Experimental investigation of thermal comfort and CO2concentration in mosques: A case study in warm temperate climate of Yalova, Turkey

Sustainable Cities and Society 52 (2020) 101809

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Experimental investigation of thermal comfort and CO2concentration in mosques: A case study in warm temperate climate of Yalova, Turkey

T

Ahmet Yüksela, Müslüm Arıcıb, , Michal Krajčíkc, Hasan Karabayb ⁎

a

Yalova University, Yalova Vocational School, Electric and Energy Department, Yalova, Turkey Kocaeli University, Engineering Faculty, Mechanical Engineering Department, 41380, Kocaeli, Turkey c Slovak University of Technology, Faculty of Civil Engineering, Radlinského 11, 81005, Bratislava, Slovakia b

ARTICLE INFO

ABSTRACT

Keywords: Mosque Thermal comfort Indoor air quality Space cooling Operation Occupancy

The strategies and techniques of heating, cooling and ventilation are different for mosques than for other types of buildings because of their large volumes, intermittent use, and hosting a great number of congregation members. We investigate potentially feasible strategies to improve thermal comfort and air quality in a representative urban mosque located in a warm temperate climate. These strategies include opening windows, turning on air conditioners, using fans, and their combinations while considering the effect of occupancy. The overall thermal sensation, draught risk, and CO2 concentration were experimentally studied during the holy month of Ramadan. In the naturally ventilated mosque, opening windows considerably improved the air quality but increased the indoor relative humidity. Using fans has the potential to enhance the air quality by reducing pollution in the occupied zone, and to improve the overall thermal sensation. The drawback of using fans was the risk of discomfort due to the peaks in air speed caused by rotation of the fans, which must be prevented to attain comfortable conditions. Turning the air conditioning on during prayers was not an efficient strategy to improve thermal comfort. It is recommended to consider pre-cooling of the mosque and keep air conditioners off during prayers.

1. Introduction Modern people spend an overwhelming majority of their lifetime in indoor areas such as dwellings, offices, sports facilities, museums, theatres, hospitals, libraries, and holy temples. A great amount of energy has been spent to create a comfortable indoor environment in these buildings. However, this may often not guarantee that the criteria on the indoor environment quality (IEQ) are met, or that they are adequate to the great amounts of energy spent. This has been the motivation behind a number of evaluation and optimization studies regarding thermal comfort and indoor air quality (IAQ), which are two important aspects of the indoor environment (Alfano, Olesen, & Palella, 2014; Atthajariyakul & Leephakpreeda, 2005; Stegou-Sagia, Antonopoulos, Angelopoulou, & Kotsiovelos, 2007). The numerous experimental and numerical studies and questionnaire surveys (e.g. Ahmed, Gao, & Kareem, 2016; Al Assaada, Habchib, Ghalia, & Ghaddara, 2018; Balaras, Tselepidaki, Santamouris, & Asimakopoulos, 1993; Kang, Hyun, & Park, 2015; Wang, 2006; Yao, Feng, & Mileer, 2000; Yu, Li, Yao, Wang, & Li, 2017) that have been performed over the decades have created a solid body of research on this subject. Despite

⁎

this long-term effort, gaps in mapping the thermal comfort and IAQ still exist. Especially holy temples belong to the type of buildings for which only limited information pertaining to the IEQ is available. However, holy temples represent a unique type of buildings due to their breadth of inner space, purpose, and use. Mosques also have certain specifics as compared to other types of holy temples, such as different type of floor covering, frequency of praying, and activities performed during the prayers. They are used at various times, including praying five times a day, Eid mornings, and Friday noon prayers (Croome, 1991). A mosque typically reaches full occupancy during Friday noon and Eid prayers as well as during “Taravih”, which are extra prayers performed at night during the Ramadan month. Although the creation of a comfortable indoor environment is critical for the worshippers to feel relaxed and attain the feeling of tranquillity, peace, and serenity (Abdullah, Majid, & Othman, 2016), contemporary research indicates frequent problems with thermal comfort in mosques. These problems usually stem from the large architecture (Hameed, 2011) and from the low level of thermal insulation and are eminent especially during peak loads (Al-Homoud, Abdou, & Budaiwi, 2009). To attain thermal comfort and keep the energy demand low it is, therefore,

Corresponding author. E-mail address: [email protected] (M. Arıcı).

https://doi.org/10.1016/j.scs.2019.101809 Received 25 May 2019; Received in revised form 7 August 2019; Accepted 26 August 2019 Available online 30 August 2019 2210-6707/ © 2019 Elsevier Ltd. All rights reserved.

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vital to optimize the design of the outer shell and provide a sufficient level of thermal insulation (Ibrahim, Baharun, & Nawi, 2014), while also providing enough natural lighting and fresh air (Jaafar, Khalil, & Abou-Deif, 2017). Especially in hot climates the envelope should be airtight, well insulated, with light-coloured surfaces and only minimum area of glass, shaded to avoid overheating (Al-Homoud, 2009). Creation of such an envelope may be a demanding task, especially in urban mosques. This is because, besides the criteria on energy demand and IEQ, the envelope also has to reflect architectural character of the region and represent local cultural, social, climatic, political, and economic circumstances (Lidelöw, Örn, Luciani, & Rizzo, 2019). Moreover, the slow thermal response of the massive envelopes requires adequate control strategies that reflect the time delay between changes in the input and the controlled variable (Al-Sanea, Zedan, & Al-Hussain, 2012; Aste, Angelotti, & Buzzetti, 2009; Braun, Montgomery, & Chaturvedi, 2001). In addition to problems with thermal comfort, several studies indicate unsatisfactory IAQ in mosques during praying time. Ocak, Kölöçvuran, Eren, Sofuoğlu, and Sofuoğlu (2012) investigated three different cleaning scenarios of the praying hall in a mosque without any mechanical ventilation: vacuuming a week before, a day before, and on the day of the prayer. In all the scenarios the ventilation was inadequate, and the number of particles and CO2 concentration was too high. (Al-Dabbous, Khan, Al-Rashidi, and Awadi, 2012) performed week-long measurements of CO2 and VOC concentration level in a mosque. They report considerable potential for reduction of the high CO2 concentration and energy demand by increasing the fresh air intake exclusively during prayer-times. Jaafar et al. (2017) recommend using mechanical ventilation with air conditioning (AC). In a mosque located in the hot climate of Saudi Arabia, this should reduce the predicted percentage of dissatisfied (PPD (Fanger, 1970; EN ISO 7730, 2005) from 25% down to 7% and the CO2 concentration from 1200 to 500 ppm when increasing air change rate from 6 to 12 ACH. The fresh air intake is important to ensure well-being and high performance of the occupants. A number of studies that included people´s responses have shown that an increase in ventilation rate is associated with a lower risk of respiratory illnesses and SBS (Gao, Wargocki, & Wang, 2014; Seppänen & Fisk, 2002a, 2002b; Seppänen, Fisk, & Mendell, 1999; Wargocki & Faria Da Silva, 2019; Wargocki & Wyon, 2007). Many mosques rely on natural ventilation, although the manual operation of windows may not be enough to provide a sufficient ventilation rate. Occupants are often not aware of the necessity to open the windows, and the frequency of windows opening can be reduced by driving factors such as the combination of natural ventilation with space cooling (Fabi, Andersen, Corgnati, & Olesen, 2012; Wargocki & Faria Da Silva, 2019). In naturally ventilated rooms, better IAQ can be achieved by using automatic operation of windows as compared to the manual operation (Gao et al., 2014). However, in warm environments opening windows can result in higher indoor temperatures, which can, in turn, deteriorate thermal comfort and working performance (Wargocki & Faria Da Silva, 2019; Wargocki & Wyon, 2007). The solution could be the installation of a mechanical ventilation system which provides enough fresh air intake and the possibility to control the air supply temperature and improves the energy balance through heat recovery (Curto, Franzitta, Longo, Montana, & Sanseverino, 2019; Gao et al., 2014). The mechanical ventilation system can be coupled with AC. However, a substantial body of evidence suggests that SBS is more prevalent in buildings with simple mechanical ventilation than in naturally ventilated buildings, and even more prevalent in AC buildings (Seppänen & Fisk, 2002a; Wargocki & Faria Da Silva, 2019; Wargocki & Wyon, 2007; Seppänen & Fisk, 2002a; Seppänen et al., 1999; Seppänen & Fisk, 2002b). This accentuates the importance of proper hygiene, commissioning, operation, and maintenance of air handling units to reduce health risks (Seppänen & Fisk, 2002a). Although it is possible to achieve comfortable conditions in holy temples solely by passive measures during certain periods of time

