Impact of Passive Energy Efficiency Measures on Cooling Energy Demand in an Architectural Campus Building in Karachi, Pakistan

sustainability

Article Impact of Passive Energy Efﬁciency Measures on Cooling Energy Demand in an Architectural Campus Building in Karachi, Pakistan

Mushk Bughio 1,2 , Muhammad Shoaib Khan 3 , Waqas Ahmed Mahar 4,5 and Thorsten Schuetze 1,*

1 Department of Architecture, College of Engineering, SungKyunKwan University, Suwon 16419, Korea; [email protected] 2 Department of Architecture, Dawood University of Engineering and Technology, Karachi 74800, Pakistan 3 Department of Civil & Environmental Engineering, Hanyang University, Seoul 04763, Korea; [email protected] 4 Department of Architecture, Balochistan University of Information Technology, Engineering and Management Sciences (BUITEMS), Quetta 87100, Pakistan; [email protected] 5 Sustainable Building Design (SBD) Lab, Department of UEE, Faculty of Applied Sciences, Université de Liège, 4000 Liège, Belgium * Correspondence: [email protected]; Tel.: +82-31-299-4763; Fax: +82-31-290-7570

Abstract: Electric appliances for cooling and lighting are responsible for most of the increase in electricity consumption in Karachi, Pakistan. This study aims to investigate the impact of passive energy efficiency measures (PEEMs) on the potential reduction of indoor temperature and cooling energy demand of an architectural campus building (ACB) in Karachi, Pakistan. PEEMs focus on the building envelope’s design and construction, which is a key factor of influence on a building’s cooling energy demand. The existing architectural campus building was modeled using the building Citation: Bughio, M.; Khan, M.S.; information modeling (BIM) software Autodesk Revit. Data related to the electricity consumption Mahar, W.A.; Schuetze, T. Impact of for cooling, building masses, occupancy conditions, utility bills, energy use intensity, as well as space Passive Energy Efficiency Measures types, were collected and analyzed to develop a virtual ACB model. The utility bill data were used on Cooling Energy Demand in an to calibrate the DesignBuilder and EnergyPlus base case models of the existing ACB. The cooling Architectural Campus Building in Karachi, Pakistan. Sustainability 2021, energy demand was compared with different alternative building envelope compositions applied as 13, 7251. https://doi.org/10.3390/ PEEMs in the renovation of the existing exemplary ACB. Finally, cooling energy demand reduction su13137251 potentials and the related potential electricity demand savings were determined. The quantification of the cooling energy demand facilitates the definition of the building’s electricity consumption Academic Editor: Graziano Salvalai benchmarks for cooling with specific technologies.

Received: 30 May 2021 Keywords: hot and humid climate; energy demand for cooling; energy efﬁciency; building envelope; Accepted: 21 June 2021 insulation; thermal mass Published: 29 June 2021

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in 1. Introduction published maps and institutional affil- High fossil energy consumption for the heating, cooling, lighting, and ventilation of iations. buildings and related greenhouse gas emissions contributes significantly to climate change and resource depletion [1,2]. Buildings account for one-third of the final global energy consumption [3]. Around 39% of CO2 emissions and 36% of the global energy consumption are attributed to the building sector [3]. The building sector in Great Britain accounts Copyright: © 2021 by the authors. for around 27% and that in the US for 38% of CO2 emissions [1]. Buildings are a major Licensee MDPI, Basel, Switzerland. contributor to global environmental impact due to their high energy consumption [1,4]. This article is an open access article The building sector consumes more energy than any other sector in Pakistan [5]. Pakistan’s distributed under the terms and highest annual increase in electric energy consumption was 8.4% in the domestic sector, conditions of the Creative Commons followed by 7.5% in the commercial sector, 5.6% in the agriculture sector, and 4.2% in the Attribution (CC BY) license (https:// industrial sector during 2017–2018 [6]. Generally, the major end-use activities in the build- creativecommons.org/licenses/by/ 4.0/). ing sector are space cooling, space heating, cooking, lighting, and refrigeration. However,

Sustainability 2021, 13, 7251. https://doi.org/10.3390/su13137251 https://www.mdpi.com/journal/sustainability Sustainability 2021, 13, 7251 2 of 35

the main contributors to the increased electricity consumption in Karachi, Pakistan, are lighting and the energy-inefficient fans used for cooling [5,7]. There is a significant rise in building energy consumption in developing countries, driven by improved access to centralized electricity supply [3]. The operational electricity consumption by buildings has the largest negative impact on the environment [1]. A major proportion of electricity in Pakistan is consumed for the provision of thermal comfort, such as space heating and cooling [1,4]. Personalized heating technologies, such as radiant heaters with a coefficient of performance (COP) of 0.85 [8], and cooling technologies, such as split air conditioners with an energy efficiency ratio (EER) of 2.7 and fans [8,9], which increase energy usage, are common in Pakistan. Therefore, passive energy efficiency measures (PEEMs) to reduce the cooling and heating energy demands of buildings are a primary research topic both in Pakistan and globally. However, PEEMs for reducing cooling energy demand are desired in Karachi. In a study, Ahsan et al. applied passive cooling techniques to reduce operational energy consumption in Pakistan. The results indicated energy savings of 35% using passive cooling techniques [4]. Sadineni et al. studied the potential of PEEMs for indoor environmental quality (IEQ), and thermal and visual comfort. The study concluded that the building envelope is a crucial PEEM for energy savings, for IEQ, and for thermal and visual comfort [10]. Okba indicated the building envelope design as a significant factor in determining the amount of energy a building consumes during its operation phase [11]. The energy conservation potential of an improved building envelope design can be achieved by retrofitting existing structures. For example, adding thermal mass and thermal insulation to existing building envelopes and installing low-emissivity and high-efficiency windows can improve building envelope efficiency. Examples show that electricity demand for heating or cooling can be reduced by as much as 20% [5]. Iwaro and Mwasha studied the impact of the building envelope design on building sustainability and energy efficiency. The results revealed that the higher the energy efficiency of a building envelope design, the higher the sustainable performance and building sustainability [12]. A number of studies have been conducted globally based on energy efficiency, building envelope, and passive design improvement measures of buildings. The studies concluded that the building envelope plays an essential role in the energy consumption of the building [10,13–21]. Building envelope codes and policies have been improved worldwide over the years. In the UK and USA, the building envelope standards have been substantially revised, and emphasize the growing need for energy conservation [10]. Similarly, in Pakistan, the National Energy Efficiency and Conservation Authority (NEECA), formerly known as the National Energy Conservation Centre (ENERCON), formulated the Building Code of Pakistan (Energy Provisions-2011) with the help of the Pakistan Engineering Council (PEC), having provisions for employing energy efficiency in the building sector of Pakistan. The Pakistan Green Building Council (PGBC) establishment is also a constructive step towards improved energy efficiency in the building sector [5]. Mahar et al. reviewed the energy efficiency policies in Pakistan and concluded that there is a lack of implementa- tion and practice of energy efficiency policies [22]. Pakistan’s poor energy policies have plunged the country into a severe economic crisis since 2006 [22,23]. The 2006 financial crisis started with a shortage of electrical energy and its insufficient production to meet the increased demand [8,23], which later changed to problems in the transmission and distribution of electrical energy [24]. The demand for electricity in Pakistan is relatively determined by concerns such as electricity prices, economic expansion, and rapid population growth. However, Pakistan’s peculiar issues and its short-term power crisis emerged from illegal electricity grid connections, lack of government interest in encouraging energy- efficient buildings, and electricity consumption in buildings exceeding the maximum grid capacity [23]. In addition to the limited grid capacity, Pakistan’s energy distribution and transmission networks are generally old and inefficient, resulting in significant line losses, such as 18.3% from 2018 to 2019 [8]. Pakistan produces its maximum electricity share from the combustion of fossil energy carrier coal (20.4%) and gas (38%). The remaining electricity Sustainability 2021, 13, 7251 3 of 35

is generated by hydroelectric (30.9%), nuclear (8.2%), and renewable energy (only 2.5%) sources [25]. Increased electricity prices have caused an immense burden of utility bills on the public since 2019, due to the reduction of government subsidies [8,26]. On the other hand, 73% of the population of Pakistan experienced electricity blackouts for an average of 2 h per day in 2006 [5], while in Karachi the electricity outage has increased to an average of 12–15 h a day in 2020 [27]. The development of energy-efficient and environmentally sound new building con- structions and energy-efficient technical equipment for building operation has progressed worldwide [28]. However, existing buildings, which account for two-thirds of the final energy consumption in Pakistan, have low thermal performance [4]. The retrofitting of existing buildings offers an opportunity to transform them into energy-efficient and environmentally sound buildings [28]. Poel et al. observed that retrofitting existing buildings will improve the energy efficiency in these buildings [28], since the existing buildings in Pakistan are energy inefficient [4]. Saleem undertook a pilot study of a college building in Mianwali, Pakistan, to investigate building energy-efficient approaches and proposed solar renewable energy sources for electricity generation [29]. Kazmi et al. investigated passive cooling, IEQ, user comfort, and energy efficiency in public buildings in Multan, Pakistan. The results showed that by adopting passive measures in the building envelope, significant energy savings for heating, cooling, lighting, and appliances could be achieved while creating a thermally comfortable indoor environment [30]. Several studies in Pakistan examined the relationship between IEQ, thermal comfort, and passive design measures [8,22,31–35]. However, no research on reducing the indoor temperature and energy demand for cooling through the building envelope and PEEMs in educational buildings in Karachi, Pakistan, has been conducted. Therefore, this research focuses on reducing the indoor temperature and energy demand for cooling through the building envelope and PEEMs in educational buildings, using the example of an architecture campus building. There are three public sector architectural campus buildings (ACB1, ACB2, and ACB3) in Karachi. ACB1 and ACB3 are located in East Karachi, while ACB2 is located in South Karachi. The aim of this research is to determine the electricity demand for cooling, and to identify different alternative building envelope compositions for the cooling energy demand reduction of an existing exemplary architectural campus building. The objectives of this research include (i) determination of the electricity demand in the existing exemplary architectural campus building, (ii) identification of alternative building envelope compositions as PEEMs in the existing exemplary architectural campus building, and (iii) determination of cooling energy demand reduction potentials through specific PEEMs.

