buildings

Article The Role of Vernacular Construction Techniques and Materials for Developing Zero-Energy Homes in Various Desert Climates

Farajallah Alrashed 1, Muhammad Asif 1,2,* and Stas Burek 1

1 School of Engineering and Built Environment, Glasgow Caledonian University, Cowcaddens Road, Glasgow G4 0BA, UK; [email protected] (F.A.); [email protected] (S.B.) 2 Department of Architectural Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia * Correspondence: [email protected]; Tel.: +44-(0)141-331-8721

Academic Editor: Francesco Guarino Received: 17 November 2016; Accepted: 14 February 2017; Published: 27 February 2017

Abstract: Hot desert regions, like Saudi Arabia, are very challenging in terms of building energy consumption. The role of the housing sector in the country is critical as it accounts for half of the total national electricity consumption. It is important to apply sustainable energy concepts in this sector, and the application of Zero-Energy Homes (ZEHs) could be an appropriate option in this regard. In ZEHs, the energy demand needs to be reduced significantly before employing renewable energy, and a way to achieve that is through applying vernacular construction techniques and materials. This study aims to investigate the role of courtyard, mushrabiyah and adobe construction for the development of ZEHs in the five main Saudi climatic zones represented by Dhahran, Guriat, Riyadh, Jeddah and Khamis Mushait. A base house is designed, modelled and compared with measured electricity values. The comparison between the base house and the houses adapted with these techniques and materials is undertaken based on the annual electricity demand and the maximum power demand, and findings reveal that mushrabiyah can reduce them by 4% and 3%, respectively, while adobe can reduce them by 6% and 19%, respectively. Courtyards are found to be not helpful in terms of energy saving.

Keywords: vernacular; courtyard; mushrabiyah; adobe construction; sustainable design; zero-energy residential building; desert climates

1. Introduction The world faces a string of serious energy and environmental challenges. Fossil fuel reserves, presently contributing to over 80% of the world’s total primary energy consumption, for example, are declining; the demand for energy is on a steep rise; and energy prices are fluctuating and rising [1]. The global primary energy consumption is reported to have increased by 29% from 2000 to 2010 and is forecasted to see a further 20% jump by 2020 [2]. While there are growing concerns about the security of energy supplies, environmental security is also one of the biggest threats for the planet. The global energy and environmental scenarios are closely interlinked; the problems with the supply and use of energy are related to wider environmental issues, including global warming. Buildings and the construction industry have a strong interaction with the global energy and environmental scenarios. Buildings are responsible for more than 40% of global energy consumption and over a third of the total global greenhouse gas (GHG) emissions [3]. A building uses energy throughout its life (i.e., from its construction to its demolition). The demand for energy in buildings in their life cycle is both direct and indirect. Direct energy is used for construction, operation, renovation and demolition

Buildings 2017, 7, 17; doi:10.3390/buildings7010017 www.mdpi.com/journal/buildings Buildings 2017, 7, 17 2 of 19 in a building; whereas indirect energy is consumed by a building for the production of material used in its construction and technical installations [4,5]. Given the crucial role buildings can play towards mitigating the energy and environmental issues, the application of energy-efficient and sustainable buildings has received significant attention across the world especially in the residential sector [6]. The residential sector represents 26% and 17% of world energy consumption and carbon dioxide (CO2), respectively [7]. Many forms of sustainable residential buildings, such as Low-energy homes, zero-energy homes, passive houses and plus-energy homes, are being developed across the world, as can be reflected through the number of buildings going for sustainability certification. For instance, the worldwide number of buildings certified by the Leadership in Energy and Environmental Design (LEED) has exceeded 70,000 [8]. In Europe, the Building Research Establishment Environmental Assessment Methodology (BREEAM) has reported more than 8500 projects that have been assessed and certified [9]. Furthermore, in Australia, the number of projects that were assessed and certified by Green Star is 993 [10]. Furthermore, there are currently more than 450 buildings in Japan that were certified by the Comprehensive Assessment System for Built Environment Efficiency (CASBEE) [11]. The present work concerns regarding the development of Zero-Energy Homes (ZEHs). A ZEH is a term widely known for residential buildings with zero net energy consumption and zero CO2 emissions. A more descriptive definition of ZEH is provided by Torcellini et al. as: “a residential building with greatly reduced energy needs through efficiency gains such that the balance of energy needs can be supplied with renewable technologies” [12]. There seems to be an understanding that in ZEHs, off-site renewable energy generation can also be employed in case the on-site renewable systems are not practical or are not sufficient to support the energy requirements of the building. The on-site renewable resources for ZEHs include solar, wind, geothermal and biomass [13]. However, one of the most critical aspects of a ZEH is that its energy needs should be reduced before applying any of the renewable energy technologies. This reduction can be met through combining suitable sustainable design features and energy-efficiency measures [14–16]. The applications of the vernacular techniques and materials have been demonstrated as sustainable options for buildings through their improved energy, environmental and thermal performance [17,18]. One third of the world’s land is located in desert regions [19]. Hot deserts are amongst the most challenging regions in terms of energy consumption in buildings due to the intensive demand for cooling, as they experiences an extreme maximum air temperature of over 50 ◦C[20]. Saudi Arabia is an example of a hot desert country that lies between 31◦ N–17.5◦ N latitude and 50◦ E–36.6◦ E longitude. Saudi Arabia, on the one hand, has experience with vernacular housing, and on the other hand, it has many climatic zones that can represent various hot desert subzones. In addition, its residential sector is set to experience a strong growth in the future as the Saudi population is rising at a rate of 2.5% per year, and only 24% of the Saudi nationals have their own homes [21]. Estimates also suggested that around two-thirds of the population are under the age of 30 years [22]. To meet the needs of the constantly growing population, the country needs to build 230 thousand new homes annually through to 2020 [23]. Currently, the Ministry of Housing is planning to build 500 thousand housing units in the major cities of Saudi Arabia [24]. On the other hand, the residential sector in Saudi Arabia is responsible for 50% of the total national electricity consumption [25]. Therefore, it is essential to apply sustainable energy concepts in this sector, and the application of ZEHs could be an option in this regard. However, in order to develop ZEHs in Saudi Arabia, the current household electricity demand for dwellings in the country needs to be reduced by up to 50% before applying any renewable energy applications [26]. In particular, the international benchmark value for ZEH is about 90 kWh/m2, while it exceeds 175 kWh/m2 in Saudi houses [27–29]. This work aims to explore the role vernacular construction techniques and material can play in developing ZEHs in hot desert climates by taking Saudi Arabia as an example. The key objectives of this study are as below.

• Review the traditional vernacular architecture techniques traditionally practiced in the hot desert climate of Saudi Arabia; Buildings 2017, 7, 17 3 of 19

• Develop the base model of a modern home aspired to be for Saudi residents; • Examine the impacts of individual vernacular features on the energy performance of the developed home under the five climatic zones of Saudi Arabia.

The present work discusses the traditional vernacular architecture, especially in Saudi Arabia, followed by describing the climatic zones in the country. It also presents the main aspects of a virtual (base) house designed based on a detailed questionnaire survey that was undertaken to determine an aspired dwelling in Saudi Arabia. Before adapting the base house with vernacular construction techniques and materials, the electricity performance of the base house itself has been compared with measured electricity values. Thereafter, a comparison between the base house and the houses adapted with vernacular construction techniques and materials has been undertaken based on the annual electricity demand and the maximum power demand.

2. Vernacular Architecture Vernacular architecture is a human construct that results from the interrelations between ecological, economic, material, political and social factors [30]. Through history, many vernacular techniques and materials shaped by the local culture, weather and geographical location were employed around the world [31–36]. In addition, many of these techniques and materials have been utilised in various regions with different climatic conditions and cultural backgrounds. For example, adobe construction (clay or mud) has been used as a main construction material for thousands of years for the construction of buildings in most inhabited regions all over the world [32,35,37–44]. Moreover, some examples of modern buildings built from adobe construction can be found in many countries that have different climatic conditions [41,45,46]. Similarly, many vernacular techniques like courtyards and wind towers (catchers) were applied in modern buildings for passive designs [47]. However, there are some vernacular techniques that have been developed for hot desert climates to seek cooling and daylighting. Alp determines these techniques as courtyards, wind towers, badgeers, domes, air vents, planting, cooling towers, roof ponds, water walls, solar chimneys, induction vents and mushrabiyah/rowshans [39]. The selection of these techniques and materials for such a building is usually dependent on the desired benefits, as well as the local availability of construction materials and skilled labour.

