The most cost effective way of lowering carbon emissions in existing homes is a heat pump. Tony Barnes, sales director of Calorex Heat Pumps, gives some pointers.
Heat pumps are recognised by major studies as a key route to providing renewable energy in the existing homes sector, especially in social housing. They can give low carbon, year round, full heating and hot water.

Once the decision on a project has been taken in principle, the important part starts: ensuring the installation delivers the renewable promise and, just as importantly, keeps the tenant warm at affordable cost. From the thousands of installations we have been involved with, we have a list of key points for success.

How is the house heated now?

It might make sense to improve rather than replace. Homes with a gas boiler can be upgraded by installing a condensing boiler and improving thermal insulation.
Where heat pumps score heavily, especially now, is in homes with oil, electricity and even solid fuel heating. Heat pumps can provide reductions in running costs (and also CO2 emissions) of 50% or greater.

It is these fossil fuels that are the greatest emitters of greenhouse gases. So heat pumps can attract the highest grant support (up to 85%) through CERT and LCBP programmes for qualifying installations.

What's the brief?

Sometimes, surprisingly, the objective is: 'Go green, never mind the costs.' Most schemes, however, are looking for a way to balance capital costs against the reduction in running costs and CO2 footprint.

Our guidance here is:
It costs much less to save heat that to generate it. Reduce heat requirements as far as you can by insulating the building.
Look at the capital costs of each kW of renewable generation. Recent reports from the government committee on climate change show heat pumps as top in the pay-back pecking order, above solar thermal, photovoltaic and wind power.

Tell the tenants

A heat pump will be a new and strange animal to tenants. It is well worthwhile explaining the what, when, how and the benefits of the system in cutting costs and giving them year round comfort. We have explanatory material, including video of operating schemes that can help with this.

Heating system - change or keep?

An existing hot water radiator system can be connected to a heat pump. It is often thought that underfloor heating is a necessity as heat pump flow temperatures are lower than with a boiler. Calorex heat pumps can provide up to 60°C flow temperatures (and 65°C for domestic hot water) Many existing radiator systems were oversized to some extent and if the building has been insulated the existing system could well be 25% oversized.

Fuel security

Regard fuel security as an issue. Six years from now the UK
will import 80% of its gas. That will change both the price and security pictures. Electricity
must become the long-term
home-grown renewable energy source and heat pumps tie into that future.

Don't forget maintenance.

After you have looked at systems and costs, do include the costs of maintenance in your decision. An average annual cost for a gas heated home, including the gas safety check, is about £168. Heat pump lifetime costs are significantly lower as routine maintenance is not required.
Which type of heat pump?

Ground source heat pump systems cost more than air source heat pumps (but don't forget grant support). They will, however, give higher output per unit of electrical power used (the COP - coefficient of performance) and the heat pump itself is small enough to be installed in the home. Air source heat pumps offer 75% of the cost saving benefit for around half the capital cost.

What type of house?

It is often thought that the dwelling needs to be on its own plot to have a ground source installation. Not so.
We have seen many successful low rise flat and maisonette schemes where the bore holes have been sunk in the communal areas. Bore hole costs are also lower where several can be drilled at the same time.

Pick the team to deliver success.

All projects need team work but with heat pumps it's vital. Once you have decided to go ahead, get your heat pump supplier, the ground work contractor and the heating installer together to ensure the design and installation responsibilities are clear.
An outside specialist project manager can ensure that the project starts with the right brief, monitor quality throughout the process and provide a final inspection. Calorex can also provide training for contractors prior to the project.

Keep the controls simple.

In smaller homes and especially where tenancies may change, simple controls are safer. We would recommend a room thermostat and time switch control.