Assessing thermal comfort in vernacular mosques with natural ventilation: a case study of Masjid Tuha Indrapuri

This paper reports the outcome of a thermal comfort study that assessed the satisfaction of occupants with their surrounding thermal conditions. The study was carried out in 10 mosque buildings around lowland Nibong Tebal, Penang and highland Cameron Highlands, Pahang. It involved determining the compliance level of thermal comfort parameters (i.e. air temperature, relative humidity and air speed) at lowland and highland and establishing relationships between ventilation systems with predicted mean vote and predicted percentage of dissatisfied at lowland and highland according to ASHRAE Standard-55. The study was conducted from 1200h to 1700h/1730h to assess the thermal conditions of the 10 mosques during Zohor/Friday and Asar prayer times. During prayer times, an active ventilation system was in operation, while before and after prayer times, only passive ventilation (windows and doors) was available. Overall, findings indicated that better thermal comfort conditions occurred during prayer time at highland compared with those at the lowland, with the thermal sensation conditions of mosques in the former ‘slightly warmer’ to ‘slightly cool’ and in the latter ‘slightly warm’ to ‘hot’. Moreover, most mosques at lowland did not provide good thermal comfort because the percentage of dissatisfied was high compared to that at highland.

Space Design for Thermal Comfort and Energy Efficiency in Summer

BIM-based framework to analyze the effect of natural ventilation on thermal comfort and energy performance in buildings

PurposeThe purpose of this paper is to analyse the thermal environment of two engineering testing centres cooled via different means using computational fluid dynamics (CFD), focussing on the indoor temperature and air movement. This computational technique has been used in the analysis of thermal environment in buildings where the profiles of thermal comfort parameters, such as air temperature and velocity, are studied.Design/methodology/approachA pilot survey was conducted at two engineering testing centres – a passively cooled workshop and an air-conditioned laboratory. Electronic sensors were used in addition to building design documentation to collect the required information for the CFD model–based prediction of air temperature and velocity distribution patterns for the laboratory and workshop. In the models, both laboratory and workshop were presumed to be fully occupied. The predictions were then compared to empirical data that were obtained from field measurements. Operative temperature and predicted mean vote (PMV)–predicted percentage dissatisfied (PPD) indices were calculated in each case in order to predict thermal comfort levels.FindingsThe simulated results indicated that the mean air temperatures of 21.5°C and 32.4°C in the laboratory and workshop, respectively, were in excess of the recommended thermal comfort ranges specified in MS1525, a local energy efficiency guideline for non-residential buildings. However, air velocities above 0.3 m/s were predicted in the two testing facilities, which would be acceptable to most occupants. Based on the calculated PMV derived from the CFD predictions, the thermal sensation of users of the air-conditioned laboratory was predicted as −1.7 where a “slightly cool” thermal experience would prevail, but machinery operators in the workshop would find their thermal environment too warm with an overall sensation score of 2.4. A comparison of the simulated and empirical results showed that the air temperatures were in good agreement with a percentage of difference below 2%. However, the level of correlation was not replicated for the air velocity results, owing to uncertainties in the selected boundary conditions, which was due to limitations in the measuring instrumentation used.Research limitations/implicationsDue to the varying designs, the simulated results of this study are only applicable to laboratory and workshop facilities located in the tropics.Practical implicationsThe results of this study will enable building services and air-conditioning engineers, especially those who are in charge of the air-conditioning and mechanical ventilation (ACMV) system design and maintenance to have a better understanding of the thermal environment and comfort conditions in the testing facilities, leading to a more effective technical and managerial planning for an optimised thermal comfort management. The method of this work can be extended to the development of CFD models for other testing facilities in educational institutions.Social implicationsThe findings of this work are particularly useful for both industry and academia as the indoor environment of real engineering testing facilities were simulated and analysed. Students and staff in the higher educational institutions would benefit from the improved thermal comfort conditions in these facilities.Originality/valueFor the time being, CFD studies have been carried out to evaluate thermal comfort conditions in various building spaces. However, the information of thermal comfort in the engineering testing centres, of particular those in the hot–humid region are scantily available. The outcomes of this simulation work showed the usefulness of CFD in assisting the management of such facilities not only in the design of efficient ACMV systems but also in enhancing indoor thermal comfort.

