Delivering good through whole building The importance of good indoor air quality

According to the World Health Organization (WHO) “Air pollution from both outdoor and indoor sources represents the single largest environmental risk to health globally”, and causes 7 million deaths a year, worldwide.

On average, people spend 90% of their lives and may be a factor in conditions such de- indoors (and some, such as the elderly, even pression and bipolar disorder. It may also Did You more). This has caused the level of indoor air have a detrimental effect on children’s learn- 91% of people living in the pollutants to increase 2-5 higher than outdoor ing ability, patient recovery and workforce levels. productivity. cities do not breathe safe air

Some indoor air pollutants can be 100 times For building owners, poor indoor air quality more damaging than outdoor equivalents (and poor indoor environments in general) which has made indoor air quality now a rec- can hit the bottom line: demands from lease- ognized key issue in to hospitals, schools and holders and tenants can result in having to factories. carry out costly remedial works to both the building fabric and M&E systems (from light- Indoor air pollution can lead to serious short ing to climate control). This can lead to high- and long-term health problems. There has also er running costs and potentially affect market been growing evidence that air pollution im- and rental values. pacts mental health The causes of poor indoor air quality

Indoor air quality is defined as the quality of the air in and Main air pollution sources around a building, particularly in relation to the health and in buildings and how they comfort of occupants. It is affected by complex and inter- affect IAQ linked factors, due to both outside and inside air pollution.

Indoor Sources Sources of outdoor air pollution include road traffic, industrial processes, waste incin- eratioin and construction and demolition sites. Pollution includes particulate matter, Human or animal activity (dead NO2, CO and pollen, all of which can be brought into a building through natural or mechanical ventilation and via through the building fabric. skin, hair, CO2, viruses and others)

But there are also pollution sources inside a building, including Volatile Organic Com- Cigarette smoke pounds (VOCs) given off by wall and floor coverings, furniture and appliances as they Dust age and degrade; dust, damp and mould; emissions from office equipment and in- Bacteria dustrial machinery and, of course, occupants themselves, who breathe out CO2 and can spread colds and viruses. Mold Whole building HVAC: striking a balance between good indoor air Volatile Organic Compounds quality and energy efficiency (VOCs - carbon-based compounds that easily evaporate) As energy efficiency standards in building design have risen in recent years, build- ings have become more insulated and airtight. This can reduce fresh air circulation, leading to low oxygen levels and increased potential for allergies and odours, as Outdoor Sources well as the risk of condensation build-up.

The solution? Installing HVAC systems which control temperature, Traffc and other and maintain air qualit y. combustion products Pollen Dust Ventilation Airflow patterns Air flitration systems Ventilation Energy Efficiency Why not just open a window? Fundamentally, ventilation aims to remove Whole building ventilation systems stale indoor air and replace it with ‘fresh’ incorporating heat recovery deliver high In the past, increasing fresh air outdoor air. HVAC systems are designed to levels of efficiency, using waste from supply was achieved by simply extract water vapour, airborne pollutants heating/cooling to reuse in different opening a window or a door. and odours, controlling humidity and areas of a building. However, this can allow the maintaining good indoor air quality, and to ingress of outdoor pollution and minimise the spread of these impurities to Manufacturers typically claim Seasonal simply may not be feasible in other areas of a building. Energy efficiency using (SEER) figures cold weather. of 3 and 4 for heat recovery systems. Systems must also provide ‘purge ventila- However, it is possible, under certain Additionally, windows in many tion’ to help remove occasionally high con- conditions for a system’s efficiency ratio modern buildings cannot be centrations of pollutants and water vapour to nearly double, when taking into con- opened, to maintain energy caused, for example, by food cooking in a sideration recovered energy. In practice, efficiency, (and in taller build- kitchen or an accidental water spill. a SEER in excess of 6 should be possible ingsfor safety reasons). Even to achieve on a fairly frequent basis. if they can, opening windows For larger buildings, ventilation can be or wedging open a door can supplied by air handling units linked to Further energy savings can be achieved have a detrimental effect on an the indoor units, controlled centrally or by using features such as variable refriger- HVAC system’s ability to provide floor, room, or zone. For smaller buildings, ant temperature control. This varies the a comfortable indoor environ- heat recovery ventilation units can be amount of flowing through ment. integrated with the overall climate control the system and alters system, to supply tempered fresh air to the the evaporating and condensing tem- indoor units. peratures to match demand.

Dramatically less power is needed as a result and efficiency rises accordingly Designing ventilation building climate control

As with any element of HVAC, the design of ventilation, whether as a stand-alone “Ventilation and filtration provided by heating, system or as part of a whole building solu- ventilating, and air-conditioning (HVAC) systems can reduce the airborne concentration of SARS-Co tion, must meet the requirements of the V-2 and thus the risk of transmission thro ugh the air. building’s occupants. Unconditioned spaces can cause thermal str ess to people that may be directly life-threatening and that may also lower resistance to infection.” The key factor in designing ventilation is that it must provide sufficient fresh air supply and extraction to minimise moisture build-up (and therefore control mould) and deal with bio-ef- ASHRAE Statement on the operation of heating, fluents (body odour), as well as to keep exposure to NO2, CO ventilating, and air-conditioning systems to reduce and VOCs to a minimum. SARS-CoV-2 transmission Utilizing ventilation to reduce the risk of substandard indoor air quality

The and filtration principle High n The more air changes we have per hour and. better filtration, the less con- taminants we will have in the indoor air . environment. Medium ntaminants concentratio Co Low 0 Low Medium High

Air changes per hour

Example of the impact of ventilation on indoor air quality World Health Organization Air quality guideline values for particu- late matter (PM)

Fine particulate matter (PM2.5) Coarse particulate matter (PM2.5) • 10 μg/m3 annual mean • 20 μg/m3 annual mean • 25 μg/m3 24-hour mean • 50 μg/m3 24-hour mean

Average one-day indoor concentrations of PM10 μg/m3 169 153

150 Mechanical ventilation is mandatory 112

100

54 50 33

Denmark Italy France Norway Sweden

Chart: Pietro Consalvo Homes Offices Hospitals and healthcare

Required ventilation rates for homes The total air supply and extraction Obviously, some healthcare environ- are based on the number of bed- is 10 l/s/person, based on the as- ment, such as operating theatres, rooms, from 13 l/s for a one bedroom sumption that the building has critical care areas and isolation units, home, to 29 l/s for a five bedroom an air permeabi