CPD Programme CPD Programme
The CIBSE Journal CPD Programme Members of the Chartered Institution of Building Services Engineers (CIBSE) and other professional bodies are required to maintain their professional competence throughout their careers. Continuing professional development (CPD) means the systematic maintenance, improvement and broadening of your knowledge and skills, and is therefore a long-term commitment to enhancing your competence. CPD is a requirement of both CIBSE and the Register of the Engineering Council (UK). CIBSE Journal is pleased to offer this module in its CPD programme. The
programme is free and can be used by any reader. It is organised jointly by CIBSE Journal and London South Bank University, and will help you to meet CIBSE’s requirement for CPD. It will equally assist members of other institutions, who should record CPD activities in accordance with their institution’s guidance. Simply study the module and complete the
questionnaire on the final page, following the instructions for its submission. Modules will remain available online at
www.cibsejournal. com/cpd while the information they contain remains current. You can also complete the questionnaire online, and receive your results by return email.
Gas-absorption heat pumps
This CPD module introduces the application of gas absorption heat pumps for large residential (for example hostels and group housing), institutional and commercial properties, for use in both heating and hot water generation applications. This is a technology that has been available for some time, but interest in the new-build sector appears to be rejuvenated due to the potentially high efficiencies and low environmental impact of this innovative application of well-established technology
and end-user to deliver heating and hot water solutions with ever-increasing system efficiencies. There is a move away from focusing on appliance efficiency to overall system efficiency, and to lifecycle environmental impact of products and solutions. This is also being driven by the Eco-Design of Energy Using Products (EuP) Directive – likely to be implemented across the whole of Europe within the next three years – which demands exceptionally high minimum system efficiencies within two years of its introduction. The directive estimates that more than
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80% of product-related environmental impacts are determined during the design phase of a product. Eco-design aims to
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here is growing pressure on the building services industry from architect, building services engineer, contractor, equipment supplier
improve the environmental performance of products throughout the lifecycle by ensuring that there is a systematic integration of environmental aspects during product design. In the UK there is also a need to work
towards zero carbon homes in 2016 and zero carbon non-domestic buildings in 2019, which, enforced through local buildings codes and regulations, will also drive the new applications of heating technology.
Principle of operation With traditional air-to-water heat pumps, electricity is used to power an induction motor that drives the refrigeration compressor. Air-sourced gas-absorption heat pumps use a gas burner to drive the refrigeration cycle, which draws on the available energy from the surrounding ambient air to increase the thermal output
significantly above that provided by the gas input. The output from the heat pump can be used to supply low-temperature hot water for space heating and/or for the production of domestic hot water via an indirect cylinder, similar to a traditional boiler. Ground-sourced gas-absorption heat pumps are based on the same principle of operation, except that the energy collected from a ground loop (trenches or bore holes) is used to augment the heat generated by the combusting gas to produce highly effective fuel efficiencies (in just the same way as with electrically powered ground source heat pumps). The gas-absorption heat pump comprises
a sealed thermodynamic circuit, normally containing an ammonia water solution that acts as the working fluid, with ammonia being the refrigerant and water the absorbent. Traditional air-to-water electric heat pumps
October 2010 CIBSE Journal
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