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Assessing the thermal comfort and ventilation in Malaysia and the surrounding regions

Ventilation strategies in healthcare facilities are mainly directed towards mechanical systems. Due to patients’ preferences or the necessity of terminal reheat/recool, Air Handler Units are often turned off or windows are opened when mechanical systems are active. This leads to poor IAQ, nosocomial infections, and energy loss. Besides, ventilation systems are not typically intended to optimize user satisfaction. Using field measurements in 140 spaces, survey studies, and statistical analysis, this study compares ventilation strategies in providing IAQ, thermal comfort, and Perceived Air Quality as an indicator of user satisfaction. 315 samples were collected for air velocity, air temperature, relative humidity, PAQ, odor intensity, and VOC concentrations. Lowest to highest pollutant concentrations were observed respectively in mechanical ventilation with two open windows, mechanical ventilation with one open window, natural ventilation with two open windows, mechanical ventilation with closed windows, natural ventilation with one open window, and nonventilated spaces. There was no evidence of an effect of ventilation strategies on environmental parameters and user satisfaction. Users’ thermal comfort and air quality satisfaction were not guaranteed even when ventilation rate, pollutant concentrations, and environmental parameters were within the permissible range. Findings support the efficient performance of natural ventilation in providing acceptable air quality.

Vernacular buildings are local buildings that have evolved overtime in one location to suit the local climate, culture and economy (Meir & Roaf, 2003). The construction of vernacular buildings uses locally available resources to address local needs. These kinds of structures evolve over time to reflect the environmental, cultural and historical context in which they exist (Coch, 1998). The building knowledge of this type of architecture is always handed down traditions and is thus more based on the knowledge achieved by trial and error and in this way handed down through the generations (Singh et al., 2009). Vernacular buildings are most often residential buildings. People have traditional lifestyles in vernacular buildings in virtually every climate in the world, from the Arctic circle to the tropics, in temperatures from below zero to over 40°C, and historically without the benefit of gas or electrically driven mechanized heating and cooling systems (Meir & Roaf, 2003). After the emergence of modernist architecture, aided by the industrial revolution, vernacular buildings are seen to be in a state of decline and are frequently looked down upon, abandoned, neglected or actively demolished. Associated, by many at least, with an out-dated past and poverty, they are steadily replaced by architectural models that favour more modern, inter-national technologies, materials and forms (Oliver, 1997). It is assumed, as in international standards such as CENASO 7730 or ASHRAE 55, that people suffer less discomfort in very closely controlled conditions, then such vernacular buildings, along with modern passive buildings, cannot provide their occupants with ‘comfortable’ indoor climates (Santamouris, 2007). But nowadays, by the more and more important issues of energy consumption in building construction sectors, the continuity of the vernacular traditions is emphasized in academic research and building practice because of its climate-response, passive model and low-energy consumption. The principles that were used in traditional buildings can very well be implemented in modern buildings so as to produce “energy saving” buildings. If these principles are sensibly adopted in modern buildings, it should be possible to build sustainable buildings for the future (Shanthi Priya, Sundarraja, Radhakrishnan, & Vijayalakshmi, 2012). We can learn a lesson from the approach of the builders who acknowledged the interdependence of human beings, buildings and physical environment (Coch, 1998). A “new vernacular” can be developed, harnessing the types of low-tech solutions that are familiar to most of us from the vernacular, together with modern passive and active renewable energy technologies and strategies to reflect the new cultural, climatic and economic realities of the 21st century (Meir & Roaf, 2003). Vernacular buildings have to adapt to the environment through low-tech methods. Changing building form and material is the most important technique to adapt to the environment to obtain the best comfortable living space, in another words, the environment deeply influenced building form design and material use. Fathy (1986) described the climate effect on building form generation in vernacular building as: “For example, the proportion of window to wall area becomes less as one moves toward the equator. In warm areas, people shun the glare and heat of the sun, as demonstrated by the decreasing size of the windows. In the subtropical and tropical zones, more distinctive changes in architectural form occur to meet the problems caused by excessive heat. In Egypt, Iraq, India, and Pakijstan, deep loggias, projecting balconies, and overhangs casting long shadows