2.1. Vernacular Architecture in Saudi Arabia Over the last few decades, the life style of Saudi nationals has substantially changed, transforming from Bedouinism (desert life) to modern urbanism, affecting the nature of their dwellings. The housing in Saudi Arabia has dramatically transferred from tents and shelters to more permanent housing. Many vernacular architectural techniques, such as wind towers, courtyards, fountains and mushrabiyas, were traditionally used for cooling and daylighting [39]. Typical dwellings had thick walls, floors and roofs for better thermal performance [39]. Vernacular housing units were constructed from local materials that were produced in situ, such as clay (adobe), limestone, coral, stone and wood [48]. Adobe is a vernacular construction material that used to be widely used in the Saudi Arabian vernacular buildings, because of its local availability and its ability to protect from the outside weather. It was the main construction material for walls, floors and roofs within all vernacular types in Saudi Arabia, and although some types do not have adobe walls, all have an adobe roof. It is made from clay, sand, silt and water and is used for construction in hot desert regions. Houses built with adobe construction materials have stood the test of time: there are examples of such buildings that are more than 500 years old [40]. A study by Saleh has shown that, because of its lower thermal conductivity, the energy performance of adobe-based houses in Saudi Arabia is better than stone-built buildings [49]. Typically, the thickness of adobe walls is about 30–50 cm, while it should be at least 45 cm thick to gain the full benefit of the thermal mass, and typically, the roof is 30–40 cm thick [50]. However, with the introduction of concrete and steel building materials, the use of adobe has largely disappeared, despite studies showing that it has superior thermal properties compared to concrete Buildings 2017, 7, 17 4 of 19

Buildings 2017, 7, 17 4 of 20 and steel based structures [38,42,49,50], to the extent that it is difficult to find modern houses in Saudi building materials, the use of adobe has largely disappeared, despite studies showing that it has ArabiaBuildings built 2017 from, 7, 17 adobe. Traditionally, the vernacular architectural types in Saudi Arabia4 of 20 can be superior thermal properties compared to concrete and steel based structures [38,42,49,50], to the categorizedbuildingextent that into materials, it fouris difficult types. the useto find of adobemodern has houses largely in disappeared,Saudi Arabia despbuiltite fr omstudies adobe. showing Traditionally, that it hasthe superiorvernacular thermal architectural properties types compared in Saudi Arabia to concrete can be and categorized steel based into structures four types [38,42,49,50]. , to the 2.1.1. The Arabian Gulf Type extent that it is difficult to find modern houses in Saudi Arabia built from adobe. Traditionally, the Thevernacular2.1.1. ArabianThe Arabian architectural Gulf Gulf type Type types is in typical Saudi Arabia of the can Eastern be categorized Province into offour Saudi types. Arabia, between the Arabian/PersianThe Arabian Gulf Gulf coast type and is the typical Najd of region, the Eastern influenced Province by of neighbouring Saudi Arabia, countries, between thesuch as 2.1.1. The Arabian Gulf Type KuwaitArabian/Persian and Bahrain Gulf[48]. coastIt is a a courtyardnd the Najd house region, constructed influenced from by neighbouring local stone and countries mud (see, such Figure as 1). The conceptKuwaitThe and of Arabian Bahrain the courtyard Gulf [48] . typeIt is was a iscourtyard typical employed house of the in constructed EasternSaudi vernacular Province from local ofhouses stone Saudi and Arabia,to mud seek (see between privacy, Figure the natural1). ventilationArabian/PersianThe concept and daylighting of the Gulf courtyard coast [51 a].nd was Depending the employed Najd region, on in the Saudi influenced size vernacular of the by house neighbouring houses and to the seek countries number privacy,, of such natural floors, as the ventilation and daylighting [51]. Depending on the size of the house and the number of floors, the wall thicknessKuwait and varies Bahrain from [48] 35. It tois a 80 courtyard cm and house roof thickness constructed between from local 30 stone and 65and cm mud [51 (see]. Figure 1). Thewall conceptthickness of var theies courtyard from 35– 80 was cm employedand roof thickness in Saudi between vernacular 30 and houses 65 cm to [51] seek. privacy, natural ventilation and daylighting [51]. Depending on the size of the house and the number of floors, the wall thickness varies from 35–80 cm and roof thickness between 30 and 65 cm [51].

Figure 1. The vernacular house of the Arabian Gulf type. Figure 1. The vernacular house of the Arabian Gulf type. 2.1.2. The Hejaz Type Figure 1. The vernacular house of the Arabian Gulf type. 2.1.2. The Hejaz Type Hejaz region is home to the holy cities Makkah and Madina. The Ottoman Empire had an impact 2.1.2. The Hejaz Type Hejazon shaping region the is Hejaz home type to thewhen holy it ruled cities the Makkah region andduring Madina. the 16th The century Ottoman [48]. The Empire buildings had an here impact on shapingare usuallyHejaz the region Hejaz multi is-storey typehome whento with the holy extensive it ruled cities theMakkah decoration region and andduring Madina. wooden the The 16thOttoman mushrabiyahs century Empire [48 (see had]. TheFigurean impact buildings 2). hereonMushrabiyah, are shaping usually the multi-storey also Hejaz called type rowshan, when with it extensive ruledis a screened the region decoration bay during window and the that 16th wooden allows century mushrabiyahsfor [48] natural. The ventilation buildings (see Figure hereand 2). Mushrabiyah,aredaylighting usually also withoutmulti called-storey affecting rowshan, with the extensive is resident’s a screened decoration privacy bay window and[51,52] wooden. that This allows type mushrabiyahs has for been natural encouraged(see ventilationFigure by2). and daylightingMushrabiyah,pilgrims’ without need alsofor affecting lodgingcalled rowshan, theand resident’sthe seasonalis a screened privacy renting bay [ 51of window, rooms,52]. This orthat typeeven allows haswhole for been floorsnatural encouraged or ventilation buildings by [48]and pilgrims’. The use of adobe is limited, and the main construction materials are wood and stone, mainly due to needdaylighting for lodging without and the affecting seasonal the renting resident’s of rooms, privacy or [51,52] even.whole This type floors has or been buildings encouraged [48]. The by use pilgrims’local availability need for of lodgingstone [48] and. The the thickness seasonal of renting walls, floors of rooms, and roofs or even is often whole between floors 50or andbuildings 60 cm [51][48].. of adobe is limited, and the main construction materials are wood and stone, mainly due to local The use of adobe is limited, and the main construction materials are wood and stone, mainly due to availabilitylocal availability of stone of [48 stone]. The [48] thickness. The thickness of walls, of walls, floors floors and and roofs roofs isis often between between 50 50and and 60 cm 60 [51] cm. [51].

Figure 2. The vernacular house of the Hejaz type [48].

Figure 2. The vernacular house of the Hejaz type [48]. Figure 2. The vernacular house of the Hejaz type [48]. Buildings 20172017,, 77,, 1717 5 of 1920 Buildings 2017, 7, 17 5 of 20 2.1.3. The Najd Type 2.1.3. The Najd Type 2.1.3. The Najd Type The Najd region is the central region of Saudi Arabia, also housing the national capital Riyadh. The Najd region is the central region of Saudi Arabia, also housing the national capital Riyadh. A NajdThe vernacular Najd region house is the can central be typified region ofas Saudisquare Arabia, or rectangular also housing with therarely national more capitalthan one Riyadh. floor A Najd vernacular house can be typified as square or rectangular with rarely more than one floor A[48] Najd. Rooms vernacular are arranged house can around be typified the central as square colonnaded or rectangular courtyard with andrarely have more small than windows one floor [(see48]. [48]. Rooms are arranged around the central colonnaded courtyard and have small windows (see RoomsFigure 3). are The arranged adobe around walls, floors the central and colonnadedroof are between courtyard 50 cm and and have 80 smallcm thick, windows or sometimes (see Figure even3). Figure 3). The adobe walls, floors and roof are between 50 cm and 80 cm thick, or sometimes even Themore adobe [48]. walls, floors and roof are between 50 cm and 80 cm thick, or sometimes even more [48]. more [48].