(Molina, Ausina, Cho, & Vivancos, 2016), the passive systems must often be combined with active techniques. Heating, ventilation and air conditioning (HVAC) systems are usually needed to create comfortable conditions during peak loads and to eliminate the mechanical risk of bio-deterioration that is inherent to movable heritage (Bughrara, Arsan, & Akkurt, 2017; Munoz-Gonzalez, León-Rodríguez, & Navarro-Casas, 2016; Munoz-Gonzalez, León-Rodríguez, Campano-Laborda, Teeling, & Baglioni, 2017; Turcanu, Verdes & Serbanoiu 2016). These systems, however, are responsible for the majority of energy consumption in mosques. A part of the existing research is therefore focused on the possibilities to reduce the energy demand in mosques by various efficiency measures. These include, e.g., the use of natural ventilation when climatic conditions allow it (Abdou, Al-Homoud, & Budaiwi, 2005; Al-Homoud, Abdou, & Budaiwi, 2005; Varzaneh, Amini, & Bemanian, 2014), but simultaneously making the envelope as air-tight as possible when the weather is hot to reduce the loads and only use the HVAC systems (Al-Homoud, 2009; Budaiwi, Abdou, & Al-Homoud, 2013). Mushtaha and Helmy (2017) estimated that integrating hybrid air-conditioning into the HVAC systems would allow designing the systems in a much smaller size and reducing the annual energy consumption by 67.5%. Ahangari and Maerefat (2019) improved the thermal comfort conditions in the interior of a building with the use of a phase change material (PCM) system and achieved 17.5% of reduction in heating energy consumption and 10.4% of cooling energy consumption. Noman, Kamsah, and Kamar (2016) suggest that optimizing the location of exhaust fans can help reduce the PMV by about 60% down to the comfortable range. Baldi, Karagevrekis, Michailidis, and Kosmatopoulos (2015) and Korkas, Baldi, Michailidis, and Kosmatopoulos (2015) developed optimized demand response strategies for energy management in photovoltaic equipped interconnected microgrids to reduce the energy demand of HVAC units through regulation of HVAC set point. Several other studies emphasize that suitable HVAC operation strategy, system over-sizing, and appropriate zoning are critical to reducing energy consumption (Budaiwi & Abdou, 2013; Capozzoli, Piscitelli, Gorrino, Ballarini, & Corrado, 2017; Pombeiro, Machado, & Silva, 2017). Mosques constitute an integral part of Muslim society and simultaneously present significant contributors to overall energy consumption. This, however, is barely discussed in the literature. Despite the number of mosques related to the Directorate of Religious Affairs reached 90,000 in 2017, the number of studies evaluating the IEQ in mosques is inadequate in Turkey. Specifically, studies on thermal comfort and IAQ during the cooling period in mosques are not available for the climatic conditions typical of Turkey. Moreover, a major part of the research related to the IEQ in mosques is focused on only one aspect of their performance. Studies aimed at a simultaneous investigation of thermal comfort and IAQ are lacking. The studies focused on thermal comfort usually pertain to overall thermal sensation, and the risk of draught associated with cool air supply and high ventilation rates to fulfil the criteria on thermal comfort and IAQ was not taken into account. Also, a direct comparison of various strategies to improve thermal comfort is missing in scientific literature, and some of the potentially feasible strategies like, e.g., using fans or combining them with AC have not been fully considered. This research adds to the existing base of knowledge by investigating the potential sources of dissatisfaction in a representative urban mosque in the warm temperate climate of Yalova, Turkey, where preliminary surveys revealed complaints on the IEQ. To accomplish this, simultaneous evaluation of overall thermal sensation, local thermal discomfort due to draught, and IAQ is performed. The overall thermal sensation is evaluated by indicators such as PMV, PPD, air temperature, and relative air humidity (RH), whereas air velocity and draught rating are used to evaluate the risk of draught. The IAQ is expressed as the concentration of CO2. Another aim of this research is to investigate potentially feasible strategies to improve thermal comfort and IAQ. These strategies include opening windows, turning on air 2

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Fig. 1. a) A view of the Hacı Hasan Sert Mosque, b) Dimensions and Orientation of the Mosque.

conditioners, using fans, and their combinations while considering also the effect of occupancy. We believe that the outcomes of this study will provide a basis for future research aimed at improvement of IEQ and reduction of energy consumption for HVAC in mosques. 2. Methodology The measurements refer to the Hacı Hasan Sert Mosque, which represents a typical urban mosque, located in the Yalova province of Turkey. Preliminary investigations in this mosque revealed complaints because of unsatisfactory IEQ. Especially dissatisfaction due to high room temperature occurred, despite the Taravih prayers being performed at night and the mosque equipped with AC. The weather conditions in Yalova represent a warm and temperate climate, considered to be Csa according to the Köppen-Geiger climate classification (Anonymous, 2019a, 2019b). It is a “Mediterranean” climate, characterized by rainy winters and dry summers.

turned on manually and operated as shown in Table 2.

