The Government’s intention is for all new homes to be zero carbon by 2016 with a major progressive tightening of the energy efficiency building regulations - by 25% in 2010 and by 44% in 2013 - up to the zero carbon target in 2016.

This drive will highlight the need for renewable technologies such as ground source heat pumps, to be effectively integrated into new buildings. The DTI’s report ‘The potential for Micro-generation’ suggests that 28,000 heat pumps will be installed by 2012, a ten-fold increase on current volumes.

The interest in heat pump technology is therefore increasing and to provide an effective solution it is important that the key issues on how these systems are integrated into buildings are understood.

As the country’s only manufacturer of a full range of ground source heat pumps, Kensa Engineering offers a solution specifically designed for the UK market. The company provides industry-leading advice and guidance on how heat pumps can help lower the CO₂ emissions of buildings and meet the requirements of Part L (Conservation of Fuel and Power) of the Building Regulations. Particular attention is paid to application engineering to ensure each installation enables trouble-free performance.

Click here for our fact sheet on how heat pumps can help lower the CO₂ emissions of buildings and meet the requirements of Part L (Conservation of Fuel and Power) of the Building Regulations.

Heat pumps ideally suit well-insulated, new buildings with an underfloor heating distribution system throughout, with land to bury the ground arrays. They can also be used in other applications; however the benefits may be reduced.

The following section covers key issues that should be considered with heat pumps such as: -

• Heating distribution systems
• Domestic hot water
• Building Regulations and Part L Compliance
• Code for Sustainable Homes
• Grant support for Kensa Heat Pumps

Heating Distribution Systems
To get the most efficient operation from a heat pump it’s important that the outlet temperature is kept as low as possible, this lends itself to underfloor heating distribution systems and when used, in conjunction with these, efficiencies of up to 400% can be achieved. Radiator systems can be used however due to the higher temperatures required the efficiency will drop to approximately 300%. Radiator systems would also need to be oversized as the maximum continuous temperature from a heat pump is generally
around 50°C.

With underfloor systems the ideal installation is to mount the underfloor in screed. Using the screed as a thermal mass allows the occupier to run the heat pump on off-peak tariffs further reducing the running costs. For first floor applications the ideal building construction is beam and block with the underfloor and screed laid on top. For suspended floors a dry/sand screed can be used either between or over joists, however with these systems structural and height considerations need to be taken into account. It may also be necessary to run the heat pump at a higher temperature to drive the heat through the overlying chipboard and final floor finish, therefore reducing its efficiency.

If heat emission plates are used off-peak tariffs cannot be effectively used as there is no thermal storage and again higher temperatures may be required.

Domestic Hot Water
All heat pumps can produce domestic hot water; however how well they do this depends on your expectations. When there is a demand for hot water the heat pump switches from space heating mode to hot water mode and the heat pump outlet temperature is increased. The maximum temperature from a heat pump is generally around 50°C, and this will reduce the operating efficiency of the heat pump. This hot water is generally piped through an indirect coil mounted in a separate hot water tank and hence the expected tank temperature will be around the 45-48°C range. The use of an immersion heater to increase the temperature may seem to be the ideal solution, however in practice the immersion heater will take the load and the heat pump will never see a demand.

Due to the additional load on the ground it is also necessary to increase the number of ground arrays.

The most cost effective way of producing DHW is to use solar thermal backed up with an off-peak immersion heater. These systems can provide up to 75% of a household’s DHW free of charge.

Building Regulations and Part L Compliance
In 2006 the UK Building Regulations changed and one of the main requirements for meeting the energy efficiency criteria of the regulations (Part L, in England and Wales, Part J in Scotland) is now based on CO₂ emissions from the proposed building.

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