Green Pioneers: Home heating that’s a fridge in reverse

The Sunday Times
June 21, 2009

Tony Mullins, chairman of the manufacturer Calorex

THERE is enough energy in Britain’s damp air to heat our homes cheaply and sustainably, argues one company boss determined to exploit the inclement weather.
“The air in Britain could be regarded as a natural resource,” said Tony Mullins, chairman of an Essex company which makes a heat pump that works like a fridge in reverse, extracting heat from the ground or the air. “There’s a surprising amount of energy in our moist and temperate maritime climate,” he said. “Even at -15C there’s energy in the air. In fact, a heat pump can still operate at -20C.”
Unlike the Continent, Britain has been slow to exploit heat-pump technology. Last year France and Germany installed 300,000 heat pumps between them while the UK put in about 3,000, said Mullins. “In Sweden 90% of new homes have heat pumps. Britain is five to six years behind much of the rest of Europe.”
Employing more heat pumps, which run on electricity rather than gas and are much more efficient than a typical boiler, could slash energy use and carbon emissions by the margin demanded by ambitious carbon-dioxide reduction targets, he said.
“Domestic energy requirements account for 40% of the UK’s carbon emissions and the biggest part of that is heating your home.”
The technology behind heat pumps is straightforward.
They concentrate heat from a network of underground pipes or from a fan and then draw it over a heat exchanger. The heat is then transferred to radiators and hot-water cylinders.
Historically, heat pumps were an economical way to heat swimming pools. Today they are being installed in schools, nursing homes and new housing developments.
Although ground-source heat pumps are slightly more efficient, they require a large hole to be dug or drilled and cost almost twice as much to install.
Thus air-source heat pumps, which look much like air-conditioning units, offer the greatest potential for widespread use in Britain, said Mullins.
“There are about 20m homes in the UK. Less than 200,000 new ones are built each year so we are stuck with our old housing stock for the foreseeable future,” he said. “This is new technology that works and that can solve the problem of our time, which is how to have a zero-carbon home.”
However, heat-pump technology can only provide carbon-free home heating if the electricity powering it is generated through renewable means. Yet it is a more realistic option than solar power or domestic-scale combined heat and power units, said Mullins.
“There’s no saying what technology might be available in the future, but right now the only way to achieve zero-carbon heating for significant numbers of homes is through heat pumps that are supplied with renewably generated electricity,” he said.
Despite slow adoption to date, heat-pump sales have started growing in the past two years. In Britain, Calorex sells ground-source heat pumps to the likes of Persimmon, the house builder, for use in new developments and has a partnership with Eon to install its technology to help households that have no access to gas.
Yet Calorex’s domestic sales make up only 5% of its £20m turnover and it exports most of its units and sells its air-source technology to hotel groups in the Far East. They heat water with it.
One of the barriers is the cost. Paying for and installing an air-source pump capable of heating an average British home costs about £6,000, although government grants can cut that by £900.
“I’m not advocating that everyone should tear out their gas boilers tomorrow, but the economic argument is becoming stronger as every day goes by,” said Mullins.
Europe will soon be installing 1m heat pumps a year and, as the number of units sold rises, the cost of the hardware will fall, he added.