2. Materials and Methods This research is based on the analysis and optimization of ACB1 due to the following reasons. ACB2 is a listed heritage site [36] and was excluded from the analysis, since the retrofitting strategies for heritage buildings are different from those for other buildings. Therefore, the findings cannot be transferred to other buildings. The construction materials used in ACB2 are also not exemplary. During the field visit conducted on the architectural campus buildings by the authors, ACB3 was found to be a shared building with the fine arts department. ACB3 has only one hall for the Department of Architecture. ACB3 mostly serves the Departments of Fine Arts and Design. Since this research’s scope is the study of an exemplary architectural campus building in Pakistan, the authors focused within this research on ACB1 to investigate the potential of PEEMs. Figure1 presents the conceptual study framework of this study, which is based on six axes, which are described in the following sections. Sustainability 2021, 13, 7251 4 of 35 Sustainability 2021, 13, x FOR PEER REVIEW 4 of 36

FigureFigure 1. 1. TheThe conceptual conceptual study study framework. framework. Legend: Legend: BIM, BIM,building building information information modeling; modeling; gbXML, gbXML, Green Building Green Building Exten- sibleExtensible Markup Markup Language; Language; WWR,WWR, window-to-wall window-to-wall ratio; HVAC, ratio; HVAC, heating, heating, ventilation ventilation,, and air-conditioning. and air-conditioning.

2.1.2.1. Base Base Case Case Building Building Modeling Modeling and and Description Description TheThe base base case case ACB1 ACB1 (ACB) (ACB) is is located located in in Karachi, Karachi, Pakistan, Pakistan, at at 24.90° 24.90◦ N,N, 67.08° 67.08◦ EE in in a a residential–commercialresidential–commercial area havinghaving aa courtyard courtyard as as a centrala central architectural architectural feature. feature. The ACBThe ACBis surrounded is surrounded by a by mosque a mosque and and a Montessori a Montessori school school to the to the north, north, residential residential quarters quarters for forthe the military military to theto the south, south, an emptyan empty plot plot owned owned by the by ACB the ACB to the to east, the andeast, a and primary a primary school schoolto the to west. the west. The surrounding The surrounding buildings buildings and vegetation and vegetation do not do cast not shadowscast shadows on the on ACB the ACBfaçades. façades. Figure Figure2 shows 2 shows the localization the localization and microclimate and microclimate of the of ACB the inACB a 1.5 in kma 1.5radius km radiusin Gulshan-e-Iqbal in Gulshan-e-Iqbal district, district, Karachi, Karachi, Pakistan. Pakistan. This This ACB ACB was was selected selected as an as exemplaryan exem- plarycase studycase study based based on the on factors the factors listed listed in Table in Table1, which 1, which are research are research findings findings published pub- lishedpreviously previously by the by authors the authors [37]. [37]. The footprint of the ACB is a simple “U” shape: the north–south façade is longer Table 1.than Criteria the for east–west ACBs 2 and façade. 3 and the The exemplary surface-area-to-volume ACB (base case) selection. ratio (S/V) of ACB is 0.46 m−1. Factors Three building clusters surround ACBs the 2 centraland 3 courtyard of Selected the ACB. Base The Case north ACB and east clusters are four-storey high, while the west cluster is two-storey high; all clusters consist HVAC systems No No of corridors for circulation. The ground floor works as an administration floor with a Thermal insulation of the building envelope No No computer laboratory; the second and third floors offer educational facilities, including Number of occupants per batch 50 50 lecture halls and offices. The fourth floor consists of laboratories in the north cluster, while Availability of architecturalthe east plans cluster includes a Unavailable display hall; in theone fourthACB floor is not in regular Available use. The north Being representative in termsfaçade of location is shaded with 0.3 mMain fixed city overhangs districts over the windows,Main and city seven districts 0.2 m fixed Educational levelvertical louvers at 5.75 m Minimum center-to-center underg distanceraduate betweenMinimum the louvers. undergraduate The overhangs The willingness of the campusand administration louvers are provided to to obstruct solar radiation through the windows. The east façade One was unwilling to cooperate Willing cooperate is provided with 0.3 m fixed overhangs over the windows. The east façade also consists Geometryof galleries on the first, second, andVarying third floors with a hollow concreteVarying mesh on external Use walls. The west façade consistsEducational of 0.6 m purpos roof eavese and 0.3 mEducational fixed overhangs purpose over the windows. The west façade also includes a terrace on the first floor. Sustainability 2021, 13, x FOR PEER REVIEW 5 of 36 Sustainability 2021, 13, 7251 5 of 35

Figure 2. 2.Location Location and and microclimate microclimate of the ACB of the (1.5 ACB km radius), (1.5 km Karachi, radius), Pakistan. Karachi, Pakistan.

Table 1. Criteria for ACBs 2 and 3 and the exemplary ACB (base case) selection. The footprint of the ACB is a simple “U” shape: the north–south façade is longer than Factorsthe east–west façade. ACBs The 2 and surface-area-to-volume 3 Selected ratio Base (S/V) Case of ACB ACB is 0.46 m−1. Three HVAC systemsbuilding clusters surround No the central courtyard of the ACB. No The north and east clusters Thermal insulation of the No No building envelope are four-storey high, while the west cluster is two-storey high; all clusters consist of corri- Number of occupants per batchdors for circulation. The 50 ground floor works as an administration 50 floor with a computer Availability of architecturallaboratory; plans the second Unavailable and in onethird ACB floors offer educational Available facilities, including lecture halls Being representative in terms of location Main city districts Main city districts Educational leveland offices. The Minimum fourth undergraduate floor consists of laboratories Minimum in undergraduatethe north cluster, while the east The willingness of the campus cluster includesOne wasa display unwilling hall; to cooperate the fourth floor is not in Willing regular use. The north façade is administration to cooperate Geometryshaded with 0.3 m fixed Varying overhangs over the windows, Varyingand seven 0.2 m fixed vertical lou- Usevers at 5.75 m center-to-center Educational purpose distance between the Educational louvers. purpose The overhangs and louvers are provided to obstruct solar radiation through the windows. The east façade is provided withTable 0.3 m2 summarizes fixed overhangs the general over building the windows. description. Th Thee east ACB façade is a hybrid also buildingconsists of galleries on withthe first, manually second, operable and third windows floors and with a majority a hollow of rooms concrete dependent mesh ononfans external for air walls. The west circulation. The opening of doors and windows facilitates free ventilation in the ACB. façade consists of 0.6 m roof eaves and 0.3 m fixed overhangs over the windows. The west Only two ofﬁces and a computer lab are cooled with personalized split air conditioners (façade2.7 EER ).also The includes fans function a terrace as cooling on the by creatingfirst floor. a wind-chill effect for the users. The main contributorsTable 2 summarizes to the electricity the general consumption building in the exemplarydescription. ACB The are theACB fans is anda hybrid building splitwith air manually conditioners operable for cooling, windows since the and standard a majori lightsty of were rooms replaced dependent with energy- on fans for air cir- efﬁcientculation. LED The lights/energy-saving opening of doors lights. and Figure windows A8 presents facilitates the breakdown free ventilation of electricity in the ACB. Only consumption of the exemplary ACB. Hence, this study focuses on the reduction of indoor temperaturetwo offices and and cooling a computer energy demand. lab are cooled with personalized split air conditioners (2.7 EER). The fans function as cooling by creating a wind-chill effect for the users. The main contributors to the electricity consumption in the exemplary ACB are the fans and split air conditioners for cooling, since the standard lights were replaced with energy-efficient LED lights/energy-saving lights. Figure A8 presents the breakdown of electricity consumption of the exemplary ACB. Hence, this study focuses on the reduction of indoor temperature and cooling energy demand.

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Table 2. Summarized general building description of the exemplary ACB.

Index Value Land plot area 1836.9 m2 Gross building area 1166.88 m2 Building form Courtyard Clusters 3 Number of ﬂoors 2 and 4 Floor-to-ﬂoor height 3.2 m Floor-to-ceiling height 3 m

The ACB floor plan layout was drawn after conducting a field survey with mea- surements. The authors also conducted a field survey to collect construction data and determine component and building material specifications. The generated ACB model is a detailed reconstruction of the existing ACB. The virtual BIM reconstruction of the exemplary ACB was executed with the software Autodesk Revit 2020 [38]. Autodesk Revit uses construction component categories, families, types, and instances. Elements are grouped to form a category that uses the model or documents a building design, and families are types of elements in a category. A family categorizes elements with a standard set of parameters, similar graphical representation, and identical use [38–41]. The BIM analytical model (AM) was generated, and spaces were defined by adding each room and manually assigning the energy analysis properties, since they are significant electricity consumption factors (Figure3). The BIM AM method gives a precise transition from the ACB Revit model to the ACB gbXML file [42]. Hence, BIM AM was used to export the ACB gbXML file. The gbXML is an industry-supported scheme used to store and share building properties between different software [43]. The ACB gbXML file was imported into DesignBuilder (DB) version 6.1.6.008 to determine the cooling energy demand. DB is specifically developed to run EnergyPlus simulations, and has been validated for accuracy and consistency [19,44]. After setting the location and weather data, discussed in the authors’ previously published research, the ACB zones were specified, and ACB schedules were created for each zone. The ACB model was divided into seven zones: naturally ventilated (NV) lecture halls, NV offices, offices having a cooling system, computer lab having a cooling system, NV common room and canteen, NV laboratories, and NV toilets. The air-conditioning system’s setpoint was 25 ◦C, as mentioned in the Building Code of Pakistan (Energy Provisions- 2011) [45]. The ACB was physically inspected to obtain information about the occupancy, lighting, and equipment with the ACB administration’s cooperation. The equipment used in the ACB were computers, printers, scanners, and microwaves. The lighting power densities and equipment power densities were calculated based on ASHRAE recommendations. The authors counted the total equipment and lighting fixtures in each zone, followed by calculating equipment power densities in compliance with the ASHRAE standard. The authors also collected electricity billing data for 72 months (January 2014 to December 2019), since the data provide information about historical annual electricity consumption. Analysis of the bills showed that the electricity consumption was low during December and January, high from February to November excluding June and October, and very low during the summer and winter vacation periods (i.e., June and October). Table3 provides a detailed description of the zones. The thermophysical properties of ACB are based on the literature and characteristics of the most common materials in Karachi. The specification of materials, building details (size, plans, and elevations), construction techniques, and layers and thicknesses of building elements are based on the existing ACB; the data were collected through interviews with faculty members and a physical observation survey conducted by the authors. The authors also reviewed similar buildings in Karachi with the same building age to verify the composition of the building envelope components and the construction of the ACB. To determine the cooling energy demand, specific occupancy schedules were defined, which AppendixA presents. Occupancy Sustainability 2021, 13, 7251 7 of 35