2.1. Description of the mosque

2.2. Cases investigated

Fig. 1 shows a photograph of the Hacı Hasan Sert Mosque. The mosque stands alone, i.e. there is no adjacent building. The praying hall has 225 m2 (15 m × 15 m) of floor area. The overall height of the dome section is 15 m; 10 m for the external walls and 5 m for the dome. The external walls and dome (roof) are constructed of aerated concrete, without any additional thermal insulation (Table 1). The external walls contain nine double pane windows with a size of 1.20 m × 1.20 m. The door (1.60 m × 2.20 m) is made of wood. The mosque has a capacity of about 350 congregation members. A hydronic floor heating system with a natural gas boiler as the energy source is installed to provide space heating in cold seasons, whilst two split type heat-pump air conditioners and two fans are utilized in the hot seasons. The air-conditioners, type Regal RAC 50 with a rated cooling capacity of 13.25 kW each, are positioned on the interior surface of the wall facing the congregation members (Fig. 2). The fans have a diameter of 0.8 m and are located 3 m above the ground, on the right and left external wall (Fig. 3). The fans and air conditioners were

In Turkey, cooling systems have been installed in most of the mosques over the recent decade. The usual operation strategy during praying times is to keep the windows and doors closed, while AC is operated to cool down the room. Such a strategy may not lead to an optimal indoor environment, especially at higher occupancy levels when larger amounts of heat and pollution are generated by the congregation members. To evaluate this strategy and provide recommendations for improvements, we established three cases representing various operation strategies. The cases were designed to help assess the effect of AC (on-off), windows (closed-open) and fans (on-off) on thermal comfort and IAQ (Table 2). In Case 1 the windows were open, AC was off, and the fans were running. In Case 2 windows were closed, AC was on, and fans were off. In Case 3, both the fans and the air conditioners were on and the windows were closed. It should be noted that during the measurements, all occupants were males, the majority of whom were adults in their 30 s. The other occupants were elderly people and children. The occupancy and

Fig. 2. Location of the air conditioners.

Table 1 Construction materials of each layer of the building envelope. Wall

Window

Floor

Roof

Materials

Exterior Plaster

Aerated Concrete

Interior Plaster

Glass

Air

Glass

Concrete

Underfloor Heating System

Carpet

Exterior Plaster

Aerated Concrete

Interior Plaster

Thickness (mm)

10

400

10

4

10

4

200

200

14

10

200

10

3

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Fig. 4. Locations of measuring instruments in the hall (“T” – Testo-480, “D1-9” – data loggers indoors, “D10” – data logger outdoors).

people are the main pollution source (EN 15251, 2007). The TESTO-480 test set was located in the centre of the mosque at a height of 0.85 m (Fig. 3). This height was chosen so that it is close to the heights recommended for evaluation of overall thermal sensation of seated (0.6 m) and standing (1.1 m) occupants (EN ISO 7726, 1998). In addition, TESTO-174H data loggers were used to record air temperature and RH at nine locations throughout the mosque once every minute with the accuracy in the range of ± 0.5 °C and ± 3%, respectively (Fig. 4). The loggers were located at heights varying from 0 m (floor) to 2 m. The heights were selected to take into account the various heights and positions in which the congregation members interact with their thermal environment. An additional data logger was placed outside to monitor the outdoor air temperature and RH. The recording started 15 min before praying time and finished 15 min after the praying time, i.e. it was done between 2200 and 2330. The mosque was actively occupied between 2215 and 2315. The average values of the data recorded, presented in Tables 4 and 5, refer to the evaluation period between 2230 and 2315. This time frame was defined so that the congregation members had time to adapt to their thermal environment after they had arrived at the mosque. Also, in some of the cases, the fans and air conditioners were turned on at 2230, and evaluation before this time would not have been meaningful. On the other hand, the boundary conditions had changed after 2315, when the congregation members started leaving the mosque. The IEQ after this time was therefore not included in the evaluation because the boundary conditions might have been inconsistent with those during the prayers.

Fig. 3. A view of the test set, fan, and air conditioner. Table 2 Cases investigated. Date Case 1 10/06/2018 Case 1 11/06/2018 Case 2 13/06/2018 Case 3 09/06/2018

Occupancy

Air-Conditioners Fans

Windows

100% (2215 40% (2215 40% (2215 40% (2215 -

Turned off

Turned on (2230 - 2315) Turned on (2230 - 2315) Turned off

Open (2215 - 2315) Open (2215 - 2315) Closed

Turned on

Closed

2315) 2315)

Turned off

Turned on 2315) (2215 - 2245) Turned on 2315) (2230 - 2315)

composition of attendees can be considered constant, as every time the same congregation members attended. The variations in thermal comfort and IAQ were studied for two occupancy levels: 40% and 100%. In order to ensure sufficient accuracy, the number of congregation members in each measurement was counted. The occupancy was always about 40% during the regular Teravih prayers. The only time when the occupancy reached 100% was during the holy night (Kandil night) when nearly all mosques in the country are fully occupied. The occupancy of 100% studied in Case 1, therefore, refers to the Kandil night, whereas the occupancy of 40%, evaluated in all the cases, refers to the Teravih prayers (Table 2).

2.4. Evaluation of thermal comfort The evaluation of overall thermal sensation was based on the PMVPPD model (Fanger, 1970; EN ISO 7730, 2005). To calculate the values of PMV and PPD, the following parameters were estimated based on the corresponding standards and tables (Aste et al., 2009; Noman et al., 2016): metabolic rate (M) 1.6 met, effective mechanical power (W) 0 W/m2, and clothing insulation (Icl) 0.57 clo. These values correspond to the activities related to worship (standing, equivalent to medium activity) and clothing typical of a congregation member (trousers, short-sleeve shirt). The rest of the parameters needed to evaluate the overall thermal sensation, such as the air temperature, radiant temperature, and air velocity, were measured. The risk of draught was determined using the following equation (Fanger, Melikov, Hanazawa, & Ring, 1988; EN ISO 7730, 2005):

2.3. Measurement procedure and instruments The experiments were performed during the holy month of Ramadan (9–13 June 2018), when the mosque was visited by a large number of congregation members compared to the other months. The weather during this period can be characterized as representative of a typical summer in the climatic conditions of Yalova, Turkey. There was no rain, and the atmosphere was dry in the course of the measurements. To evaluate thermal comfort, air temperature, mean radiant temperature (MRT), RH, and air velocity were measured simultaneously each second by a TESTO-480 test set with the accuracy variable in the range of ± 0.5 °C, ± 1%, and ± 0.03 m/s, respectively. The TESTO-480 test set also recorded the concentration of CO2 with the accuracy in the range of ± 50 ppm. The concentration of CO2 is a suitable indicator for evaluation of the IAQ especially in naturally ventilated buildings where

DR = (34

ta,i)(v¯a,i

0.05)0.62 (0.37*v¯a,i*Tu + 3.14)

(1)

where ta,i is the local air temperature (°C), 20 °C–26 °C; v¯a,i is the local mean air velocity (m/s), < 0.5 m/s (for v¯a,i < 0.05 m/s: use v¯a,i = 0.05 m/s); Tu is the local turbulence intensity (%), 10%–60%. The turbulence intensity was calculated by: 4

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Table 3 Criteria on the indoor environment (CEN CR 1752, 1998CEN CR 1752, 1998; EN 15251, 2007; EN ISO 7730, 2005).

