Analysis of critical climate related factors for the applicationof zero-energy homes in Saudi Arabia

Farajallah Alrashed a,n, Muhammad Asif a,b

a School of Engineering and Built Environment, Glasgow Caledonian University, Cowcaddens Road, Glasgow G4 0BA, United Kingdomb Department of Architectural Engineering, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia

a r t i c l e i n f o

Article history:Received 11 April 2014Received in revised form30 August 2014Accepted 27 September 2014Available online 17 October 2014

Keywords:Zero-energy homeBuilding energy simulationSensitivity analysisSaudi housingSaudi climatic zonesRenewable energy

a b s t r a c t

The Saudi construction industry is led by housing sector that imposes enormous energy and environ-mental challenges for the country. The housing sector is growing rapidly and is responsible for 52% of thetotal national electricity consumption. In order to promote sustainable development it is vital for SaudiArabia to adopt sustainable housing practices such as zero-energy homes (ZEHs). The concept is new toSaudi Arabia though a number of ZEHs have already been developed around the world. One of the mostsignificant challenges facing the application of ZEHs in Saudi Arabia is uncertainty about theiradaptability in local climate. The present work aims to investigate this uncertainty, mainly focusingon the four climatic factors related to the application of ZEHs including air temperature, relativehumidity, wind speed and global solar radiation. This is fulfilled by reviewing climatic condition of SaudiArabia and the concept of ZEHs and examining some of these homes built across the globe in climatessimilar to the Saudi climatic zones. In this respect, five ZEHs globally developed in climates matchingwith the five main Saudi climatic zones have been investigated as case studies. A typical-virtual homehas been designed on the basis of a questionnaire survey. With the help of the Integrated EnvironmentalSolution ⟨Virtual Environment⟩ software a modelling exercise has been carried out to compare its energyperformance at the five selected international locations with their corresponding Saudi locations. Thiscomparison is based upon the maximum and mean power demand. Furthermore, to cater for thedifferences in climatic conditions between the Saudi locations and their counterpart global locations, asensitivity analysis for the studied locations has been undertaken for the four climate factors.

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Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13952. Zero energy homes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13963. Climatic zones in Saudi Arabia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13964. Case studies of zero energy homes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13965. The study model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13986. Energy performance analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13997. Discussion and conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1401References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1402

1. Introduction

The world faces a string of serious energy and environmentalchallenges. The global energy and environmental scenarios are

closely interlinked; the problems with the supply and use ofenergy are related to wider environmental issues including globalwarming, air pollution, deforestation, ozone depletion and radio-active waste. The building sector has a major role to play intackling these issues, as it is responsible for over 40% of the world’stotal primary energy consumption and up to 30% of the totalCarbon Dioxide (CO2) emissions [1].

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Renewable and Sustainable Energy Reviews

http://dx.doi.org/10.1016/j.rser.2014.09.0311364-0321/& 2014 Elsevier Ltd. All rights reserved.

n Corresponding author. Tel.: þ44 1413318480; fax: þ44 1413313370.E-mail address: farajallah.alrashed@gcu.ac.uk (F. Alrashed).

Renewable and Sustainable Energy Reviews 41 (2015) 1395–1403

The energy and environmental situation of Saudi Arabia is alsoexperiencing strains and the building sector is inflicting even alarger burden in comparison with the global levels. The per capitaCO2 emissions in Saudi Arabia, for example, is over 18 metric ton(mt) that is much higher than the world’s average per capitaconsumption of less than 5 mt [2]. On the other hand, the demandfor electricity is experiencing a rapid growth in Saudi Arabia. Theresidential sector is the biggest consumer of electricity; it accountsfor 52% of the total national electricity consumption [3]. Owing tofactors like burgeoning population, high economic growth, andlow tariffs, the electricity demand in this sector is expected todouble by the year 2025 [4]. An analysis of the construction sectorsuggests that most of the projects being undertaken are residentialbuildings in order to meet the demand for new homes [5]. Theresidential sector is expected to experience a significant growth infuture as the population is rising at a rate of 2.5% per year and only24% of the Saudi nationals have their own homes [6]. Whilearound two-third of the population is under the age of 30years [7], estimates suggest that in order to meet the needs ofthe growing population, the country has to build 2.32 million newhomes by 2020 [8]. In order to appropriately tackle the energy andenvironmental challenges to be imposed by the building sector infuture, the country needs to move towards sustainable buildingsector. The development of zero-energy homes (ZEHs) could be auseful sustainable solution for Saudi residential sector.