schedules determined the presence of users in each zone, and were defined to be consistent with the users’ routines. The occupancy determined the presence of users in the ACB during the working hours for students (09:00 to 16:00) and staff, including teachers (07:00 to 18:00) on working days (Monday to Friday). Holidays, other than summer and winter vacations, were defined with the value of 14 days per year, consistent with the annual academic calendar collected from the ACB. During the summers (May to August), the mean outdoor temperature is 30.7 ◦C with 59.7% relative humidity in Karachi [37], while the comfort range during summers is 26 to 28 ◦C[37]. June was excluded from the analysis, since that month is a vacation period for the ACB, and the inclusion of June might cause a discrepancy in the analysis due to the unrealistic internal heat gains/losses from non- occupancy. Table3 presents the simulated mean indoor temperatures of the north, west, and east clusters during summer’s occupied months. Temperature differences of 3.78, 2.47, and 1.45 ◦C, are observed from the outdoor to the indoor environment in the north, east, and west clusters, respectively. The authors assumed the building infiltration value of 2.5 air change rate (ACH), since the buildings in Pakistan are not airtight. The values are consistent with the previous studies in Pakistan [8,29]. The ventilation profiles were assumed based on physical inspection, and interviews with faculty members and students. Table3 presents the simulated airflow rate for each cluster. The proposed airflow rate in EN 15251 is 0.007 m3/s per person [46]. The airflow rate in ACB is higher than the proposed standards, which is attributed to the poor airtightness of ACB, free passage of air in the ACB through the semi-covered corridors located in all clusters, galleries located in the east cluster, and a terrace situated in the west cluster. Figure1 presents the detailed conceptual framework. Figure3 presents the ground floor plan, north elevation, section, 3D model, and the AM of the exemplary ACB. Table4 illustrates the base case building envelope components. The majority of buildings in Karachi are constructed using the same building materials and construction techniques. The conventional construction materials in Karachi are concrete block walls (high thermal conductivity and low specific heat capacity) with RCC slab (low specific heat capacity) roof [34]. The thermophysical properties of ACB are actual construction compositions based on interviews, the authors’ observations, common practice, and literature studies in Karachi. The ACB consists of a medium-weight concrete block wall with plaster of light color on both the inside and the outside, and has a U-value of 2.7 W/m2 K, which is higher than the maximum U-value proposed by ENERCON of 0.57 W/m2 K for external walls [45]. The roof consists of an RCC slab, with plaster on both the inside and the outside, and has a U-value of 2.58 W/m2 K, which is also higher than the maximum value proposed by ENERCON of 0.44 W/m2 K for roofs [45]. The windows are single-glazed (U-value = 5.7 W/m2 K) sliding windows with 50% opening, and have an aluminum frame with a U-value of 5.88 W/m2 K. Both values are higher than the maximum value for windows of 3.5 W/m2 K proposed by ENERCON [45]. The ACB components have highly comparable U-values. It is expected that modification of the ACB components will significantly impact the indoor environmental comfort, and accordingly facilitate annual electricity savings. Hence, parametric simulation was carried out using EnergyPlus software considering different parameters discussed in the subsequent sections. SustainabilitySustainability2021 2021, 13, 13, 7251, x FOR PEER REVIEW 8 of7 of 35 36

(a)

(b) (c)

FigureFigure 3. 3.(a ()a Ground) Ground ﬂoor floor plan, plan, north north elevation, elevation, and and section section AA, AA, respectively respectively of theof the exemplary exemplary ACB. ACB. (b) Isometric(b) Isometric view view of of the exemplary ACB in the north direction. (c) Analytical model (AM) of the exemplary ACB in the north direction. the exemplary ACB in the north direction. (c) Analytical model (AM) of the exemplary ACB in the north direction.

The ACB model was divided into seven zones: naturally ventilated (NV) lecture halls, NV offices, offices having a cooling system, computer lab having a cooling system, NV common room and canteen, NV laboratories, and NV toilets. The air-conditioning system’s setpoint was 25 °C, as mentioned in the Building Code of Pakistan (Energy Pro- visions-2011) [45]. The ACB was physically inspected to obtain information about the oc- Sustainability 2021, 13, 7251 9 of 35

Table 3. Building description and zone assumptions of the exemplary ACB. Legend: WWR, window-to-wall ratio; LPD, lighting power density; EPD, equipment power density; SA, surface area; V, volume; N, north cluster; W, west cluster; E, east cluster.

Measure Category Input Measures Values/Parameters North façade = 27, south façade = 5.5, WWR (%) east and west façades = 14 Windows (W/m2 K) U-value = 5.7 Shading coefﬁcient of glass (SC) 0.7 Solar heat gain coefﬁcient (SHGC) 0.81 Light transmission (LT) 0.88 Awnings (overhangs) (m) projection above the windows on the north, east, 0.3 Building envelope and west façades Eaves (m) over the roof of the 0.6 west façade Wall (W/m2 K) U-value = 2.7 Roof (W/m2 K) U-value = 2.5 Floor (W/m2 K) U-value = 1.11 Door (W/m2 K) U-value = 2.5 Airtightness (ACH) 2.5 Mean outdoor temperature (◦C) 30.7 during summer Relative humidity (%) 59.7 Temperature and humidity Comparison of mean outdoor (◦C) and indoor temperatures (◦C) Figure 11 Description during summer Land plot area of the building (m2) 1836.9 Land plot area and SA/V ratio (m−1) 0.46 building description Building drawings Figures3 and A11 Density (persons/usable building 2 0.29 Occupancy and density area in m ) Total occupancy (people) 350 January 1331.1 February 2073.17 March 2176.84 April 2073.17 May 2111.01 June 337.29

Simulated monthly July 2384.15 electricity demand (kWh) August 2280.49 September 2176.84 October 390.54 November 2176.84 December 1464.04 Simulated annual electricity demand 20,975.48 Breakdown of monthly Figure A8 electricity demand Sustainability 2021, 13, 7251 10 of 35

Table 3. Cont.

Measure Category Input Measures Values/Parameters Summer (clo) 0.40 Clothing and activity Winter (clo) 0.66 Metabolic rate (met) 1.0 Occupancy (people) 50 Type of system (cooled, Natural ventilation. Fans used for natural ventilation) air movement. Weekday occupancy schedule Figure A1 North cluster = 0.46 Airflow rate (m3/s) East cluster = 0.40 Lecture halls West cluster = 0.58 North cluster = 34.48 Mean indoor temperature (◦C) East cluster = 33.2 during summer West cluster = 32.2 Temperature thresholds Opening threshold = 23 for windows (◦C) Closing threshold = 18 LPD (W/m2) 10 EPD (W/m2) 15 Occupancy (people) 02 Type of system (cooled, Natural ventilation. Fans used for natural ventilation) air movement. Weekday occupancy schedule Figure A2 Airflow rate (m3/s) East cluster = 0.40 Naturally ventilated offices Mean indoor temperature (◦C) East cluster = 33.2 during summer Zone Temperature thresholds for Opening threshold = 23 windows (◦C) Closing threshold = 18 LPD (W/m2) 10 EPD (W/m2) 10 Occupancy (people) 02

1. Natural ventilation. Fans used Type of system (cooled, for air movement. natural ventilation) 2. Split air-conditioning (AC) used for cooling.

Energy efficiency ratio (EER) of the 2.7 Conditioned offices cooling system Cooling temperature setpoint (◦C) 25 Weekday occupancy schedule Figure A3 Airflow rate (m3/s) West cluster = 0.58 Mean indoor temperature (◦C) during West cluster = 32.2 summer without AC turned on LPD (W/m2) 15 EPD (W/m2) 15 Sustainability 2021, 13, 7251 11 of 35

Table 3. Cont.

Measure Category Input Measures Values/Parameters Occupancy (people) 40

1. Natural ventilation. Fans used Type of system (cooled, for air movement. natural ventilation) 2. Split air-conditioning (AC) used for cooling.

Energy efficiency ratio (EER) of the 2.7 Computer lab cooling system Cooling temperature setpoint (◦C) 25 Weekday occupancy schedule Figure A4 Airflow rate (m3/s) North cluster = 0.46 Mean indoor temperature (◦C) during North cluster = 34.48 summer without AC turned on LPD (W/m2) 20 EPD (W/m2) 25 Occupancy (people) 15 Type of system (cooled, Natural ventilation. Fans used for natural ventilation) air movement. Weekday occupancy schedule Figure A5 Airflow rate (m3/s) East cluster = 0.40 Common room and canteen Mean indoor temperature (◦C) East cluster = 33.2 during summer Temperature thresholds for Opening threshold = 23 windows (◦C) Closing threshold = 18 LPD (W/m2) 10 EPD (W/m2) 10 Occupancy (people) 25 Type of system (cooled, Natural ventilation. Fans used for natural ventilation) air movement. Weekday occupancy schedule Figure A6 North cluster = 0.46 Airflow rate (m3/s) East cluster = 0.40 Laboratories West cluster = 0.58 North cluster = 34.48 Mean indoor temperature (◦C) East cluster = 33.2 during summers West cluster = 32.2 Temperature thresholds for Opening threshold = 23 windows (◦C) Closing threshold = 18 LPD (W/m2) 10 EPD (W/m2) 10 Occupancy (people) 04 Type of system (cooled, natural Toilets Natural ventilation. Ventilation) Weekday occupancy schedule Figure A7 Sustainability 2021, 13, 7251 12 of 35

Table 4. Detailed base case building envelope components with thermal properties and materials and their total U-values. Legend: PCC, plain cement concrete; RCC, reinforced cement concrete.

Conductivity Speciﬁc Heat Building Elements Density (kg/m3) Thickness (cm) (W/m K) Capacity (J/kg K) Exterior Walls (3 Layers) Outermost Plaster 0.431 1088 1250 0.95 Concrete block, 1.3 840 1800 20 medium weight Innermost Plaster 0.431 1088 1250 0.95 U-value 2.7 W/m2 K Ground Floor (5 Layers) Outermost Ceramic tiles 0.39 656 1900 0.95 PCC 0.753 656 2000 5 Aggregate 1.8 840 2240 7 Sand 1.74 840 2240 10 Innermost Earth/soil 0.837 1046 1300 22 U-value 1.117 W/m2 K Intermediate ﬂoors (4 Layers) Outermost Ceramic tiles 0.39 656 1900 0.95 PCC 0.753 656 2000 5 RCC slab 0.753 656.9 2300 10 Plaster 0.38 840 1150 0.95 U-value 1.46 W/m2 K Roof (3 Layers) Outermost Plaster 0.38 840 1150 0.95 RCC slab 0.753 656.9 2300 10 Innermost Plaster 0.38 840 1150 0.95 U-value 2.58 W/m2 K Single Clear 6 mm Glass Window with Aluminum Frame Single clear 6 mm U-value 5.7 W/m2 K glass Aluminum frame U-value 5.88 W/m2 K Overhangs 30 cm Door (3 Layers) Outermost Plywood 0.14 1400 530 0.31 Air gap 5.56 1004 1.3 4.6 Innermost Plywood 0.14 1400 530 0.31 U-value 2.5 W/m2 K

2.2. Calibration of the Model The ASHRAE Guideline 14-2014 [47] was used to validate the ACB model. There are two indices mentioned in the guideline that present the variability of the measured and simulated electricity consumption data. Normalized mean bias error (NMBE) and coefﬁcient of variation of the root mean square error (CVRMSE) are the indices that determine variability by comparing the simulation predicted electricity demand to the electricity Sustainability 2021, 13, 7251 13 of 35

consumption from the electricity bills. The simulated electricity demand was compared with the measured (electricity billing) data to calibrate the ACB model. The ACB model was graphically represented to analyze the difference between the simulated and measured electricity consumption. For the ACB model’s calibration, some suitable modiﬁcations, including occupancy, equipment, and lighting schedule setting, were applied. A linear regression statistical approach was also used after manual calibration to assess the model’s correlation and precision. According to the ASHRAE Guideline 14-2014 [47], the model is considered calibrated when the NMBE and CV (RMSE) are not larger than 5 and 15%, respectively, when the monthly data are used [8,48,49]. The mathematical equations are presented below: Normalized Mean Bias Error

Np ∑ (Mi − Si) = i=1 ( ) NMBE Np % (1) ∑i=1 Mi Coefﬁcient of Variation of Root Square Mean Error

s Np 2 1 ∑ (Mi − Si) CV(RMSE) = i=1 (%) (2) M Np

In the above equations, Np is the total number of data values, Mi (where i = 1, 2, . . . , Np) represents the measured data, and Si (where i = 1, 2, ... , Np) represents the simulated data.

