Carbon Trust guide shows how heat recovery can cut energy bills with quick pay back

September 13th, 2011 by Carbon Trust

A Carbon Trust guide, launched on 5 September 2011, sets out how a wide range of organisations from retailers to leisure centres and hotels to manufacturing companies can cut energy bills by reducing the heat wasted in their buildings and processes.

Heat recovery – the collection and re-use of heat that would otherwise be lost – can be used to reduce wasted energy from ventilation systems, boiler gases, air compressors and refrigeration equipment.

The guide includes a useful, simple checklist and examples of best practice, and can be downloaded from the Carbon Trust website

(click on Guide cover to go to Carbon Trust download page)

Richard Rugg, Director of Carbon Trust Programmes, said “waste heat and you are wasting money. Even though it’s been slightly warmer outside, there’s still plenty of opportunity to make heat savings inside. From office-based businesses to retailers and manufacturers, there are significant opportunities to recover and reuse heat, save money and boost your bottom line”.

The Heat Recovery Overview Guide includes a range of useful tips on heat recovery applications in industry:

In a typical supermarket heat recovered from refrigeration units could be used to provide 75-90% of the building’s hot water needs – equivalent to 2-3% of its total CO2 emissions.

For a typical new build 250-person office, installing a de-superheater to capture heat from cooling equipment could cut £1,000 from gas bills by providing energy for space heating.

Server rooms produce a significant amount of heat and where refrigerant cooling is used the resulting waste heat from the condensing units can be reused elsewhere in the building, such as for heating water.

Using recovered heat to raise the combustion air temperature of a boiler by 20°C increases boiler efficiency by 1%.

Boilers lose on average 25% of their heat. Investing £6 to £8,000 on installing boiler flue economisers in an office with an annual energy spend of £15,000 could see a payback in four years.

Thermal wheel technology, a heat transfer system based on a rotating wheel with high thermal capacity, can typically recover 65-75% of the heat from a ventilation system, and could pay back your investment within two years.

Similarly fitting a 70% efficient plate heat exchanger in a typical office could cut your total gas consumption by 38%.

Most of the electricity supplied to an air compressor is converted to heat. It is possible to recover anywhere from 50% to 90% of this thermal energy and use it to heat workspace air or water.

In the dairy industry, pasteurisation is already highly efficient in terms of heat recovery; however sterilisation, particularly bottle sterilisation, is energy intensive and provides a greater opportunity for waste heat recovery.

By investing in a simple mechanical ventilation system to remove the waste heat from the compressor room, Diamond Power, a boiler cleaning and ash-handling systems producer, had their investment paid back in just over three years. A global drinks manufacturer which installed a flue economiser after upgrading to a new steam boiler managed to save 4.1% on gas consumption. The economiser cost 10.5% of the overall budget for the boiler and achieved full payback in two years.

The guide forms part of the Carbon Trust’s Expert in Energy series which includes the previously published Refrigeration Systems guide.

For further advice on energy saving and ways you can reduce carbon emissions call the UK’s Carbon Trust advice line on 0800 085 2005.

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