ZEHs rely on renewable energy to meet their energy needs. It istherefore critical to have sufficient renewable resources to helpZEHs sustain their energy needs. The geographic location of SaudiArabia is ideal for harnessing solar energy in particular as has beenhighlighted in a number of studies since as early as 1970s [9–13].According to the Saudi Solar Radiation Atlas [14], the countryannually receives around 3245 sunshine hours accounting for asolar radiation figure of over 2200 kW h/m2.

This article attempts to promote the case for ZEHs in SaudiArabia by providing an overview of the concept of ZEHs andrelevant developments being made across the world. Discussingthe main climatic zones in Saudi Arabia it examines the viability ofZEHs in the country by looking into these types of homes success-fully built around the world in matching climatic conditions.

2. Zero energy homes

ZEH is a term widely known for residential buildings with zeronet energy consumption and zero CO2 emissions. There is howevernot any unanimous definition for ZEHs in the literature. One of theoldest definitions is the one provided by Esbensen and Korsgaard[15] when they described an experimental zero energy house inDenmark as a “dimensioned to be self-sufficient on space heatingand hot-water supply during normal climatic conditions in Den-mark”. Furthermore, in a study for zero energy houses in Nether-lands undertaken by Gilijamse [16], he stated that “A zero-energyhouse is defined as a house where no fossil fuels are consumed,and annual electricity consumption equals annual electricity pro-duction”. A more detailed description of the concept of the ZEH wasprovided by Iqbal [17] when he stated that “Zero energy home isthe term used for a home that optimally combines commerciallyavailable renewable energy technology with the state of the artenergy efficiency construction techniques. In a zero energy home nofossil fuels are consumed and its annual electricity consumptionequals annual electricity production. A zero energy home may ormay not be grid connected”. Another focused definition is providedby Trocellini et al. [18] as: “a residential building with greatlyreduced energy needs through efficiency gains such that thebalance of energy needs can be supplied with renewable technol-ogies”. In ZEHs, off-sit renewable energy generation can also be

employed in case the on-site renewable systems are not practical orare not sufficient to support the energy requirements of thebuilding as highlighted in Fig. 1 [18–19].

Over the years, the framework for ZEH has been furtherdeveloped by researchers and a significant attention has beenpaid to the concept of ZEH around the world. A number ofcountries have already developed these homes, mainly for thedemonstration/experimental purposes [20–28]; while others areworking on the feasibility and development of ZEHs [29–32]. TheUS Department of Energy (DOE), for example, has set up a strategicgoal to achieve ‘marketable Zero-Energy Homes in 2020’ [33]. TheUK has also developed four ZEH projects. One of these is theBeddington Zero-Energy Development. Besides incorporatingexcellent insulation features, this development employs solarphotovoltaic (PV) and biomass resources to generate energy [34].Despite these global developments, the concept of ZEH has notbeen appropriately realised in Saudi Arabia as yet. Althoughseveral studies have been carried out on improving energyefficiency in buildings the subject of ZEHs has not been dulyattended by the academic and research community [35].

3. Climatic zones in Saudi Arabia

Climate conditions are immensely important both in terms ofenergy consumption in buildings and the potential for renewableenergy. To examine the viability of ZEHs across Saudi Arabia it istherefore critical to investigate the climatic conditions in thecountry.

Saudi Arabia lies between 311N–17.51N latitude and 501E–36.61E longitude. It is a large country with an area of 2.3 millionsquare kilometres and a land elevation that varies from 0 to3000 m above the mean sea level [36]. With such a large landarea and variation with regards to sea level, different parts of thecountry have distinctive climatic features as are clearly noticeablein day to day life.

