active mass is resulting in a too positive evaluation of the drying effect of the solar air collector in longer periods without solar radiation. This is due to the parts of the walls, with a larger distance from the inner surface, also will have importance for the relative humidity of the indoor air. On the other hand the moisture active mass will probably provide a sensible picture of the indoor air relative humidity on days, with sun shine and where there are significant variations of the indoor temperatures.

Moisture production

For moisture production internal of the building it is assumed that a family of 4 with two adults and two children produce about 8.5 kg/day. If it is assumed that clothes is not dried in the building and that exhaust ventilation is used during the time for cooking the effective moisture production supplied to the rooms is assumed to be 6.0 kg/day. For reasons of simplicity it is further assumed the moisture production in the building is limited to be between the hours 18.00 and 7.00 which in 13 hours gives an hourly moisture production of 0.115 kg/hour for one person in these hours.

Results

The building model described has been used as a basis for simulations with different sizes of the So- larVenti SV14 modules. In the reference case 3 modules is used in order to make the function of the system more clear. The characteristics has been calculated with and without the use of the SolarVen- ti system

Following parameters from the calculations are investigated, since they are considered the most important to illustrate the effect on the drying, the thermal comfort and the energy performance:

- Ventilation rate - Room temperature - Relative humidity - Moisture content in the buildings - Supplied solar heat from the solar collectors

The solar irradiation on and the ventilation for one SV14 module are shown on figure E.3 during one year. The calculations is done with the SV14 in operation all the year in principle even though the system should not be operated in periods with overheating problems. The figure shows that the solar air ventilator only operate outside the summer period. This is because of the vertical position of the SV14 modules leads to a reduced solar irradiation due to a large solar height during this period.

In figure E.4 and E.5 is shown the indoor temperature with 3 SV14 modules and without any modules. It shows that the SV14 gives a temperature increase of up to 2-3 K during the winter time.

In figure E.6 and E.7 is shown the total ventilation rate for the building, including both infiltration (0.5 h-1), excess ventilation in three hours and ventilation from the SV14 modules. The figures show a significant increase of the ventilation by the use of 3 SV14 modules. During day time the ventilation flow rate is enhanced to up to 380 m³/h compared to the normal 0.5 h-1 = 90 m³/h and 1.1 h-1 = 197 m³/h. This even without a decrease in indoor temperature but on the contrary with an increase as seen in figure E.5.

81 In figure E.8 is shown for the whole year the average relative humidity for the previous 24 hours with and without the use of 3 SV14 modules. The use of 24 hours average makes the reduction of the relative humidity with the use of the solar air collectors more legible since the actual values are fluctuating so much that the differences are invisible when data is shown for the whole year. On figure E.9 are the actual relative humidity shown for a shorter time period of the year. On this figure a significant reduction of the relative humidity can be seen in periods with solar radiation – up to 20 % point.

There is also shown some periods where there is an increase in the relative humidity – green circles in figure E.9. This is the same with and without the use of SV14 modules and is due to periods without much solar radiation. A reason for the increase in humidity can be explained by the way the simulations are done. The focus has been on a representative simulation of short time (diurnal) variations and not variations on longer time periods. Therefore there will in real practice be an influence of the moisture capacity deeper in the materials which will influence and reduce the relative humidity for a longer time period. Therefore it is expected there will be a lower relative humidity in these cases when solar air heaters are used.

The change of the moisture content in the active moisture mass by using 3 SV14 modules is shown in figure E.10 and E.11. It can be seen there is a reduction in the moisture content in a large number of periods up to 2 kg. This major drying out will stabilize the humidity of the indoor air at a lower level during a longer period, - also because layers deeper in the constructions starts to dry out.

The total heat gain from both the heating system, the solar gain through windows and from the 3 SV14 modules is shown in the figures E.12 and E.13. It can be seen that there is a significant heat gain from the SV14 modules at the middle of the day – up to 1500 W.

Figure E.3. Solar irradiation at a vertical south oriented surface (W/m²) and ventilation rate from one SV14 module (m³/h).

Figure E.4. Calculated room temperature during the whole year with 3 SV14 modules and without SV14 modules.

Figure E.5. Calculated room temperature with 3 SV14 modules and without SV14 modules for the period from 2. February to 27. February.

Figure E.6. Calculated ventilation rate during the whole building (infiltration, excess ventilation and from SV14) during the whole year with 3 SV14 modules and without SV14 modules.

Figure E.7. Calculated ventilation rate with 3 SV14 modules and without SV14 modules for the period from 2. February to 27. February.

Figure E.8. Calculated relative humidity averaged over the previous 24 hours during a whole year with 3 SV14 modules.

Figure E.9. Calculated relative humidity during from hour 500 (21. January) to hour 2000 (23. March) with 3 SV14 modules and without SV14 modules.

Figure E.10. Calculated moisture content in constructions during the whole year with 3 SV14 modules and without SV14 modules.

Figure E.11. Calculated moisture content in constructions during from hour 500 (21. January) to hour 2000 (23. March) with 3 SV14 modules and without SV14 modules.

Figure E.12. Calculated total heat gain from the heating system, solar gain through windows and heat from 3 SV14 modules and without SV14 modules.

