Micro-CHP
At a large scale, combined heat and power (CHP sometimes referred to as cogeneration) is generally a process in which the heat that is created as a by-product of power generation is captured and used rather than being wasted. Typically, a gas-powered turbine or reciprocating engine is used to produce electricity, and the heat recovered is used for local water or space heating, or to support an industrial process.
Microgeneration (or micro-generation) is the local production of electricity and/or heat on a very small scale. Typically, microgeneration has an output of under 45kW for heat and under 50kW for electricity.
Micro-CHP or micro combined heat and power is the small-scale generation of heat and electricity from a single energy source.
Micro-CHP is becoming more common in domestic buildings, where it can be installed as direct replacement for gas-fired boilers as micro-CHP units (sometimes referred to as CHP boilers) are similar in size and shape to conventional domestic boilers and can be floor standing or wall hung.
The main output of domestic micro-CHP units is generally heat, with some electricity generation, in the ratio of around 6:1. Typically, domestic units can generate up to 1 kW of electricity. This can be used to power the dwelling, or sold back to the grid.
Currently, domestic scale micro CHP units tend to generate electricity using a stirling engine. The boiler element of the unit heats water for central heating and to provide a hot water supply, and the ‘waste’ heat from the boiler heats an enclosed working gas such as helium in the stirling engine. The gas expands and contracts as it is heated and cools, pushing a magnetic piston up and down within copper coil windings, generating an alternating current.
Domestic micro CHP units tend to be powered by natural gas or by liquefied petroleum gas (LPG) and because of their efficiency they are considered to be a low-carbon technology. In the future, they may use bio-fuels, and so might be considered to be a ‘renewable’ technology. They may also develop to adopt fuel cell CHP technology which may be more efficient than gas turbines or stirling engines.
Consumers who generate their own electricity from a renewable or low-carbon source can qualify for a payment known as the feed-in tariff (FIT) for each unit of electricity generated. Consumers can also qualify for an ‘export tariff’ by selling surplus electricity back to their supplier. Micro-CHP is an allowable technology, qualifying for the feed in tariff.
[edit] Related articles on Designing Buildings Wiki.
- CHP.
- Condensing boiler.
- District energy.
- Domestic micro-generation.
- Feed in Tariff.
- Fuel cell.
- Future of electricity in domestic buildings.
- Green Deal.
- Microgeneration.
- Microgeneration certification scheme.
- Micro-grid.
- On-site generation of heat and power.
- Smart Export Guarantee SEG.
- Solar photovoltaics.
- Solar thermal panels.
- Types of boiler.
Featured articles and news
Shading for housing, a design guide
A look back at embedding a new culture of shading.
The Architectural Technology Awards
The AT Awards 2025 are open for entries!
ECA Blueprint for Electrification
The 'mosaic of interconnected challenges' and how to deliver the UK’s Transition to Clean Power.
Grenfell Tower Principal Contractor Award notice
Tower repair and maintenance contractor announced as demolition contractor.
Passivhaus social homes benefit from heat pump service
Sixteen new homes designed and built to achieve Passivhaus constructed in Dumfries & Galloway.
CABE Publishes Results of 2025 Building Control Survey
Concern over lack of understanding of how roles have changed since the introduction of the BSA 2022.
British Architectural Sculpture 1851-1951
A rich heritage of decorative and figurative sculpture. Book review.
A programme to tackle the lack of diversity.
Independent Building Control review panel
Five members of the newly established, Grenfell Tower Inquiry recommended, panel appointed.
Welsh Recharging Electrical Skills Charter progresses
ECA progressing on the ‘asks’ of the Recharging Electrical Skills Charter at the Senedd in Wales.
A brief history from 1890s to 2020s.
CIOB and CORBON combine forces
To elevate professional standards in Nigeria’s construction industry.
Amendment to the GB Energy Bill welcomed by ECA
Move prevents nationally-owned energy company from investing in solar panels produced by modern slavery.
Gregor Harvie argues that AI is state-sanctioned theft of IP.
Experimental AI housing target help for councils
Experimental AI could help councils meet housing targets by digitising records.
BSRIA Occupant Wellbeing survey BOW
Occupant satisfaction and wellbeing tool inc. physical environment, indoor facilities, functionality and accessibility.