on the walls of buildings are found. Wooden or marble lattices fill large openings to subdue the glare of the sun while permitting the breeze to pass through. Such arrangements characterize the architecture of hot zones, and evoke comfort as well as aesthetic satisfaction with the visible endeavour of man to protect himself against the excessive heat”. In recent years, a significant amount of research has looked specifically at environmental performance issues of vernacular architecture, including its thermal properties, energy consumption and resources (Foruzanmehr & Vellinga, 2011). Both qualitative and quantitative such as field measurements, field surveys, statistical methods, comparative study and computer simulation methods are used in the investigation of the performance of vernacular buildings. Professor Paul Oliver of Oxford University compiled the book “Dwellings: Encyclopedia of Vernacular Architecture” and published in 1997 with 4000 pages collection of research by over 750 authors from 80 countries. With two volumes categorized by climate and the ‘‘vernacular responses’’ of a plethora of cultures and another volume focused on materials, resources and production, it is the world’s foremost source for research in the area (Zhai & Previtali, 2010). Zhai and Previtali (2010) introduced an approach to categorizing distinct vernacular regions and evaluate energy performance of ancient vernacular homes as well as identify optimal constructions using vernacular building techniques. Chandel, Sharma, and Marwah (2016) reviewed the vernacular architecture features affecting indoor thermal comfort conditions and energy efficiency for adaptation in modern architecture to suit present day lifestyles. Singh et al. (2009) carried out a qualitative analysis on the vernacular buildings in north-east India. And Shanthi Priya et al. (2012) have conducted the qualitative and quantitative analysis to investigate the indoor environmental condition of a vernacular residential building in coastal region of Nagapatinam, India. Cardinale, Rospi, and Stefanizzi (2013) performed one experimental research on two types of vernacular buildings which lie in Southern Italy. Nguyen, Tran, Tran, and Reiter (2011) carried out an investigation on climate responsive design strategies of vernacular housing in Vietnam by a new research methodology which is adapted to the natural and social context of Vietnam. Ng and Lin (2012) analysed the microclimate of two Minangkabau vernacular houses in villages of Balimbing of Bukittinggi, Sumatra, Indonesia. Ali-Toudert, Djenane, Bensalem, and Mayer (2005) addressed the issue of outdoor thermal comfort in a hot and dry climate in relation to urban geometry. Beccali, Strazzeri, Germanà, Melluso, and Galatioto (2017) reviewed some models evaluating thermal comfort in natural ventilated vernacular buildings, based on adaptive approaches. Borong et al. (2004) concluded that sun shading and insulation are of great importance while natural ventilation is just considered as an auxiliary approach for the design principles of the traditional Chinese vernacular dwellings, based on the field measurements of the thermal environment parameters and a long-term auto-recorder of the indoor and outdoor temperature at four typical traditional vernacular dwellings at Wannan area in summer. Bouillot (2008) studied six Chinese vernacular houses in different provinces and found that the value and the diversity of the Chinese housing stock is due to the combination of the specific structure of the Chinese eastern climates, which creates the contrast of cold-dry winters and hothumid summers, with the structure of the Ming t’ang, which contains the opposition of the yin and the yang. Liu et al. (2011)’s study interprets the characteristic of warm in winter and cool in summer in traditional Yaodong dwelling by measuring the indoor, outdoor and the wall’s temperatures in winter and summer. The results show that the Yaodong thick wall effectively damps the external temperature wave and keeps a steady inner surface temperature, are the chief causes of warm in winter and cool in summer in Yaodong. Gou et al. (2015) focused on a qualitative analysis of ancient dwellings located in the village of Xinye, in the hot summer and cold winter region of China. According to the analysis, the climate responsive strategies of the dwellings are mainly focused on natural ventilation, sun-shading and thermal insulation, illustrated by different building aspects such as the building location, building group layout and orientation, internal space arrangement, opening design, among other variables. Soflaei, Shokouhian, and Zhu (2017) investigated the potential of traditional courtyard houses in Iran and China in responding to environmental challenges alongside social norms over a long period of time. The social and environmental dimensions of the sustainability as well as the main elements of traditional courtyard houses in Iran and China were identified. Because of the advantage of vernacular building using passive ways to achieve thermal comfort and energy efficiency as mentioned above, this research will start with the investigation of a Chinese vernacular buildings in chapter 4. The next part of the literature review is an overview of passive cooling techniques.