1

The ranges of operative temperature correspond to the limits on PPD. In the calculation of comfort limits the air temperature is assumed equal to the mean radiant temperature. 3 The ranges of air velocity correspond to the limits on draught rate. 4 Air temperature of 26 °C and turbulence intensity of 60% were used as the maximum values allowed in the calculation of draught rate, despite the actual values being almost always higher (see Table 4). Key: RH – relative air humidity; va – air velocity; Icl – thermal insulation of clothing; M – metabolic activity; θa – air temperature; Tu – turbulence intensity. 2

¯

Tu =

Table 5 Average values of measured parameters and the corresponding draught rate.

(va´2, i )1/2 (2)

v¯a,i

Case

Occupancy (%)

Air velocity (m/s)

Turbulence intensity (%)

Air temperature (°C)

Draught rate* (%)

(1a) (1b) (2) (3)

100 40 40 40

0.11 0.25 0.17 0.31

58 81 43 75

28.3 27.0 25.0 26.1

7±1 28 ± 20 14 ± 4 35 ± 4

¯ (va´2, i )1/2

where is the root mean square (RMS) of the velocity fluctuation (m/s), as defined in the original study of Fanger et al. (1988). The draught rate was determined from 3-minute integration intervals over the evaluation period 2230 – 2315.

* The draught rate was calculated from 3-minute integration intervals over the evaluation period 2230 – 2315. The averages of draught rate were calculated by averaging the values obtained over the integration intervals.

2.5. Criteria on thermal comfort and IAQ Given that the metabolic rate, effective mechanical power, and clothing insulation were approximately constant throughout the measurements, the thermal comfort and IAQ were evaluated based on the criteria as defined in Refs. EN ISO 7730, 2005, EN 15251, 2007, ANSI/ ASHRAE Standard 55 (2017) (Table 3). The criteria are represented by the categories A, B, and C as determined by EN ISO 7730 EN ISO 7730, 2005 and categories I, II, and III as determined by EN 15251, 2007. The categories defined in these two standards correspond to each other. The criteria on relative humidity are defined in EN 15251, 2007 for buildings with (de)humidification. As there is no dehumidification installed in the mosque, general criteria on relative air humidity of 30%–70% were used as defined in CR 1752 (CEN CR 1752, 1998CEN CR 1752, 1998). The criteria on the operative temperature in Table 3 were calculated based on the PMV-PPD model. The inputs regarding relative humidity and air velocity were measured, whereas the inputs regarding metabolic activity and insulation of clothing were estimated based on observation. The ranges of required operative temperature and air velocity take into consideration the variance in the input values over the measurement period, and also the uncertainty in the estimation of metabolic activity and insulation of clothing.

3. Results The indoor air temperature and RH presented represent mean values of the data obtained by the nine data loggers (D1-9 in Fig. 4), averaged over the evaluation period. The outdoor air temperature and RH were recorded by the external data logger (D10 in Fig. 4). The average radiant temperature, air velocity, and CO2 concentration are based on measurements with the TESTO-480 instrument (T in Fig. 4). 3.1. Overall thermal sensation Table 4 shows the averages of the recorded data, accompanied by standard deviations. The standard deviation of time-averaged air temperatures, measured in different locations in the mosque by the nine data loggers (Fig. 4), was less than 0.5 °C. In Case 1a, at full occupancy, and Case 2, there is a notable difference between the air temperature and the mean radiant temperature. The difference was highest in Case 1a at full occupancy (2.2 °C). The reason was likely the presence of the congregation members close to the measuring instrument, which was true especially when the mosque was crowded. On the contrary, in Case 1b at 40% occupancy, the difference

Table 4 Average values of the measured indicators and corresponding PMV and PPD. Case

Occupancy (%)

Outdoor air temp. (oC)

Outdoor RH (%)

Indoor air temp. (oC)

MRT (oC)

(1a) (1b) (2) (3)

100 40 40 40

22.6 21.9 22.2 23.3

68.1 64.0 66.3 74.7

26.7 26.4 25.3 26.7

28.3 26.6 24.4 25.3

± ± ± ±

0.8 1.5 1.5 0.7

± ± ± ±

2 5 4 3

± ± ± ±

0.3 0.1 0.2 0.2

± ± ± ±

0.5 0.3 0.8 0.3

* The PMV and PPD were calculated from input data averaged over the evaluation interval 2230 – 2315. 5

Indoor RH (%)

Air velocity (m/s)

58 55 52 61

0.11 0.25 0.17 0.31

± ± ± ±

2 2 3 1

± ± ± ±

0.06 0.29 0.08 0.24

PMV* (-)

PPD* (%)

1.3 0.9 0.63 0.85

40 23 13 20

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Fig. 5. The effect of occupancy on indoor air temperature in Case 1.

was small, which indicates the temperature of the surrounding surfaces close to the air temperature. Air temperature is expected to be relatively close to operative temperature, and it is therefore used as a proxy for the operative temperature. The discrepancy between the air temperatures in Cases 1 and 2 was caused primarily by the air conditioners turned on during the prayers in Case 2. The air temperatures in Cases 1 and 3 are slightly higher than the recommended limits in Table 2, which is confirmed by the relatively high PPD. The PPD was more favourable in Case 3 because the high air temperature was compensated for by the increased air velocity caused by the fans. The PPD increased by 17% as the occupancy rate risen from 40% to 100%. The observable effect of occupancy on thermal comfort is the increase in mean radiant temperature, which in turn resulted in higher operative temperature perceived by the congregation members. The changes in indoor air temperature with respect to occupancy are shown in Fig. 5. Habitually, worshippers used to reach the hall in a few minutes after the praying call, at around 2215. The fans were turned on at 2230. The maximum difference between the indoor and outdoor air temperature was about 6 °C at the occupancy of 40% and about 5 °C at full occupancy. The increasing difference between the outdoor temperatures for the two occupancy levels does not fully correspond with the difference between the indoor air temperatures. This indicates a limited immediate effect of outdoor air temperature on the room temperature despite the windows open. The probable cause was the high thermal inertia of the mosque, a low level of infiltration of the outdoor air, and imperfect distribution of the fresh cool air to the occupied zone. The effect of various operation strategies on indoor air temperature

