As well as this 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, help meet level three of the Code for Sustainable Homes and lower the tenants heating costs. Particular attention is paid to application engineering to ensure each installation enables trouble-free performance.

The following section covers key issues that should be considered with heat pumps in the Social Housing Sector such as:

• Grant Support For Kensa Heat Pumps
• Heat Distribution Systems and Domestic Hot Water
• Part L Compliance Strategies
• Installation Options
• Budget Costs

Grant Support For Kensa Heat Pumps
The Government now requires energy companies to spend considerable sums providing grant support for various measures aimed at reducing carbon emissions. The CERT (Carbon Emission Reduction Target) 2008-2011 programme will commence in April 2008 and the government proposes the total CERT obligation to be a lifetime saving of 42 million tonnes of carbon (MtC). Since many of the more obvious energy saving measures have been implemented across the social housing stock, energy companies are expanding their schemes and many CERT-supported schemes will offer grants for renewable technologies, including ground source heat pumps.

As of January 2008, the precise CERT proposals have just been published and the energy companies are now developing schemes for the measures to be favoured. Kensa is in detailed discussions with several energy companies. This grant funding will be available for heat pumps commissioned after April 1 2008.

In the meantime, Kensa has access to a scheme under EEC2, which provides a variable level of grant support depending upon the efficiency of the heat pump, the size of the property, the fuel to be displaced and the proportion of home occupiers who are recognised as being a Priority Group. The level of grant support under CERT will exceed any EEC scheme; even so, EEC grant support can cover the entire cost of the heat pump.

Social housing developers are faced with a choice – installing a small heat pump appliance in each individual unit or installing a central plant with flow meter technology allowing separate bills for each property. Since the cost per kilowatt of output decreases as the heat pump increases in size, there are economies linked to the central plant option. Generally, Kensa would recommend that two or three heat pumps were installed in any central plant configuration to provide some capacity control (ie. all heat pumps would only be working on the coldest days) and to ensure some output in the unlikely event that an individual heat pump fails in service.

Heat Distribution Systems and Domestic Hot Water
Heat pumps work most efficiently delivering water at the lowest possible temperature into the heat distribution system. For this reason, underfloor heating – with its larger heat emitting area - has generally been favoured, however the minimal heat demand typical to many social houses means that radiators can be used. If radiators are selected, they should generally be designed with a flow temperature of 45ºC, which means they will need to be slightly larger than radiators linked to a conventional boiler.

Underfloor heating should be considered if the floor construction features a screed layer since the flow temperature could generally be reduced to around 30-35ºC. The likelihood of screed being used is far greater within traditionally built apartment developments than two storey dwellings with joisted first floor constructions. Where suspended timber floors are present, any underfloor heating pipework, typically installed within the joist void, would need to be embraced by a steel heat transfer plate, which not only increases cost but also slows the build programme. Since the flow temperature into these underfloor circuits would need to be increased to around 45ºC (to drive the heat through the overlying chipboard and final floor finish), there is no greater operating efficiency than if the heat pump was serving radiators.

Any Kensa heat pump can be linked to a mains pressure cylinder to provide domestic hot water although the required output temperature – 45-50ºC – will certainly impact efficiency. One alternative is to provide a mains pressure cylinder complete with immersion heaters and, if possible, link to an Economy Seven, or preferably, an Economy Ten tariff so the water can be heated during low cost periods. If only Economy Seven is available, a larger cylinder might be required to reduce the occasions when higher priced electricity is required to produce hot water. All cylinder manufacturers provide models which can receive an input from solar panels, if installed, to reduce dependence upon electricity.

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