Figure 3. The vernacular house of the Najd type [53]. Figure 3. The vernacular house of the Najd type [53] [53].. 2.1.4. The Asir Type 2.1.4. The Asir Type The Asir house can be a single or multi-storey, up to four floors. An Asir house with more than The Asir house can be a single or multi-storey, up to four floors. An Asir house with more than The Asir house can be a single or multi-storey, up to four floors. An Asir house2 with more than two floors is usually called Al-Qasabat. It has a relatively small area (about 100 m2 ) and with a height two floors floors is usually called Al-Qasabat.Al-Qasabat. It has a relatively small area (about 100100 mm2) and with a height up to 10 m (see Figure 4) [51,54]. Asir houses are massive in terms of construction material, mainly up to 1010 mm (see(see FigureFigure4 )[4) 51[51,54],54].. Asir Asir houses houses are are massive massive in in terms terms of of construction construction material, material, mainly mainly for for security reasons and to protect against weather [55]. The thickness of walls is from 60–100 cm [51]. forsecurity security reasons reasons and and toprotect to protect against against weather weather [55 [55]]. The. The thickness thickness of wallsof walls is fromis from 60 60 to– 100100 cmcm [[51]51]..

Figure 4. The vernacular house of the Asir type [54]. Figure 4. The vernacular house of the Asir type [54]. Figure 4. The vernacular house of the Asir type [54]. 2.2. Modern Houses in Saudi Arabia 2.2. Modern Houses in Saudi Arabia 2.2. Modern Houses in Saudi Arabia The applications of the vernacular construction techniques and materials have been The applications of the vernacular construction techniques and materials have been demonstratedThe applications as a sustainable of the vernacular option for construction buildings techniques[17,18]. However, and materials these techniques have been demonstratedand materials demonstrated as a sustainable option for buildings [17,18]. However, these techniques and materials asare a not sustainable being employed option foranymore buildings in the [17 Saudi,18]. However,building industry these techniques [56]. In fact, and energy materials-intensive are not heating, being are not being employed anymore in the Saudi building industry [56]. In fact, energy-intensive heating, employedventilating anymore and air conditioning in the Saudi building(HVAC) industrysystems [have56]. Inled fact, to a energy-intensive move away from heating, these sustainable ventilating ventilating and air conditioning (HVAC) systems have led to a move away from these sustainable andfeature airs, conditioning and much of (HVAC) the architectural systems haveknowledge led to built a move up over away the from previous these sustainablecenturies appears features, to features, and much of the architectural knowledge built up over the previous centuries appears to andhave much been forgotten of the architectural [39]. On the knowledge other hand, built the up modern over the houses previous have centuriesthinner walls appears and roofs to have and been are have been forgotten [39]. On the other hand, the modern houses have thinner walls and roofs and are forgottenmade mostly [39]. from On the hollow other hand,blocks the and modern reinforced houses concrete have thinner (see Figure walls and5). Consequently, roofs and are made these made mostly from hollow blocks and reinforced concrete (see Figure 5). Consequently, these mostlybuildings from are hollow mainly blocks dependent and reinforced on HVAC concretesystems (seethat Figureconsume5). Consequently,massive amount theses of buildingsenergy. are buildings are mainly dependent on HVAC systems that consume massive amounts of energy. mainly dependent on HVAC systems that consume massive amounts of energy. Buildings 2017, 7, 17 6 of 19 Buildings 2017, 7, 17 6 of 20

Buildings 2017, 7, 17 6 of 20

Figure 5. Sample modern houses in Saudi Arabia. Figure 5. Sample modern houses in Saudi Arabia. 3. Climatic Zones and Solar Energy in Saudi Arabia 3. Climatic Zones and Solar EnergyFigure 5. in Sample Saudi modern Arabia houses in Saudi Arabia. Saudi Arabia is a large country with an area of 2.3 million square kilometres and a land elevation Saudi3.that Climatic varies Arabia fromZones is 0 a –and large3000 Solar m country above Energy the with in mean Saudi an areasea Arabia level of 2.3 [57] million. With squaresuch a large kilometres land area and and a land variation elevation that varieswith regards from 0to to sea 3000 level, m different above the parts mean of the sea country level have [57]. distinctive With such climatic a large features land area, as are and clearly variation Saudi Arabia is a large country with an area of 2.3 million square kilometres and a land elevation with regardsnoticeable to in sea day level, to day different life. Over parts the of years the country, Saudi Arabia have distinctive has been regionalized climatic features, climatically as are by clearly thatscientific varies and from adminis 0–3000trative m above bodies the inmean several sea wayslevel ;[57] it has. With been such classified a large individually, land area and part variation of the noticeable in day to day life. Over the years, Saudi Arabia has been regionalized climatically by withGulf regardsCooperation to sea Council level, different (GCC) Countries, parts of the part country of the have Arab distinctive World and climatic part of thfeaturese Middle, as Eastare clearly North scientific and administrative bodies in several ways; it has been classified individually, part of the noticeableAfrica (MENA) in day region to day [58] life.. The Over majority the years of these, Saudi classifications Arabia has beendescribed regionalized the country climatically either as by a Gulfscientific Cooperationdesert or andarid adminis Councilregion (trativei.e., (GCC) as onebodies Countries, or twoin several climatic part ways of zones). the; itArab has Köppen been World -classifiedGeiger, and partfor individually, examp of thele, Middle has part classified Eastof the North AfricaGulfthe (MENA) country Cooperation regioninto two Council [58 climatic]. The (GCC majorityzones) Countries,, including of these part the classificationsof thedesert Arab cold World arid described and zone part in the ofthe th countrysouthwesterne Middle either East regionNorth as a desert or aridAfricaand region the (MENA) remaining (i.e., region as as one a desert[58] or. twoThe hot climaticmaridajority zone of zones). [59] these. This classifications Köppen-Geiger, simple description described for is misleading example, the country, has as eitherit classified conceals as a the countrydesertsignificant into or twoarid climatic climaticregion differences (i.e., zones, as one includingamongst or two variousclimatic the desert regions zones). cold ofKöppen the arid country. zone-Geiger, in for the examp southwesternle, has classified region and the country into two climatic zones, including the desert cold arid zone in the southwestern region the remainingSaid et as al. aclassifies desert the hot country arid zone into [six59 climatic]. This zones simple [60] description. Given the fact is misleading,that the Empty as Quarter it conceals and the remaining as a desert hot arid zone [59]. This simple description is misleading, as it conceals significantis an uninhabited climatic differences region; five amongst locations are various selected regions as representative of the country. of the five habited climatic zones: significant climatic differences amongst various regions of the country. SaidDhahran, et al. Guriat, classifies Riyadh, the countryJeddah and into Khamis six climatic Mushait. zones Figure [60 ].6 and Given Table the 1 factshow that the therepresentative Empty Quarter citiesSaid and etthe al. climatic classifies characteristics the country into of these six climatic climatic zones zones. [60] . Given the fact that the Empty Quarter is anis uninhabited an uninhabited region; region; five five locations locations are are selected selected as representative representative of of the the five five habited habited climatic climatic zones zones:: Dhahran,Dhahran, Guriat, Guriat, Riyadh, Riyadh, Jeddah Jeddah and and Khamis Khamis Mushait.Mushait. Figure Figure 66 and and Table Table 1 1show show the the representative representative citiescities and and the climaticthe climatic characteristics characteristics of of these these climaticclimatic zones. zones.

Figure 6. The climatic zones in Saudi Arabia [60].