Morocco faces tremendous climate constraints; the climate is hot and dry in most parts of the country, and when selecting an energy-saving approach, the architectural landscape becomes essential.Designer and building professionals seem to have neglected this large-scale integration. Sustainable development programs in terms of sustainable architecture are ongoing in countries around the world. One part of this trend is the growing concern shown in the high environmental efficiency of vernacular architecture. It is within this prescriptive framework that this research study is being conducted, which reveals novel architectural style integrating thermal comfort, energy efficient characteristics, passive solar elements architecture, and construction techniques inspired from the vernacular Ksourian architectural configurations. The goal of the present research study is to identify features of energy efficient vernacular architecture and thermal performances that affect indoor thermal comfort conditions for adaptation to current lifestyles in modern architecture. The key characteristics developed are; built mass structure, building orientation, space planning, availability of sunspace, building techniques, and new coating materials for manufacturing and roofing. The suggested methodology enables to analyze the thermal performance analysis, applying an experimental research using experimental testing measurement and comparative optimization processes for thermal efficiency and comfort evaluation of a traditional vernacular earthen house.Series of experimental thermophysical characterization measurements have been carried out in order to quantify on a real scale the thermophysical properties that characterize the Rissani earth. Thusthermophysical characterization results are operated as input data for the thermal dynamic simulation for the purpose to evaluate thermal performances and comfort under the weather conditions and control natural comfort in both summer and winter, without using heating or cooling systems. Ultimately, the simulations carried out make it possible to identify the optimal orientation, revealing an effective decrease in interior temperatures during summer and providing good thermal comfort in winter.

In the following article the author proposes the solution for a properly functioning natural ventilation system based on the use of supply and exhaust ducts, i.e. by designing a natural balanced ventilation system. The paper is devoted to test results of air flow through natural ventilation supply-exhaust ducts in the rooms located on the lower floor of the building. The simulations conducted in ANSYS Fluent software relate to such issues as: pressure system inside the room and in the exhaust duct, distribution of air temperatures in the room, vector direction of airflow through supplyexhaust ducts and in the analysed room. Three types of solutions were selected for the tests: air inflow into the room through the air intake located at the basement level, air inflow through the window ventilator (although no longer used, this solution can be found in many existing residential buildings) and the natural ventilation system supported with the so-called “solar chimney”. All simulations were conducted with an outdoor temperature of +3 degrees C. The indoor temperature is + 20 degrees C, considered to be the minimum thermal comfort level. In the era of common building sealing, the presented ventilation system may be a good solution that guarantees proper functioning of natural ventilation. In all cases presented, it meets the normative regulations and requirements for the ventilation air stream and the air exchange rate in the room. The paper (first part) describes test results concerning the room located on the lower floor of the building, i.e. with a short supply duct and a 12-meter long exhaust duct.

