Following the major field trial of domestic heating pumps, the Energy Saving Trust has compiled a list of questions for everyone who’s considering using one in their household.

So here’s the first theoretical question about heating pumps and it’s the biggie: when should you consider using one?

The simple answer, is that the ideal candidate at the moment (bear in mind this is a new technology), is someone who lives in an existing property (or one about to be built) which is properly insulated and one off the gas network. Compared to other fuel types when gas is not available – coal, electricity, oil and LPG – heating pumps can reduce both energy costs and carbon emissions over the system’s lifetime.

Next question: when you get a heating pump, how do you get it to perform to its best capabilities?

First things first, make sure that your house is well insulated, up to the latest standards and recommendations. Basics are, good cavity and loft insulation, which should be both installed before the heat pump goes in. If you don’t have these in place, then forget this system; it won’t work to the level you need. Secondly, when it comes to the choice of ancillary systems, ensure that you choose low temperature under-floor heating, or radiators that are sized properly. Thirdly, get controls that you can understand and operate without confusion. If you install a system that you can’t control, or refine, then again, forget it, it will work poorly. In short, check that all the ancillary and support equipment is up to scratch.

Next question, For anyone that used to traditional heating systems, just what can you expect.

Don’t expect boiling hot radiators. When using a domestic heat pump system, the radiators will be warm, rather than hot. If radiators are used rather than a under-floor pipe system, then they will likely heat up more slowly. Expect also the pump to be working for longer periods than a conventional boiler. Some people also express the doubt that some systems will be able to cope with a large property’s needs in terms of heating and hot water, despite being specified properly. So it makes sense to install a secondary electric immersion heater.

Chief Scientific Adviser David Mackay, who’s at the Department of Energy and Climate Change, said:
“Heat pumps will be a crucial component of our low-carbon future, provided they perform well. It’s therefore essential to conduct trials to establish best practice, and perfect this technology for use in building throughout the UK.”

It is also essential that people fully understand not only how heating pumps work, but how they should be installed and used correctly.

Guest Article by Neil Camp

In the largest ever UK field trial of domestic heat pumps to date, it’s been concluded that whilst such installations can indeed result in carbon savings, more work has to be done to improve installation practices to ensure that the savings become an actual reality.

The field trial was commissioned by the Energy Saving Trust, the body that advises householders how to save energy and reduce their carbon emissions. They also provide advice to communities, local authorities, manufacturers and installers.

The key finding of the major study was that the industry has to improve the installation techniques for both air and ground source domestic heat pumps. If this happens, then there is a fair chance that they will become a mainstream technology for people; one that is consistent and quality in nature.

The field trial is split into a number of phases and the first has now been completed. It studied domestic heat pumps at some 83 sites. Four of these involved ground source systems; the remaining 29 centred on air source systems.

Lasting a full 12 months, the trial was started in early 2009 and involved a who’s who of the energy sector. These included: EDF Energy; NIE Energy; British Gas; Scottish Power Ltd; Scottish & Southern Energy plc; E.ON; RWE npower; The Scottish Government; The Department of Energy and Climate Change; The North West Regional Development Agency; Worcester Bosch; Baxi Group; Mitsubishi Electric; Danfoss UK
NIBE Energy Systems; and, Earth Energy Ltd.

Crucially, it was determined that the domestic heat pump installations operated at an overall efficiency rating of three and above. This effectively means that in return for every unit of electricity invested, the heat output was three times that, or more. This means that they performed very well in the tests.

The ground source heat pumps performed slightly better than the air source versions.

Now that the initial test has been completed, there are a number of key conclusions to be learnt.

Firstly, although they performed well, the heat pumps are sensitive to factors in their design, installation, commissioning and operation. Which makes the point that unless each part of the process is correctly carried out to high standards, then the heat pumps will not perform to expectations.

Secondly, the most simple systems performed the best. Those systems which were complicated, in terms of their design, or installation, were the systems which underperformed.

Thirdly, it remains unclear as to the impact of hot water production on the overall system. Heat pumps can deliver water at the appropriate temperatures, but it was not clear the effect this had on the system itself and more research is needed.
Fourthly, the controls for heat pump systems need to be installed correctly and then operated correctly. Controls are often misunderstood and used incorrectly.

Fifthly, where possible, the installation of heat pump systems should be the responsibility of one company, which would ensure a better after-sales service. Having a number of suppliers and installers work on system can be a recipe for later difficulties.

Finally, and perhaps not unsurprisingly, more study is needed into the domestic heat pump sector. The area is still in its infancy and far more background work is needed.

The Head of Business Development for the Energy Saving Trust, Mr Simon Green, said:
“We have a responsibility to make sure that customers’ investments are spent on measures that lead to the greatest potential to save carbon and reduce energy bills.

“This trial shows that when installed and operated correctly, heat pump technologies will save significant amounts of CO2 in the UK, when replacing oil or traditional electric heating.”

He went on to say that:
“Over its lifetime, a high performing heat pump installed today will save CO2 even when replacing gas condensing boilers due to the planned decarbonisation of the grid.

“But there is no doubt that the results are more varied than were expected, with results showing both high and low performing heat pumps.

“We are securing funding to extend the trial, with the objective of defining the reasons for variation in performance levels so that we can inform industry about good practice and advise householders on exactly what to look out for.”

The domestic heat pump sector may be in its infancy, but there is no doubt that it is beginning to make its prescence felt.

Guest Article by Neil Camp

Geothermal heating is a new greener way to heat your home. It takes advantage of the earth’s constant temperature below the frost line and harnesses the heat to use in your house, office or commercial building. Experts say that a full geothermal heating system can save you up to 40% on your energy bills while decreasing your household emissions dramatically. On the surface it sounds like the best thing since electricity but how does it really work and are the benefits worth the rather large investment?

The Principles Behind Geothermal Heating Systems

The idea behind this great new energy source involves harnessing the Earth’s heat and using it to warm your house. This is done by drilling a series of boreholes close to your property and inserting looped pipes filled with a conductive fluid, such as water with added antifreeze. The average property needs 2 or 3 boreholes to provide adequate geothermal energy and they need to be between 150-300ft deep to be effective! Once the looped pipes are in place, they can then be linked up with a Ground Source Heat Pump which circulates the fluid around the pipe. As it circulates, the fluid absorbs the earth’s heat, which is a constant 57 degrees Fahrenheit below the frost level, and brings it to the surface where it is extracted by a heat exchanger. From here the heat goes to each of the rooms in the house via a suitable heating system.

Obviously this description is a simplification but it gives the general idea behind the process. Once in the house, the heat is distributed to where it is needed by means of individual heat pumps in each room. So for example, if you want more heat in a specific room then you simply turn up the thermostat and more heat is pumped from the Ground Source Heat Pump into the room.

The Benefits of Geothermal Heating

As already mentioned, geothermal heating systems can reduce your heating costs by up to 40% however the average household sees savings of around 25%. Also, once installed the system virtually cares for itself and problems are very rarely encountered. You can vary the amount of heat released into each individual room and easily turn rooms off when not in use. In the warmer months, the main ground pump can be used in reverse so that it pumps heat out of the house and back into the ground which means that it effectively acts as a cooling system for the entire home.

The Downside

Unfortunately there is always a downside with new concepts and geothermal heating is no exception. The entire heating system is required to get the best from this type of energy source and with a starting price of around £6000 it doesn’t come cheap. Based on the average annual savings that you could attain, it would still take you a very long time to recoup your investment however if money is no object then this is definitely one of the better renewable energy sources to go for.

Guest Article by Clare Lynock