Table 1. Climatic parameters for the represented locations [61]. Figure 6. The climatic zones in Saudi Arabia [60]. Geographic CoordiFigurenates 6. The climatic zonesAir Temperature in Saudi Arabia [60]. Relative Humidity Location Latitude Longitude Elevation Minimum Maximum Mean Minimum Maximum Mean Table 1. Climatic parameters for the represented locations [61]. (°N) Table(°E) 1. Climatic(m) parameters (°C) for the represented(°C) (°C) locations (%) [61 ]. (%) (%) Dhahran 26.3Geographic 50.1 Coordi nates22 5.0 Air Temperature45.7 25.8 19 Relative Humidity99 57 LocationGuriat 31.3 37.4 502 -3.3 43.9 19.8 12 100 40 Latitude GeographicLongitude CoordinatesElevation Minimum AirMaximum Temperature Mean Minimum RelativeMaximum Humidity Mean Riyadh (24.7°N) (46.8°E) (m)583 (2.2°C) (43.7°C) (25.1°C) (%)10 (%)91 (%)32 JeddahLocation 21.5Latitude 39.2Longitude 33Elevation 13.9Minimum Maximum41.7 27.9Mean Minimum37 Maximum100 65Mean Dhahran 26.3 ◦ 50.1 ◦ 22 5.0 ◦ 45.7◦ 25.8◦ 19 99 57 Khamis ( N) ( E) (m) ( C) ( C) ( C) (%) (%) (%) Guriat 31.318.3 37.442.7 2051502 -2.73.3 43.934.3 19.818.9 1217 100 4051 MushaitRiyadhDhahran 24.7 26.346.8 50.1583 222.2 5.043.7 45.7 25.1 25.8 10 1991 9932 57 JeddahGuriat 21.5 31.339.2 37.433 50213.9-3.3 41.7 43.9 27.9 19.8 37 12100 100 65 40 KhamisRiyadh 24.7 46.8 583 2.2 43.7 25.1 10 91 32 Jeddah18.3 21.542.7 39.22051 332.7 13.934.3 41.7 18.9 27.9 17 37100 100 51 65 Mushait Khamis Mushait 18.3 42.7 2051 2.7 34.3 18.9 17 100 51 Buildings 2017, 7, 17 7 of 19

SaudiBuildings Arabia 2017 has, 7, 17 a healthy potential for renewable energy, especially solar energy. The7 of geographic20 location of SaudiSaudi Arabia Arabia is has ideal a healthy for harnessing potential for solar renewable energy. energy According, especially to the solar Saudi energy. Solar The Radiation Atlas, thegeographic country location annually of Saudi receives Arabia aroundis ideal for 3245 harnessing sunshine solar energy. hours According accounting to the for Saudi an Solar annual solar radiationRadiation figure ofAtlas, over the 2200country kWh/m annually2 receives[62]. In around the five 3245 climatic sunshine zones hours accounting of Saudi for Arabia, an annual the weather solar radiation figure of over 2200 kWh/m2 [62]. In the five climatic zones of Saudi Arabia, the weather records have shown that the annual global solar radiation level ranges from 1715 kWh/m2 (in Dhahran) to records have shown that the annual global solar radiation level ranges from 1715 kWh/m2 (in 2 2275 kWh/mDhahran)(in toJeddah), 2275 kWh/m while2 (in the Jeddah) number, while of sunshine the number hours of sunshine varies from hours 2698 varies (in from Khamis 2698 (in Mushait) to 2 3397 (in Riyadh)Khamis Mushait) [61]. The to monthly 3397 (in Riyadh) data showed [61]. The that monthly the solar data radiation showed that level the varies solar radiation between level 170 kWh/m (in Dhahran)varies and between 250 170 kWh/m kWh/m2 2(in (in Guriat)Dhahran) during and 250 the kWh/m summer2 (in Guriat) months during and the between summer 90months kWh/m 2 (in 2 2 Guriat) toand 190 between kWh/m 90 kWh/m2 (in Khamis (in Guriat) Mushait) to 190 kWh/m during (in the Khamis winter Mushait) months during (see the Figure winter7 ).months The monthly (see Figure 7). The monthly sunshine hours were observed to vary from 165 (in Khamis Mushait) to sunshine383 hours (in Riyadh) were observedduring the tosummer vary months from 165and (infrom Khamis 181 (in Guriat) Mushait) to 236 to (in 383 Riyadh) (in Riyadh) during the during the summer monthswinter months and from(see Figure 181 (in 7). Guriat) to 236 (in Riyadh) during the winter months (see Figure7).

Dhahran Guriat Riyadh Dhahran Guriat Riyadh

Jeddah Khamis Mushait Jeddah Khamis Mushait

) ) 2 300 450 400 250 350

200 300 250 150 200

100 150 100 50

50 Monthly Average for Sunshine Duration (hr/month) Duration Sunshine for Average Monthly

Monthly Average for Global (kWh/m Global Average Radiation Solar Monthlyfor 0 0

JUL SEP

JUL

SEP

JAN FEB JUN

JAN JUN

FEB

APR

APR

OCT DEC

OCT DEC

AUG NOV

AUG NOV

MAR

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MAY MAY Month Month

Figure 7.FigureThe monthly7. The monthly global global solar solar radiation radiation inin the five five main main climatic climatic zones zones of Saudi of Arabia Saudi [61] Arabia. [61].

In order to examine the electricity generation from solar photovoltaics (PV), a sensitivity analysis In orderwas applied to examine using the hypothetical electricity PV generation ratings in all from locations. solar The photovoltaics used software (PV), to achieve a sensitivity that is analysis was appliedIntegrated using Environmental hypothetical Solutions PV ratings all locations. (IES The ). used The software selected type to achieve of PV that is system is monocrystalline with 15% nominal efficiency. The results showed that the annual electricity Integrated Environmental Solutions (IES ). The selected type of PV generation from 1.0 kW PV is between 1400 kWh/m2 and 2000 kWh/m2 depending on the location system is(see monocrystalline Figure 8). with 15% nominal efficiency. The results showed that the annual electricity generation from 1.0 kW PV is between 1400 kWh/m2 and 2000 kWh/m2 depending on the location (see FigureBuildings8). 2017, 7, 17 8 of 20

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15,000

10,000

5,000 Annual Electricity Generation (kWh/m 0 0 5 10 15 20 PV rating (kW) FigureFigure 8. The 8. electricity The electricity generation generation from from various solar solar PVs PVs for all for locations. all locations. 4. The Study Models The present work aims to examine the energy performance of some vernacular construction techniques and material in the five Saudi climatic zones. In a previous work, the authors explored, through a questionnaire survey, the attractiveness of some vernacular techniques that were employed in Saudi vernacular houses to the Saudi nationals [63]. The results of this work revealed that courtyard and mushrabiyah are the most attractive vernacular techniques to the participants in comparison to other techniques like dome structure and cooling towers [63]. Thus, the current work concerns examining the energy performance of the courtyard and mushrabiyah adapted in a modern Saudi dwelling. The courtyard is a vernacular technique that has been used in Arabian Gulf and Najd types; while mushrabiyah has been employed as a vernacular technique in the Hejaz type. In addition, the adobe construction was selected for this work as the main construction material due to the better thermal performance in comparison to other vernacular construction materials used in Saudi Arabia. It was the main construction material for walls, floors and roofs within all vernacular types in Saudi Arabia. In order to examine these techniques and material, a virtual (base) house was modelled in all concerned locations using IES . The weather files used in the simulation were extracted from Meteonorm 5.1. Meteonorm generates hourly time series for the desired location on the basis of well- validated models and data banks of tens of years [61].