Over the years Saudi Arabia has been regionalized climaticallyby scientific and administrative bodies in several ways—it has beenclassified individually, part of the Gulf Cooperation Council (GCC)Countries, part of the Arab World and part of the Middles East andNorth Africa (MENA) region. Majority of these classificationsdescribe the country either as a desert or arid region (i.e. as oneclimatic zone). This simple description could be misleading as itconceals significant climatic differences amongst various regionsof the country. There is also an observation that often these studiesand existing atlases did not tackle the classification issue as theyare based on either analysing the climatic elements and processesor selecting geographical regions and finding their climatic fea-tures [37]. It is also observed that there is a lack of scholarshipwhen it comes to climatic classification of Saudi Arabia withregards to building design applications (there are only two studiesundertaken by Zuhairy and Sayigh [38] and by Said et al. [39]which discusses climatic zones for building design purposes). Thework done by Said et al. [39] is found to be relevant and suitablefor this study on the basis of a number of factors including comp-rehensiveness and robustness of the used weather data. It classi-fies the country into six climatic zones. Given the fact that theEmpty Quarter is an uninhabited region; five locations are selectedas representative of the five habited climatic zones: Dhahran,Guriat, Riyadh, Jeddah and Khamis Mushait. These climatic zonesand their representative cities are shown in Fig. 2.

4. Case studies of zero energy homes

This study attempts to investigate the viability of ZEHs across allof the above mentioned five main climatic zones in Saudi Arabia. In

F. Alrashed, M. Asif / Renewable and Sustainable Energy Reviews 41 (2015) 1395–14031396

theory, if a ZEH was successfully developed in a certain climate, theclimate uncertainty of its applicability in a similar climate anywherein the world is quite low. On the basis of available weather data, 18ZEHs developed in regions with climatic conditions similar to theSaudi climate were identified as shown in Fig. 3.

The 18 identified locations were compared with their Saudicorresponding locations. The comparison of climate conditionswas made on the basis of four of the main parameters that affectthe energy performance of a house. These parameters are airtemperature, relative humidity, wind speed and solar radiation.Due to that the number of ZEHs in climate that similar to the Saudiclimate is limited, the selection for a counterpart for each Saudirepresented location was based on the most similarity. Conse-quently, ZEHs at five locations were selected for this study. Theseinternational locations are: Borrego Springs (matching with theDhahran climatic zone), Tucson (matching with the Guriat climaticzone), Phoenix (matching with the Riyadh climatic zone), LakeBennett (matching with the Jeddah climatic zone), and Cupertino(matching with the Khamis Mushait climatic zone) (see Table 1).

The Clarum Homes in Borrego Springs, consisting of four singlestorey three-bedroom ZEHs, was selected as a case study for

Dhahran. Each of these homes, having an area of approximately185 m2, is powered by a 3.2 kW grid-connected PV system andhas some distinctive energy-efficient features. According to Russell[21] the project is one of the successful examples of ZEHs built inthe United States (US). In addition, Hammon [22] highlighted thaton annual basis, the PV system within these homes is producingmore electricity than their respective needs.

The case study selected for Guriat is the Armory Park del SolZEH2 (APdS ZEH2) in Tucson. It is the second ZEH developedwithin the same development to demonstrate the feasibility ofZEHs in hot/mixed dry climate of Southern Arizona [23]. In 2003,the first ZEH was developed with the view of meeting all itselectricity needs through its PV system. Although, it was designedto be a true net-zero energy house, the actual electricity produc-tion from the PV systemmet about 70% of its needs in the first year(i.e. against an annual household requirement of 11,104 kW h theelectricity produced form the PV system was 7340 kW h). Subse-quently, the APdS ZEH2 was built with additional energy-efficiencymeasures and a larger PV array to ensure its net-zero status. Basedon the experience of the first ZEH in the development, a number ofdesign improvements were incorporated to achieve a net-zero

Fig. 2. The climatic zones in Saudi Arabia [39].

Supply-sideReduce site energy though low-energy building technologies

On-site Supply1. Renewable energy within building footprint

2. Renewable energy within site

Off-site supply3. Renewable energy off site to generate

energy on site.4. Purchase off-site renewable energy

sources.

Fig. 1. Renewable energy supply hierarchy in ZEH [18].

