Abstract

The use of new construction materials, active cooling and heating systems, and rising global temperatures are surprisingly harming our environment and are contributing to pollution and the depletion of the ozone layer. The study focuses on several thermal comfort strategies for residential building designs and passive design techniques used in Abbottabad, Pakistan, traditional houses. The research also offers a descriptive examination of a traditional and a modern built house, highlighting the problems caused by the absence of conventional passive design elements in the latter. The research comes to a conclusion and suggests environmental protection measures that modern homes should use in the future.

Key Words

Comparative Study, Traditional, Environmental Impact Assesment

Introduction

The increasing concern about global warming has been one of the burgeoning problems in the last few years. The Intergovernmental Panel on Climate Change (IPPC) has projected that between 2080 and 2100, average global temperatures would increase by 2.6°C to 4.8°C, as depicted in Figure 1 (Saari, 2013). In addition, temperatures in South Asia (Bhutan, Nepal, India, Pakistan, and South China) are predicted to rise by an average of 2-3 degrees Celsius between 2046 and 2065. In terms of rainy season dates, rains, water shortages, etc., the effects of climate change in Pakistan can also observe.

Figure 1

Depicts expected surface temperature variations from 2020 to 2029 and 2090 to 2099, depending on expected population growth (Saari, 2013).



Buildings are one of the primary contributors to climate change, and their energy consumption contributes significantly to global warming. The building's energy use accounts for almost 40% of the world's overall energy use. In 2015, buildings utilized 2.941 Mtoe (million tons of oil equivalent energy). (Nezhad, 2009) Residential and public-sector energy consumption totalled 2,569 Mtoe, with the residential sector accounting for two-thirds of overall energy consumption. Energy demand in the building sector expects to rise to 5,257 Mtoe in the baseline scenario by 2050, with the residential sector contributing 60% of this increase to 60% (Nezhad, 2009). Also, the primary source of emissions to the atmosphere of greenhouse gases (GHG) and carbon dioxide (CO2) is energy consumption in different sectors (Bahrami, 2008).

Buildings' construction offers an opportunity to help deal with these issues by consumption, considering the current climate change scenario and electricity costs. Building houses for more energy, in this case, efficiency would be very acceptable, and one of the ways is the growing use of passive architecture techniques in modern buildings.

Much of Pakistan's cities lack a correct, well-designed bye-law building code. Abbottabad is a city with more vital by-laws compared to other cities in Pakistan. Even then, it can seem that the gap is enormous. In terms of thermal comfort, current requirements apply. Every standard concerning insulation, airtightness, etc., which helps preserve and achieve thermal comfort, is absent in the bye-laws. During the shifting seasons, this has contributed to the problem of modern buildings getting overheated or cold. Also, it illustrates those excessive quantities of electricity are being used and will continue to maintain warmth inside the structures in the future.

Literature Review

Thermal Comfort

Thermal comfort is a feeling that reflects satisfaction with one's thermal surroundings. Thermal warmth is contextual because it varies from person to person. It is preserved because the heat produced by human metabolism is allowed to dissipate at a pace that keeps the body at a steady temperature. Any extra heat gain or loss creates considerable discomfort. The quantity of heat generated and lost must balance out in order to maintain thermal comfort. One of the most crucial components of living in a house is having the appropriate level of thermal comfort. There is no absolute norm for temperature since people may live and thrive in a variety of conditions, from highly hot to extremely cold. (Darby and White, 2005). It is defined by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) Standard as a mental state signifying satisfaction with the thermal environment. The air temperature, mean radiant temperature, humidity, relative airspeed, and hidden features are among the environmental factors that influence thermal comfort in terms of clothing and activity. By properly integrating these components, a thermally comfortable atmosphere may be created. 

It has long been known that factors other than room temperature may impact how hot or cold you feel. Thermal comfort is impacted by six main elements.