4.1. Base Model The base house in this study was designed on the basis of a detailed questionnaire survey that was undertaken to determine the aspired dwelling in Saudi Arabia. The participants were selected randomly from different regions covering all climatic zones in Saudi Arabia. Survey participants were asked about the type, size, number of floors and functional spaces of their possible future (inspired) dwelling. The survey was conducted between December 2011 and February 2012 employing web-based and in-person approaches. A total of 453 responses were received from dwelling users employing web-based and in-person approaches. The majority of the questionnaire survey participants have chosen their targeted future home to be a two-storey detached house (villa) with a total site area between 400 m2 and 600 m2. It consists of a master bedroom, three regular bedrooms, four bathrooms and toilets, two guestrooms (one each for men and women), two kitchens (one internal and the other is external), a living room, a dining room, an office, a multi-purpose room, a laundry and storage. Some of the main features of the designed home are highlighted in Figure 9 and Table 2. Buildings 2017, 7, 17 8 of 19

4. The Study Models The present work aims to examine the energy performance of some vernacular construction techniques and material in the five Saudi climatic zones. In a previous work, the authors explored, through a questionnaire survey, the attractiveness of some vernacular techniques that were employed in Saudi vernacular houses to the Saudi nationals [63]. The results of this work revealed that courtyard and mushrabiyah are the most attractive vernacular techniques to the participants in comparison to other techniques like dome structure and cooling towers [63]. Thus, the current work concerns examining the energy performance of the courtyard and mushrabiyah adapted in a modern Saudi dwelling. The courtyard is a vernacular technique that has been used in Arabian Gulf and Najd types; while mushrabiyah has been employed as a vernacular technique in the Hejaz type. In addition, the adobe construction was selected for this work as the main construction material due to the better thermal performance in comparison to other vernacular construction materials used in Saudi Arabia. It was the main construction material for walls, floors and roofs within all vernacular types in Saudi Arabia. In order to examine these techniques and material, a virtual (base) house was modelled in all concerned locations using IES . The weather files used in the simulation were extracted from Meteonorm 5.1. Meteonorm generates hourly time series for the desired location on the basis of well-validated models and data banks of tens of years [61].

4.1. Base Model The base house in this study was designed on the basis of a detailed questionnaire survey that was undertaken to determine the aspired dwelling in Saudi Arabia. The participants were selected randomly from different regions covering all climatic zones in Saudi Arabia. Survey participants were asked about the type, size, number of floors and functional spaces of their possible future (inspired) dwelling. The survey was conducted between December 2011 and February 2012 employing web-based and in-person approaches. A total of 453 responses were received from dwelling users employing web-based and in-person approaches. The majority of the questionnaire survey participants have chosen their targeted future home to be a two-storey detached house (villa) with a total site area between 400 m2 and 600 m2. It consists of a master bedroom, three regular bedrooms, four bathrooms and toilets, two guestrooms (one each for men and women), two kitchens (one internal and the other is external), a living room, a dining room, an office, a multi-purpose room, a laundry and storage. Some of the main features of the designed home are highlighted in Figure9 and Table2.

Table 2. Key features of the base house.

House Feature Description Ground Floor Area 214.1 m2 First Floor Area 214.1 m2 Total Glazed Area 55.2 m2 Total External wall Area 446.8 m2 Total Roof Area 228.1 m2 Lettable Area 76% Circulation Area 24% Window-to-Wall Ratio (WWR) 10% Construction Materials (25 mm Stucco + 75 mm Concrete Block + 50 mm Polystyrene + 75 mm Concrete Block + External Wall 25 mm Stucco) U-Value = 0.49 W/m2·K Internal Wall (25 mm Stucco + 100 mm Concrete Block + 25 mm Stucco) U-Value = 2.50 W/m2·K (25 mm Terrazzo + 25 mm Mortar + 4 mm Bitumen Layer + 150 mm Cast Concrete + Roof 200 mm Concrete Block + 25 mm Stucco + 15 mm Gypsum Board) U-Value = 1.74 W/m2·K (20 mm Granite + 25 mm Mortar + 150 mm Cast Concrete + 200 mm Concrete Block + Ceiling 25 mm Stucco + 15 mm Gypsum Board) U-Value = 1.57 W/m2·K Ground Floor (15 mm Granite + 25 mm Mortar + 100 mm Cast Concrete) U-Value = 0.48 W/m2·K Windows Aluminium Window with thermal break, U-Value = 3.43 W/m2·K External Doors External Door (Aluminium Door—Aluminium frame with thermal break) U-Value = 6.42 W/m2·K Internal Doors Internal Door (40 mm Wooden door) U-Value = 2.60 W/m2·K Buildings 2017, 7, 17 9 of 19

Table 2. Cont.

Systems HVAC System Min. Flow rate = 8 L/s/person for Mini Split System Tungsten Halogen Lamps at (Bathrooms, Toilets, and Kitchens), and Lighting System Compact Fluorescent Lamps at (All other Spaces) Domestic Hot Water 190 litter (90% Delivery Efficiency) Auxiliary ventilation Kitchen = 50 L/s, Toilets and bathrooms = 25 L/s Kitchen Appliances Maximum Power Consumption = 30 W/m2 [64] Living Zone Appliances Maximum Power Consumption = 7 W/m2 [64] Sleeping Zone Appliances Maximum Power Consumption = 7 W/m2 [64] Guest Zone Appliances Maximum Power Consumption = 5 W/m2 [64] Heating Simulation set-point 20.0 ◦C ◦ BuildingsCooling 2017 Simulation, 7, 17 set-point 24.0 C 9 of 20

Figure 9 9.. Model and floor floor plans for the base house.

Table 2. Key features of the base house. The base house designed in this work was modelled in the five climatic zones of Saudi Arabia. Since theHouse electricity Feature performance of buildings is influencedDescrip by theirtion orientation, the modelled home Ground Floor Area 214.1 m2 was simulated at each location for eight different orientations covering the 360◦ compass range in First Floor Area 214.1 m2 ◦ steps ofTotal 45 Glazed. The orientationArea was optimized on the basis of the55.2 minimum m2 annual household electricity requirement.Total External Generally, wall Area the orientation of buildings is found446.8 to influence m2 the electricity performance of dwellingsTotal Roof by less Area than 0.5%. The optimum orientation was found228.1 m2 to be the north, similar to Figure9, Lettable Area 76% for all locations, except for Jeddah, where it is found to be the east. The simulation results revealed Circulation Area 24% thatWindow Dhahran-to-Wall and Ratio Jeddah (WWR) are the most challenging locations in10% terms of annual electricity demand and the peak power demand due to theirConstruction higher air Materials temperature and relative humidity especially External Wall (25 mm Stucco + 75 mm Concrete Block + 50 mm Polystyrene + 75 mm Concrete Block + 25 mm Stucco) U-Value = 0.49 W/m2·K Internal Wall (25 mm Stucco + 100 mm Concrete Block + 25 mm Stucco) U-Value = 2.50 W/m2·K Roof (25 mm Terrazzo + 25 mm Mortar + 4 mm Bitumen Layer + 150 mm Cast Concrete + 200 mm Concrete Block + 25 mm Stucco + 15 mm Gypsum Board) U-Value = 1.74 W/m2·K Ceiling (20 mm Granite + 25 mm Mortar + 150 mm Cast Concrete + 200 mm Concrete Block + 25 mm Stucco + 15 mm Gypsum Board) U-Value = 1.57 W/m2·K Ground Floor (15 mm Granite + 25 mm Mortar + 100 mm Cast Concrete) U-Value = 0.48 W/m2·K Windows Aluminium Window with thermal break, U-Value = 3.43 W/m2·K External Doors External Door (Aluminium Door—Aluminium frame with thermal break) U-Value = 6.42 W/m2·K Internal Doors Internal Door (40 mm Wooden door) U-Value = 2.60 W/m2·K Systems HVAC System Min. Flow rate = 8 L/s/person for Mini Split System Lighting System Tungsten Halogen Lamps at (Bathrooms, Toilets, and Kitchens), and Compact Fluorescent Lamps at (All other Spaces) Domestic Hot Water 190 litter (90% Delivery Efficiency) BuildingsBuildings 2017 2017, ,7 7, ,1 177 1010 of of 20 20

AuxiliaryAuxiliary ventilation ventilation KKitchenitchen = = 50 50 L L/s,/s, Toilets Toilets and and bathrooms bathrooms = = 25 25 L L/s/s KitchenKitchen Appliances Appliances MaximumMaximum Power Power Consumption Consumption = = 30 30 W/ W/mm2 2[64] [64] LivingLiving Zone Zone Appliances Appliances MaximumMaximum Power Power Consumption Consumption = = 7 7 W/ W/mm2 2[64] [64] SleepingSleeping Zone Zone Appliances Appliances MaximumMaximum Power Power Consumption Consumption = = 7 7 W/ W/mm2 2[64] [64] GuestGuest Zone Zone Appliances Appliances MaximumMaximum Power Power Consumption Consumption = = 5 5 W/ W/mm2 2[64] [64] HeatingHeating Simulation Simulation set set--pointpoint 20.020.0 °C °C CoolingCooling Simulation Simulation set set--pointpoint 24.024.0 °C °C

