Environmentally Sustainable Design Building - Term Paper Example

Envirоnmеntаlly Sustаinаblе Dеsign Building Student Name Professor Course University affiliate Date Executive summary The aim of this study is to analyse the various applications of engineering science in the field of architecture in order to come up with a sustainable building designs. The various design aspects such as thermal conductivity of building materials, solar geometry, and solar loads of a building are focused on. It further explains on the importance of considering a building is glazing characteristics in the design process. Building design has been evolving, and this report covers on the modern and more efficient techniques in order to achieve environmentally sustainable design building. These methods include, shading techniques, material selection, as well as orientation of buildings. In material selection, material properties such as thermal conductivity, transmittance, density, thermal resistance, etc. are analysed. In buildings, thermal mass can reduce the peak cooling loads as well as indoor temperature swings. The various factors affecting the thermal mass performance are reviewed. Introduction Architectural design and urban planning are majorly affected by climate that also related to the buildings energy consumption. Residential buildings are the architectural structures consuming a higher percentage of energy in the world. This study, therefore, analyses thermal of buildings in relation to the various aspects as well as its impact on thermal comfort. The research also analyses the thermal performance relation to various shapes and orientation of buildings and an approach to solutions for optimum performance. Thermal mass is defined as the building’s mass that can be used for storage of thermal energy for cooling or heating purposes. It can be used to minimize the fluctuations of outdoor temperatures that could be very wide. It also offers architectures and engineers an opportunity to be able to manage energy flows in the building. Typical components being adopted with this concept of thermal mass include; External thermal mass which is, usually, exposed to the ambient temperature fluctuation and it includes roofs and walls. Internal thermal mass which is exposed to the indoor air temperature and includes furniture. Applications of engineering science in sustainable building design The operation of architects is based on many planes ranging from, aesthetic, social, economic, political, etc. whereas engineers makes it more precise. From this view, a particular rhizomaticity emerges concerning architectures whereas engineering science is displayed as a stratified system of knowledge, design rules, assemblage of facts and building codes. Therefore appreciating engineering science can create new and visionary stationing of building materials to come up with interesting and functional spaces. In creative effort, engineering science heightens the transversality coefficient. It induces rhizomaticity. Other pressures shaping the architectural profession evolution include: Environmental concerns and this has encouraged architects to come up with building designs that are ecological benign. Information technology –this has enabled knowledge sharing as well as access of useful information. Form of building The form, configuration and spacing of a building in its neighbourhood, can affect solar and wind factor. They control the amount of solar radiation that is received by the surface of a building and the air flow around it. Therefore, to maintain thermal balance, it is required that the building surface should have a small surface to volume ratio. The form of a building determines direction of its exterior shell, which is exposed to the outer environment. Therefore, it affects its thermal performance. By using an optimum shape, envelope and orientation, energy intake can be lessened up to 40%. The roof structure is another aspect. The buildings' ceiling height is also an aspect of roof form. The coefficient and area of heat transfer by convection of curved roofs are greater than flat roofs having the same base. A buildings orientation also affects thermal performance. For instance, a particular orientation minimizes the direct solar radiation into the envelope of the building. The building's envelope is also an important aspect to consider since it affects a buildings heat gain, as well as heat transfer coefficient. It is, therefore, necessary that, a building envelope has a level of thermal resistance and to have a minimum of thermal bridges so as to avoid water vapour penetration. Moreover, there are other forms, for example, the L-type and H-type which can provide self-shading of surfaces decreasing the direct solar radiation. Self-shading of a building, usually, depends on the building shape as well as the layout arrangement. Form also affect air flow patterns and wind channeling. Large capacity buildings, often, have more energy efficiency when compared to smaller volume building. Similarly, taller and narrower buildings tend to be energy efficient. Geometries providing Self-shading in buildings however Material properties Properties of materials for building components significantly controls the heat transfer process. The primary thermal properties include: Thermal conductivity-it is a materials property representing quantity of heat per unit time in watts flowing through a 1 metre thick material with a 1m2 area and 1 kelvin temperature gradient. Thermal conductivity is, usually, inversely proportional to thermal transmission and vice versa. Thermal resistance- refers to the resistance to heat flow between two points on the surface at different temperatures. It is, usually, expressed as the R-value and is the reciprocal of thermal conductivity. Transmittance U- refers air to air measure of thermal insulating ability of a material. Its value can be found by taking the reciprocal of the material's thermal resistance.