3. Results The climate of Karachi is hot and humid [37]; hence reducing the heat gains in buildings remains a priority for indoor environmental comfort. Conduction has a large impact on the building’s load values [1,4]. The passive gains of ACB were analyzed to provide a graphical representation of contributing factors. Figure4 indicates the monthly heat balance of the building envelope, and internal and solar gains in the base case building. It is observed that the solar gains are higher than the internal gains. This is mainly due to the conduction of the building envelope and radiation through transparent windows. Adding thermal mass and thermal insulation and improving window glazing in the existing building envelope can improve the building envelope efﬁciency, which will improve indoor Sustainability 2021, 13, x FOR PEER REVIEW 15 of 36 environmental comfort, and accordingly, facilitate annual electricity savings. Low internal gains during June and October are due to the vacations in the ACB.

Windows Walls Roof Internal gains Solar gains External Infiltration External Natural Ventilation Sensible cooling

8500 7500 6500 5500 4500 3500 2500 1500 Heat Balance (kWh) 500 —500 —1500

Months

FigureFigure 4. Heat 4. Heat transmission transmission in in th thee base base casecase building. building.

3.1. Calibration of the Model In order to calibrate the model, NMBE and CV (RMSE) equations were applied in compliance with ASHRAE standard 14-2014, considering allowable limits [47]. The model was calibrated manually, and several modifications, including occupancy, equipment, and lighting schedule setting, were applied to calibrate the model. The simulated and measured electricity consumption data were compared. Linear regression analysis was also performed to assess the accuracy, precision, and correlation of the calibration. NMBE, CV (RMSE), and the correlation coefficient (R2) values 2.26%, 13.8%, and 0.9921 of the final simulation were found suitable to verify the simulation model’s calibration. Figure 5a,b presents the calibration of the simulated model:

Measured data (kWh) Simulated data (kWh) 2500

2000

1500

1000 (kWh) 500

Electricity Consumption Consumption Electricity 0 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 Months (a) Sustainability 2021, 13, x FOR PEER REVIEW 15 of 36

Windows Walls Roof Internal gains Solar gains External Infiltration External Natural Ventilation Sensible cooling

8500 7500 6500 5500 4500 3500 2500 1500 Heat Balance (kWh) 500 —500 —1500

Months Sustainability 2021, 13, 7251 14 of 35 Figure 4. Heat transmission in the base case building.

3.1. Calibration3.1. Calibration of the Model of the Model In order Into ordercalibrate to calibratethe model, the NMBE model, an NMBEd CV (RMSE) and CV equations (RMSE) equations were applied were in applied in compliancecompliance with ASHRAE with ASHRAE standard standard14-2014, co 14-2014,nsidering considering allowable allowable limits [47]. limits The [model47]. The model was calibratedwas calibrated manually, manually, and several and modifications, several modifications, including including occupancy, occupancy, equipment, equipment, and lightingand schedule lighting schedulesetting, were setting, appli wereed to applied calibrate to calibratethe model. the The model. simulated The simulated and and measuredmeasured electricity electricity consumption consumption data were data compared. were compared. Linear regression Linear regression analysis analysiswas was also performedalso performed to assess the to assess accuracy, the accuracy,precision, precision, and correlation and correlation of the calibration. of the calibration. NMBE, NMBE, CV (RMSE),CV and (RMSE), the correlation and the correlation coefficient coefficient (R2) values (R 22.26%,) values 13.8%, 2.26%, and 13.8%, 0.9921 and of 0.9921the final of the final simulationsimulation were found were suitable found to suitable verify tothe verify simulation the simulation model’s model’scalibration. calibration. Figure 5a,b Figure 5a,b presents presentsthe calibration the calibration of the simulated of the simulated model: model:

Measured data (kWh) Simulated data (kWh) 2500

2000

1500

1000 (kWh) 500

Electricity Consumption Consumption Electricity 0 Sustainability 2021, 13, x FOR PEER REVIEW 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 16 of 36

Months (a) 2700

2400 y = 0.9703x — 3.7799 2100 R² = 0.9921 1800 1500 (kWh) 1200 900

Simulated consumption consumption Simulated 600 300 300 600 900 1200 1500 1800 2100 2400 2700 Measured consumption (kWh)

(b)

Figure 5. Figure(a) A 72-Month 5. (a) A (January 72-Month 2014 (January to December 2014 to 2019) December comparison 2019) between comparison the measured between theelec- measured tricity consumptionelectricity consumption and the simulated and the electricity simulated demand electricity for cooling, demand lighting, for cooling, and lighting,equipment. and ( equipment.b) Linear regression analysis of calibration of the simulated model (72 months). (b) Linear regression analysis of calibration of the simulated model (72 months).

3.2. PEEM3.2. PEEM After theAfter ACB the model ACB calibration, model calibration, different different PEEM cases PEEM for cases external for externalwall, roof, wall, win- roof, windows, anddows, doors and were doors tested were based tested on previous based on research previous [4,10,14,19,34,50–52] research [4,10,14,19 in,34 a ,hot50– and52] in a hot humid climate.and humid The authors climate. visited The authors local market visiteds to local check markets the availability to check of the the availability materials of the in Karachi.materials Concrete inKarachi. block walls, Concrete RCC blockslab, and walls, single-glazed RCC slab, and windows single-glazed having windows high U- having values arehigh commonU-values practice are common in Karach practicei, without in Karachi, considering without the considering standard theU-values standard de-U-values fined by deﬁnedENERCON by ENERCON [45]. Hence, [ 45considering]. Hence, considering the benchmark the benchmarkU-values byU ENERCON-values by and ENERCON the materialand theavailability material availabilityin Karachi, inthe Karachi, authors the chose authors the chosecompositions the compositions in the following in the following sections sectionsfrom previous from previous studies in studies a hot inand a hothumid and climate. humid climate.

3.2.1. PEEM Alternative #1 (Wall) A significant amount of heat conduction in buildings is carried out through external walls [53]. Being an essential component of the building envelope, the external walls play a significant role in providing indoor environmental comfort and energy conservation [53]. The amount of heat conduction through external walls is highly dependent on the thermal mass and thermal insulation [54]. The existing wall component, medium-weight concrete block of the building, was replaced by alternative materials, such as aerated concrete block, and added thermal insulation to identify materials and insulation with better energy performance while retaining the building’s existing structure. Different thermal insulation materials were considered for the study depending on their availability in Karachi. Insulation was also applied on the outside to include thermal mass in the analysis, since in a hot and humid climate, thermal mass and night ventilation substantially impact electricity consumption [54,55]. Table 5 and Figure A9 present the alternative wall compositions. Figure 6 and Table 6 indicate that case-W7 provides the most significant reduction in cooling demand of 13.56%, while case-W1 offers no reduction in cooling demand. The thermal conductivity and specific heat capacity of thermal insulation material exert a strong influence on the energy performance; low thermal conductivity and a high specific heat capacity of external walls are favorable for energy efficiency in buildings [2,56]. Case-W7 insulation material (EPS) has the lowest thermal conductivity and the highest specific heat capacity among the investigated insulation materials and is therefore found to be the most effective insulating material in renovation systems with similar thickness. Case-W4 (glass mineral wool) and case-W5 (rock mineral wool) have similar conductivity values as EPS, but low comparative specific heat capacity. Therefore, they are less effective insulating materials as compared to EPS for energy efficiency in the ACB. Case-W1 (aerated concrete block) is Sustainability 2021, 13, 7251 15 of 35

3.2.1. PEEM Alternative #1 (Wall) A significant amount of heat conduction in buildings is carried out through external walls [53]. Being an essential component of the building envelope, the external walls play a significant role in providing indoor environmental comfort and energy conservation [53]. The amount of heat conduction through external walls is highly dependent on the thermal mass and thermal insulation [54]. The existing wall component, medium-weight concrete block of the building, was replaced by alternative materials, such as aerated concrete block, and added thermal insulation to identify materials and insulation with better energy performance while retaining the building’s existing structure. Different thermal insulation materials were considered for the study depending on their availability in Karachi. Insulation was also applied on the outside to include thermal mass in the analysis, since in a hot and humid climate, thermal mass and night ventilation substantially impact electricity consumption [54,55]. Table5 and Figure A9 present the alternative wall compositions. Figure6 and Table6 indicate that case-W7 provides the most significant reduction in cooling demand of 13.56%, while case-W1 offers no reduction in cooling demand. The thermal conductivity and specific heat capacity of thermal insulation material exert a strong influence on the energy performance; low thermal conductivity and a high specific heat capacity of external walls are favorable for energy efficiency in buildings [2,56]. Case-W7 insulation material (EPS) has the lowest thermal conductivity and the highest specific heat capacity among the investigated insulation materials and is therefore found to be the most effective insulating material in renovation systems with similar thickness. Case-W4 (glass mineral wool) and case-W5 (rock mineral wool) have similar conductivity values as EPS, but low comparative specific heat capacity. Therefore, they are less effective insulating materials as compared to EPS for energy efficiency in the ACB. Case-W1 (aerated concrete block) is the common practice in renovation strategies; however, consideration of the standard U-values presented by ENERCON is neglected in Karachi. It is observed that using insulation in wall composition will improve indoor environmental conditions, and accordingly will reduce cooling energy demand. Moreover, the results show that expanded polystyrene (EPS) is the most effective insulating material in lowering cooling energy demand, which is attributed to its thermophysical properties. The results are consistent with the previous study [4].