is illustrated in Fig. 6. The free cooling by natural ventilation in Case 1 did not help decrease the indoor air temperature. The effect of AC was apparent both in Case 2 and 3. In Case 2, the air conditioners were powered on and the indoor air temperature decreased between 2215 and 2245. The air temperature started to rise again after turning off the AC at 2245. In Case 3, AC was turned on at 2230, and the indoor air temperature started to drop. In both cases turning on the AC had a limited impact on the indoor air temperature, as it dropped by only about 1 °C. In all the cases investigated the indoor air temperature was about 26 °C towards the end of the prayers. Referring to Table 3, this suggests that the thermal environment was slightly warmer than optimal. 3.2. Relative air humidity When the mosque was fully occupied, the indoor RH increased steeply towards the end of the prayers (Fig. 7). This was caused by the latent heat produced by perspiration and respiration processes of the congregation members. The amount of vapour produced by the congregation members was substantially lower at the occupancy of 40%. The increase in indoor RH was also partially caused by infiltration of the warm humid outdoor air. Although this is a rather negative effect of opening the windows, no problems with the RH too high occurred throughout the measurements. Turning on the AC resulted in a slight drop in the relative air humidity by 5–10% (Fig. 8). The plausible explanation is a condensation of vapour on coolers of the air conditioners, with surface temperatures below the dew point. Despite the variations in indoor RH, in all the cases investigated the indoor RH was safely

Fig. 6. The effect of operation strategy on mean air temperature at occupancy of 40%. 6

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Fig. 7. The effect of occupancy on indoor RH in Case 1.

within the recommended limit of 30–70% (Table 4).

480 instrument, located in the centre of the mosque, were used to assure consistency. Table 5 shows the averages of the input data obtained throughout the evaluation period. The averages of draught rate are accompanied by standard deviations. In Cases 1b and 3, the turbulence intensity was high primarily due to the fluctuations caused by horizontal rotation of the fans. In Cases 1a and 2, the fluctuations were lower than in Cases 1b and 3, but still relatively high compared to the average air velocity. In these cases, the high turbulence intensity was caused primarily by movements of the congregation members. In the calculation of DR, the input air temperature and turbulence intensity were limited by the maximums of 26 °C and 60%, respectively, because of the constraints of the empirical model (Eq. 1). Despite not taking the turbulence intensity fully into account, DR was clearly out of the comfort range in Case 3, when both the fans and air conditioners were turned on. Although in Case 1b the DR could be partially compensated for by the higher air temperature, the high turbulence intensity (Table 5) and the peaks in air velocity in Cases 1b and 3, caused by horizontal rotation of the fans (Fig. 9), present a precondition for perception of discomfort due to draught.

3.3. Air velocity and the risk of draught Referring to Table 5 and Fig. 9, the air velocity with the fans turned on was substantially higher at 40% occupancy than at full occupancy. The fluctuations in air velocity shown in Fig. 9 were caused by horizontal rotation of the fans between 0° and 180°. As the number of congregation members increased, i.e. at full occupancy, the airflow in the occupied area slowed down. This was likely caused by the large number of people, who presented obstacles to the airflow. At the occupancy of 40%, the larger spacing of the congregation members allowed the air to flow more freely in the praying hall. This resulted in an increase in the average air velocity by 0.14 m/s (Table 4) and in a rise of the maximum air velocity from 0.5 m/s to 1.3 m/s. The average air velocity in Case 2, when the fans were turned off, was lowest from all the cases with the occupancy of 40%. The air velocity was highest in Case 3 because of the simultaneous operation of AC and fans, resulting in an increased air movement. This could to a certain extent enhance the overall thermal sensation of the congregation members by mitigating the overheating effect of the relatively high air temperature. This assumption is backed-up by the improvement in PPD at the high air velocities obtained in Case 3 (Table 3). In the calculation of DR (Eq. 1), only data recorded by the TESTO-

3.4. Indoor air quality Assuming an outside CO2 concentration of about 450 ppm, realistic for an urban environment (Lee, Christen, Ketler, & Nesic, 2017;

Fig. 8. The effect of operation strategy on mean indoor RH at occupancy of 40%. 7

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Fig. 9. The effect of occupancy on air velocity in Case 1.

Nemethova, Petras, & Krajcik, 2016; Roth et al., 2017; Vervoort et al., 2018), the limit on CO2 concentration indoors is close to 1250 ppm for cat. III as defined in EN 15251, 2007 (Table 3). The CO2 concentration of about 1000 ppm for the occupancy of 40% in Fig. 10 is well within this limit, whereas the approximately 1500 ppm that was reached at full occupancy hardly meets this requirement. This implies that natural ventilation by open windows may not be sufficient at high occupancy levels. However, the IAQ was still substantially better than in cases when the windows were closed. With the windows open, even at full occupancy, the IAQ was considerably better than that for the occupancy of 40% and windows closed (Fig. 11). Although the initial concentration of CO2 was similar in all the cases investigated, the differences in IAQ at the end of the prayers were substantial (Fig. 11). A good IAQ was attained in Case 1 by opening the windows and turning the fans on. In the other two cases with the windows closed the CO2 concentration was high above the recommended limits. However, the CO2 concentration was much lower in Case 3, when the fans were turned on. The plausible explanation is that the air distribution in the mosque was more homogeneous because of the mixing by fans. The CO2 was being distributed more evenly throughout the mosque, even in the parts outside the occupied zone such as the dome. Consequently, its concentration in the occupied zone

was lower. This means that although the role of ventilation is pivotal, mixing of the indoor air by fans also contributes to the improvement of IAQ. 4. Discussion Referring to Table 4 and Figs. 5 and 6, the results suggest a slightly warmer thermal environment than comfortable. The present study is comparable with the research of Hussin, Salleh, Chan, and Mat (2015) because of its similar character and parameters monitored (Table 6). Only the number of congregation members and outdoor air temperature were notably different. Hussin et al. (2015) concluded that despite the warmer air temperature and PMV than recommended, the thermal environment was well acceptable to the congregation members. Their findings were consistent with some of the other studies performed in hot environments (Al-ajmi & Loveday, 2010; Al-ajmi, 2010). Hussin et al. (2015) attribute this to the behavioural adaptation of the occupants, who have been typically living in warm environments, whereas Fanger and Toftum (2002) suggest that in warm climates and non-airconditioned buildings occupants perceive the warmth as being less severe than the PMV predicts because of their low expectations. Even though this might be the case of mosques such as the one in the present

Fig. 10. The effect of occupancy on IAQ in Case 1. 8

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Fig. 11. The effect of operation strategy on IAQ at occupancy of 40%.

