Proper Designs For Air Conditioning In Mosques Environmental Sciences Essay

To maintain comfortable thermal conditions for the occupants is the basic requirement for any environment, because the thermal conditions have direct impact on the health, morale and productivity of human. Throughout the history using by using the intelligence and by being creative humans has been able to create environments which are comfortable for them to perform their activities and to keep maintaining such environments is very important. A complete thermal comfort occurs when the net heat gained by body is equal to the net heat loss from the body, in other terms; there occurs no storage of heat in the body. This is situation is known as thermal balanced situation. Thus to achieve thermal comfort it is is important to achieve thermal balance. It is possible to attain the thermal balance at a large range of environmental conditions but the thermal comfort is mainly achievable in conditions which are readily adjustable for the body. Thermal comfort is infact the state of mind which shows satisfaction within the existing thermal environment (Hutchean, 1989). There are many parameters involved which decide the thermal comfort conditions. These parameters are those which are related to the body heat loss and gains. Some of the important parameters which determine the heat balance in a particular thermal environment for a human body are: Air velocity, air temperature, humidity of air, activity levels of human, human clothing, means radiant temperature etc. Different models are being used till date by many people in order to relate the human comforts with these parameters in a particular environment. In many cases body has been considered as a thermal object which exchanges heat with the surrounding environment through different modes like: convection, conduction, radiation and is able to loose heat to the surroundings through evaporation and by adapting to the environment using the regulatory system of the body. (Cheng, 2006) Thus prediction of thermal comforts in different environments is of substantial importance for people and organizations like ASHRAE which deal with air conditioning. Thus one important part of the present research would be to develop an approach which would be helpful for assessing the thermal comforts and problems for the buildings which would then be utilized for a pilot study on some of the mosques of Kuwait and near by areas where the environment is harsh and humid. During harsh hot and humid climatic conditions, an effective air conditioning system is required for buildings, which can provide an acceptable thermal comfort level. Although such systems exists in many places but in many situations either the buildings gets over cooled or in many cases proper levels of thermal comfort are not achieved because of improperly designed system, or improper operation practices with lack of maintenance and thus resulting into an inefficient air-conditioning system. Thus the other important aspect of the research would be to conduct a study for Mosques in harsh hot and humid climatic conditions. Mosques are a type of building which has their own unique operating schedule which depends on the time of prayers or others. So in the work a designed study would be carried out to monitor the thermal comfort conditions and to monitor the energy use of a number of mosques during hot and humid conditions so as to assess accurately the thermal comfort conditions and the energy efficiency in such buildings during the occupancy period so that an efficient air-conditioning system can be designed for them.

1.2 Problem statement

One of the important essential requirements from an indoor environment is that it should be able to provide proper thermal comforts in order to satisfy human desires. Undesirable conditions can result in human dissatisfaction and in turn affecting their activities. Thus in this scenario it is very essential to give urgent consideration and attention to the thermal comfort conditions of the buildings especially building in the harsh hot and humid climatic conditions like Mosques where occupant satisfaction is very important during peak hours of prayers etc. In most of the buildings today the comfort levels are achieved through complex air conditioning systems but this might result into to the thermal comfort problems which can occur because daily operations in the building. Many a times it can be very difficult to identify thermal comfort problems and solve them because they can be very diverse in nature and can be cause because of large number of factors. Thus there is a need of developing a systematic approach so as to deal with the problems of thermal comforts in building, which in the present case is Mosque. Mosques are the place of great importance for the worshipers and it is needed that the worshipers feel calm and comfortable in the mosque and when they leave the mosque they have the feeling of peace and tranquility. Thus a careful evaluation of mosques is needed for thermal comforts and requirement of energy. Till date only a few studies have been conducted to fulfill this requirements for Mosques and thus there is a need of systematic study which can be helpful in monitoring the thermal comforts and energy use for Mosques so as to assess accurately the thermal comfort conditions and the energy efficiency in such buildings during the occupancy period so that an efficient air-conditioning system can be designed for them.

1.3 Objectives of the Research

Detailed study on the methods for predicting the thermal comforts and energy use and previous work done by people in predicting the thermal comforts in buildings

Development of a systematic approach for identifying and treating thermal-comfort problems

Investigating the Basic design Elements of Mosques

Monitoring thermal comfort conditions and energy use in some of the mosques of Kuwait and near by areas

Suggesting recommendations for achievement of proper thermal comfort levels and properly designing air-conditioning systems for Mosques

1.4 Methodology

The methodology adopted for performing the research and to meet the desired objectives is as below:

Step 1: First of all the problem is identified through thorough discussion and observation of the area to be studied. After than understanding the background of the problem and finding out the necessity areas where the research needs to be conducted

Step 2: Exhaustive study about the existing models and approaches for thermal comfort problem’s identification and ways to solve them. Studying the previous research done in the desired area for Mosques or similar kind of buildings in different environmental conditions and there by making a roadmap for the present research.

