Heat pumps as the key to reducing carbon emissions
Air conditioning is a fact of commercial life to help meet indoor air quality and temperature legislation. Using heat-pump technology in air-conditioning systems can both meet those requirements and reduce carbon emissions — as Philip Ord explains.
The splits and VRF air-conditioning sector could account for up to 1.6 Mt of CO2 emissions per annum for cooling, and this figure could increase to around 2.4 Mt of CO2 per annum (even with increasing efficiency) by 2016 if current behaviour is not changed. Those emissions are based on calculations by my company, Mitsubishi Electric.
Yet getting rid of this marvel of modern technology is simply not the option some would have us believe, as with legislation governing air quality and internal temperatures, let alone cultural requirements, we must have ways of controlling and conditioning indoor air.
However, we can ensure that all air conditioning is the most efficient possible, and I believe we can take a lead by demonstrating the true environmental value of the heat pump in helping to fundamentally alter the way we heat and cool our buildings.
The added advantage of heat-pump systems is that they can also save businesses money by reducing fuel bills, so they really can offer a win-win situation for both the customer and the environment.
This is vital because throughout Europe, over 40% of our energy is spent on heating, lighting, cooling and running our homes and offices. In the UK, 50% of CO2 emissions are directly attributable to the built environment and over 27% currently come from energy use in buildings.
There is a real need to minimise energy usage for environmental and political reasons, but there are also real financial benefits for businesses in examining their energy consumption and heating/cooling requirements.
This is where heat pumps can come to the rescue. The technology is used for both heating and cooling around the globe. Modern heat pumps have advanced over recent years and can outperform an equivalent gas boiler for heating by at least 3 to 1.
Tests conducted at our Hatfield offices over 12 months clearly demonstrate that a VRF ground-source heat-pump air-conditioning system is much more effective at heating and cooling a building than the traditional combination of boiler for heating and chiller for cooling.
The heat-pump system can move energy around the air-conditioning’s refrigerant circuit to transfer heating or cooling and offset the energy required for one against the other to reduce the overall energy consumption.
The results also demonstrate that the much more common air-source VRF heat-pump system is also much more energy efficient and cost effective than the traditional method — but it doesn’t stop there! We are now seeing heat pumps being used in different ways in new sectors, such as air curtains and water heating.
Air-curtain specialist Thermoscreens recently helped us to develop a heat-pump air curtain which offers a 67% reduction in running costs and emissions over a conventional direct electric equivalent.
Other developments now see heat-pump water heating becoming a reality, and these systems offer a serious and viable alternative to both commercial and residential gas boilers.
For commercial buildings, one of the new specialised heat-pump units can divert excess heat energy from a VRF air-conditioning system to supply domestic hot water at up to 70ºC — offering the potential for all hot water to be free!
In the residential sector, heat-pump water and space-heating systems are available to suit almost any property from the 1970s onwards. They can cut fuel bills by around 30% whilst reducing emissions by 50%.
As a company, we announced over two years ago that we were against any major growth in residential air conditioning and that we would no longer supply commercial cooling-only air conditioning as we recognised that heat-pumps system can significantly reduce the energy consumption of a building by removing the need for ‘traditional’ heating systems.
However, whilst we recognise that there are few situations were cooling-only equipment is required, cooling and ventilation account for just 3% of an average commercial building’s energy use, according to comprehensive research from the BRE Report ‘Carbon dioxide emissions from non-domestic buildings, 2000 and beyond’ *.
More importantly, the report also shows heating and hot water accounting for 65% of energy consumption whilst producing annual carbon emissions of 10.4 Mt.
This is supported by figures from the more recent Defra’s Market Transformation Programme (2006) which shows that the provision of heating and hot water accounts for over 50% of energy consumption in non-domestic buildings. Initial modelling from the Defra study of gas and oil-fired water heating boilers and warm-air and radiant systems resulted in annual carbon emissions of 10.8 Mt.
If we are to get anywhere near the emissions reduction targets for the UK that the Government has set, we must find more energy-efficient ways of providing the comfort levels for our buildings that modern life and legislation demands. I believe the humble heat pump is one major way forward in this quest.
Philip Ord is product marketing manager for Mitsubishi Electric. The issues discussed here are all part of Mitsubishi Electric’s Green Gateway Initiative which highlights how we can all reduce energy consumption in our built environment. Further details can be found at the dedicated website: www.greengatewayinitiative.co.uk