F. Alrashed, M. Asif / Renewable and Sustainable Energy Reviews 41 (2015) 1395–1403 1397

energy consumption on annual basis. The APdS ZEH2 is a singlestorey house with three bedrooms, featured with 6.9 kW PV system.It was completed in 2007 with a total area of 201.4 m2. The APdSZEH2 is currently producing more energy than it is consuming (i.e.against an annual household requirement of 10,208 kW h, its PVsystem is reported to produce 11,840 kW h of electricity) [24].

The Legacy Home in Phoenix was selected as a case study forRiyadh. The project is a 129 m2 single-storey three-bedroom housethat was built in 2009. The house, a Leadership in Energy andEnvironmental Design (LEED) platinum rated project, features a5.2 kW PV system. Its annual electricity consumption is reportedto be 6848 kW h while the total annual electricity produced formthe PV system is 9363 kW h [41].

The case study selected for Jeddah is the Rozak House in LakeBennett, Australia. It is a single-storey house located in a remoteand separately developed region. It was built in 2002 with an areaof 92 m2 and has four bedrooms. According to Guzowski [25], thehouse incorporates a number of features including passive design,11.5 kW PV system and energy-efficient appliances to achieveenergy self-efficiency.

The Kaneda Residence in Cupertino was selected as a casestudy for Khamis Mushait. The project, completed in 2010, iscertified with LEED Platinum rating. It is a single-storey house

with three bedrooms and an area of 255 m2. Its 7.0 kW PV systemprovides more electricity than it needs (i.e. against an annualhousehold requirement of 8494 kW h, the electricity producedfrom the PV system is reported to be 11,508 kW h) [42].

5. The study model

In order to examine the applicability of the ZEH concept inSaudi Arabia, a virtual house was developed for all concernedlocations (the representative Saudi climatic zones and theircorresponding climates from across the world where ZEHs havebeen developed) using Integrated Environmental Solutions ⟨Vir-tual Environment⟩ (IES ⟨VE⟩). The weather files used in thesimulation were extracted from Meteonorm 5.1. The Meteonormgenerates hourly time series for the desired location on the basisof well-validated models and data banks of tens of years [40].To cater for the differences in climatic conditions between theSaudi locations and their counterpart international locations,a sensitivity analysis for the studied locations has been undertakenfor the mainly concerned weather parameters.

The developed house in this study was designed on the basis of adetailed questionnaire survey that was undertaken to determine

Fig. 3. Map of zero-energy homes.

Table 1The climatic parameters for identified and represented locations [40].

Annual temperature (1C) Relative humidity (%) Annual wind speed (m/s) Annual mean globalsolar radiation (W/m2)

Minimum Maximum Mean Minimum Maximum Mean Minimum Maximum Mean

Dhahran, Saudi Arabia 5.0 45.7 25.8 19 99 56.9 0 5.7 0.9 195Borrego Springs, California, US 2.3 48.4 24.7 13 78 38.5 0 18.4 3.9 219Guriat, Saudi Arabia �3.3 43.9 19.8 12 100 39.6 0 16.3 4.2 235Tucson, Arizona, US �2.1 43.2 20.4 10 79 33.9 0.1 13.1 3.9 236Riyadh, Saudi Arabia 2.2 43.7 25.1 10 91 32.2 0 11.9 3.1 252Phoenix, Arizona, US �2.8 46.1 22.5 4 100 36.3 0 16.5 3.0 240Jeddah, Saudi Arabia 13.9 41.7 27.9 37 100 64.7 0 11.2 2.6 257Lake Bennett, Northern Territory, Australia 15.6 35.8 27.7 40 100 70.6 0 13.4 3.3 236KhamisMushait, Saudi Arabia 2.7 34.3 18.9 17 100 50.8 0 12.4 3.1 289Cupertino and Santa Clara, California, US �0.2 37.2 16.6 28 98 63.3 0 17.3 3.3 196

F. Alrashed, M. Asif / Renewable and Sustainable Energy Reviews 41 (2015) 1395–14031398

the aspired dwelling in Saudi Arabia. The participants were selectedrandomly from different regions covering all climatic zones in SaudiArabia. A total of 453 responses were received from residentialbuilding users employing web based and in-person approach. Themajority of the questionnaire survey participants have chosen theirtargeted future home to be two-storey detached house (villa) with atotal site area between 400 m2 and 600 m2. Some of the mainfeatures of the designed home are highlighted in Fig. 4 and Table 2.

