Key Issues

3. Part L Compliance Strategies

In 2006, Part L of the Building Regulations in England and Wales were altered to require more energy efficient dwellings judged by their CO₂ emissions. Part L now states that the annual CO₂ emission rate or Dwelling Emission Rate (DER) of the completed building must not exceed a Target Emission Rate (TER) set by reference to a notional building of the same size and shape. The DER and TER are calculated according to the Standard Assessment Procedure (SAP) 2005 for domestic buildings and are dependent upon a number of factors including the type of heat source to be used for space heating and domestic hot water production, the effectiveness of the fabric insulation and the standard of the property’s air tightness. As such, the assessor performing the SAP calculations has a number of options to reduce any property’s DER below the TER.  You can find an explaination of all of this on the Energy Savings Trust Website within the Information Library.

Merely achieving the DER is insufficient to attract Housing Corporation funding; instead, level three of the Code for Sustainable Homes, representing a 25% improvement on Part L, must be achieved with level four (44% improvement) increasingly becoming the target.

How can heat pumps help achieve compliance?

The following table has been produced by the BERR (formally the DTI) in conjunction with BRE and gives CO₂ emissions per kWh for different fuels.

Although a ground source heat pump uses electricity, the fuel with the highest emissions, to run the compressor and circulation pumps, its ability to be 400% efficient (ie. convert one kilowatt of electricity into four kilowatts of heat output) means the typical CO₂ emission rate for providing heat to a building equipped with underfloor heating is 0.135kg CO₂/kWh. This shows a CO₂ reduction of 29% over gas and 46% over oil.

As a result, the current SAP assessment software packages reflect this energy efficiency in their hard-coded settings (320% if the heat pump is linked to underfloor heating, 320% x 0.7 if radiators are used, with a further 0.7 factor applied if the heat pump is also providing the domestic hot water). As a consequence, the DER is significantly reduced. Such is the reduction, there might be an opportunityto downgrade the insulation specification and still achieve an acceptable DER. However, this tactic is not recommended because any increase in the property’s heat load will result in a higher flow temperature, a less efficient heat pump and higher running costs. Later editions of the SAP software are likely to demonstrate even higher efficiencies as BRE, the auditors of the scheme, recognise improved performance data supplied by various manufacturers.

4. Installation Options

Kensa is a manufacturer with an objective to remove any ‘mystery’ linked to heat pump technology and the installation of the appliances. The most challenging element to any project is the ‘application engineering’ to ensure the correct sizing of the groundworks, heat pump and distribution system. Far more straightforward is the physical on-site work linked to the installation of a heat pump. This work can be handled by any plumbing contractor without the need for prior experience, extensive training or specialist tools. As a result, plumbers already working for the contract builder can provide the service eliminating the need to contract with ‘specialist’ installers who might seek premium rates for their supposed ‘expertise’. It should be emphasized that the installation of a heat pump should take no longer than the fitting of a gas boiler, once the groundworks have been completed. Since Kensa fit a multitude of sensors on their units, the heat pump can be commissioned by a Kensa engineer over the telephone to reduce project costs.

It would be sensible to split the overall installation scope so that a separate contractor is handling the groundworks. If there is sufficient land for Slinkies, any groundworks contractor would be able to dig the horizontal trenches – following a plan supplied by Kensa - and install the pipework leaving the plumbing contractor to perform a pressure test. If vertical boreholes are required, Kensa can recommend a number of drilling contractors who, generally, would also install the pipework and grout.

Some social housing providers have expressed an initial desire to have all the work handled by a single contractor, primarily because of some ‘nervousness’ linked to the performance of the technology. The groundwork contractor is merely providing a connection to the ‘heat source’ in the same way that the utility companies are responsible for providing connections to the gas, electricity or water grids. In a typical project featuring a gas boiler, the plumber would only be responsible for installing the boiler and would not handle the provision of the gas supply to the property. Kensa is merely mirroring this approach.

5. Typical Project Costs

There may be strong reasons for considering central plant rooms for certain new build developments.

However, if the intent is merely to replace an oil or gas boiler with a small heat pump, Kensa has developed a number of affordable units specifically aimed at the social housing sector. These units can either be installed within a kitchen cabinet, positioned under the stairs or within any integral garage or garden shed. For most social housing units, a 4kW heat pump will suffice. Prices will vary depending upon the quantities to be purchased – Kensa would be able to provide an indicative budget price upon receiving the development plan. This price would reflect whatever grant support is available.

Upon receipt of basic information, Kensa can provide a budget costing within 48 hours and   outline most suitable fulfilment strategies.  In addition, Kensa can advise upon the most  attractive grant funding source.

For new build schemes, information required includes:

• Site layout plan with details of property sizes.
• Proposed heat distribution system – underfloor heating or radiators.
• Function of heat pump – space heating only or space heating and DHW.

For retrofit schemes, information required includes:

• Total number of properties.
• Existing fuel source.
• Details of properties – (detached, semi-detached, terraced).
• Size of properties – number of bedrooms.
• Penetration of priority group tenants across the entire estate.

Contact Kensa with the above information and request a call within a few hours of submitting your information for a detailled proposal.