Table 5. Alternative wall compositions used in wall modiﬁcation. Legend: EPS, expanded polystyrene; W, wall.

Conductivity Speciﬁc Heat Density Thickness Cases (W/m K) Capacity (J/kg K) (kg/m3) (cm) Case-W1 Outermost Plaster 0.431 1088 1250 0.95 Concrete block 0.24 1000 750 20 aerated Innermost Plaster 0.431 1088 1250 0.95 U-value 0.943 W/m2 K Case-W2 Outermost Plaster 0.431 1088 1250 0.95 Loose-ﬁll cellulose 0.04 1380 43 10 insulation Concrete block, 1.3 840 1800 20 medium weight Innermost Plaster 0.431 1088 1250 0.95 U-value 0.344 W/m2 K Sustainability 2021, 13, 7251 16 of 35

Table 5. Cont.

Conductivity Speciﬁc Heat Density Thickness Cases (W/m K) Capacity (J/kg K) (kg/m3) (cm) Case-W3 Outermost Plaster 0.431 1088 1250 0.95 EPS (standard) 0.04 1500 15 5 Concrete block, 1.3 840 1800 20 medium weight Innermost Plaster 0.431 1088 1250 0.95 U-value 0.619 W/m2 K Case-W4 Outermost Plaster 0.431 1088 1250 0.95 Glass mineral wool 0.04 830 15 10 Concrete block, 1.3 840 1800 20 medium weight Innermost Plaster 0.431 1088 1250 0.95 U-value 0.349 W/m2 K Case-W5 Outermost Plaster 0.431 1088 1250 0.95 Rock mineral wool 0.038 840 140 10 Concrete block, 1.3 840 1800 20 medium weight Innermost Plaster 0.431 1088 1250 0.95 U-value 0.334 W/m2 K Case-W6 Outermost Plaster 0.431 1088 1250 0.95 EPS (lightweight) 0.046 1400 10 10 Concrete block, 1.3 840 1800 20 medium weight Innermost Plaster 0.431 1088 1250 0.95 U-value 0.388 W/m2 K Case-W7 Outermost Plaster 0.431 1088 1250 0.95 EPS (standard) 0.04 1500 15 10 Concrete block, 1.3 840 1800 20 medium weight Innermost Plaster 0.431 1088 1250 0.95 U-value 0.320 W/m2 K Case-W8 Outermost Plaster 0.431 1088 1250 0.95 EPS (standard) 0.04 1500 15 7.5 Concrete block, 1.3 840 1800 20 medium weight Innermost Plaster 0.431 1088 1250 0.95 U-value 0.446 W/m2 K Sustainability 2021, 13, x FOR PEER REVIEW 18 of 36

Concrete block, medium 1.3 840 1800 20 weight Innermost Plaster 0.431 1088 1250 0.95 U-value 0.388 W/m2 K SustainabilityCase-W7 2021, 13, 7251 17 of 35 Outermost Plaster 0.431 1088 1250 0.95 EPS (standard) 0.04 1500 15 10 Concrete block, medium 3.2.2. PEEM Alternative1.3 #2 (Roof) 840 1800 20 weight The roof is the primary source of heat gains in the ACB, because of the high U-value Innermost Plasterin the base case. By 0.431insulating the existing1088 roof with different 1250 materials (Table 0.95 7 and U-value Figure A10), i.e., bitumen, EPS, and polyurethane,0.320 W/m reductions2 K in cooling demand of 2.3, Case-W8 5.5, and 5.1%, respectively, were achieved. The roof was insulated to minimize the heat Outermost Plastergains in the building. 0.431 Case-R1 is not recommended,1088 since the1250 insulating layer 0.95 “bitumen” EPS (standard)has a high conductivity0.04 value compared1500 to EPS and polyurethane 15 and is mainly 7.5 used for waterproofing. Case-R3 (polyurethane) and case-R4 (EPS) have similar construction and Concrete block, medium thickness; however, case-R41.3 (EPS) has a lower840 U-value and is 1800 found to be the most 20 effective weight insulating material in the renovation system. Hence, case-R4 was further modified, and Innermost Plastera significant reduction 0.431 in cooling energy1088 demand of 8.8% was 1250 achieved by using 0.95 case-R5 U-value (Figure7, Table8). 0.446 W/m2 K

Figure 6. Alternative wall modifications presenting simulated energy demand compared to the base case. Figure 6. Alternative wall modiﬁcations presenting simulated energy demand compared to the base case.

Table 6. Impact of alternative wall compositions on the reduction of cooling energy demand. Cost of insulation acquired Table 6. Impact of alternative wall compositions on the reduction of cooling energy demand. Cost of insulation acquired from the local market. from the local market. Cost of Insulation in Energy Demand Reduction in Energy De- Cases Insulation Cost of Insulation in Energy Demand Reduction in Energy Cases Insulation USD (kWh) mand (%) USD (kWh) Demand (%) Base case No - 20,975.48 0 Base case No - 20,975.48 0 W1 No - 20,975.48 0 W2 W1 Loose-fill cellulose Noinsulation 34.54 per - kg 18,667.75 20,975.48 11.1 0 Loose-ﬁll cellulose 2 W3 W2 0.05 m EPS (standard) 11–1634.54 per per m kg 19,842.35 18,667.75 5.4 11.1 insulation W4 Glass mineral wool 1–3 per m2 19,234.08 8.3 2 W5 W3 Rock 0.05mineral m EPS wool (standard) 0.98–1.8411–16 per m 2 19,045.319,842.35 9.2 5.4 W6 W4 EPS (light Glass weight) mineral wool 11–131–3 per per m m22 19,338.9519,234.08 7.8 8.3 W7 W5 0.1 m EPS Rock (standard) mineral wool 11–160.98–1.84 per perm2 m2 18,130.7919,045.3 13.56 9.2 2 W8 W6 0.075 m EPS EPS (standard) (light weight) 11–1611–13 per per m m 2 19,569.6819,338.95 6.7 7.8 W7 0.1 m EPS (standard) 11–16 per m2 18,130.79 13.56 W8 0.075 m EPS (standard) 11–16 per m2 19,569.68 6.7 Sustainability 2021, 13, 7251 18 of 35

Table 7. Alternative roof compositions used in roof modiﬁcation. Legend: PCC, plain cement concrete; RCC, reinforced cement concrete; R, roof.

Conductivity Specific Heat Density Thickness Cases (W/m K) Capacity (J/kg K) (kg/m3) (cm) Case-R1 Outermost Screed 0.4 840 1200 0.95 Bitumen layer 0.5 1000 1700 0.4 RCC slab 0.753 656.9 2300 10 Innermost Plaster 0.38 840 1150 0.95 U-value 2.53 W/m2 K Case-R2 Outermost Screed 0.4 840 1200 0.95 Waterproofing 0.5 1800 980 0.05 layer EPS (lightweight) 0.046 1400 10 10 RCC slab 0.753 656.9 2300 10 Innermost Plaster 0.38 840 1150 0.95 U-value 0.341 W/m2 K Case-R3 Outermost Screed 0.4 840 1200 0.95 Waterproofing 0.5 1800 980 0.05 layer Polyurethane 0.05 1470 70 10 RCC slab 0.753 656.9 2300 10 Innermost Plaster 0.38 840 1150 0.95 U-value 0.434 W/m2 K Case-R4 Outermost Screed 0.4 840 1200 0.95 Waterproofing 0.5 1800 980 0.05 layer EPS (standard) 0.04 1500 15 10 RCC slab 0.753 656.9 2300 10 Innermost Plaster 0.38 840 1150 0.95 U-value 0.319 W/m2 K Case-R5 Outermost Roof tiles 0.84 800 1900 3.8 PCC 0.209 656 950 50 Waterproofing 0.5 1800 980 0.05 layer EPS (standard) 0.04 1500 15 10 RCC slab 0.753 656.9 2300 10 Innermost Plaster 0.38 840 1150 0.95 U-value 0.214 W/m2 K Sustainability 2021, 13, x FOR PEER REVIEW 20 of 36

Sustainability 2021,RCC13, 7251 slab 0.753 656.9 2300 10 19 of 35 Innermost Plaster 0.38 840 1150 0.95 U-value 0.214 W/m2 K

FigureFigure 7. Alternative 7. Alternative roof modiﬁcations roof modifications presenting presenting simulated simulated energy demandenergy demand as compared as compared to the base to the case. base case. Table 8. Impact of alternative roof compositions on the reduction of energy demand. Table 8. Impact of alternative roof compositions on the reduction of energy demand. Cost of Insulation in Energy Demand Reduction in Energy CasesCost Insulation of Insulation in Energy Demand Reduction in Energy Demand Cases Insulation USD per m2 (kWh) Demand (%) USD per m2 (kWh) (%) Base case No - 20,975.48 0 Base case No - 20,975.48 0 R1 Bitumen 1.42–1.97 20,933.53 0.2 R1 R2Bitumen EPS (lightweight) 1.42–1.97 11–1320,933.53 19,821.8 0.2 5.5 R2 EPS R3(lightweight) Polyurethane 11–13 2.99–5.6 19,821.8 19,968.66 5.5 4.8 R3 PolyurethaneR4 EPS (standard) 2.99–5.6 11–16 19,968.66 19,486.224.8 7.1 R4 EPSR5 (standard) EPS (standard) 11–16 11–16 19,486.22 19,129.6 7.1 8.8 R5 EPS (standard) 11–16 19,129.6 8.8 3.2.3. PEEM Alternative #3 (Windows) 3.2.3. PEEM AlternativeThe glazing #3 (Windows) type and layers directly impact the amount of heat transmission through The glazingthe windows type and bylayers either directly solar radiation impact the or conductionamount of heat heat transmission transfer mechanisms through [ 17]. Glazing the windowsplays by either a crucial solarrole radiation in the or heat conduction balance of heat a building. transfer mechanisms The existing [17]. single-glazed Glaz- window ing plays a crucialis the dominantrole in the typeheat ofbalance window of a glazing building. in Karachi,The existing with single-glazed a high U-value win- (5.7 W/m2 K) dow is the dominantand solar type heat of gain window coefﬁcient glazing (SHGC) in Karachi, (0.81), highwith heata high gain, U-value and heat (5.7 transmittance.W/m2 The K) and solar replacementheat gain coefficient of an existing (SHGC) single-glazed (0.81), high window heat gain, with and other heat materials transmittance. (Table9 ), such as a The replacementdouble of an clear existing glass single-glazed window, clear window triple glass, with double other materials tinted glass, (Table and 9), double such low-E clear as a double clearglass, glass gave window, up to 8.6% clear reduction triple glass, in cooling double energy tinted glass, demand. and Case-WW3double low- hasE the lowest clear glass, gaveSHGC, up to which 8.6% makes reduction this in glazing cooling type energy most demand. suitable. Case-WW3 However, case-WW3has the low- also has a low est SHGC, whichlight transmittancemakes this glazing value type (0.50), most which suitable. is not desiredHowever, in educationalcase-WW3 also buildings. has a Case-WW1 low light transmittancehas the highest value light (0.50), transmittance which is not value desired (0.81) in with educational a high SHGC buildings. (0.76). HenceCase- this glazing WW1 has theis highest also unsuitable. light transm Useittance of double value low- (0.81)E clearwith glassa high in SHGC case-WW6 (0.76). provides Hence this the maximum glazing is alsoreduction unsuitable. in coolingUse of double energy low- demandE clear of glass 8.6% in with case-WW6 SHGC provides (0.56) and the light max- transmittance imum reduction(0.74), in andcooling is attributed energy demand to the of thermal 8.6% with properties SHGC (0.56) of this and glazing light type,transmit- which prevents tance (0.74), anddirect is attributed heat gain to in the the thermal building pr (Figureoperties8, of Table this glazing10). Hence, type, case-WW6 which prevents provides a good direct heat gaincompromise in the building between (Figure thermal 8, Table loss/gain 10). andHence, natural case-WW6 light quality provides [46 ,a57 good]. It is found that compromise thebetween glazing thermal type is loss/gain the main and factor natural that determines light quality the [46,57]. energy performanceIt is found that of the window. the glazing typeShading is thewas main also factor provided, that det keepingermines all the other energy parameters performance as in of the the base window. case to investigate Shading wasthe also effect provided, of shading keeping on theall other reduction parameters of cooling as in energy the base demand. case to The investigate results indicated that the longer the shading, the greater the savings. The maximum energy demand reduction of 2.5% was achieved with 1.0 m overhangs, but this is not recommended, because the effectiveness of the extended shading length starts to level off (Figure8, Table 10). The results are in agreement with previous studies [19,20]. Sustainability 2021, 13, 7251 20 of 35