Before undertaking the investigation, the energy performanceof the virtual house was validated with measured electricity valuesgathered from 20 dwellings that were similar to the virtual housein terms of air-conditioning system, thermal insulation, type ofwindows, and energy source for cooking. The energy data for thesehomes, located in the Dhahran Zone, was obtained from theirmonthly electricity bills for period between January 2012 andDecember 2012. The annual electricity consumption for the virtualhouse in Dhahran was found to be 135.5 kW h/m2, which is inclose proximity with the average for the 20 dwellings in samelocation—the mean and median electricity consumption values forthe survey dwellings are 146.7 kW h/m2 and 137.4 kW h/m2,respectively. In terms of the monthly electricity consumption,the findings of this study have shown a clear correlation betweenthe values for the virtual house and the surveyed dwellings (seeFig. 5).

6. Energy performance analysis

The energy performance of buildings is influenced by theirorientation. In this study, the virtual house was simulated in eachlocation to eight different orientations covering the 3601 compassrange in steps of 451. The orientation was optimized on the basis ofthe minimum total household electricity requirement. The differ-ence between the optimum and the worst orientation vary fromlocation to location. For instance, the difference between the worstand optimum orientations for Phoenix house is more than230 kW h of the annual electricity consumption, while the differ-ence for Dhahran house is about 102 kW h.

The results indicate that the minimum power requirementdoes not change with orientation. Thus, the comparison of thebuilding energy performance between corresponding locations isbased on two variables: the maximum and the mean powerdemand. The maximum and mean power demand is critical todetermine the total annual energy requirements and subsequentlythe capacity for renewable technologies. The simulation resultsreveal that the maximum power demand for Guriat, Riyadh andKhamis Mushait is lower than their counterparts, and almost equalbetween Dhahran and its counterpart Borrego Springs. However,Jeddah has about 4 kW higher maximum power demand incomparison to its counterpart Lake Bennett (see Table 3).

Results suggest that the annual electricity consumption forDhahran house is more than Borrego Springs house where theannual electricity consumption for the Dhahran house is about7.8 MW h higher than the Borrego Springs house (see Table 3). The

Fig. 4. Model and floor plans for virtual house.

Table 2Key features of the simulated house.

House feature Description

AreasGround floor area 214.07 m2

First floor area 214.07 m2

Total glazed area 55.16 m2

Total external wallarea

446.8 m2

Total roof area 228.14 m2

Lettable area 76%Circulation area 24%

Construction materialsExternal wall (25 mm stuccoþ75 mm concrete blockþ50 mm

polystyreneþ75 mm concrete blockþ25 mm stucco)U-value¼0.4948 W/m2 K

Internal wall (25 mm stuccoþ100 mm concrete blockþ25 mm stucco)U-value¼2.5009 W/m2 K

Roof (25 mm terrazoþ25 mm mortarþ4 mm bitumenlayerþ150 mm cast concreteþ200 mm concreteblockþ25 mm stucco þ15 mm gypsum board)U-value¼1.7356 W/m2 K

Ceiling (20 mm graniteþ25 mm mortarþ150 mm castconcreteþ200 mm concrete blockþ25 mmstuccoþ15 mm gypsum board) U-value¼1.5730 W/m2 K

Ground floor (15 mm graniteþ25 mm mortarþ100 mm cast concrete)U-value¼3.5900 W/m2 K

Windows Aluminium window with thermal break,U-value¼3.4266 W/m2 K

External doors External door (aluminium door–aluminium frame withthermal break) U-value¼6.4165 W/m2 K

Internal doors Internal door (40 mm wooden door)U-value¼2.5975W/m2 K

SystemsHVAC system Min. flow rate¼8 l/s/person for mini split systemLighting system Tungsten halogen lamps at (bathrooms, toilets, and

kitchens), and CFLs at (all other spaces)Domestic hot water 190 l (90% delivery efficiency)Auxiliary ventilation (Kitchen¼50 l/s, toilets and bathrooms¼25 l/s)Kitchen appliances Maximum power consumption¼30 W/m2