study, the body of research and the practical experience proves that employing passive and active techniques is often needed to create a healthy and comfortable IEQ. Overall, the results highlight the contradiction between the requirements on thermal comfort and IAQ. Although opening windows during the prayers lead to a significantly better IAQ, it did not considerably reduce the indoor air temperature and resulted in higher indoor RH. On the other hand, operating air conditioners with the windows closed reduced the indoor air temperature, but it resulted in a significantly worse IAQ. With the windows closed, the CO2 concentrations highly exceeded the recommended values (Fig. 11). Similar results were obtained by Ocak et al. (2012) for a mosque in Gulbahce, Turkey. With the windows closed, the maximum CO2 concentrations reached up to about 2450 ppm above the outdoor level. Even in the case when the occupancy was only two-thirds of the full capacity, the peak CO2 concentration was at least 1300 ppm above the outdoor concentration, exceeding the recommended limits (Table 3). On the other hand, during a one-week campaign, Al-Dabbous et al. (2012) found that with the windows open, the measured CO2 concentrations were always within the specified standard guideline. Even at full attendance, the concentration did not exceed 1000 ppm above outdoor level. The two studies emphasize that opening windows is a powerful strategy to attain sufficient IAQ, however, they provide no information about how opening and closing the windows affected thermal comfort. Fig. 6 shows that turning the AC on during the prayers was not a particularly efficient strategy to improve the overall thermal sensation of the congregation members. This strategy decreased the indoor air temperature by a maximum of 1 °C. Simultaneously, under hot climatic conditions, AC is usually the single most energy-intensive system in the mosque (Al-Homoud et al., 2009). Lower room temperature might be achieved by pre-cooling the indoor air before the arrival of the congregation members. In such a case, Budaiwi et al. (2013) suggest that in hot climate AC operation should precede occupancy by at least two hours. An exception could be the mosques that contain artworks, in

which case operation of air handling units and humidifiers over longer periods may be required to reduce the risk of mechanical degradation and bio-deterioration of the artworks (Munoz-Gonzalez et al., 2017). The results of PPD in Table 3 suggest that using fans can be an efficient strategy to improve IEQ, considering the significantly lower energy consumption as compared to AC (Al-Homoud, 2009; Al-Homoud et al., 2009). Fans can help improve the overall thermal sensation by enhancing the heat transfer from occupants to the surrounding environment by evaporation and convection. Mixing of the room air by fans also positively impacted the IAQ by causing a more homogeneous distribution of airborne pollutants throughout the mosque and thereby reducing their concentration in the occupied zone (Fig. 11). This phenomenon was also observed by Ocak et al. (2012). In one of their campaigns, turning on the air conditioners resulted in higher air velocities and better mixing of the indoor air. The air blown at high speeds dispersed the particles into the upper parts of the volume above human height, resulting in lower CO2 concentrations because of the delay of the concentration increase onset. On the contrary, as Turcanu et al. (2016) point out, inducing high air speeds may not be an optimal strategy in buildings that contain objects made of wood, paintings on canvas, old books, and similar. The high-speed air causes a superficial drying of such objects, and it may cause movement of smoke from the candles that affect the paintings. In such a case, mechanical ventilation can be preferable to control the air movement. Combining the fans with AC did not bring any significant drop in the indoor air temperature, but it resulted in a considerable improvement in PPD. While AC cooled down the room air, the enhanced airflow increased the heat transfer from occupants to the surrounding environment by evaporation and convection. This confirms the findings of AlHomoud et al. (2009) based on long-term monitoring of several mosques. They conclude that in a hot and humid climate, fans are needed to induce air movement to supplement AC during summer months and that the fans can even replace the AC during moderate weather conditions. As the results of draught rate in Table 5 suggest, the risk of

Table 6 Comparison of average values obtained in the reference Hussin et al. (2015) and the present study. Study

Praying Time

Number of Occupants

Outdoor Air Temperature

Indoor Air Temperature

Mean Radiant Temperature

Outdoor RH

Indoor RH

Air Velocity

PMV

Reference

Isyak 2000 – 2100 Taravih 2200 – 2330

66

30°C

26.8 °C

29 °C

70%

67%

0.2 m/s

0.9

140

23.8 °C

26.6 °C

25.6 °C

73%

61%

0.28 m/s

0.87

Present (Case 3)

9

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using fans can be the potential discomfort because of high air speeds close to the occupants. The risk was further exacerbated by the peaks in air velocity caused by horizontal rotation of the fans (Fig. 9). This situation could be improved by, e.g., mounting several fans along the praying hall to eliminate the need for their horizontal rotation. Thereby a more uniform airflow could be created.

Acknowledgements This work was supported by Kocaeli University Scientific Research Project Coordination Unit BAP Project no 2015/069HD and by the Ministry of Education, Science, Research and Sport of the Slovak Republic under VEGA Grants 1/0807/17 and 1/0847/18. References