Table 9. Alternative window compositions and overhang sizes used in window modiﬁcation. Legend: WW, window; light transmittance, LT; solar heat gain coefﬁcient, SHGC; LoE, low emissivity.

Cases Speciﬁcations Case-WW1 Double clear 3 mm glass /13 mm air window U-value = 2.7 W/m2 K SHGC = 0.76 LT = 0.81 Case-WW2 Triple clear 6 mm glass /25 mm air window U-value = 1.9 W/m2 K SHGC = 0.60 LT = 0.69 Case-WW3 Double tinted 6 mm glass /13 mm air window U-value = 2.6 W/m2 K SHGC = 0.49 LT = 0.50 Case-WW4 Double tinted 3 mm glass /13 mm air window U-value = 2.7 W/m2 K SHGC = 0.62 LT = 0.61 Case-WW5 Triple clear 3 mm glass /13 mm air window U-value = 1.75 W/m2 K SHGC = 0.68 LT = 0.73 Case-WW6 Double LoE clear 6 mm glass/13 mm argon U-value = 1.49 W/m2 K SHGC = 0.56 LT = 0.74 Case-O1 40 cm overhang Case-O2 50 cm overhang Case-O3 60 cm overhang Sustainability 2021, 13, x FOR PEER REVIEW 22 of 36 Case-O4 100 cm overhang

Figure 8. Alternative window modifications presenting simulated energy demand as compared to Figure 8. Alternative window modifications presenting simulated energy demand as compared to the base case. the base case. The optimum window-to-wall ratio (WWR) at different façades was also calculated. The optimumThe WWR window-to-wall in three façades: ratio (WWR) north, at east, different and west, façades was was investigated also calculated. from 0 to 100%, in The WWR in threesteps façades: of 5%. First, north, the east, WWR and of west all, three was investigated façades was from changed 0 to 100%, to 5%, in then steps 10%, and so on. of 5%. First, theWith WWR 25% of WWR all three on the façades north was façade, changed the maximum to 5%, then cooling 10%, demand and so on. reduction With of 0.1% was 25% WWR onobserved. the north façade, The WWR the valuemaximum of 15% cooling on the demand west and reductio east façadesn of 0.1% gave was a coolingob- demand served. The WWRreduction value of of 0.3%. 15% Theon the results west show and east 5% discrepancyfaçades gave in a thecooling east anddemand west re- façades, and no duction of 0.3%.disparity The results in the show north 5% and discre southpancy façades in the to the east results and west of previous façades, studies and no in the hot and disparity in thehumid north climates and south of Asiafaçades [58 ,59to ].th Thee results discrepancy of previous is because studies of in the the different hot and sun angles of humid climatesdifferent of Asia cities. [58,59]. The The WWR discrepancy modification is because is not included of the different in the final sun recommendations, angles of since different cities.the The existing WWR WWR modification (north façade is not = included 27%, east in and the west final façades recommendations, = 14%) of all façades have since the existing WWR (north façade = 27%, east and west façades = 14%) of all façades have optimum results in terms of cooling energy reduction. The existing WWR has also been proved to be effective in reducing the energy demand from previous studies in a hot and humid climate [58,59].

3.2.4. PEEM Alternative #4 (Door) Two different alternatives based on common practice in Karachi were considered substitutes for hollow core plywood doors (Table 11). Figure 9 indicates the cooling energy demand reductions achieved by using alternative doors. There is a slight reduction in cooling energy demand, and case-D2 provides a 0.2% reduction (Figure 9, Table 12).

Table 11. Alternative door compositions used in the modification of doors. Legend: D, door.

Cases Specifications Case-D1 3.5 cm painted oak door U-value 2.82 W/m2 K Case-D2 4.2 cm painted oak door U-value 2.557 W/m2 K Sustainability 2021, 13, 7251 21 of 35

optimum results in terms of cooling energy reduction. The existing WWR has also been proved to be effective in reducing the energy demand from previous studies in a hot and humid climate [58,59].

Table 10. Impact of alternative window compositions on cooling energy demand.

Energy Demand Reduction in Cases (kWh) Energy Demand (%) Base case 20,975.48 0 WW1 20,073.5 4.3 WW2 19,423.2 7.4 WW3 19,779.8 5.7 WW4 19,716.9 6 WW5 19,675 6.2 WW6 19,171.5 8.6 O1 20,891.5 0.4 O2 20,807.6 0.8 O3 20,702.7 1.3 O4 20,451 2.5

3.2.4. PEEM Alternative #4 (Door) Two different alternatives based on common practice in Karachi were considered substitutes for hollow core plywood doors (Table 11). Figure9 indicates the cooling energy demand reductions achieved by using alternative doors. There is a slight reduction in cooling energy demand, and case-D2 provides a 0.2% reduction (Figure9, Table 12).

Table 11. Alternative door compositions used in the modiﬁcation of doors. Legend: D, door.

Cases Speciﬁcations Case-D1 3.5 cm painted oak door U-value 2.82 W/m2 K Case-D2 4.2 cm painted oak door Sustainability 2021, 13, x FOR PEER REVIEW 2 23 of 36 U-value 2.557 W/m K

Figure 9. Alternative door modifications presenting simulated energy demand as compared to the Figure 9. Alternative door modiﬁcations presenting simulated energy demand as compared to the base case. base case. Table 12. Impact of alternative door compositions on cooling energy demand.

Energy Demand Reduction in Cases (kWh) Energy Demand (%) Base case 20,975.48 0 D1 20,975.48 0 D2 20,933.53 0.2

3.2.5. PEEM Alternative #5 (Combination of Modifications) After investigating the modification strategies for each element of the ACB, the com- bined effect of all these modification strategies in reducing cooling energy demand and comfort temperature of the ACB was studied. Table 13 presents a combination of the modifications: airtightness, airflow, indoor temperature, and cooling energy demand reduction achieved by modifying the existing building envelope. The combination can reduce the cooling energy demand by 31.96% annually. Cases A and B illustrate a cooling energy demand reduction of 31.96% each, but case A is recommended, since case B includes an O4 (1 m overhangs) modification strategy, which is not recommended, as discussed in Section 3.2.3. Figure 10 represents the temperature curve for the outdoor and indoor temperatures with a comfortable temperature range in Karachi of 26–28 °C. In Karachi, there is a need for frequent and balanced airflow and air change [60]; however, high airflow was observed in the base case ACB. Natural ventilation rooms are dependent on outdoor temperatures and the existence of openings allowing airflow between the rooms and ad- jacent environments [61]. Case A is suitable for ACB modification, since it gives the highest reduction in energy demand and is the closest to the comfortable temperatures, and the airtightness standard of 0.6 ACH [62,63] and the airflow standard of 0.35 m3/s [46] in Karachi. Figure 11 presents the heat transmission in the modified building envelope. The modified building envelope minimizes the heat transfer through walls by 51%, windows by 50%, and roof by 30%. Solar gains are also minimized by 57% (Figure 10).

Sustainability 2021, 13, 7251 22 of 35

Table 12. Impact of alternative door compositions on cooling energy demand.

Energy Demand Reduction in Cases (kWh) Energy Demand (%) Base case 20,975.48 0 D1 20,975.48 0 D2 20,933.53 0.2

3.2.5. PEEM Alternative #5 (Combination of Modifications) After investigating the modification strategies for each element of the ACB, the com- bined effect of all these modification strategies in reducing cooling energy demand and comfort temperature of the ACB was studied. Table 13 presents a combination of the modifications: airtightness, airflow, indoor temperature, and cooling energy demand reduction achieved by modifying the existing building envelope. The combination can reduce the cooling energy demand by 31.96% annually. Cases A and B illustrate a cooling energy demand reduction of 31.96% each, but case A is recommended, since case B includes an O4 (1 m overhangs) modification strategy, which is not recommended, as discussed in Section 3.2.3. Figure 10 represents the temperature curve for the outdoor and indoor temperatures with a comfortable temperature range in Karachi of 26–28 ◦C. In Karachi, there is a need for frequent and balanced airflow and air change [60]; however, high airflow was observed in the base case ACB. Natural ventilation rooms are dependent on outdoor temperatures and the existence of openings allowing airflow between the rooms and adja- cent environments [61]. Case A is suitable for ACB modification, since it gives the highest reduction in energy demand and is the closest to the comfortable temperatures, and the airtightness standard of 0.6 ACH [62,63] and the airflow standard of 0.35 m3/s [46] in Karachi. Figure 11 presents the heat transmission in the modified building envelope. The modified building envelope minimizes the heat transfer through walls by 51%, windows by 50%, and roof by 30%. Solar gains are also minimized by 57% (Figure 10).