Figure E.13. Calculated total heat gain from the heating system, solar gain through windows and heat from 3 SV14 modules and without SV14 modules from hour 800 (2. February) to hour 1400 (27. February).

87 Sensitivity study

The SolarVenti system is especial applicable in the winter time where the natural ventilation is limited due to reduction of draught problems and to avoid too low temperatures. Below are reported results for the period between 1. November to the middle of March which is considered to be representative for the winter period. The length of this period is 134 days which corresponds to 3216 hours.

In order to investigate the influence of varying sizes of solar collectors and infiltration loss in the building the performance has been investigated with different numbers of SV14 systems (from 0 to 10) and where the infiltration has been increased from an air change of 0.5 h¯¹ to 1.0 h¯¹. The results are shown below in figure E.14 and E.15.

0.5 h-1

From figure E.14 it can be seen there is an increase in the average room temperature from about 15 °C to about 17 °C if 10 SV14 modules are installed. The curve shows that the increase in temperature per module is largest when the first SV14 modules are installed.

The relative humidity decreases from about 63 % RH to about 54 % RH when 10 SV14 modules are installed. The decrease is largest when up to 4 modules are installed. When more modules are installed the change in the relative humidity will be smaller.

1.0 h-1

When the air change rate is doubled (to 1.0 h¯¹) it leads to a lower average room air temperature due to the amount of heat released in the building is not increased correspondingly. But the increase in temperature with increasing number of SV14 modules corresponds to the curve when the air change rate is 0.5 h-1. The increased air change will also lead to a lower relative humidity level. The reduction in relative humidity will be less when the number of SV14 modules is increased than in the case of lower air change rates (0.5 h¯¹).

Ventilation and moisture content

The dependence of the average ventilation rate in the building on the number of SV14 modules is shown on figure E.15. It can be seen that the first module only increase the ventilation slightly because of the normal infiltration of the apartment, - this is seen more clearly for 1.0 h-1. One SV14 has a max flow rate of 127 m³/h, while the infiltration is 179 m³/h in the case of 1.0 h-1. When more modules are used the average ventilation rate increases linearly with the number of modules – for 0.5 h-1. When the air change rate of the building is larger (1.0 h-1) the total average ventilation rate is increased in the same way as at smaller air change rates (0.5 h-1) but first after applying 3 modules.

The average moisture level in the constructions is reduced linearly up to about 5 SV14 modules. When more modules are added the decrease is slightly less. When the air change rate in the building is larger (1.0 h-1) the moisture level will be lower but the variation corresponds to the curve with an air change rate of 0.5 h-1.

Figure E.14. Relative humidity and the average room temperature in dependence of the number of SV14 modules used and the air change rate.

Figure E.15. The average ventilation rate and the average moisture in the constructions in dependence of the number of SV14 modules used and the air change.

89 Evaluation of the relative humidity

The risk of mould growth can be seen in figure E.16 where the risk on a wooden surface is shown in dependence of the relative humidity and the surface temperature. It can be seen that there is no risk at a relative humidity below 75 %. Above this level there will be a risk. It can also be seen that the risk increases significant with increasing relative humidities when the level is above 80 %. It must be remembered that in buildings, especially with relative small thicknesses of insulation in the construction, the interior surface temperature will be significant lower than the room temperature. This will lead to a larger relative humidity at the surface and an increased risk for mould growth at the surface. Therefore even minor decreases of the relative humidities can be of importance for the reduction of the risk for mould growth.

risk of mould growth

% RF at the surface

Figure E.16. Risk of mould growth in dependence of relative humidity and temperature ( Valbjørn, 2003).

Conclusion

The efficiency of the drying effect of the SolarVenti system is evaluated by a simple calculation model taking the building construction, the ventilation and the user behavior into consideration. The model uses climatic data for a typical year for Shanghai.

The sensitivity study show that applying a SolarVenti system on Chinese homes will have an impact on the indoor environment.

Based on figures E14 and E.15 it can be summarized that the SV14 in the considered apartment is able during the winter (November 1th-March 15th) per applied SV14 (up to 3 systems) to:

90 - increase the mean indoor temperature by 0.27 K - increase the mean ventilation of the apartment by 12.5 m³/h - decrease the mean relative humidity of the indoor air by 1-1.6 % point (lowest for an infiltration of 1.0 h-1) - decrease the mean moisture content of the constructions/furniture by 0,1-0,18 kg (lowest for an infiltration of 1.0 h-1)

However, the hourly influence may be much higher when looking at figure E.4-E.13. For an air change rate of 0.5 h-1 and 3 SV14:

This will have a large impact on the daily life in a home.

Figure E.15 shows that one SV14 has a drying effect even if it is not able to raise the mean ventilation flow rate of the apartment.

It was not possible by the model to determine the reduction in mould growth. This is not only dependent on the indoor relative humidity and air temperature but also on the surface temperatures of the construction. The later may be low in Chinese homes due to the high U-value of the external constructions. For this reason: only a slight reduction in the indoor relative humidity may have a large reducing effect on mould growth and further the often more excessive drying out may also seriously reduce mould growth.

The applied model may be modified to simulate the indoor environment of any buildings under any climatic conditions. But it should be remembered that the model has not yet been validated based on real measured performance of the SolarVenti system. The next step forward should, therefore, be to perform comparative tests as in chapter 5, however, in real inhabited homes.