5. Conclusions

Abdou, A., Al-Homoud, M. S., & Budaiwi, I. M. (2005). Mosque energy performance, part I: Energy audit and use trends based on the analysis of utility billing data. JKAU: Engineering Sciences Journal. 16, 165–184. Abdullah, F. H., Majid, N. H. A., & Othman, R. (2016). Defining issue of thermal comfort control through urban mosque façade design. Procedia-Social and Behavioral Sciences. 234, 416–423. Ahangari, M., & Maerefat, M. (2019). An innovative PCM system for thermal comfort improvement and energy demand reduction in building under different climate conditions. Sustainable Cities and Society, 44, 120–129. Ahmed, A. Q., Gao, S., & Kareem, A. K. (2016). A numerical study on the effects of exhaust locations on energy consumption and thermal environment in an office room served by displacement ventilation. Energy Conversion and Management, 117, 74–85. Al Assaada, D., Habchib, C., Ghalia, K., & Ghaddara, N. (2018). Simplified model for thermal comfort, IAQ and energy savings in rooms conditioned by displacement ventilation aided with transient personalized ventilation. Energy Conversion and Management, 162, 203–217. Al-ajmi, F. F. (2010). Thermal comfort in air-conditioned mosques in the dry desert climate. Building and Environment, 45, 2407–2413. Al-ajmi, F. F., & Loveday, D. L. (2010). Indoor thermal conditions and thermal comfort in air-conditioned domestic buildings in the dry-desert climate of Kuwait. Building and Environment, 45, 704–710. Al-Dabbous, A. N., Khan, A. R., Al-Rashidi, M. S., & Awadi, L. (2012). Carbon dioxide and volatile organic compounds levels in mosque in hot arid climate. Indoor and Built Environment, 22, 1–9. Alfano, F. R., Olesen, B. W., Palella, B. I., & Riccio, G. (2014). Thermal comfort: design and assessment for energy saving. Energy and Buildings, 81, 326–336. Al-Homoud, M. S. (2009). Envelope thermal design optimization of buildings with intermittent occupancy. Journal of Building Physics, 33, 65–82. Al-Homoud, M. S., Abdou, A. A., & Budaiwi, I. M. (2005). Mosque energy performance, part II: Monitoring of energy end use in a hot-humid climate. JKAU: Engineering Sciences Journal, 16, 185–202. Al-Homoud, M. S., Abdou, A. A., & Budaiwi, I. M. (2009). Assessment of monitored energy use and thermal comfort conditions in mosques in Hot-Humid Climates. Energy and Buildings, 41, 607–614. Al-Sanea, S. A., Zedan, M. F., & Al-Hussain, S. N. (2012). Effect of thermal mass on performance of insulated building walls and the concept of energy savings potential. Applied Energy, 89, 430–442. https://en.climate-data.org/asia/turkey/yalova/yalova-194/, (Accessed 1 April 2019). https://www.britannica.com/science/Koppen-climate-classification, (Accessed 1 April 2019). ANSI/ASHRAE Standard 55 (2017). Thermal environmental conditions for human occupancy. Atlanta: ASHRAE. Aste, N., Angelotti, A., & Buzzetti, M. (2009). The influence of the external walls thermal inertia on the energy performance of well insulated buildings. Energy and Buildings, 41, 1181–1187. Atthajariyakul, S., & Leephakpreeda, T. (2005). Neural computing thermal comfort index for HVAC systems. Energy Conversion and Management, 46, 2553–2565. Balaras, C., Tselepidaki, I., Santamouris, M., & Asimakopoulos, D. (1993). Analysis of thermal comfort conditions in Athens. Greece. Energy Conversion and Management. 34, 281–285. Baldi, S., Karagevrekis, A., Michailidis, I., & Kosmatopoulos, E. B. (2015). Joint Energy Demand and Thermal Comfort Optimization in Photovoltaic-Equipped Interconnected Microgrids. Energy Conversion and Management, 101, 352–363. Braun, J. E., Montgomery, K. W., & Chaturvedi, N. (2001). Evaluating the performance of building thermal mass control strategies. HVAC&R Research, 7, 403–428. Budaiwi, I., & Abdou, A. (2013). HVAC system operational strategies for reduced energy consumption in buildings with intermittent occupancy: The case of mosques. Energy Conversion and Management, 73, 37–50. Budaiwi, M., Abdou, A. A., & Al-Homoud, M. S. (2013). Envelope retrofit and air conditioning operational strategies for reduced energy consumption in mosques in hot climates. Build Simulation, 6, 33–50. Bughrara, K., Arsan, Z., & Akkurt, G. (2017). Applying underfloor heating system for improvement of thermal comfort in historic mosques: The case study of Salepçioǧlu Mosque, Izmir, Turkey. Energy Procedia, 133, 290–299. Capozzoli, A., Piscitelli, M. S., Gorrino, A., Ballarini, I., & Corrado, V. (2017). Data analytics for occupancy pattern learning to reduce the energy consumption of HVAC systems in office buildings. Sustainable Cities and Society, 35, 191–208. CEN CR 1752 (1998). Ventilation for buildings - design criteria for the indoor environment. Brussels: European Committee for Standardization. Croome, D. J. (1991). Application of environmental engineering to the design of mosques in Saudi Arabia. Energy Conservation in Buildings, 125–129. Curto, D., Franzitta, V., Longo, S., Montana, F., & Sanseverino, E. R. (2019). Investigating energy saving potential in a big shopping centre through ventilation control. Sustainable Cities and Society, 49, 101525.

We investigated the effect of occupancy and operation status of air conditioners, fans, and windows on IEQ in a typical urban mosque located in Yalova, Turkey. Performance indicators such as the air and mean radiant temperature, relative air humidity, air velocity, and CO2 concentration were recorded during the night prayers. In addition, PMV and PPD were computed. The conclusions that can be drawn from this study are as follows:

• Ventilation • • • •

by windows is pivotal in creating good indoor air quality. At high occupancy levels, such ventilation may not be enough to attain a good IAQ. Requirements on thermal comfort and IAQ may contradict each other. AC at closed windows reduced the indoor air temperature but lead to a significantly worse IAQ. Opening windows resulted in better IAQ, but it did not reduce the indoor air temperature and resulted in increased indoor RH. Using fans helped improve both the overall thermal sensation and IAQ. Combining fans with open windows can lead to acceptable overall thermal sensation at good IAQ. Turning the AC on during the prayers was not a particularly efficient strategy to improve thermal comfort. The effects of combining AC with open windows require further investigation. Coupling fans with AC could significantly improve the overall thermal sensation. However, operation of fans may pose an inherent risk of discomfort due to high air speeds and the peaks in air speed caused by rotation of the fans.

This means that the usual operation strategy to keep the windows and doors closed while turning on AC during praying times did not lead to an optimal indoor environment. Hence, to attain acceptable IEQ in a typical mosque located in a warm temperature climate such as the one in Yalova, Turkey, we recommend concentrating on the following key points: (1) Ventilate the mosque before the prayers. Keep at least part of the windows open during the prayers to attain sufficient IAQ. During periods with no occupancy and hot weather conditions, close the windows to prevent overheating. (2) Consider pre-cooling of the mosque and keeping the air conditioners off during the prayers. This allows keeping the indoor air temperature sufficiently low, avoiding the risk of draught close to the air conditioners, and saving energy during hot weather conditions. (3) Overall thermal sensation and IAQ can be improved by operating fans. Avoid peeks in air speed to prevent potential discomfort. This could be accomplished by, e.g., mounting several fans along the hall to eliminate the need for horizontal rotation and thereby create a more uniform air movement. Further investigations should verify this strategy and evaluate the various operation strategies with respect to energy efficiency. Future measurements should include details on the vertical distribution of air temperature, RH, CO2 concentration, and air velocity as well as subjective evaluation of thermal comfort by the congregation members.