Table 13. Effect of modiﬁcation strategies on the indoor temperature, airtightness, airﬂow, and total reduction of energy demand (%). Legend: N, north cluster; E, east cluster; W, west cluster.

Combination of Reduction of Indoor Airtightness Airﬂow Case Modiﬁcations Energy Demand (%) Temperature(◦C) (ACH) (m3/s) N = 0.46, E = 0.40, Base case 0 34.3 2.5 W = 0.58 N = 0.40, E = 0.35, A W7, R4, WW6, O2, D2 31.96 29.4 1.2 W = 0.45 N = 0.42, E = 0.36, B W7, R5, WW6, O4, D2 31.96 29.5 1.3 W = 0.49 N = 0.43, E = 0.37, C W8, R4, WW2, O2, D2 24.9 31 2 W = 0.51 N = 0.44, E = 0.38, D W8, R5, WW2, O2, D2 23.2 31.5 1.5 W = 0.53 Sustainability 2021, 13, x FOR PEER REVIEW 24 of 36

Table 13. Effect of modification strategies on the indoor temperature, airtightness, airflow, and total reduction of energy demand (%). Legend: N, north cluster; E, east cluster; W, west cluster.

Combination of Mod- Reduction of Energy Indoor Temperature Airtightness Airflow Case ifications Demand (%) (°C) (ACH) (m3/s) N = 0.46, E = 0.40, W Base case 0 34.3 2.5 = 0.58 N = 0.40, E = 0.35, W A W7, R4, WW6, O2, D2 31.96 29.4 1.2 = 0.45 N = 0.42, E = 0.36, W B W7, R5, WW6, O4, D2 31.96 29.5 1.3 = 0.49 N = 0.43, E = 0.37, W C W8, R4, WW2, O2, D2 24.9 31 2 = 0.51 Sustainability 2021, 13, 7251 23 of 35 N = 0.44, E = 0.38, W D W8, R5, WW2, O2, D2 23.2 31.5 1.5 = 0.53

Comfort range Basecase Indoor Temperature Outdoor Temperature (◦C) Case A Indoor Temperature Case C Indoor Temperature Case D Indoor Temperature 42 Case B Indoor Temperature 40 C) ◦ 38 36 34 32 Temperature ( 30 28 26 24 00:00—01:00 01:00—02:00 02:00—03:00 03:00—04:00 04:00—05:00 05:00—06:00 06:00—07:00 07:00—08:00 08:00—09:00 09:00—10:00 10:00—11:00 11:00—12:00 12:00—13:00 13:00—14:00 14:00—15:00 15:00—16:00 16:00—17:00 17:00—18:00 18:00—19:00 19:00—20:00 20:00—21:00 21:00—22:00 22:00—23:00 23:00—24:00 Time (Hour) Sustainability 2021, 13, x FOR PEER REVIEW 25 of 36 FigureFigure 10.10.Temperature Temperature curve curve for for the the outdoor outdoor temperature, temperature, base base case ca indoorse indoor temperature, temperature, and modiﬁedand modified building building envelope’s enve- indoorlope’s indoor temperature temperature during during summer summer (May to (May August). to August).

Windows Walls Roof Internal gains Solar gains External Infiltration External Natural Ventilation Sensible cooling 5000

4000

3000

2000

1000 Heat Balance (kWh) 0

—1000

Months Figure 11. HeatHeat transmission transmission in the modified modiﬁed building envelope.

4.4. Discussion Discussion 4.1.4.1. Key Key Findings Findings and and Recommendations Recommendations TheThe study study selected selected an an exemplary exemplary ACB, ACB, whic whichh was was simulated, simulated, and and then then calibrated calibrated us- ingusing electricity electricity billing billing data. data. PEEMs PEEMs were were applied applied to identify to identify the thebest best case case for forreducing reducing in- doorindoor temperature temperature and and energy energy demand demand for for coolin cooling.g. Modification Modiﬁcation measures measures of of walls, walls, roof, roof, windows,windows, and and doors doors were were considered considered with better energy energy performance while retaining the building’sbuilding’s existing existing structure. structure. The The results results showed showed that that thermal thermal insulation insulation in the in thewall wall is the is bestthe bestmodification modiﬁcation measure measure for forreducing reducing energy energy demand demand for for cooling. cooling. It It was was found found that PEEMPEEM plays plays a a crucial crucial role in reducing ener energygy demand for cooling in the exemplary ACB. The study proved that PEEM is significantly effective in improving indoor environmental comfort, and accordingly, minimizing electricity demand in ACB. The results showed that using insulation in the building envelope positively impacts indoor environmental comfort, and reduces the energy demand for cooling. Moreover, the results revealed that among the investigated insulation materials, EPS had the lowest thermal conductivity and the highest specific heat capacity, and was therefore the most effective insulating material in renovation systems with similar thickness for reducing the indoor temperature and the related energy demand for cooling. The following recommendations are given based on the significant findings as resources to help architects in setting out the design plan for existing educational buildings using PEEMs in a hot and humid climate: • Building users consume a major proportion of electricity for thermal comfort, such as cooling in Karachi. This consumption can be reduced by using PEEMs. Building envelope modification is a crucial PEEM for thermal comfort and reduction in energy demand for cooling. By using PEEMs, a 31.96% reduction in energy demand for cooling can be achieved. • Thermal insulation of 100 mm outside the thermal mass (200 mm) in the wall plays a significant role in reducing the maximum indoor temperature in hybrid buildings, and accordingly, reducing the electricity demand of a building. • The common practice in Karachi is the use of single-glazed windows with high U- values (5.7 W/m2 K). By replacing the single-glazed windows with double-glazed low-E reflective glass windows, the cooling energy demand can be reduced by 8.6%. • Awnings (overhangs) above the windows are provided to reduce heat gains in the building. This study showed that the longer the overhangs, the greater the reduction Sustainability 2021, 13, 7251 24 of 35

The study proved that PEEM is significantly effective in improving indoor environmental comfort, and accordingly, minimizing electricity demand in ACB. The results showed that using insulation in the building envelope positively impacts indoor environmental comfort, and reduces the energy demand for cooling. Moreover, the results revealed that among the investigated insulation materials, EPS had the lowest thermal conductivity and the highest specific heat capacity, and was therefore the most effective insulating material in renovation systems with similar thickness for reducing the indoor temperature and the related energy demand for cooling. The following recommendations are given based on the significant findings as resources to help architects in setting out the design plan for existing educational buildings using PEEMs in a hot and humid climate: • Building users consume a major proportion of electricity for thermal comfort, such as cooling in Karachi. This consumption can be reduced by using PEEMs. Building envelope modification is a crucial PEEM for thermal comfort and reduction in energy demand for cooling. By using PEEMs, a 31.96% reduction in energy demand for cooling can be achieved. • Thermal insulation of 100 mm outside the thermal mass (200 mm) in the wall plays a significant role in reducing the maximum indoor temperature in hybrid buildings, and accordingly, reducing the electricity demand of a building. • The common practice in Karachi is the use of single-glazed windows with high U- values (5.7 W/m2 K). By replacing the single-glazed windows with double-glazed low-E reflective glass windows, the cooling energy demand can be reduced by 8.6%. • Awnings (overhangs) above the windows are provided to reduce heat gains in the building. This study showed that the longer the overhangs, the greater the reduction in energy demand for cooling. However, long fixed overhangs are not practical, because they limit the solar heat gain in winter, as well as natural light. Hence, adjustable shading devices can be useful, since adjustable shading devices allow greater flexibility to make adjustments in response to changing weather conditions. • Pakistan’s urban population experiences 12–15 h of electricity blackout (load shedding) per day. Hence, reliance on active systems is not possible, and PEEMs are recommended. Retrofitting existing buildings to improve building energy efficiency is a better solution to such problems, since the existing buildings in Pakistan are energy inefficient.

4.2. Strengths and Limitations In this study, the possibility and capability of BIM and building performance simulation (BPS) to virtually model and assess building energy demand against modification strategies, such as PEEMs, offer the opportunity to explore alternatives for an existing ACB. This provides an excellent opportunity to avoid mistakes that might arise when the building is being assessed using manual or traditional techniques. Furthermore, when such errors occur, it is difficult to correct them when the building has already been modified. The study used a virtual model based on physical observations and surveys, which was calibrated using actual data by validated calibration methods. Using advanced building performance simulation provided reliable results to understand the electricity demand and potential reduction in electricity demand for cooling by applying PEEMs. The strength of this study is associated with the selection of the base case ACB. Furthermore, the novelty of this study lies in the context, climate, and building type. The findings not only investigate the potential of PEEMs in reducing energy demand for cooling, but can set live (good-practice) examples for students (future architects) who are studying ACB to design the buildings considering PEEMs. Although this research focused on one ACB in Karachi, the implications made would be helpful in creating the general performance of energy efficiency in architecture campus buildings in a hot and humid climate, which would assist architects while designing architecture campus buildings in comparable climates. However, there are limitations to Sustainability 2021, 13, 7251 25 of 35

the generalizability of the results, since the building use, microclimate, and design of each building is different. Consequently, it will not be advisable to develop design strategies based on the investigation of only one building. However, the method used in this research can be considered for developing design strategies in a similar climate and for similar building use. Secondly, this research focused on construction materials and thermal properties, and other associated building properties; lighting issues may be investigated for more detailed insights. Thirdly, the degree of the building’s airtightness may be investigated using airtightness testing to identify air inﬁltration through the building envelope.

4.3. Study Implications and Future Research Karachi is a metropolitan city, and is the most populous city of Pakistan, where most buildings are not designed considering energy efficiency. As in many other cities of Pakistan [31], the building users rely on active measures, such as personalized split air conditioners. This results in high electricity bills, which create a financial burden on the building users. These active measures do not perform during the electricity blackout hours, which decrease building users’ thermal comfort. For this reason, the renovation of existing buildings through PEEMs is a more suitable solution to such problems. However, these building owners do not undertake the necessary building renovations due to upfront cost and high hurdle rates, lack of information and awareness, absence of incentives, financing difficulties, mispricing, and lack of attention and materiality [64]. The government of Pakistan should encourage energy-efficient renovations, which are uncommon in Pakistan. Future research on ACB will focus on (i) earth-to-air heat exchangers as a PEEM to improve thermal comfort and reduce energy demand in the exemplary ACB; (ii) sensitivity analysis of the impact of passive design strategies on thermal comfort and energy efficiency in the hot and humid climate of Karachi; and (iii) combining active and passive measures to achieve optimal thermal comfort in the ACB.

