Table D1 to Part J Appendix D: Demonstrating compliance with the elemental standards
|
STEP |
ACTION [Note 1] |
|
1Estimate if the SAP energy rating of the proposed dwelling is likely to be 60 or less. |
The examples in Appendix C, Annex D will help in estimating the SAP energy rating. If it is likely to be 60 or less, the Elemental Method requires more stringent U-values, as set out in Table 2 to J2.2. |
|
2 Check that exposed walls and basement walls achieve a U-value of 0.45 W/m2K. |
Use the tables in Appendix E to calculate the thickness of insulation. |
|
3Check that exposed floors, ground floors and basement
floors achieve a U-value of - |
a. calculate the perimeter to area ratio as explained in Appendix F,
and |
|
4 Check that semi-exposed floors and walls achieve aU-value of 0.6 W/m2K. |
Use the tables in Appendix E to calculate the thickness of insulation. |
|
5 Check that pitched roofs with a roof space achieve aU-value
of - |
Use the tables in Appendix E to calculate the thickness of insulation. |
|
6 Check that roofs other than those at step 5 above |
Use the tables in Appendix E to calculate the thickness of insulation.achieve a U-value of - |
|
7 Calculate the average U-value for windows, doors and rooflights, |
Use Table 2 to J2.2 to give the U-values for windows, doors and rooflights (see example). |
|
8 Check that the total area of glazing and doors does not exceed the permitted amount, |
Using the average U-value from step 7 above, use Table 3 to J2.2 to determine the maximum permitted area of glazing and doors. |
|
9 Check that the proposals will achieve a SAP of morethan 60 if this was the original basis for the calculations. |
Complete the worksheet in Appendix C. |
Notes:
1. Where test results for insulation have been certified by an independent
test house these should be used in
preference to the indicative values given in the tables in Appendix E.
2. Alternatively follow the procedure in Appendix F.
Table D2 to Part J Appendix D: Demonstrating that buildings other than dwellings meet the elemental standards
|
STEP |
ACTION [Note 1] |
|
1 Check that exposed walls and basement walls achieve a U-value of 0.45 W/m2K. |
Use the tables in Appendix E to calculate the thickness of insulation. |
|
2 Check that exposed floors, ground floors and basement floors achieve a U-value of 0.45 W/m2K. |
a. calculate the perimeter to area ratio as explained in Appendix
F, and |
|
3 Check that semi-exposed floors and walls achieve a U-value of 0.6 W/m2K. |
Use the tables in Appendix E to calculate the thickness of insulation. |
|
4 Check that pitched roofs with a roof space achieve aU-value of 0.25 W/m2K. |
Use the tables in Appendix E to calculate the thickness of insulation. |
|
5 Check that roofs other than those at step 4 above achieve a U-value
of - |
Use the tables in Appendix E to calculate the thickness of insulation. |
|
6 Calculate the average U-value and areas forwindows, personnel doors and rooflights. |
Use Tables 2, 3 and 4 to J3,2 (see example). |
|
7 Check the average U-value for vehicle and large doors. |
Use Tables 3 and 4 to J3.2 or manufacturers' information. |
|
8 Check that the total area of glazing and doors does not exceed the permitted amount. |
Note that there are no area restrictions on vehicle access doors. |
Notes:
1. Where test results for insulation have been certified by an independent
test house these should be used in preference to the indicative values given
in the tables in Appendix E.
2. Alternatively follow the procedure in Appendix F.
CALCULATIONS TO DETERMINE THE PERMISSIBLE AREA OF WINDOWS, DOORS AND ROOFLIGHTS IN THE ELEMENTAL METHOD
Example 1: Dwellings
D1 A proposed dwelling has a total floor area of 80 m2. It has two half-single-glazed doors and double-glazed windows as described in Table D3.
Table D3 to Part J Appendix D: Window and door openings for a proposed dwelling
|
Element |
Area |
U-Value |
Rate of heat loss |
|
Windows |
15.4 |
2.9 |
44.66 |
|
Two doors |
3.8 |
3.7 |
14.06 |
|
Totals |
19.2 |
58.72 |
D2 The average U-value for windows and doors is given by: formula
From Table D3 above this ratio is:formula
D3 The total area of openings is formula
D4 It can be seen from Table 3 to J2.2 that the permitted area of windows, doors and rooflights for a U-value of 3.1 W/m2K is 21.5% of the floor area if the dwelling has a SAP energy rating of 60 or less, 24% if the rating is more than 60. The proposed design therefore satisfies the requirements of the Technical Standards only if the SAP energy rating is more than 60.
Example 2: Buildings other than dwellings
D5 A proposed single-storey assembly building has plan dimensions of 16 m by 8 m. Its height to the eaves is to be 4 m and the open-trussed roof is to be double-pitched at 30° with insulation fixed between and over the rafters. Windows, personnel doors and rooflights are to be provided as indicated in Table D4 below.
Table D4 to Part J Appendix D: Proposed assembly building windows, personnel doors and rooflights
|
Element |
Area |
U-Value |
Rate of heat loss |
|
Windows |
60.0 |
3.6 |
216.0 |
|
Personnel doors |
9.5 |
3.0 |
28.5 |
|
Totals for windows and personnel doors |
69.5 |
— |
244.5 |
|
Rooflights |
25.0 |
3.8 |
— |
D6 The average U-value for windows and doors is given by:
formula
D7 The gross wall area of the proposed building is 192 m2
and thus the area of windows and
personnel doors is:
formula
D8 The area of the roof in the plane of insulation is: formula
The rooflights are hence:formula
D9 The proposed design meets the requirements of the Technical Standards, therefore, because Table 4 to J3.2 indicates that:
a. the permitted area of windows and personnel doors having an average U-value of 3.5 W/m2K is 37% of the wall area.
b. the permitted area of rooflights having a U-value of 3.8 W/m2K is 17% of the roof area.