Z E M C H 2 0 1 2 I n t e r n a t i o n a l C o n f e r e n c e
194
Table 3: Calculation of Section 6 Average U-values
Section 6 U-
Values
U-
Values
SAP
Areas
SAP Heat
Loss
PassivHaus
Areas
PassivHaus Heat
Loss
Ground floor
0.15
48.00
7.20
56.76
8.51
Roof
0.13
48.00
6.24
56.76
7.38
Walls Gross
140.00
170.24
Windows
1.50
24.00
18.00
24
36.00
Walls Net
0.19
116.00
24.32
146.24
27.79
Total /
average
236.00
0.30
283.76
0.34
Table 4: Calculation of PassivHaus Average U-values
PassivHaus U-
Values
U-
Values
SAP
Areas
SAP Heat
Loss
PassivHaus
Areas
PassivHaus Heat
Loss
Ground floor
0.13
48.00
6.24
59.84
7.78
Roof
0.09
48.00
4.32
59.84
5.39
Walls Gross
140.00
180.96
Windows
0.80
24.00
9.60
24
19.20
Walls Net
0.14
116.00
17.92
156.96
21.97
Total /
average
236.00
0.19
300.64
0.23
For the purpose of Tables 5 and 6 the thermal bridges at openings and air infiltration
have been ignored. The average γ-value for the junctions between walls, floors and roof
have been calculated in the first example using the default γ-values in Appendix K to
SAP2009 and in the second case using the Accredited Construction Details (Scotland)
2010.
Table 5: Fabric Loss Section 6 Targets
Based on Section 6 (Gas Fuel
Package) Notional Values and
Appendix K γ- values
SAP
PHPP
Surface Area of Envelop
236.00m
2
283.76m
2
Heat Loss per °K assuming an
average U-value of 0.30
70.80 w/°K
-
Heat Loss per °K assuming an
average U-value of 0.34
-
96.48 w/°K
104m thermal bridging average γ-
value of 0.2877
29.92 w/°K
-
Totals
100.72 w/°K
96.48 w/°K
Table 6: Fabric Loss PassivHaus Targets
Based on PassivHaus Typical
Values & Accredited Details
SAP
PHPP
Surface Area of Envelop
236.00m
2
300.64m
2
Heat Loss per °K assuming an
average U-value of 0.19
44.84 w/°K
-
Heat Loss per °K assuming an
average U-value of 0.23
-
69.15 w/°K
104m thermal bridging average γ-
value of 0.0926
9.63 w/°K
-
Totals
55.47 w/°K
69.15 w/°K