5. Conclusions This research focused on PEEMs to investigate various building components with different materials to mitigate heat transmission from/into the ACB, and improve the building performance in reducing indoor temperature and energy demand for cooling with the aid of BIM and parametric analysis using building performance simulation. This research also analyzed various building envelope compositions for the reduction in energy demand for the cooling perspective. Modifications of building envelope components are generally referred to as PEEMs. The investigated ACB showed significant potential in reducing indoor temperature and energy demand for cooling by adding thermal insulation outside of the opaque building envelope. The reduction in energy demand for cooling can be achieved by replacing the clear single-glazed windows (with high U-value) to double low-E electro reflective glass windows (with low U-value). A broader conclusion can be derived that a high-thermal-mass building with thermal insulation outside of the opaque building envelope performs well in a hot and humid climate. This conclusion is in agreement with the results of previous studies conducted in a hot and humid climate [55,65,66]. Based on this research, the following conclusions are made: 1. Thermal insulation of walls is found to be the best modification measure to reduce cooling energy demand. 2. Replacing single-glazed windows with double low-E electro reflective glass gave 8.6% reduction in cooling energy demand. 3. Thermal insulation with the lowest thermal conductivity and the highest specific heat capacity with similar thickness among the investigated insulation materials is the most effective insulating material for lowering the cooling energy demand. 4. The indoor temperature of the base case ACB was 34.3 ◦C. The modification strategies applied in case A reduced the indoor temperature to 29.4 ◦C. Case B, case C, and case D reduced the indoor temperature to 29.5, 31, and 31.5 ◦C, respectively. Sustainability 2021, 13, 7251 26 of 35

5. An architect and designer can use building thermal modeling to design an energy- efficient building by analyzing the effectiveness of various construction and material alternatives. Hence, it is recommended to use BIM and building performance simulation to investigate energy-efficient measures. 6. In Pakistan, building owners lack the knowledge, interest, expertise, and awareness in the retrofitting of buildings for energy efficiency. Therefore, the government should provide incentives to facilitate the retrofitting of buildings to achieve energy efficiency.

Author Contributions: Conceptualization, M.B., M.S.K., W.A.M. and T.S.; methodology, M.B., M.S.K., W.A.M. and T.S.; software, M.B., M.S.K. and W.A.M.; validation, M.B. and W.A.M.; formal analysis, M.B.; investigation, M.B., M.S.K. and W.A.M.; resources, M.B. and T.S.; data curation, M.B.; writing—original draft preparation, M.B.; writing—review and editing, M.B., M.S.K., W.A.M. and T.S.; visualization, M.B.; supervision, T.S.; project administration, M.B. and T.S.; funding acquisi- tion, M.B., M.S.K., W.A.M. and T.S. All authors have read and agreed to the published version of the manuscript. Funding: The authors acknowledge the Higher Education Commission (HEC) of Pakistan for providing the necessary funds and resources to complete the PhD studies of the first author under the HRDI-UESTP scholarship program Batch III with ref. no. 50022580. The study is part of a PhD research program being carried out at SKKU, Korea. No funding was provided for conducting and publishing this research. The funding agency has no role in selecting the research topics, research domain, methodology, or the results of this PhD. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: The data presented in this study are available on request from the first author. Acknowledgments: The authors are grateful to Faizullah Abbasi (Vice Chancellor), Dost Ali Khowaja (Academic Coordinator), and Rabia Siddique (Chairperson of the Architecture Department) of Dawood University of Engineering and Technology (DUET), Karachi, for their help in the field surveys and data collection. Conflicts of Interest: The authors declare that they have no conflict of interest. Nomenclature The following abbreviations are used in this paper: ACB architectural campus building AM analytical model ASHRAE American Society of Heating, Refrigeration, and Air-Conditioning Engineers BIM building information modeling BPS building performance simulation CV(RMSE) coefficient of variation of root square mean error D door DB DesignBuilder EPS expanded polystyrene gbXML Green Building Extensible Markup Language HVAC heating, ventilation, and air-conditioning LT light transmission NMBE normalized mean bias error O overhang PCC plain cement concrete PEC Pakistan Engineering Council PEEMs passive energy efficiency measures PGBC Pakistan Green Building Council R roof RCC reinforced cement concrete Sustainability 2021, 13, x FOR PEER REVIEW 28 of 36

Informed Consent Statement: Not applicable. Data Availability Statement: The data presented in this study are available on request from the first author. Acknowledgments: The authors are grateful to Faizullah Abbasi (Vice Chancellor), Dost Ali Khow- aja (Academic Coordinator), and Rabia Siddique (Chairperson of the Architecture Department) of Dawood University of Engineering and Technology (DUET), Karachi, for their help in the field surveys and data collection. Conflicts of Interest: The authors declare that they have no conflict of interest.

Nomenclature The following abbreviations are used in this paper: ACB architectural campus building AM analytical model ASHRAE American Society of Heating, Refrigeration, and Air-Conditioning Engineers BIM building information modeling BPS building performance simulation CV(RMSE) coefficient of variation of root square mean error D door DB DesignBuilder EPS expanded polystyrene gbXML Green Building Extensible Markup Language HVAC heating, ventilation, and air-conditioning LT light transmission NMBE normalized mean bias error O overhang PCC plain cement concrete PEC Pakistan Engineering Council PEEMs passive energy efficiency measures PGBC Pakistan Green Building Council

SustainabilityR 2021, 13, 7251roof 27 of 35 RCC reinforced cement concrete SHGC solar heat gain coefficient W wall SHGC solar heat gain coefﬁcient WW windowW wall WW window WWR window-to-wallWWR window-to-wall ratio ratio

Appendix A. OccupancyAppendix Schedules A. Occupancy Schedules

100

0 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 Occupancy Percentage (%) 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 Time ( Hours) Sustainability 2021, 13, x FOR PEER REVIEW 29 of 36

Figure A1. Lecture hall occupancyFigure A1. schedule.Lecture hall occupancy schedule.

100 90 80 70 60 50 40 30 20 10 0 Occupancy Percentage (%) 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 Time ( Hours)

Figure A2. Naturally ventilatedFigure A2. Naturally office occupancy ventilated ofﬁce schedule. occupancy schedule.

Figure A3. Conditioned office occupancy schedule.

Figure A4. Computer lab occupancy schedule. Sustainability 2021, 13, x FOR PEER REVIEW 29 of 36 Sustainability 2021, 13, x FOR PEER REVIEW 29 of 36

100 10090 9080 8070 7060 6050 5040 4030 3020 2010 100

Occupancy Percentage (%) 0 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 Occupancy Percentage (%) 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 Time10:00 11:00 ( Hours)12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 Sustainability 2021, 13, 7251 28 of 35 Time ( Hours) Figure A2. Naturally ventilated office occupancy schedule. Figure A2. Naturally ventilated office occupancy schedule.

100 10090 9080 8070 7060 6050 5040 4030 3020 2010 100 0 Occupancy Percentage (%) 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 Occupancy Percentage (%) 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 Time10:00 11:00 ( Hours)12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 Time ( Hours)

Figure A3. ConditionedFigure office A3. occupancyConditioned schedule. ofﬁce occupancy schedule. Figure A3. Conditioned office occupancy schedule.

Sustainability 2021, 13, x FOR PEER REVIEWFigure A4. Computer lab occupancy schedule. 30 of 36 Figure A4. Computer labFigure occupancy A4. Computer schedule. lab occupancy schedule.

Figure A5. CommonFigure room A5. Common and canteen room occupancy and canteen schedule. occupancy schedule.

Figure A6. Laboratory occupancy schedule.

Figure A7. Toilet occupancy schedule.

Appendix B. Breakdown of Monthly Electricity Demand Sustainability 2021, 13, x FOR PEER REVIEW 30 of 36 Sustainability 2021, 13, x FOR PEER REVIEW 30 of 36

100 10090 8090 7080 6070 5060 4050 3040 2030 1020 100

Occupancy Percentage (%) 0 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 Occupancy Percentage (%) 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 Time10:00 (11:00 Hours)12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 Sustainability 2021, 13, 7251 29 of 35 Time ( Hours)

Figure A5. Common room and canteen occupancy schedule. Figure A5. Common room and canteen occupancy schedule.

100 10090 8090 7080 6070 5060 4050 3040 2030 1020 100 0 Occupancy Percentage (%) 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 Occupancy Percentage (%) 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 Time10:00 (11:00 Hours)12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 Time ( Hours)

FigureFigure A6.A6.Laboratory Laboratory occupancyoccupancy schedule.schedule. Figure A6. Laboratory occupancy schedule.

100 10090 8090 7080 6070 5060 4050 3040 2030 1020 100

Figure A7. Toilet occupancy schedule. Figure A7. Toilet occupancy schedule. Figure A7. Toilet occupancy schedule. Appendix B. Breakdown of Monthly Electricity Demand Sustainability 2021, 13, x FOR PEER REVIEW 31 of 36 AppendixAppendix B. B. Breakdown Breakdown of of Monthly Monthly Electricity Electricity Demand Demand

LIGHTS FANS EQUIPMENT COOLING

1400

1200

1000

800

600

400

200 Electricity demand demand (kWh) Electricity

Months Figure A8. Breakdown of monthly electricity demand. Figure A8. Breakdown of monthly electricity demand. Appendix C. Cross Sections of Alternative Wall and Roof Compositions

Sustainability 2021, 13, 7251 30 of 35 Sustainability 2021, 13, x FOR PEER REVIEW 31 of 36

Appendix C. Cross Sections of Alternative Wall and Roof Compositions Appendix C. Cross Sections of Alternative Wall and Roof Compositions

Figure A9. Cont.

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SustainabilitySustainability2021 ,202113, 7251, 13, x FOR PEER REVIEW 31 of32 35 of 36

W6W6

W7W7

W8W8

FigureFigureFigure A9. A9. CrossA9. Cross Cross sections sections sections of alternative of of alternative alternative wall wall wall compositions. compositions. compositions.

R1R1

R2R2

Figure A10. Cont.

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Sustainability 2021, 13, x FOR PEER REVIEW 33 of 36

R3 R3

R4 R4

R5 R5

FigureFigure A10. A10.Cross Cross sections sections of alternativeof alternative roof roof compositions. compositions. Figure A10. Cross sections of alternative roof compositions. AppendixAppendix D. D. Floor Floor Plans Plans of of the the ACB ACB Appendix D. Floor Plans of the ACB

(a) (a)

Figure A11. Cont. Sustainability 2021, 13, 7251 33 of 35 Sustainability 2021, 13, x FOR PEER REVIEW 34 of 36

(b) (c)

FigureFigure A11. A11.Floor Floor plans plans of of the the ACB: ACB: (a )(a first) first floor, floor, (b )(b second) second floor, floor, and and (c) ( thirdc) third floor. floor.

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