TheThe basebase househouse designeddesigned inin thisthis workwork waswas modelledmodelled inin thethe fivefive climaticclimatic zoneszones ofof SaudiSaudi Arabia.Arabia. SinceSince thethe electricityelectricity performanceperformance ofof buildingsbuildings isis influencedinfluenced byby theirtheir orientation,orientation, thethe modelledmodelled homehome waswas simulatedsimulated atat eacheach locationlocation forfor eighteight differentdifferent orientatioorientationsns coveringcovering thethe 360°360° compasscompass rangerange inin stepssteps of of 45°. 45°. The The orientation orientation was was optimized optimized on on the the basis basis of of the the minimum minimum annual annual household household electricity electricity requirement.requirement. Generally, Generally, the the orientation orientation of of buildings buildings is is found found to to influence influence the the electricity electricity performance performance ofof dwellings dwellings b byy less less than than 0.5%. 0.5%. The The optimum optimum orientation orientation was was found found to to be be the the north, north, similar similar to to Figure Figure 9 9, , forBuildingsfor allall locationslocations2017, 7, 17, , exceptexcept forfor JeddahJeddah, , wherewhere itit isis foundfound toto bebe thethe easteast. . TheThe simulationsimulation resultsresults revealedrevealed10 of 19 thatthat DhahranDhahran andand JeddahJeddah areare thethe mostmost challengingchallenging locationslocations inin termsterms ofof annualannual electricityelectricity demanddemand andand thethe peakpeak powerpower demanddemand duedue toto theirtheir higherhigher airair temperaturetemperature andand relativerelative humidityhumidity especiallyespecially duringduring the the summer summer months months (see (see Figure FiguresFiguress 1010 andandand 11).1111).). The The simulation simulation results results revealed revealed that that the the annual annual 2 electricityelectricity demand demand demand for for for houses houses houses in Dhahran,in in Dhahran, Dhahran, Guriat, Guriat, Guriat, Riyadh, Riyadh, Riyadh, Jeddah Jeddah Jeddah and Khamis and and Khamis Khamis Mushait Mushait Mushait is 129 kWh/m is is 129 129 , 2 2 2 2 kWh/m91kWh/m kWh/m22, ,91 91 kWh/m ,kWh/m 112 kWh/m22, ,112 112 kWh/m kWh/m, 165 kWh/m22, ,165 165 kWh/m kWh/mand 6022 and and kWh/m 60 60 kWh/m kWh/m, respectively.22, ,respectively. respectively.

DhahranDhahran GuriatGuriat RiyadhRiyadh JeddahJeddah KhamisKhamis Mushait Mushait 99

88

77

66

55

44

33

22

11

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MAY MAY MonthMonth FigureFigure 10. 10.10. MonthlyMonthlyMonthly elect electricityelectricityricity consumption consumption for for the the base base house house based based on on the thethe optimum optimumoptimum orientation orientationorientation in in thethethe five fivefive climatic climaticclimatic zones. zones.zones.

4545

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Annaul peak power demand (kW) demand powerpeak Annaul Annaul peak power demand (kW) demand powerpeak Annaul 55

00 DhahranDhahran GuriatGuriat RiyadhRiyadh JeddahJeddah KhamisKhamis MushaitMushait LocationLocation FigureFigure 11. 11.11. AnnualAnnual peak peak power power demand demand for for the the base base house house based based on on the thethe optimum optimumoptimum orientation orientation in in the the fivefivefive climatic climatic zones. zones.zones.

Before undertaking the investigation, the electricity performance of the base house was compared with measured electricity values gathered from 20 dwellings that were similar to the base house in terms of air-conditioning (A/C) system, thermal insulation, type of windows and energy source for cooking. The electricity data for these homes, located in the Dhahran Zone, were obtained from their monthly electricity bills for period between January 2012 and December 2012. Dhahran is a main representative city in the Eastern Province, which has the highest maximum temperature among all climatic zones (see Table1). The Eastern Province is a vital region in Saudi Arabia because of its large land area, accounting for almost one third of the entire country. Due to its harsh weather conditions, it is one of the most challenging areas in Saudi Arabia in terms of residential electricity demand as indicated in Figures 10 and 11. The annual electricity consumption for the base house in Dhahran was found to be 129 kWh/m2, which is in close proximity with the average for the 20 dwellings in the same location; the mean and median electricity consumption values for the survey dwellings Buildings 2017, 7, 17 11 of 19 are 147 kWh/m2 and 137 kWh/m2, respectively (see Table3). In terms of the monthly electricity consumption, the findings of this study have shown a clear correlation between the values for the base house and the surveyed dwellings in most of the months (see Figure 12). However, the monthly electricity consumption for the surveyed dwellings is a bit higher during the cold season, and this could be because the winter in 2012 was colder in comparison to the extracted weather file from Meteonorm 5.1 [65].

Table 3. Conditioned area and electricity consumption for the base and surveyed houses.

Conditioned Area Electricity Consumption Electricity Consumption House (m2) (kWh/Year) (kWh/m2/Year) Base 428 55,222 129 1 180 23,434 130 2 180 14,986 83 3 180 22,789 127 4 80 14,031 175 5 400 71,763 179 6 460 68,886 150 7 100 13,649 137 8 175 30,536 175 9 80 9770 122 10 360 63,196 176 11 400 47,394 119 12 135 19,963 148 13 125 23,491 188 14 120 15,202 127 15 200 54,983 275 16 110 15,202 138 17 130 21,356 164 18 240 29,069 121 19 365 43,031 118 Buildings 2017, 7,20 17 150 12,401 83 12 of 20

Base House Surveyed Houses

) 22

m² 20 18 16 14 12 10 8 6 4 2

0 Monthly Electricity Consumption (kWh/ Consumption Electricity Monthly

Month FigureFigure 12.12. MonthlyMonthly electricityelectricity consumptionconsumption forfor thethe basebase househouse andand surveyedsurveyed houses.houses.

4.2.4.2. CourtyardCourtyard ModelModel TheThe basebase house house in in this this study study was was adapted adapted with with an internalan internal courtyard courtyard that hasthat a floorhas a areafloor of area 16 m of2, as16 shownm2, as inshown Figure in 13 Figure. This 13. has This revealed has revealed a decreasing a decreasing in the house in the floor house area, floor roof area, area roof and area external and wallsexternal area walls by 7.5%, area 6%by 7.5%, and 22%, 6% and respectively. 22%, respectively. On the other On hand,the other through hand, incorporating through incorporating 38 m2 of window38 m2 of areawindow to the area courtyard, to the courtyard, the house the window-to-wall house window ratio-to-wall has increasedratio has increased by 2%. by 2%.

Figure 13. Floor plans and 3D isometric view of the base house after incorporating the courtyard. Buildings 2017, 7, 17 12 of 20

Base House Surveyed Houses

) 22

m² 20 18 16 14 12 10 8 6 4 2

0 Monthly Electricity Consumption (kWh/ Consumption Electricity Monthly

Month Figure 12. Monthly electricity consumption for the base house and surveyed houses.

4.2. Courtyard Model The base house in this study was adapted with an internal courtyard that has a floor area of 16 m2, as shown in Figure 13. This has revealed a decreasing in the house floor area, roof area and Buildingsexternal2017 walls, 7, 17 area by 7.5%, 6% and 22%, respectively. On the other hand, through incorporating12 of 19 38 m2 of window area to the courtyard, the house window-to-wall ratio has increased by 2%.

Figure 13. Floor plans and 3D isometric view of the base house after incorporating the courtyard. Figure 13. Floor plans and 3D isometric view of the base house after incorporating the courtyard.