Living zoneappliances

Maximum power consumption¼7 W/m2

Sleeping zoneappliances

Maximum power consumption¼7 W/m2

Guest zoneappliances

Maximum power consumption¼5 W/m2

Heating simulationset-point

20.0 1C

Cooling simulationset-point

24.0 1C

F. Alrashed, M. Asif / Renewable and Sustainable Energy Reviews 41 (2015) 1395–1403 1399

virtual house at both locations has almost identical electricityrequirements for the winter months (December–February) whilstthe maximum difference in monthly energy needs is estimated tobe 1.9 MW h occurring in May and October (see Fig. 6a). Sensitivityanalysis results reveal that the virtual model is remarkablysensitive to air temperature for Dhahran and Borrego Springs(see Fig. 6b) where the mean air temperature for Dhahran is about1.2 1C higher than Borrego Springs (see Table 1). In addition, thevirtual house is sensitive to relative humidity for Dhahran only.Despite the high different between Dhahran and Borrego Springsin terms of wind speed (see Table 1), the sensitivity analysis resultsreveal no significant difference to wind speed (see Fig. 6b).

The results of the Guriat–Tuscon comparison show that theirmonthly electricity consumption profiles are in close proximity formost of the months (see Fig. 7a). The greatest difference isobserved in June where the monthly electricity consumption forthe former is about 0.7 MW h higher than the latter. Guriat andTucson are strongly matching each other in the four climateparameters (see Table 1). This was reflects on the results observedfrom the sensitivity analysis for both locations where both almostmatching each other’s mean power demand except a little bitmore sensitivity for Tucson house to the increase of air tempera-ture (see Fig. 7b).

The scenarios for monthly electricity consumption for Riyadhand Phoenix houses are very close (see Fig. 8a). The greatestdifference is observed for May when the monthly electricityconsumption for Riyadh house is about 1.6 MW h higher than

the Phoenix house. Actually, the maximum power for virtualhouse in Phoenix is 4.7 kW higher than in Riyadh, while the meanpower for Riyadh is about 0.4 kW higher than for Phoenix. This isdue to that the mean air temperature for Riyadh is 2.6 1C higherthan Phoenix, while the maximum air temperature for Phoenix inis 3.6 1C higher than Riyadh (see Table 1). However, it is observedfrom the sensitivity analysis that the virtual house in bothlocations mostly sensitive to air temperature with almost samescenario (see Fig. 8b).

The maximum power for the Jeddah house is found to behigher than the Lake Bennett house because Jeddah has maximumair temperature higher than the maximum for Lake Bennett byalmost 6 1C (see Table 1). Additionally, the mean consumption inLake Bennett is a bit higher than Jeddah. The electricity consump-tion for Lake Bennett is generally higher than Jeddah duringwinter and springs seasons (see Fig. 9a). The sensitivity analysisfor both houses in Jeddah and Lake Bennett shows a goodcorrelation between both locations for all the climate parameters(see Fig. 9b).

Table 3The power demand and optimum orientation for the investigated homes.

Location Maximumpower (kW)

Meanpower(kW)

Annualenergy(MW h)

Optimumorientation

Dhahran (Saudi) 40.1 6.6 57.99 NorthBorrego Springs(counterpart)

40.0 5.7 50.13 North

Guriat (Saudi) 29.0 4.8 41.98 NorthTucson(counterpart)

29.4 4.9 42.94 North

Riyadh (Saudi) 30.8 5.8 50.91 NorthPhoenix(counterpart)

35.5 5.5 47.84 North

Jeddah (Saudi) 38.8 8.3 72.56 EastLake Bennett(counterpart)

34.7 8.5 74.75 North West

KhamisMushait(Saudi)

15.5 3.0 25.96 North

Cupertino(counterpart)

26.0 3.5 30.97 North

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Fig. 6. (a) The monthly electricity consumption of the virtual house in Dhahran andBorrego Springs; (b) sensitivity analysis of climate parameters for Dhahran andBorrego Springs based on mean power demand.

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Results suggest that the values for the maximum and meanpower for Cupertino are higher than for Khamis Mushait (seeTable 3). The highest difference is observed in winter monthsbecause Cupertino is a colder place compared to Khamis Mushait(see Fig. 10a). It is observed from the sensitivity analysis thatKhamis Mushait is more sensitive to the increase of air tempera-ture and less sensitive to the increase of relative humidity (seeFig. 10b).

