Today's quest for energy-efficient and low-carbon building services plant puts manufacturers under pressure to keep in step. Is it possible that an old favourite can fly phoenix-like to the rescue of a buffeted building services industry? Old-timer Eric Asquith, of air conditioning distributor Shorts Environmental, thinks so
AS Spanish philosopher George Santayana once said: 'Those who cannot remember history are condemned to repeat it'. Words of wisdom, especially in today's climate of environmental concern. As an elder statesman of the industry, I would agree that it is perilous to forget the past in the rush to reach the future.
Technologies often mentioned in the government's plans to reduce the carbon footprint of buildings, like me, have been around for years. Photo-voltaic generation and solar thermal collectors have been popular around the world for some time. Similarly, CHP has been around for several years. Last but not least, the technology often quoted as the most efficient way of heating a building, is that old favourite, the heat pump.
Poor reputation
One of the biggest drawbacks to heat pump technology is its operational limitations which are well known in the industry and which may ultimately limit its widespread acceptance. But there is a heat pump product, and one that has also been around for a long time, that does not exhibit these operational shortfalls. I am talking about the gas-fired absorption heat pump. Could this really be the way back to the future?
The concept of absorption cooling has been around since the late 18th century but the origins of today's highly efficient gas-fired absorption heat pump dates back to work carried out on domestic refrigerators for the Servel company in the US by Albert Einstein in the late 1920s. More than four million absorption refrigerators and more than 300,000 commercial chillers have been sold over the years.
But in the last five years there has been a real technological leap - the development of gas-fired absorption heat pumps by Italian manufacturer Robur. These units turn all efficiency, running cost and environmental arguments head over heels. Typically, air source Robur heat pumps can produce hot water for heating at efficiencies of more than 140%. When compared with the most modern condensing boiler, this is a considerable improvement.
High efficiencies, running cost savings and environmental benefits are all inextricably linked, and gas-fired absorption heat pumps can provide a big tick in all of these boxes.
Typically, a 35kW Robur heat pump produces 3.9tonnes of CO2 a year less than a commercial boiler. From a carbon offsetting point of view, the alternative would be to go out and plant around 560 trees every year.
Conventional air source electric heat pumps dramatically lose output and efficiency with decreasing ambient temperature, and supplementary heating is required. Not only does this result in higher capital costs, but the running costs of the supplementary heating will be higher and more environmentally damaging. Unlike electric heat pumps, these gas-fired systems can maintain their output capacity and good operating efficiencies at ambient temperatures as low as -20˚C.
Full circle
On top of this, all electric heat pumps contribute to global warming on a second front: directly through the gradual leakage of greenhouse gas refrigerants (HFCs) from the plant.
The use of a natural ammonia/water mixture (with an ozone depletion potential of zero) as the refrigerant in place of the more conventional HFC one gives the air cooled absorption system a second major plus in the battle against global warming. And it is also a tremendous answer to the dictates of the F-gas regulation.
Maybe it is a little strong to say that there is nothing new under the sun, but the world does indeed turn and it appears to have come full circle for absorption cooling and heating. The time is right for the hvac industry to once again embrace the benefits of absorption technology as this really is a case of back to the future.
www.shorts-env.co.uk