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A. Yüksel, et al. EN 15251 (2007). Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics. Brussels: European Committee for Standardization. EN ISO 7726 (1998). Ergonomics of the thermal environment. Instruments for measuring physical quantities. Geneva: International Organization for Standardization. EN ISO 7730 (2005). Ergonomics of the thermal environment–Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria. Geneva: International Organization for Standardization. Fabi, V., Andersen, R. V., Corgnati, S., & Olesen, B. W. (2012). Occupants’ window opening behaviour: a literature review of factors influencing occupant behaviour and models. Building and Environment, 58, 188–198. Fanger, P. O. (1970). Thermal comfort. Analysis and applications in environmental engineering. Copenhagen: Danish Technical Press. Fanger, O., & Toftum, J. (2002). Extension of the PMV model to non-air-Conditioned buildings in warm climates. Energy and Buildings, 34, 533–536. Fanger, P. O., Melikov, A. K., Hanazawa, H., & Ring, J. (1988). Air turbulence and sensation of draught. Energy and Buildings, 12, 21–39. Gao, J., Wargocki, P., & Wang, Y. (2014). Ventilation system type, classroom environmental quality and pupils’ perceptions and symptoms. Building and Environment, 75, 46–57. Hameed, A. N. A. (2011). Thermal comfort assessment to building envelope: A case study for new mosque design in Baghdad. International Transaction Journal of Engineering, Management & Applied Sciences & Technologies. 2, 249–264. Hussin, A., Salleh, E., Chan, H. Y., & Mat, S. (2015). The reliability of predicted mean vote model predictions in an air-conditioned mosque during daily prayer times in Malaysia. Architectural Science Review, 58, 67–76. Ibrahim, S. H., Baharun, A., & Nawi, M. N. M. J. (2014). Assessment of Thermal Comfort in the Mosque in Sarawak, Malaysia. International Journal of Energy and Environment, 5, 327–334. Jaafar, R. K., Khalil, E. E., & Abou-Deif, T. M. (2017). Numerical investigations of indoor air quality inside Al-Haram Mosque in Makkah. Procedia Engineering, 205, 4179–4186. Kang, C. S., Hyun, C. H., & Park, M. (2015). Fuzzy logic-based advanced on-off control for thermal comfort in residential buildings. Applied Energy, 155, 270–283. Korkas, C. D., Baldi, S., Michailidis, I., & Kosmatopoulos, E. B. (2015). Intelligent energy and thermal comfort management in grid-connected microgrids with heterogenous occupancy schedule. Applied Energy, 149, 194–203. Lee, J. K., Christen, A., Ketler, R., & Nesic, Z. (2017). A mobile sensor network to map carbon dioxide emissions in urban environments. Atmospheric Measurement Techniques, 10, 645–665. Lidelöw, S., Örn, T., Luciani, A., & Rizzo, A. (2019). Energy-efficiency measures for heritage buildings: A literature review. Sustainable Cities and Society, 45, 231–242. Molina, A. M., Ausina, I. T., Cho, S., & Vivancos, J. L. (2016). Energy efficiency and thermal comfort in historic buildings: A review. Renewable and Sustainable Energy Reviews, 61, 70–85. Munoz-Gonzalez, C. M., León-Rodríguez, A. L., & Navarro-Casas, J. (2016). Air conditioning and passive environmental techniques in historic churches in mediterranean climate. a proposed method to assess damage risk and thermal comfort preintervention, simulation-based. Energy and Buildings, 130, 567–577. Munoz-Gonzalez, C. M., León-Rodríguez, A. L., Campano-Laborda, M., Teeling, C., & Baglioni, R. (2017). The assessment of environmental conditioning techniques and their energy performance in historic churches located in mediterranean climate.

Journal of Cultural Heritage. https://doi.org/10.1016/j.culher.2018.02.012. Mushtaha, E., & Helmy, O. (2017). Impact of building forms on thermal performance and thermal comfort conditions in religious buildings in hot climates: A case study in Sharjah City. International Journal of Sustainable Energy, 36, 926–944. Nemethova, E., Petras, D., & Krajcik, M. (2016). Indoor environment in a High-rise building with lightweight envelope and thermally active ceiling. CLIMA 2016 - proceedings of the 12th REHVA world congress. Noman, F. G., Kamsah, N., & Kamar, H. M. (2016). Improvement of thermal comfort inside a mosque building. Jurnal Teknologi, 78, 9–18. Ocak, Y., Kılıçvuran, A., Eren, A. B., Sofuoğlu, A., & Sofuoğlu, S. C. (2012). Exposure to particulate matter in a mosque. Atmospheric Environment, 56, 169–176. Pombeiro, H., Machado, M. J., & Silva, C. (2017). Dynamic programming and genetic algorithms to control an HVAC system: Maximizing thermal comfort and minimizing cost with PV production and storage. Sustainable Cities and Society, 34, 228–238. Roth, M., Jansson, C., & Velasco, E. (2017). Multi-year energy balance and carbon dioxide fluxes over a residential neighbourhood in a tropical city. International Journal of Climatology, 37, 2679–2698. Seppänen, O. A., & Fisk, W. J. (2002a). Summary of human responses to ventilation. Indoor Air, 12, 113–128. Seppänen, O. A., & Fisk, W. J. (2002b). Relationship of SBS-symptoms and ventilation system type in office buildings. Lawrence Berkeley National Laboratory LBNL Paper LBNL50046. Seppänen, O. A., Fisk, W. J., & Mendell, M. J. (1999). Association of ventilation rates and CO2 concentrations with health and other responses in commercial and institutional buildings. Indoor Air, 9, 226–252. Stegou-Sagia, A., Antonopoulos, K., Angelopoulou, C., & Kotsiovelos, G. (2007). The impact of glazing on energy consumption and comfort. Energy Conversion and Management, 48, 2844–2852. Turcanu, F. E., Verdes, M., & Serbanoiu, I. (2016). Churches heating: the optimal balance between cost management and thermal comfort. (9th International Conference Interdisciplinarity in Engineering, INTER-ENG 2015, 8-9 October 2015, Tirgu-Mures, Romania). Procedia Technology, (22), 821–828. Varzaneh, E. H., Amini, M., & Bemanian, M. R. (2014). Impact of hot and arid climate on architecture (case study: varzaneh jame mosque), MRS Singapore - ICMAT symposia proceedings, 7th international conference on materials for advanced technologies. Procedia Engineering, 94, 25–32. Vervoort, J., Boerstra, A., Virta, M., Mishra, A., Loomans, M., Frijins, A., et al. (2018). Healty Low energy redesigns for schools in Delhi: Inventory of the current conditions. Proc. roomvent and ventilation, Helsinki, REHVA. Wang, Z. (2006). A field study of the thermal comfort in residential buildings in Harbin. Building and Environment, 41, 1034–1039. Wargocki, P., & Faria Da Silva, N. A. (2019). Use of CO2 feedback as a retrofit solution for improving air quality in naturally ventilated classrooms. Proceedings of the 10th International Conference on Healthy Buildings. Wargocki, P., & Wyon, D. P. (2007). The effects of moderately raised classroom temperatures and classroom ventilation rate on the performance of schoolwork by children (RP-1257). HVAC&R Research, 13, 193–220. Yao, R., Feng, Y., & Mileer, A. (2000). The use of earth tube system as a means of improving indoor thermal comfort in South China. The energy for the 21th century world renewable energy congress VI (WREC2000), 665–668. Yu, W., Li, B., Yao, R., Wang, D., & Li, K. (2017). A study of thermal comfort in residential buildings on the Tibetan Plateau, China. Building and Environment, 119, 71–86.

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