# APPLY PRINCIPLES OF ENERGY EFFICIENT DESIGN TO BUILDINGS Essay Example

PART 1: MANUAL CALCULATION

Since the house is in climate zone 5 the conductance constant Cu is 13.464 (13.5) as seen from table 3.12.2.1. The house has a floor that is in direct contact with the ground and the air movement is standard.

The solar heat gain constant for the house as obtained from table 3.12.2.1 is 0.122

Allowed solar heat gain =Area x CSHGC

Therefore the solar heat gain allowance = 0.123X300

In this case the assumption is that the height from the bottom of all windows to the eaves is 2200 mm. So the P/H value is 450/2200 = 0.2

The P/H is used to locate the appropriate Ew value in the table. Due to the fact that not all the P/H values and there respective Es values have been included in the table ,interpolation was used to obtain the required values. The Ew values were as follows

Ew1 value for A1= 0.78

Ew2 value for A2 = 1.56

Ew3 value for A3 =0.7

Ew4 value for A4 = 0.19

[(A1 x U1) + (A2 x U2) + …] / [(A1 x SHGC1 x Ew1) + (A2 x SHGC2 x Ew2) + …] =

Aggregate Conductance

{(42×7.9)+(8.4×7.9)+(16.8.×7.9)+(6×7.9)}/{(42×0.81×0.78)+(8.4×0.81×1.56)+(16.8×0.81×0.7)+(6×0.81×0.19)}

= 378.28/47.59 = 7.94

This aggregate conductance value of 7.94 does not exceed the allowance of 13.5 and therefore complies.

From the table for summer exposure factors it are obtained for the different glazing areas.

The P/H is used to locate the appropriate Es value in the table. Due to the fact that not all the P/H values and there respective Es values have been included in the table interpolation was used to obtain the required values. The Es values were as follows

ES1 value for A1= ES1=1.6

ES2 value for A2 = 0.38

ES3 value for A3 =1.1

ES4 value for A4 = 0.43

[(A1 x SHGC2 x Es1) + (A2 x SHGC2 x Es2) + (A3 x SHGC3 x Es3) +(A4 x SHGC4 x Es4)] =

Aggregate solar heat gain

{(42×0.81×1.06) + (8.4×0.81×0.38)+(16.8×0.81×1.1)+(6×0.81×0.43)}

This aggregate solar heat gain value of 55.70 does exceeds the allowance of 36.9 and therefore there is no compliance.

PART 2: CALCULATOR

– The input climate zone is a cell where the appropriate BCA climate zone was entered and in this case the climate zone was taken to be 3. After entering the climate zone and the air movement was entered as standard while the floor type was given as direct contact. After input this details the calculator automatically gave the conductance as – and solar heat gain constants for the climate zone as — Climate zone

– in this cell the storey was entered as 1Storey

all of which was direct contact type. It should also be noted that while the area is being entered the units are not supposed to be entered as this is automatically done when the numerical value has been entered.2– area was given as 300mFloor area

— this cells did not require the entering of any data as there was automatic change of the constants after selecting the climate zone, the type of floor and the air movement level. There was also automatic field change when the floor and type of air movement had been given. Conductance and Solar Heat Gain constants and allowances

Details for Glazing elements

— the calculator has a default list of numbers ranging from 1 to 40. The numbers that are visible is determined by the number of rows which has been chosen to be displayed in glazing element. In the current case the number selected was 4.ID

Description – this gives the desired description for the glazing element. In case for description were Area1, Area2, Area3 and Area4.

– this gives information about the direction where the glazing element is facing. The eight sectors are available for choosing in a drop down list. In this case for sectors were used including West, South, North and East.Facing sector

– Usually when there are rectangular glazing elements the description is given by height and width these being the dimensions of the outside frame. Height, width, area

When the input include the width and the height the inputting of the area is not a necessity. In the case where a larger area is input that the one that results from the dimensions the large area takes precedence. In the current example the elements were identical and thus they were grouped together. This is also applicable in a situation where the element areas are not in rectangular form.

Performance

– these are inputs that are necessary in the spread sheet and usually are obtained from the manufacturer. The total U value which used was 7.9 while for the case of glazing SHGC the value used was 0.81 and 0.65. Glazing Total U-Value and Glazing SHGC

– this value is given by the horizontal distance in metres from the glass face up to the shadow casting edge of the shading projection. In this case there was the P value was the eave measurement of 0.45m. Shading P

– this is a distance measured from the glazing element base to the shadow casting edge of the projections like the eaves and gutter. In this case the H value used was either 2.2m or 1.6m depending on the height of the elements. Shading H

Calculation data

The use has no access to the cells that show the values in use when calculating solar heat gain and conductance of each of the glazing elements. These values include P/H value that is calculated from the P and H values. The exposure factors (Es or Ew) and Es/Ew are also calculated and displayed. It should be noted that the three values can only be viewed one at a time through making appropriate selection. Area used is also displayed and it is the product of height and with or any area that is given in the area column, with the preference being the larger area.

Calculated outcomes

– This is where there is automatic calculation of the conductance of the various glazing elements. U x area / winter access (Conductance)

— This field is can be useful when understood as it comes in handy when optimizing the design. These are two percentages which are separated by “of”. The first figure gives the contribution the individual glazing element towards the aggregate conductance. Using this value it is easy for the user to identify the glazing element that has the largest impact. The second value is a comparison of aggregate performance and the conductance allowance. Element share of % of allowance used

— This gives the automatic calculation of the solar heat gain of each glazing element. SHGC x Es x area (Solar heat gain)

— The information given here is similar to the conductance details only that it is now based on the solar heat gain outcome. Element share of % of allowance used

– the result of whether the design meets the desired standards is given in the table which is below outcomes calculated. If there is a tick it means the result is YES while a cross stands for a NO. Compliance indicator

Reference

Changes Introduced in BCA 2010 and Advanced Glazing Calculator Techniques.ABCB (2011) Energy Efficiency Glazing Provisions for BCA Volume Two.