With Part L of the Building Regulations and the Code for Sustainable Homes both driving the reduction of carbon emissions in buildings, the design and specification of the building fabric will have to be improved, whatever the fuel. If you are a developer or homebuilder, it’s good to know that compliance with Building Regulations Part L can be straightforward using the latest Dimplex heating systems. Here are eight key areas where simple adjustments can be made to the building design to reduce the Target Emissions Rate (TER) and help achieve Part L compliance and improve the Code for Sustainable Homes rating.
1. Heat communal areas
For multiple occupancy dwellings like flats, specifying a low level of background heating in the communal areas, such as hallways, allows these walls to be disregarded from the SAP calculation as they no longer represent a heat loss
2. Reduce hot water cylinder capacity
The cylinder efficiency is not affected by improvements in the thermal performance of the building fabric. However, the Building Regulations’ TER calculation assumes a 170L cylinder capacity, so reducing this provides a carbon saving. Dimplex SCXn cylinders out perform the SAP default figures in terms of their heat loss in 24 hours. Figures show that with a 150 litre cylinder in a new build property this can be almost equivalent to 1kgCO2/M2/year.
3. Include Solar Thermal Hot Water or Solar PV
One of the easiest and quickest solutions, as solar thermal provides up to 60% of a property’s water heating needs. For multiple dwelling developments (such as flats) it’s possible to use whole block methodology to demonstrate compliance with Part L. Solar hot water can be fitted to the top floor apartments to give a lower carbon dioxide emission, which is then traded off against the lower floors which may have higher emission rates. When inputting the data into SAP, using the net collector area and the (a1) and (ηO) figures can have a marked improvement on the DER. Solar PV which generates electricity from daylight is also an ideal solution.
4. Reduce air permeability
Improving air tightness beyond the mandatory level reduces emissions at relatively low cost. Electric heating has an advantage here as it reduces the quantity of pipes/holes in the building fabric. Reducing this too far may make MVHR mandatory. A key feature of SAP 2009 is that party walls with unfilled and un sealed cavities are assumed to have a U value of 0.5W/m2 k. The national dwelling used in calculating the TER assumes a U value for cavity party walls of 0.0W/m2 k.
This compares to 0.4W/m2 k in last years Part L1A 2010 consultation. This means that insulating/sealing cavity party walls will not count towards the 25% improvement target.
Realistically it means that unless they are filled and sealed they will be a big negative towards your target of compliance.
5. Improve Controllability
The more controllable the heating appliance, the lower the carbon emissions. Dimplex electronic panel heaters or DuoHeat storage radiators score highly in SAP due to their controllability and energy efficiency.
6. Basic fabric improvements
The notional building used to calculate the TER assumes u-values at the 2002 elemental level, i.e. walls at 0.35, glazing at 2.0, etc. Improving these by a modest amount to reduce the energy required to heat the building, e.g. walls to 0.3, glazing to 1.8, roof to 0.20 provides an immediate carbon dioxide emissions saving.
7. Reduce glazed area
The Building Regulations’ TER calculation assumes glazing occupies up to 25% of the floor area. In practice, however, the glazed area for flats is generally much lower than this, reducing the level of improvement that specifiers need to achieve.
8. Include mechanical ventilation with heat recovery
The use of a high efficiency mechanical ventilation system with the ability to recover waste heat helps to reduce carbon emissions by recovering heat that would have been lost.