This page will be periodically updated as data becomes available. Figures quoted are from calculated (c), estimated (e), measured (m), or certified (x) values, as stated.
Fabric Efficiency |
Original | Achieved | |
Value | Value | Unit | |
Windows | 2.4 to 3.2 (e)1 | 0.9 (x) | W/m2 K |
---|---|---|---|
Doors | 3.6 (e) | 0.9 (x) | W/m2 K |
Existing Walls | 1.4 to 1.6 (c) | 0.12 to 0.17² (c) | W/m2 K |
Extension Walls | N/A | 0.14 (c) | W/m2 K |
Pitched Roof | 0.7 (c) | 0.10 (c) | W/m2 K |
Concrete Flat Roof | 4.65 | 0.14 (c) | W/m2 K |
Extension Sedum Roof | N/A | 0.14 (c) | W/m2 K |
Ply Flat Roof | 3.0 (c) | N/A | W/m2 K |
Air Permeability | 18.4 (m) | 1.78 (m)³ | m3.h-1.m-2 @50Pa |
Heat Loss Coefficient | 840 (c) | 163 (c) | W/K |
Heat Loss Parameter | 5.42 (c) | 0.73 (c) | W/m2 K |
CO2 EMISSIONS | 11,575 (c) | 2,040 (c) | Kg/yr |
1. Reflects the varied ages of double glazed units, estimated using SAP 2009 data
2. Existing walls with external wall insulation (approx 90% of available wall area) will be 0.12 W/m2 K; some small areas, e.g. existing retaining walls, can only be insulated internally, where the U-value will be 0.17 W/m2 K.
3. Target was <2.0 m3.h-1.m-2 @50Pa. There is still some potential to improve upon the tested value in the table.
Energy consumption of the existing house as measured during 2010/2011 was 4,155 kWh/yr for electricity and 24,500 kWh/yr for gas, which serves space heating and hot water. Estimating the amount of gas used for space heating equates to approximately 145 kWh/m²/yr. By comparison, low energy standards, such as Passivhaus, requires the specific energy used for space heating should be no more than 15 kWh/m²/yr. The Passivhaus retrofit standard (EnerPHit), allows a slightly more relaxed 25 kWh/m²/yr. This means that we have to reduce the energy currently used for space heating by some 85% – a considerable challenge.