( U=1/R) Density, porosity- Density is mass per unit volume. Porosity is, usually, linked to the density. A more porous material is less dense and vice versa. A lighter material has more insulating capabilities while a heavier material has more heat storing capability. Properties of materials for building components significantly control the heat transfer process. Building’s orientation in different climate As earlier stated, selecting a suitable orientation for a building will control the solar radiation as well as wind entering. (a) Cold climate Use of double or triple glazing is used. If the summer is, usually, hot, Large glazed areas may require shading in particular directions. The windows facing the equator direction should be reduced. A building need to be oriented for maximum solar heat reception into the living areas for the provision of warmth. (b) Temperate climate In these regions, it is, usually, humid and thus, buildings should have proper ventilation. They should also be oriented in a way that they benefit from the summer winds. However, orientation for high buildings should be ‘determined’ by wind effect. (c) Hot-arid climate The orientation should be based on the sun. In case there is a cooler season, the windows will need to be correctly placed and oriented to improve comfort during winter. Buildings can be arranged in clusters for the purpose of heat absorption as well as shading opportunities and also protection from east and west exposures. (d) Warm-Humid Climate The building is oriented according to prevailing wind. Care should be observed in order to admit the desired winds and also protect from cold winds in case there is a cooler season. The science of glazing for energy efficiency For improved comfort, health and productivity, a building should be well ventilated as well as have sufficient lighting. Despite these, windows can be a source of unwanted heat losses, condensation problems and discomfort. For the purpose of increasing window efficiencies, there has been a technological revolution on the same. The development of new technology glazing systems is aimed at cutting energy consumption as well as reduces pollution sources since they have reduced heat loss, less leakage and most important a warmer surfaces that provide more comfort. These high-performance windows include; Double glazing Triple glazing Specialized transparent coatings Insulating gas sandwiched gas between panes Improved panes Window systems, usually, consists of structural frames, glass panes and sealants. A careful specification of these glazing systems is, therefore, necessary for the purpose of comfort and efficiency of buildings. Options of window and glazing to be considered Heat losses and gains Thermal comfort Condensation control Shading and sun control Acaustic control Colour effects Daylighting Energy requirements The choices of window and glazing systems on factors such as, the use of building, utility, local climate and the buildings orientation. Characteristics to be specified when specifying window systems include: U-value The value indicates the heat flow rate through a window due to conduction, radiation and convection due to differences in temperature between inside and outside. A higher U-factor means that larger amount is transferred (lost) in winter through the window. The standard unit for U-factor is Btus per hour per square feet. It, usually, range from 0.2 to 1.3 depending on the type window design. A window with a –factor say, 0.6 will probably lose twice as much heat as one with a 0.3 U-factor under the same condition. Solar heat gain coefficient (SHGC). It shows how much energy from the sun is transmitted through the window in the form of heat. The solar gain potential increases with an increase with increased SHGC. SHGC usually ranges from 0 to 1 and a SHGC value of 0 means that none of the incident solar gain is transferred through the window while a value of 1 means that all of the solar energy is transmitted through the window. Typically, windows having small values of SHGC are desirable in buildings that have High air-conditioning loads whereas windows having a higher value are desirable in cases where passive solar heating is required. Visible transmittance This parameter indicates the percentage of the visible part of the solar spectrum transmitted through a glass product. UV rays having short wavelengths are mostly invisible but cause fabric and fading and also skin damage. Visible light can be detected by naked eye and has about 47% of sunlight’s energy. Coolness index is a term used to describe a given glazing system and refers to the ratio between Tvis-glass and the shading coefficient. Tints (colour) and coatings Tinting or applying of various different layers can alter properties of glass. Apart from aesthetic purposes glass tints also help in a reduction of solar gains. Coatings in the form of metal oxides can also be used in glass tinting. Low-emissivity coatings can help reduce radiant heat transfer in between glass panes by restricting some or all of the IR wavelengths. These coatings reduce the U-factor of windows. Specification of tints and coatings should, therefore, be carefully done since their application can impact the window’s heat loss as well as heat gain. Conclusion The issues of thermal performance of buildings have been fully addressed in this study. It also focused on the energy uses in a building so as to improve thermal performance as well as achieve thermal comfort for the occupants. The study also elaborated the factors that, usually, affect thermal performance and how to achieve a thermal balance between heat loss and gain. From this study, it is clear that, utilization of renewable energy sources is necessary so as to mitigate the environment-related problems, as well as use of conventional energy sources. It is necessary to ‘eliminate’ the thermal rate of transfer between the building’s envelope and the surrounding through conduction, radiation and convection so as to maintain the thermal balance. There is a need to control architectural aspects and properties of building materials with respect to climatic factors. It is also essential to utilize passive solar design approaches (Kreider,Curtis and Rabl 2002). Reference Kreider, J.F., Curtiss, P.S.& Rabl, A 2002, Heating and Cooling in Buildings. 10th ed. New York: McGraw Hill. Read More