7. Discussion and conclusions

The article addresses the applicability of ZEHs in Saudi climatesby examining various ZEHs built around the world in matchingclimatic conditions. The five internationally built ZEHs selected forthis study are located in Borrego Springs, Tucson, Phoenix, LakeBennett and Cupertino. The corresponding Saudi cities are respec-tively Dhahran, Guriat, Riyadh, Jeddah and Khamis Mushait, eachrepresenting a key climatic zone in the country. A virtual house isdesigned with the help of IES ⟨VE⟩ for the five Saudi cities and theirglobal counterparts. The energy parameters used for this compar-ison are the maximum and the mean power requirements.

It is observed that all of the studied ZEHs are self-sufficient intheir energy needs and some of them are even generating moreenergy than their requirement. The PV systems of the Cupertinoand Tucson ZEHs, for example, are respectively producing 26% and14% more electricity than their needs. The results also show thatthe electricity consumption for the Saudi virtual houses is almostdouble compared to their international counterparts—the annualelectricity consumption for homes in Dhahran, Guriat, Riyadh,Jeddah, and Khamis Mushait is 135 kW h/m2, 98 kW h/m2,119 kW h/m2, 170 kW h/m2, and 61 kW h/m2, respectively, whilefor Borrego Springs, Tucson, Phoenix, Lake Bennett, and Cupertinothe value is 50 kW h/m2 [43], 51 kW h/m2 [24], 53 kW h/m2 [41],18 kW h/m2 [44], and 33 kW h/m2 [42], respectively. The very lowannual electricity consumption for the ZEH in Lake Bennett is dueto the fact that it does not employ mechanical cooling system [44].The high electricity consumption figures for Saudi virtual housesin comparison to their ZEH global counterparts could be due tofactors such as size and type of dwelling, occupant’s standard ofliving, occupant’s behaviour, and poor energy-efficiency for thebuilding construction as well as the domestic equipment andappliances. To help development of ZEH in Saudi Arabia, thebroader energy consumption trends need to be addressed toreduce the energy demand on the first place. Incorporation of

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Fig. 8. (a) The annual electricity performance of the virtual house in Riyadh andPhoenix; (b) sensitivity analysis of climate parameters for Riyadh and Phoenixbased on mean power demand.

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Fig. 7. (a) The annual electricity performance of the virtual house in Guriat andTucson; (b) sensitivity analysis of climate parameters for Guriat and Tucson basedon mean power demand.

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energy efficient construction techniques and improvement inhuman attitude is critical in this respect.

In order to cater for the differences in climatic conditionsbetween the Saudi locations and their counterpart global locations,a sensitivity analysis for the studied locations is undertaken on theclimate factors related to the application of ZEH including airtemperature, relative humidity, wind speed and global solar radia-tion. The results of the sensitivity analysis reveal that in generalwind speed and solar radiation do not have a significant influenceon the energy performance of the designed homes. On the otherhand, solar radiation determines the potential energy that can begenerated by these homes to meet their requirements. The inves-tigated Saudi locations tend to have a better potential for solarenergy in comparisonwith their corresponding global locations (seeTable 1). In terms of relative humidity, the results show that it has avery limited impact on the energy performance for the Guriat,Riyadh and Khamis Mushait as well as their counterparts Tucson,Phoenix, and Cupertino. The sensitivity analysis for Jeddah and LakeBennett reveals that both locations have quite identical level ofsensitivity for relative humidity and air temperature. Dhahran isobserved to have higher relative humidity than its counterpartBorrego Springs and is also more sensitive to it.

The findings of the sensitivity analysis indicate that the keyrelevant climatic conditions for the five selected Saudi climaticzones and their corresponding global locations with alreadydeveloped ZEHs are in close proximity. It is therefore concludedthat the Saudi climate is not an obstacle to the application of ZEHsin the country. Within Saudi Arabia, however, the prevailingclimatic conditions could make the application of ZEHs morechallenging in locations like Jeddah compared to locations likeKhamis Mushait.

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