The level of Indoor Air Quality (IAQ) has become a big topic of research, and improving it using passive ventilation methods is imperative due to the cost saving potentials. Designing lecture buildings to use less energy or Zero Energy (ZE) has become more important, and analysing buildings before construction can save money in design changes. This research analyses the performance (thermal comfort [TC]) of a lecture room, investigate the use of passive ventilation methods and determine the energy-saving potential of the proposed passive ventilation method using Computational Fluid Dynamics (CFD). Results obtained showed that air change per hour at a wind velocity of 0.05 m/s was 3.10, which was below standards. Therefore, the lecture hall needs external passive ventilation systems (Solar Chimney [SC]) for improved indoor air quality at minimum cost. Also, it was observed that the proposed passive ventilation (SC) system with the size between 1 and 100 m3, made an improvement upon the natural ventilation in the room. There was a 66.69% increase after 10 years in the saving of energy and cost using Solar Chimney as compared to Fans, which depicts that truly energy and cost were saved using passive ventilation systems rather than mechanical ventilation systems.

Thermal comfort is important for buildings, especially in tropical climates. The issue of increasing indoor temperature is influenced by various factors that cause occupants to face thermal discomfort in cafeterias that uses both mechanical and natural ventilation systems. This study aims to determine the perception of occupants and evaluate parameter variations of thermal comfort in the cafeteria of Pagoh Campus Residential College, UTHM Pagoh Branch Campus. This study was conducted through the measurements of subjective and physical parameters. Data collection is carried out in two days, which are weekdays and weekends. This study uses some parameters variation which are thermal sensation vote index (TSV), predicted mean vote index (PMV), predicted percentage of dissatisfaction (PPD), operative temperature (To) and neutral operative temperature (Tneutop) to determine the thermal comfort conditions in the cafeteria. The results shows that the average values of air temperature, mean radiation temperature, relative humidity and air velocity from environmental measurements were 30.2 °C, 30.6 °C, 66% and 0.1 m/s respectively. In addition, PMV and PPD values were 2.0 and 76% from environmental measurements, while 1.36 and 43% from questionnaires. For To and Tneutop, the average values obtained are 30.4 °C and 28.6 °C. Furthermore, the findings showed that only the morning session was in the acceptable operative temperature range and complied with ASHRAE Standard 55 for both the 80% and 90% acceptability limits. At the end of the study, it was found that the values from the thermal environment measurements and surveys exceeded those recommended by ASHRAE Standard 55. This concluded that the quality of the occupants’ environment in the cafeteria is outside the satisfactory thermal comfort level. Therefore, the improvement through mechanical ventilation may very helpful in improving a good ventilation system as well as encouraging an increase in thermal comfort in the building.

Energy implications of meeting indoor air quality and thermal comfort standards in Mediterranean schools using natural and mechanical ventilation strategies

The success of educational institutions is fundamentally intertwined with the well-being and academic progress of their students. In this context, indoor air quality (IAQ) and thermal comfort play a critical role in creating conducive learning environments that support both health and academic performance. This work evaluates six ventilation systems and strategies for enhancing IAQ and thermal comfort, which prevail in educational buildings in the Spanish region of Catalonia. To do so, a multi-criteria analysis is performed based on the Analytic Hierarchy Process (AHP) method, considering economic, social, and environmental aspects. Ventilation systems are pairwise compared in terms of six criteria: initial and maintenance cost, classroom air quality, students’ thermal comfort in summer and winter, and energy consumption. Subsequently, weighted combinations of these criteria are established to rank the ventilation systems under five case scenarios. The results indicate that natural ventilation systems, particularly those with atriums and courtyards (N-AAC), offer a balanced solution, achieving satisfactory IAQ and thermal comfort while being more cost-effective and environmentally sustainable in certain contexts. The variation in the best solution across different scenarios demonstrates that the optimal choice is highly context-dependent, influenced by factors such as budget, climate, and infrastructure. This research provides a valuable foundation and methodology for decision-makers in educational institutions, supporting the selection of ventilation systems that maximize sustainability while enhancing students’ comfort and fostering learning environments.

Comparison of physical performances of the ventilation systems in low-energy residential houses