Step 3: On the basis of the detailed analysis of the various approaches and by putting up new ideas through discussion and thorough observation of area, a systematic approach for identifying and treating thermal-comfort problems in building swould be developed which would then be applied for the Mosques of Kuwait or near by places

Step 4: Before carrying out the analysis of comfort levels of mosques a study on the basic design elements of the Mosques would be performed in order to make the research more effective

Step 5: Finally with the help of developed approach thermal comfort conditions and energy use in some of the mosques of Kuwait and near by cities would be monitored and the problems related to thermal comforts would be identified

Step 6: At last a list of recommendations would be generated which would be helpful in improving the air conditioning performance, thermal comfort levels and efficient energy use.

Step 7: And the research would then be completed by concluding the findings from the study and giving a future vision to the study and some points of research in future.

1.5 Expected Outcomes

A systematic approach would be proposed with the help of which thermal comfort problems can be identified assessed and can be dealt with in a proper way.

The developed approach will acts as a helpful tool for the building managers and the operators in order to deal with the thermal comfort problems arising in a building.

Based on the study conducted for the mosques a list of recommendations would be generated. Although this recommendations would be genrated from the mosques in hot and humid climatic conditions but an attempt would be made to make them generic so that they can be applicable in any mosques in general.

Chapter 2:

LITERATURE REVIEW

Mosques represent a place of great importance and unique function and operation as worshipers using the mosque need to feel comfortable and calm, and be able to leave with a feeling of tranquility and peace. Consequently, they need to be carefully evaluated in terms of thermal comfort and energy requirements. However, only a limited number of studies have dealt with these requirements of mosques. A study on thermal comfort requirements for Friday prayer during the hot season in Riyadh (Saeed, 1996) indicated that most people are comfortable and few prefer cooler conditions. Thermal comfort considerations are usually paramount in most buildings involving people occupancy. This requires the addition or extraction of heat from the space depending mainly on the season and type of activities performed indoors. The thermal environment parameters involved are all those affecting body heat gains and losses. Air temperature, air humidity, air velocity, mean radiant temperature as well as human clothing and activity levels are factors that determine the heat balance of a human body in a given thermal environment. Several models are available in the literature to relate the human sensation of comfort to those factors. Prediction of thermal comfort has been of substantial interest to ASHRAE.

ASHRAE has developed a comfort index which is based on the effective temperature. The effective temperature is defined on the basis of 50 % relative humidity. The basis of the definition is that the effective temperature describes the uniform temperature of enclosure which is radiantly black at 50% RH (ASHRAE, 1997) and in which the comfort, heat exchange and physiological strain experienced by the occupant would be same as that of the actual environment with same air velocity. Fanger, 1970 has done a very elaborative study on the prediction of thermal comfort levels under steady state conditions. Fanger, 1970 formulated a comprehensive equation for heat balance which was based on the various parameters of heat exchange. Fanger, 1970 developed a comfort equation which involved the use of two empirical relations which relates skin temperature and evaporative heat loss to the metabolic rate. With the help of the equation developed by Fanger, 1970 comfort conditions for any type of environmental conditions with any type of parameters of clothing and rate of metabolism can be calculated. The other major development in this study by Fanger was the estimation of the PMV (Predicted Mean Vote) for a space in which there are differences in the thermal sensation from the optimal the optimal value. This PMV is helpful in predicting the percentage of dissatisfied people. Considering the variability of thermal sensation under the same conditions, Fanger devised a means of estimating a predicted mean vote (PMV) of the subjects in a space in which there are deviations from optimal in the thermal sensation. Using the PMV, the percentage of people dissatisfied (PPD) can be predicted.

The impact of air movement and the effect of its flow patterns on thermal comfort have been the subject of many theoretical and experimental studies(Jiang, 1992) (Chow, 1994). Results from those studies have emphasized the role of air velocity and air distribution patterns as a determinant factor of thermal comfort. Furthermore, models for predicting comfort at different flow regimes and air distribution patterns have been suggested. Charles (Charles, 2003) reviewed and assessed the validity of Fanger’s Predicted Mean Vote (PMV) Model, and Fanger’s Draught Model. The review also suggested that the bias in PMV predictions varies by context. The model was a better predictor in air-conditioned buildings than naturally ventilated ones, in part because of the influence of outdoor temperature, and opportunities for adaptation. Ji et al, 2006, examined the thermal comfort of people in naturally ventilated environments in a field study in Shanghai, China. The study suggested that people residing in such hot area have adapted to its climate and their expectations for comfort allow them to endure heat better than expected

