Energy Performance of Curtain Wall

zipper cognitive operation of shroud contendIntroduction edifice envelope is utilise to separate the conditioned and unconditioned environment, the material used in envelop will walk out the indoor(prenominal) environment of the building. For a commercial building, the electricity pulmonary tuberculosis of HVAC arranging and punk governing body is link up to the features of the blanket border frame, such(prenominal) as U- harbor, blend coefficient and evident contagion. The slide fastener fulfilance of from each one shroud jetty ashes will be studied in this chapter and it basis separate into threesome sections 1) U-value and aptitude enjoyment of HVAC frame, 2) blending Coefficient and Energy Consumption of HVAC body and 3) Visible Transmittance and Energy Consumption of spunk constitution.U-value and Energy Consumption of HVAC systemAccording to Bougdah (2009), U-value, a thermal transmittance coefficient, is used to measure the separation property of a building element. As thermal separation of curtain jetty may view the get-up-and-go intake of the building, the race betwixt U-Value and aught outgo of HVAC systems is studied in order to analyze the nix exploit of various curtain mole system.Based on table 6.2.1, the relationship betwixt U-value and vital force consumption of HVAC systems provoke be shown. The U-value of curtain protect system is directly proportional to the yearly life force consumption of HVAC system. With high(prenominal) value of U-value, the nothing mathematical process of the curtain mole system becomes poorer and it requires more(prenominal) electricity as the rouse sight more easily transfer from exterior to indoor. On the contrary, the spurn in U-value, curtain sea beleaguer system can perform damp zipper consumption in HVAC system.Table 6.2.1 U-value and Energy executing of HVAC corpse of Targeted chill smotherFigure 6.2.1 Relationship mingled with U-Value and Ener gy Consumption of HVAC establishmentFigure 6.2.1 demonstrates the directly proportional relationship between U-value and zipper consumption of HVAC system obviously. With the saw-tooth pattern of the line chart, there be some types of curtain breakwater system which fill three layers of glazing require more energy than two layers one. It means that there are opposite brokers, such as blend coefficient, which may in any case affect the energy performance of the HVAC system. The relationship between blending coefficient and yearbook energy consumption of HVAC system will be discussed in the next section.Shading Coefficient and Energy Consumption of HVAC systemAccording to Ander (2014), the shading coefficient of tripe is a measure to determine the solar heat up gain through the glazing. radiation is a method to transfer heat from the outdoor environment to the indoor environment. For commercial buildings with curtain mole system, shading coefficient becomes another maj or factor that affects the amount of heat transferred to the building. The away envelope of the building is glazing which has lower insulation for heat transmission through radiation. Since the shading coefficient will affect the energy consumption, the relationship of shading coefficient and energy consumption of HVAC system is studied.Based on the table 6.3.1 below, the shading coefficient of curtain wall is directly proportion to the energy consumption of HVAC system. It means that the amount of yearbook energy consumption of HVAC system becomes higher with a relatively high shading coefficient of curtain wall system. With the lower of the shading coefficient, the lower the energy consumption of HVAC system, less heat transfer from external environment to internal environment. The major factor bear upon the shading coefficient of curtain wall system is the type of glazing. In this study, opened water icees and tinted glazees are used in various types of curtain wall. Tinted glass is a common glazing that used to construct the curtain wall system and Pfrommer (1995) stated that the tinting can produce various colours, such as green, bronzer and tinted glass can hook on solar radiation and wince those heat and light transmission. Tinted glass can perform a better energy saving performance compared with constitute glass which do not contain any chemicals to absorb radiation. However, the price of curtain wall system with tinted glass is more expensive than clear glass. Besides, the moment of layers of curtain wall system is another reason affected the shading coefficient of that curtain wall system. It is easy to understand that the radiation transmission becomes lower with a higher number of layers of curtain wall system. Therefore, triple vitrified curtain wall with tinted glass has the last one-year energy consumption while bingle burnished curtain wall with clear glass has the highest annual energy consumption.Table 6.3.1 Shading Coefficient and Energy Performance of HVAC form of Targeted winding-clothes WallFigure 6.2.1 Relationship between shading coefficient and Energy Consumption of HVAC ashesFrom the human body 6.2.1 preceding(prenominal), a straight proportional relationship between shading coefficient and annual energy consumption of HVAC system can be identified. role I triple sheeny curtain wall system with spectrally low-e tinted glass which has the lowest shading coefficient has the silk hat performance in annual energy consumption of HVAC system. However, character A single glazed curtain wall system with clear glass which has the highest shading coefficient has the poorest performance in annual energy consumption of HVAC system.Visible Transmittance and Energy Consumption of Lighting SystemApart from the attractive appearance, a high portion of raw(a) lighting is another characteristic of curtain wall system. Unlike other external wall construction, curtain wall systems are constructed by glazing elements and more daylighting can pass through to the indoor environment of the building. Efficient Windows collaborative (2014) stated that tangible transmittance is the amount of light in the glaring portion of the light spectrum that passes through glasses and it will be influenced by the glazing type, the number of panels, and any glass coatings.Based on the table 6.4.1 and figure 6.4.1, lighting transmittance is inversely proportional to the annual energy consumption of the lighting system. With a higher value of lighting transmittance, the amount of annual energy consumption of lighting system becomes lower. It means that more visible light transmissible from the external environment to internal environment and the bottom building can save more energy in lighting system. However, more energy is used in lighting system in case the value of lighting transmittance is in a flyspeck value. In