Energy Effeciency Definition - Assignment Example

Revised questions: a. Part 3.12.2 of the BCA (Vol 2) has a diagram that shows how shade projections (P) and the height of windows (H) effects sunlight entry into dwellings. Note how the diagram shows how to measure P and H. Dividing P by H (i.e. P/H) provides a value that can be used to find P/H value in Table 3.12.2.2 which turn allows to you find applicable E values (exposure factors) . What is the figure number of this diagram? The figure number of this diagram is figure 3.12.2.2. This diagram indicates how the P and H values are determined. The chapter describes how designs affect the energy efficiency of buildings. It also indicates the variation of E values with reference to climate zones and the change in the value of P/H. in addition the chapter also indicates how the value of e changes with the change in orientation or position of windows. b. Do E values increase or decrease as the P/H values increase? (See ‘Explanatory information’ after table 3.12.2.(b) The E values depend on orientation, orientation refers to the position. A number of orientations are considered including, north, north east, east, south east, south, south west, west and north west. The E values will also differ with the season, some climate zones consider the winter and summer values. The climate zone is anther factor that affect the E values and the E values tables provide values for the various climate zones. For Ew as the value of P/H increases, then the Ew declines, this is evident in table 3.12.2.2a. For Es as the P/H values increase then the Es values decline, however the values depend on orientation whereby the E values defer depending on orientation. However given that orientation remains the same an increase in P/H will reduce the value of Ew and Es. A higher Ew is preferred whereas a lower Es is preferred. c. State what happens to a house as the E values increase? Es refers to the summer E value; the E value refers the level of how efficient a building is in terms heat gain. As this value increase it means that that a building is not efficient in terms of heat gain during the summer season given that these heat gain is unwanted, a lower value is preferred because it means less unwanted heat will enter the building. Ew refers to winter E values, the E value refers the level of how efficient a building is in terms heat gain. as Ew increases, this means that the building is efficient with reference to heat gain during the winter season and therefore a higher value is preferred. From the above discussion therefore it is evident that a higher Ew value is preferred because this indicates that a building will gain more heat during the winter season, a lower Es value is preferred because this means that a building will gain less unwanted heat during the summer season. d. A single storey house is being built in Hobart Tasmania. For a window on the northern side of the building assume H is 2100mm and the shading projection is 525mm from the glazing. What is the E value for that window? To estimate or determine the E value it is important to find the P/H of the building. Under common circumstances, the H is given as the size of the glazing 2.1 The P value =525 The H value = 2100 P/H=525/2100 P/H = 0.25 From the E values table, the E value is determined taking into consideration the location of building. The E value with reference to the value p/h = 0.25, from the table the value is approximately 0.37 e. For the same situation above, what is the E value for that window when the shading projection is 110mm (instead of 525mm)?if we were to change the shading projection then we shall find that In this case p = 110 H = 2100 P/H=110/2200. P/H = 0.05 From the E values table, the E value is determined taking into consideration the location of building. The E value with reference to the value p/h = 0.05, from the table the value is approximately 1.89 f. A single storey house is being built in Townsville. For a window on the northern west side of the building assume H is 2100mm and the shading projection is 630mm from the glazing. What is the E value for that window? Townville lies within the second and eight categories under BCA. This means it has no big difference when compared to the scenario above. Thus we can deduce that P = 630 and H = 2100 For our analysis it is then clear that P/H = 630/2100 P/H = 0.3 To estimate or determine the E value it is important to find the P/H of the building. Under common circumstances, the H is given as the size of the glazing Townsville lies in climate zone 1, for this reason the table section of interest will be the one labeled zone 1. Orientation: from the above the window is on the northern west side of the building E values: These values are determined from the table, Summer E is approximately 0.47 Therefore the answer for E is approximately 0.47 g. For the same situation above, what is the E value for that window when the shading projection is 110mm (instead of 630mm)? Is the shading is changed to 110 mm, then P/H = 110/2100 This will give us a P/H equal to 0.052 which is approximately 0.05 Townsville lies in climate zone 1, for this reason the table section of interest will be the one labeled zone 1. Orientation: from the above the window is on the northern west side of the building E values: These values are determined from the table, Summer E is approximately 0.75 Therefore the answer for E is approximately 0.75 h. For the same home in Townsville, what is the E value for a window on the north west side if the shading projection is 630mm (from the glazing) and H is 600mm (instead of 2100)? See the note at the end of Table 3.12.2.2 P/H = 630/600 This will give us a P/H equal to 1.05 Townsville lies in climate zone 1 Orientation: from the above the window is on the northern west side of the building E values: These values are determined from the table, Summer E is approximately 0.26 Therefore the answer for E is approximately 0.26 i. Do you think external permanent shading projections are the best design solution for both of the above climate zones? Briefly explain why or why not. From the reading, it is not mandatory to have permanent shading projections. This is because these are set as compliance standard and temporary elements like dark blinds can be used. This is because changes in weather or climate patterns can cause an increase or reduction in the level of conduction available. The E values depend on the climate zone; the P value, H value and the orientation which refers to the position of the window are factors that affect the E value. Both grazing methods are not appropriate for climate zone 1 and climate zone 2. This is because a higher Ew is preferred whereas a lower Es is preferred, from the results the differences in the E values shows that this type of glazing is appropriate for climate zone 1. Alternative to permanent grazing could be used in order to have higher Es and lower Ew values as required during the seasons. j. Nominate the specific part number of the BCA that allows for an alternative to external permanent shading projections. Clause 3.12.2.2 outlines an alternative to external permanent glazing, according to this section external shading devices can be used, these devices include blinds, shutters or screens. Volume one section J, PART J2 GLAZING also provides alternatives to both permanent and temporary alternatives to grazing options. References: ABCB, BCA Volume 1 and 2, Australian Building Standards, 2011. Web. Read More