Many studies have been conducted and carried out in different environmental conditions in order to find out the difference in requirement of thermal comfort levels based on parameters related to sex, body build and age. Results showed that there is no significant difference in the comfort conditions required by male or female, elderly or young etc. (Chung, 1990), (Cheng, 2006). Dear and Brager, 2002 summarized earlier adaptive comfort research, presented some of its findings for naturally ventilated buildings, and discussed the process of getting the adaptive comfort incorporated into Standard 55. Adaptive models include in some way the variations in outdoor climate for determining thermal preferences indoors. Cheng and Ng, 2006 discussed in a recent study the adaptive model in thermal comfort, which has been included in the new revision of ASHRAE Standard 55-2004. Furthermore, it demonstrated the development of a comfort temperature chart for naturally ventilated buildings in Hong Kong. Van Hoof et al (2007) discussed two implementations of the adaptive comfort model in terms of usability and energy use for moderate maritime climate zones by means of literature study, a case study comprising temperature measurements, and building performance simulation. The study concluded that for moderate climate zones the adaptive model is only applicable during summer months, and can reduce energy for naturally conditioned buildings. The subject of thermal comfort in buildings is intimately related to the energy consumption/conservation issue as most of the time either heating or cooling is needed to maintain the space at a comfortable level. Many studies have been carried out to investigate this relationship and explore means and ways to conserve energy without compromising comfort (Tham, 1993). A multidisciplinary approach for achieving energy saving and thermal comfort simultaneously was developed (Tham, 1993). The impact of various energy conservation measures and HVAC system and component characteristics on building thermal performance including thermal comfort has been investigated. Results have indicated that adaptation of a higher temperature set point in summer can lead to a significant reduction in cooling energy without loss of thermal comfort. The energy consumption by building heating, ventilating, and air-conditioning (HVAC) systems has evoked increasing attention to promote energy efficient control and operation of HVAC systems(Mathews, 2000 and 2002). Many other measures related to the design and operation of the HVAC system can be considered for conserving energy. However, in no circumstances should the comfort of occupants be compromised. In hot and cold climates, thermal comfort in building is achieved by HVAC systems, resulting in considerable energy costs. In many situations, buildings are over cooled or the HVAC system is kept running for a much longer time than needed. This will allow considerable opportunities to conserve energy while achieving better comfort conditions or at least maintaining the desired comfort conditions at a reduced level of energy consumption. Recently, Budaiwi (2007) proposed and implemented a multi-phase approach to investigate and remedy thermal comfort problems in buildings. Although mosques are important buildings with a unique function and intermittent operation, evaluation of their thermal performance, problems and, subsequently, possible remedies did not receive adequate attention by researchers. This paper presents the results of a study monitoring energy use and indoor environmental conditions in a number of mosques in order to assess the quality of their thermal comfort conditions especially during occupancy periods in such intermittently operated buildings in hot-humid climates. This study is part of a comprehensive research conducted on mosque thermal performance (Budaiwi, 2005). In this part of the study, energy use and thermal indoor conditions for three mosques were monitored over a period of one year. These mosques were selected to represent the common types of a single-zone daily prayers mosque, a single-zone Friday (large) mosque, and a two-zone Friday mosque. The criteria of representative mosques selection as well as their physical and operational characteristics have been presented in previous work.

Chapter 3

CHARACTERISTICS OF MOSQUE

Before going further on the discussion related to the thermal comfort conditions and energy use it is important to first briefly discuss the basic and important elements of a typical design of mosque and the different activity modes in mosque.

3.1. Basic Elements of typical design of Mosque

Mosque is generally a simple rectangular wall enclosed building having a roofed prayer hall. The longer side of the rectangular shape has orientation in the direction of the Makkah City having the holy mosque. This longer wall is normally termed as ‘Qibla Wall’. In the center of the wall is a recess in the form of niche wall which is called as ‘Mihrab’. It also includes an elevated floor commonly termed as ‘Minbar’, in the right of Mihrab, from which Imam delivers or preaches the speech on Friday, i.e. ‘Khutba’.These are some of the essential elements of any mosque design. In Fiugre1 an isometric and a plan of a typical simple design of a mosque has been shown emphasizing the basic elements of design of a mosque. Although from the functional point the mosques are not different and have remained unchanged but the space, building materials, architectural forms and the construction systems have evolved and developed to very different extent in the different parts of the world of Islam which are influenced by many other factors as well.

Figure 1: The basic design elements of a simple mosque (a) plan, and (b) isometric [Reference: [22]].

Figure2: The geometric configurations (plans) of the investigated mosques.

3.2. Activity modes in a mosque

The design of the mosque is greatly influenced by the worship considerations. There are usually two modes of worship in a mosque. The first mode is the prayer mode which involves doing prayers either in groups or individually as per the religious prescription. Generally while performing group prayers the worshippers stand, prostrate, bow and sit behind the Imam in parallel rows and on the same floor level which are aligned parallel to the Qibla Wall having a distance of approximately 1.2 m. The second mode of worship is the preaching mode, in which the worshippers seat in random rows and listens to the Imam who preaches and deliver Khutba, standing on the Minbar which is a elevated floor. The height of the Minbar floor is different in different mosques. The mosque capacity is dependent upon the floor area and is determined by dividing the area of the floor with the average area required by a worshipper for performing the prayer which is approximately 0.80 * 1.2 = 0.96 m2.

Gantt Chart

Thermal Comfort in Mosques

Nov

Dec

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Feb

TASKS

Submission of Research Proposal

Literature Survey

Interim Report Submission

Development of Systematic Approach

Field study of Mosques

Result analysis

Concluding Remarks and Recommendations

Final Project Submission