Energy Efficiency Standard for Social Housing: peer review
Peer review scrutinising the example dwellings in the Energy Efficiency Standard for Social Housing consultation document.
Appendix E - Loft Insulation Summary
All U-values detailed in the table below are based on a pitched (slate or tile) roof with insulation positioned between the joists. The proposed 1990 baseline assumptions detailed in column (vi) are consistent with the original 1990 baseline assumptions detailed in column (ii), subject to the following exceptions:
- - An assumed loft insulation thickness of 12mm has been specified for example group D, corresponding to a U-value of 1.5 W/m 2.K. This is based on data detailed by the CE84 document for dwellings constructed between 1955 and 1975. Observations from the 2004/05 SHCS also noted that a quarter of the houses without loft insulation were constructed between 1945 and 1964, however this only represents 5% of the dwellings from this construction period [1] .
- - An increased loft insulation thickness of 150mm has been suggested for example group G, in line with the default RdSAP assumption relative to age band H and the data reported in the CE84 document. This corresponds to an improved U-value of 0.29 W/m 2.K, compared to the original 0.40 W/m 2.K.
| (i) | (ii) | (iii) | (iv) | (v) | (vi) | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| RdSAP age band | Example groups: 1990 Baseline (W/m 2.K) |
RdSAP Assumed Roof U-value | CE84 Roof U-value [2] | Proposed Loft Insulation properties for example groups 1990 Baseline (W/m 2.k) | ||||||
| Relative to age band [3] (W/m 2.K) |
Relative to example group thickness [4] (W/m 2.K) |
Relative to construction period [5] (W/m 2.K) |
Relative to example group specified thickness [6] (W/m 2.K) |
|||||||
| A (Before 1900) | A: No insulation | 2.3 (none) | 2.3 (none) | (until 1954) 1.6* (none) |
2.3 (none) 1.6* (none) |
2.3 (none) | ||||
| B (1919 - 1929) | C: No insulation | 2.3 (none) | 2.3 (none) 1.6* (none) |
2.3 (none) | ||||||
| C (1930 - 1949) | B: No insulation | 2.3 (none) | 2.3 (none) 1.6* (none) |
2.3 (none) | ||||||
| D (1950 - 1964) | D: No insulation | 2.3 (none) | (1955 - 1975) 1.5 (12mm) 1.1* (12mm) |
2.3 (none) 1.6* (none) |
1.5 (12mm) | |||||
| E (1965 - 1975) | 1.5 (12mm) | |||||||||
| F (1976 - 1983) | E: 50mm | 0.68 (50mm) | 0.68 (50mm) | 0.68 (50mm) | 0.68 (50mm) 0.60* (50mm) | 0.68 (50mm) | ||||
| G (1984 - 1991) | F: 100mm | 0.40 (100mm) | 0.40 (100mm) | 0.40 (100mm) | 0.40 (100mm) 0.37* (100mm) |
0.40 (100mm) | ||||
| H (1992 - 1998) | G: 100mm | 0.29 (150mm) | 0.40 (100mm) | 0.29 (150mm) | 0.40 (100mm) 0.37* (100mm) |
0.29 (150mm) | ||||
| I (1999 - 2002) | H: 200mm | 0.26 (150mm) | 0.20 (200mm) | 0.26 (150mm) | 0.20 (200mm) 0.19* (200mm) |
0.20 (200mm) | ||||
| J (2003 - 2007) | 0.16 (250mm) | 0.16 (250mm) | ||||||||
* U-value calculated assuming unventilated sarking board, as featured in many older houses. The effect of ventilation, or specification of sarking felt, tends to raise the U-value slightly, contributing to increased heat loss
1. The Housing (Scotland) Act 2006: Guidance for local authorities Volume 4: The Tolerable Standard.
2. ' CE84 Scotland: Assessing U-values of existing housing, Energy Efficiency Best Practice in Housing', Energy Saving Trust, August 2004
3. 'Table S10: Assumed roof U-value when Table S9 does not apply', RdSAP 2009 version 9.91
4. ' Table S9: Roof U-values when loft insulation thickness at joists is known', RdSAP 2009 version 9.91
5. 'Table 4: Default U-values for roofs by age, with known quantities of loft insulation thickness or unknown levels of roof insulation', CE84, August 2004
6. 'Table 3: Default U-values when loft insulation thickness is known', CE84, August 2004
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Email: Agnes Meany
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