4.3. Mushrabiyah Model Buildings 2017, 7, 17 13 of 20 Subsequently, all windows in the typical house were featured with mushrabiyah, as indicated 4.3. Mushrabiyah Model in Figure 14. Mushrabiyah is an efficient passive design feature that controls the passage of air current to reduceSubsequently, temperature, all windows as it in reduces the typical the house reflected were featured heat and with solar mushrabiyah radiation, as and indicated allows air to in Figure 14. Mushrabiyah is an efficient passive design feature that controls the passage of air current pass through freely [52]. Its role towards reducing electricity demand can be understood from the to reduce temperature, as it reduces the reflected heat and solar radiation and allows air to pass controlthrough of direct freely solar [52] radiation. Its role towards on windows reducing and electricity the help demand in utilising can be understood both daylighting from the control and natural ventilation.of direct It controlssolar radiation the on passage windows of and direct the help lights in utilising and reduces both daylighting the air temperature. and natural ventilation. Additionally, the mushrabiyahIt controls the was passage originally of direct used lights asand a reduce waters the drinking air temperat place;ure. therefore, Additionally, it hasthe mushrabiyah the ability also of increasingwas the originally humidity. used as a water drinking place; therefore, it has the ability also of increasing the humidity.

Figure 14. 3D isometric of the base house featured with mushrabiyahs. Figure 14. 3D isometric of the base house featured with mushrabiyahs. 4.4. Adobe Construction Model Furthermore, adobe construction has been chosen for this study due to better thermal performance in comparison to the stone [49]. Tables 4 and 5 provide the thermal properties of the adobe construction and the materials used in adobe construction.

Table 4. Thermal properties of the materials used in adobe construction.

Thickness Conductivity Density Specific Heat Capacity Material Source (m) (W/(m·K)) (kg/m3) (J/(kg·K)) Adobe wall 0.500 0.730 1650 1000 [66] Adobe roof/slab 0.300 0.730 1650 1000 [66] Adobe with straw 0.025 0.180 440 900 [67] Palm tree fronds-mat 0.015 0.166 600 1200 [68]

Table 5. Description and U-Values for the adobe construction systems.

System Description Roof (4 mm bitumen layer + 300 mm adobe roof + 15 mm palm tree fronds-mat + 15 mm gypsum board) U-Value = 1.35 W/m2·K External wall (25 mm adobe with Straw + 500 mm adobe wall + 25 mm Adobe with straw) U-Value = 0.90 W/m2·K Slab on-grade (20 mm granite + 25 mm mortar + 300 mm adobe slab) U-Value = 0.41 W/m2·K Internal wall (25 mm adobe with Straw + 500 mm adobe wall + 25 mm adobe with Straw) U-Value = 0.83 W/m2·K Internal (20 mm granite + 25 mm mortar + 300 mm adobe slab + 15 mm Palm tree floor/ceiling fronds-mat + 15 mm gypsum board) U-Value = 1.18 W/m2·K

5. Results The simulation results of adapting the base house with a courtyard revealed an increase of annual electricity demand in all of the examined locations (see Table 6). However, the mushrabiyah house has shown savings in demand for electricity on an annual basis in comparison to the base and Buildings 2017, 7, 17 13 of 19

4.4. Adobe Construction Model Furthermore, adobe construction has been chosen for this study due to better thermal performance in comparison to the stone [49]. Tables4 and5 provide the thermal properties of the adobe construction and the materials used in adobe construction.

Table 4. Thermal properties of the materials used in adobe construction.

Thickness Conductivity Density Specific Heat Capacity Material Source (m) (W/(m·K)) (kg/m3) (J/(kg·K)) Adobe wall 0.500 0.730 1650 1000 [66] Adobe roof/slab 0.300 0.730 1650 1000 [66] Adobe with straw 0.025 0.180 440 900 [67] Palm tree fronds-mat 0.015 0.166 600 1200 [68]

Table 5. Description and U-Values for the adobe construction systems.

System Description (4 mm bitumen layer + 300 mm adobe roof + 15 mm palm tree fronds-mat + Roof 15 mm gypsum board) U-Value = 1.35 W/m2·K (25 mm adobe with Straw + 500 mm adobe wall + 25 mm Adobe with straw) External wall U-Value = 0.90 W/m2·K Slab on-grade (20 mm granite + 25 mm mortar + 300 mm adobe slab) U-Value = 0.41 W/m2·K (25 mm adobe with Straw + 500 mm adobe wall + 25 mm adobe with Straw) Internal wall U-Value = 0.83 W/m2·K (20 mm granite + 25 mm mortar + 300 mm adobe slab + 15 mm Palm tree Internal floor/ceiling fronds-mat + 15 mm gypsum board) U-Value = 1.18 W/m2·K

5. Results The simulation results of adapting the base house with a courtyard revealed an increase of annual electricity demand in all of the examined locations (see Table6). However, the mushrabiyah house has shown savings in demand for electricity on an annual basis in comparison to the base and courtyard houses within all locations (see Table6). Similarly, the adobe construction house has shown more savings in demand for electricity compared to all of the developed models, as indicated in Table6.

Table 6. The annual electricity demand in kWh/m2.

Location Base Courtyard Mushrabiyah Adobe Construction Dhahran 129 136 125 123 Guriat 92 95 90 87 Riyadh 112 118 109 106 Jeddah 165 175 158 158 Khamis Mushait 60 61 59 58

The simulated monthly electricity consumptions for the adapted models (i.e., courtyard, mushrabiayah and adobe construction) in each of the climatic zones are shown in Figure 15. It is clear that, in every case, the base model with modern construction showed higher demand for electricity during at least part of the year in comparison to houses with mushrabiyah and adobe construction. In particular, adapting the house with either mushrabiayah or adobe construction has shown a reduction in the demand for electricity during the summer months from May–September (see Figure 15). Mushrabiyahs have contributed to reducing the annual electricity demand by between 1% and 4% in Khamis Mushait and Jeddah, respectively, while adobe construction has helped in reducing the electricity demand by 3%–6% in Khamis Mushait and Riyadh, respectively (see Table6 and Figure 16). The simulation results revealed that, due to the extreme hot climates of the examined locations, the courtyard has increased the annual electricity demand by around 4% in all locations with the exception of Khamis Mushait, the location with Buildings 2017, 7, 17 14 of 19 the lowest annual electricity demand, where the results have shown a clear correlation for the monthly electricity demand between the base and courtyard houses (see Table6, Figures 15 and 16 ). In terms of the peak power demand, the results revealed that mushrabiyah can contribute to reducing the demand by around 3% in all locations while adobe construction can reduce the demand by between 5% in Dhahran to 19% in Khamis Mushait (see Table7). In fact, the energy reductions from these vernacular Buildings 2017, 7, 17 15 of 20 techniques and construction materials are mainly associated with the demand for lighting and HVAC systems. In particular, the adaptationTable 8. The annual of mushrabiyah demand for HVAC into load the in basekWh/m house2. has shown a reduction in the HVAC load byLocation almost 4%–6%Base in allCourtyard locations; Mushrabiyah however, the adaptationAdobe Construction of adobe construction has shown a reductionDhahran between 6%84.47 in Jeddah92.34 to 13% in80.80 Khamis Mushait78.22 for the HVAC system (see Table8). Additionally,Guriat the adaptation47.02 of the52.12 courtyard has45.33 reduced the demand42.04 for lighting by 8% in all locations. On theRiyadh other hand, the67.60 courtyard 74.70 has contributed64.91 to increasing61.17 the demand for the HVAC Jeddah 120.79 131.52 113.90 113.56 system between 9% in Jeddah to 11% in Khamis Mushait (see Table8). Khamis Mushait 15.80 17.55 14.94 13.71

(a) Dhahran (b) Guriat Base Courtyard Base Courtyard Mushrabiyah Adobe construction 22 Mushrabiyah Adobe construction 22

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Figure 15.FigureThe 15. annualThe annual electricity electricity performance performance of the the base, base, courtyard, courtyard, mushrabiyah mushrabiyah and adobe and adobe constructionconstruction houses houses in (a )in Dhahran; (a) Dhahran (b; )(b Guriat;) Guriat; ( c(c)) Riyadh;Riyadh; (d (d) Jeddah;) Jeddah; and and (e) Khamis (e) Khamis Mushait. Mushait. Buildings 2017, 7, 17 15 of 19 Buildings 2017, 7, 17 16 of 20

Mushrabiyah Courtyard Adobe Construction

6% 5% 4% 3% 2% 1% 0% -1%

-2% electricitydemand -3% -4%

-5% The percentage of the annual saving in savingannual the of percentage The -6% Dhahran Guriat Riyadh Jeddah Khamis Mushait Location FigureFigure 16.16.The The annuallyannually saved saved electricity electricity by by adapting adapting vernacular vernacular techniques techniques and and adobe adobe construction construction in allin locations.all locations.

