Coincidence factor
Heat Interface Units (BG 62/2015) was written by Reginald Brown and published by BSRIA in December 2015. It states: ‘The coincidence factor is formally defined as the design flow rate for downstream domestic hot water outlets divided by the sum of maximum flow rates for individual downstream domestic hot water outlets. In a heat network with HIUs (Heat Interface Units), the coincidence factor is alternatively expressed in terms of the design energy input necessary to achieve the domestic hot water requirements, divided by the sum of maximum energy inputs for individual downstream domestic hot water outlets and used as part of the pipe sizing methodology for the heat network.’
--BSRIA
[edit] Related articles on Designing Buildings
- A technical guide to district heating (FB 72).
- Big growth in district heating markets - now and on the horizon.
- BSRIA articles.
- BSRIA definitions.
- BSRIA guide to heat interface units.
- Communal heating.
- Direct heat interface unit.
- District energy networks
- Domestic micro-generation.
- Heat interface unit.
- Indirect heat interface unit.
Featured articles
Check out some of the best features and news from Designing Buildings as well as key stories from around the web.
New and updated CLC building safety guidance.
New UK National Buildings Database.
Building Safety Wiki Interviews
Chief executive of the British Woodworking Federation.
Planning condition discharge in England and Wales
A brief explanation from a building compliance expert, with further links.
Overheating guidance and tools for building designers
Guidance for dealing with element of building fabric control that have increasing importance.
Shading for housing, a design guide
From the Good Homes Alliance and British Blind and Shutter Association.
UK Standard Skills Classification (SSC)
A shared framework for describing skills needs.
Social media ban consultation comes to close
CIOB urges UK Government to consider social media’s role in careers guidance in ban debate.
The latest of eight Skills England apprenticeship units
The addition of battery manufacturing welcomed by ECA with a warning about the risks of fast-tracked apprenticeship units.
Building Control Independent Panel final report
A precis of a key report led by Dame Hackitt with full recommendations and link to the government response.
Building Safety recap April, 2026
A short and longer run-through of the month, with links to further information and sources.