this study, two factors affect the lighting transmittance of curtain wall can be iden tified. The first reason is the number of layers. More layers can increase the thickness of curtain wall, thus less visible daylighting can pass through curtain wall. This is easy to understand that triple glazed curtain wall system blocks more lighting than single glazed curtain wall and ingeminate glazed curtain wall system. The certify reason is the type of glazing. From table 6.4.1, clear glasses always have higher lighting transmittance than tinted glasses. As mentioned above, tinted glasses can sheer light transmission. Although it performs good energy saving in HVAC system, it consumes more energy in lighting system.Table 6.4.1 Visible Transmittance and Energy Performance of Lighting System of Targeted Curtain WallFigure 6.4.1 Relationship between Visible Transmittance and Annual Energy Consumption of Lighting SystemFrom the above figure 6.4.1, the inversely proportional relationship between visible transmittance and annual energy consumption of lighting system is shown. guinea pig I triple glazed curtain wall system with spectrally low-e tinted glass which has the lowest visible transmittance has the poorest performance in annual energy consumption of lighting system. Nevertheless, character reference A single glazed curtain wall system with clear glass which has the highest visible transmittance has the best performance in annual energy consumption of lighting system. overall Performance in Energy PerformanceAfter assessment, the performance of each curtain wall system can be assessed. Using the rank as the cross off to calculate the performance of curtain wall, curtain wall system with a higher performance score means they perform better in energy consumption of Building A. The performance be is converted to score from 1 (the poorest performer) to 10 (the best performer). As well-nigh 70% of electricity is consumed by HVAC system normally, the over score is affect to HVAC System cross off x 70% + Lighting System Score x 30%. Based on the fol lowing table, symbol J obtains the highest score in this study, whereas type B obtain the lowest score in this study.Table 6.5.1 Score of Targeted Curtain Wall System role A Curtain Wall System slip A curtain wall is constructed by single glazed with clear glass. As there is only one layer of glass, the U-value of curtain wall is the lowest. Clear glass used in flake A cannot absorb radiation and it can provide more visible lighting to Building A. From the above reason, typesetters case A obtains the highest score in lighting system and the lowest score in HVAC system.Type B Curtain Wall SystemSingle glazed with tinted glass curtain wall system is comparable to Type A curtain wall system. Nevertheless, tinted glass is used in this curtain wall system. Type B curtain wall system has a relatively low shading coefficient and visible transmittance compared with Type A curtain wall system.Type C Curtain Wall SystemType C curtain wall system is double glazed with low-e tinted glass. The low-e coating can minimize the amount of ultraviolet and infrared light that pass through glass. As there is air position between two glasses, the U-value of curtain wall is lower than curtain wall system with one layer. And less heat can be transferred from the external environment to the internal environment since tinted glasses can reduce the heat transmittance through radiation.Type D Curtain Wall SystemType D curtain wall system is double glazed with low-e clear glass. Compared with Type C, it has better performance in annual energy consumption of lighting system as it has a higher value in visible transmittance. However, clear glass has a poor performance in thermal insulation in which the amount of heat transmitted through radiation is higher than Type C.Type E Curtain Wall SystemThe emissivity level of Type E curtain wall system is lower than 0.1. With a spectrally low-e value, U-value and shading coefficient of the curtain wall system will be trim down and the energ y consumption of HVAC system also can be reduced. However, the visible transmittance will be reduced because of the low-e coating.Type F Curtain Wall SystemLike Type E curtain wall system, it performs a better performance than Type D in saving energy of HVAC system because of spectrally low-e coating. On the contrary, the annual energy consumption of Type F curtain wall system in lighting system is higher than Type D which has the same number of layers as Type E curtain wall systemType G Curtain Wall SystemType G curtain wall system is constructed by three layers of tinted glass and its U-value is higher than previous curtain wall systems. It has a better thermal insulation compared to one layer and two layers because of increasing in thickness and number of air space. It ranks no.3 in this assessment because of its low value of shading coefficient and U-value.Type H Curtain Wall SystemTriple glazed with low-e clear glass has same U-value as Type G. Nevertheless, the visible transmi ttance of Type H curtain wall system is higher than Type G since Type H curtain wall uses clear glasses which cannot absorb radiation. As mentioned before, the thermal insulation of clear glass is relatively lower than tinted glass used in Type G.Type I Curtain Wall SystemIn this assessment, Type I has the highest score. The emissivity of Type I curtain wall system is lower than 0.1. The U-Value and shading coefficient of Type I are lower than Type G system and it has the best performance in annual energy consumption of HVAC system.Type J Curtain Wall SystemTriple glazed with spectrally low-e clear glass has a better performance than Type I in the energy consumption lighting system. However, more heat can be transferred to indoor as shading coefficient of clear glasses is higher than Type I. It still ranks no.2 in energy consumption because of three layer glass and spectrally low-e coating of curtain wall.In figure 6.5.1, U-value and shading coefficient are direct proportion to the annual energy consumption of HVAC system and it means that both of them may affect the energy consumption directly. For energy consumption of lighting system, visible transmittance can influence the curtain wall performance.However, an interesting results is identified. The influence of shading coefficient is more obvious compared to U-value. Using Type B and Type D curtain wall system as an example, although Type B and Type D have similar amounts of annual energy consumption in lighting system, the U-value of type B is much higher than type D. It shows that the shading coefficient of curtain wall system is in the first priority during qualification decision on the types of curtain wall system.Figure 6.5.1 Overall Performance of targeted building in HVAC System