6. Discussion and ConclusionsTable 7. The annual peak power demand in W/m2. Given the energy and environmental challenges, residential buildings can play a significant role Location Base Courtyard Mushrabiyah Adobe Construction in improving the situation. Due to their high temperatures, deserts are among the most challenging regions whenDhahran it comes to residential 85.6 energy 90.1consumption. In this 83.2 study, Saudi Arabia 81.7 was undertaken Guriat 57.6 60.4 56.0 51.5 as an exampleRiyadh as it can represent 62.5 various desert 65.2 climatic zones. 61.0 The selected locations 57.8 that represent the Saudi Jeddahclimatic zones in this 90.6 study are Dhahran, 95.4 Guriat, Riyadh, 88.5 Jeddah and Khamis 82.4 Mushait. The SaudiKhamis resident Mushaitial sector suffers 36.3 from high 37.2demand for electricity 35.5 to meet the comfort 29.4 and life style needs for residents. Therefore, it is crucial to consider sustainable energy concepts in this sector, and the application of ZEHsTable can 8.beThe an annualoption demand in this forrespect. HVAC Verna load incular kWh/m construction2. techniques and materials have traditionally been used in this part of the world, though they have ceased to be employedLocation in the wake of Basethe modern Courtyard construction boom Mushrabiyah in recent decades. Adobe This Construction study aims to investigateDhahran the role of courtyard, 84.47 mushrabiyah 92.34 and adobe construction 80.80 in developing 78.22 ZEHs in all climatic zonesGuriat of Saudi Arabia. 47.02 52.12 45.33 42.04 The comparisonRiyadh for the 67.60 three models (courtyard, 74.70 mushrabiyah 64.91 and adobe construction) 61.17 with the Jeddah 120.79 131.52 113.90 113.56 base modelKhamis for Mushait each location 15.80 in this study is 17.55 based on two parameters: 14.94 the annual electricity 13.71 demand, as a measure of energy efficiency, and the maximum power demand, as an important parameter in designing the renewable technologies for any ZEH. It was observed from this study that the annual 6. Discussion and Conclusions electricity consumption for houses in Dhahran, Guriat, Riyadh, Jeddah and Khamis Mushait is 129 kWh/mGiven2, 91 the kWh/m energy2, and112 kWh/m environmental2, 165 kWh/m challenges,2 and residential60 kWh/m2 buildings, respectively. canplay Thisa leads significant to the rolefact inthat improving the household the situation. electricity Due demand to their high needs temperatures, to be reduced deserts significantly are among, especially the most inchallenging Dhahran, regionsRiyadh whenand Jeddah it comes, as to it residentialis higher than energy the consumption.international Inbenchmark this study, values Saudi for Arabia ZEH was, which undertaken is about as90 ankWh/m example2. as it can represent various desert climatic zones. The selected locations that represent the SaudiThe findings climatic of zones this work in this have study showed are Dhahran, electricity Guriat, savings Riyadh, by the adaptation Jeddah and of Khamismushrabiyah Mushait. and Theadobe Saudi construction residential material sector suffersin a modern fromhigh Saudi demand dwelling for in electricity terms of tototal meet electricity the comfort demand and and life stylemaximum needs power for residents. demand. Therefore, The use of it ismushrabiyah crucial to consider can contribute sustainable in reducing energy conceptsthe electricity in this demand sector, andand themaximum application power of demand ZEHs can by beup an to option4% and in 3% this, respectively. respect. Vernacular The findings construction also revealed techniques that the andmushrabiyahs materials havecould traditionally save up to 6% been of the used HVAC in this load. part Interestingly, of the world, the though maximum they electricity have ceased saving to beby employedmushrabiyah in the was wake observed of the in modern Jeddah construction, where it is booman aspect in recent of its decades.vernacular This type. study Adobe aims is to a investigatethermally-efficient, the role sustainable of courtyard, and mushrabiyah durable material and adobewidely construction available locally. in developing It is inexpensive, ZEHs in easy all climaticto produce zones and of Saudirequires Arabia. fewer manufacturing skills and less production energy compared to the currentlyThe comparison widely-used for theconstruction three models materials (courtyard, (i.e., mushrabiyahconcrete and and steel). adobe Particularly, construction) the with adobe the baseconstruction model for can each redu locationce the annual in this studyelectricity is based demand on two and parameters: peak power the demand annual by electricity up to 6% demand,and 19%, asrespectively. a measure It of can energy also reduce efficiency, the HVAC and the load maximum by up to power 13%. demand, as an important parameter in designingThe simulation the renewable results technologies revealed that, for due any to ZEH. the harsh It was weather observed conditions from this of study the examined that the locations, the courtyard has increased the annual electricity demand by around 4% in all locations Buildings 2017, 7, 17 16 of 19 annual electricity consumption for houses in Dhahran, Guriat, Riyadh, Jeddah and Khamis Mushait is 129 kWh/m2, 91 kWh/m2, 112 kWh/m2, 165 kWh/m2 and 60 kWh/m2, respectively. This leads to the fact that the household electricity demand needs to be reduced significantly, especially in Dhahran, Riyadh and Jeddah, as it is higher than the international benchmark values for ZEH, which is about 90 kWh/m2. The findings of this work have showed electricity savings by the adaptation of mushrabiyah and adobe construction material in a modern Saudi dwelling in terms of total electricity demand and maximum power demand. The use of mushrabiyah can contribute in reducing the electricity demand and maximum power demand by up to 4% and 3%, respectively. The findings also revealed that the mushrabiyahs could save up to 6% of the HVAC load. Interestingly, the maximum electricity saving by mushrabiyah was observed in Jeddah, where it is an aspect of its vernacular type. Adobe is a thermally-efficient, sustainable and durable material widely available locally. It is inexpensive, easy to produce and requires fewer manufacturing skills and less production energy compared to the currently widely-used construction materials (i.e., concrete and steel). Particularly, the adobe construction can reduce the annual electricity demand and peak power demand by up to 6% and 19%, respectively. It can also reduce the HVAC load by up to 13%. The simulation results revealed that, due to the harsh weather conditions of the examined locations, the courtyard has increased the annual electricity demand by around 4% in all locations with the exception of Khamish Mushait, where the results have shown a clear correlation for the monthly electricity demand between the base and courtyard houses. Although, the adaptation of the courtyard has contributed to reducing the demand for lighting by 8% in all locations, it has increased the demand for the HVAC system between 9% in Jeddah and 11% in Khamis Mushait. This can be understood from the fact that adapting the courtyard has increased the exposed area that includes solid walls and windows to the direct solar radiations and harsh weather conditions, which result in adding more loads to the HVAC system and increasing the demand for electricity. This work showed that houses built with both traditional construction methods, using adobe as the principal building material, and mushrabiyah as a vernacular design feature could reduce the annual electricity demand of these houses by 8% in almost all locations and, therefore, recommends the development of ZEH in Saudi Arabia using them as a step towards reducing the electricity demand. Moreover, the application of other vernacular techniques, sustainable design features and energy-efficiency measures should also be taken into account to meet the targeted reduction in demand for electricity similar to the ZEH benchmark. This work also showed that the courtyard is technically unviable for Saudi dwellings. In further research, it is essential to investigate the role that can be played by other vernacular techniques in developing ZEHs. However, attention should be paid to the fact that the application of some of these techniques may face obstacles especially in terms of their attractiveness to the Saudi residents.

Author Contributions: Farajallah Alrashed and Stas Burek conceived and designed the modelling work; Farajallah Alrashed performed the modelling work, Muhammad Asif and Farajallah Alrashed analysed the results and wrote the paper. Conflicts of Interest: The authors declare no conflict of interest.

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