? Air Temperature (Real feel of the Air Temperature)

? Radiant temperature (surface temperature in the environment) 

? Relative humidity (Percentage of water vapours in the air) 

? Air movement (the speed of air at which it comes in contact with the human body) 

? Metabolism Rate (the quantity of energy used)

? Insulation in clothing (materials used to keep or lose body heat).

Figure 2

Parameters of thermal comfort for residence design (Parsons, 2003).



Air Flow

Air flow has an impact on the majority of people. As a result, air flow may start to play a big role in thermal comfort. People will feel sleepy and uncomfortable in the presence of stillness or quiet air in artificially created interior environments. Wind speed increases the amount of heat lost without increasing air temperature; however, convective heat loss increases considerably when the air temperature is lower than the skin temperature. 

Furthermore, rigorous activity may aid in increasing air circulation (Liping et al., 2007). The calculation of air velocity faces various difficulties due to the irregular flow and trajectory of air. The ideal solution is to maintain a small measuring sphere with steady dimensions and characteristics.




Relative Humidity

Relative humidity (RH) is the amount of moisture carried in the air expressed as a percentage of the actual amount carried at that temperature (Parsons, 2003). Relative humidity is defined as the difference between the mole fraction of water vapour in dry air and the mole fraction in wet air at a given temperature and barometric pressure. Additionally, relative humidity is defined as the difference between the partial pressure or density of water vapour and the saturation pressure or density of air at the same temperature. Heat stress is mostly caused by air humidity, which has minimal bearing on thermal comfort.




Air Temperature

Air temperature is the temperature of the air around a human body (Ta). In addition, the ambient temperature has a big effect on heat exhaustion. It

stands for the area of the atmosphere that has an impact on how heat is transferred from the body to the air. The air's temperature changes (Randall, 2005). Humans frequently experience temperature changes, and the limit of heat flow is not necessarily determined by the air temperature that passes over the bulk of the body's surface. Air temperature is not comparable to a dressed body representation and is frequently affected by "border circumstances." And when it's chilly outside, for instance, the body is covered in warmer air. The air temperature is thought to be the most important climatic factor affecting thermal comfort. But there should also be other factors taken into account.




Mean Radiant Temperature

Radiant temperature is the amount of heat that passes unaltered from a body at a higher temperature to a mass at a lower temperature (Tr). The ASHRAE Standard-specified temperature of a hypothetical space or enclosure at which radiant heat transfer from a human body is balanced with that from its surroundings (55-1992). Because the ISO estimates the mean radiant temperature around the human body, spherical globe thermometers that are used to measure heat stress closely resemble the body form of a seated person.

An occupied room's floor, walls, and ceiling may have temperatures that are amazingly close to air temperature. Radiant temperature can occasionally be close to the same as the surrounding air's temperature in both directions. In locations with radiating floors or other types of radiant heating, the average radiant temperature is higher than the air temperature throughout the heating season.

Figure 3

Design elements with the thermal comfort study (Randall, 2005).



Clothing Insulation

Changes in clothing can greatly influence the transfer of heat between both the body and its surroundings. Clothes can act as a heat shield, masking temperature and velocity differences between objects. Clothing functions as an insulator, decreasing heat loss from the body and enhancing endurance and comfort in colder conditions, according to the ASHRAE Standard (55-1992) on covered parts of the body. It is necessary to know about the inhabitants' clothes in order to gauge the area's level of thermal comfort since the thermal resistance of their clothing permits heat to move between the human body and the surroundings.

Figure 4

Double Glazed Glass

References

• Ahmed, N. (2019). Cities Weekly Weather Outlook. Abbottabad | Hazara | Pakistan Meteorological Department.
• Darby, S. & White, R. (2005). "Thermal Comfort". Environmental Change Institute, University of Oxford.
• DeKay, M., & Brown, G. (2013). Sun, wind, and light: architectural design strategies. John Wiley & Sons.
• Kumar, R., Garg, S., & Kaushik, S. (2005). Performance evaluation of multi-passive solar applications of a non air-conditioned building. International journal ofenvironmental technology and management, 5(1), 60-75.