Useful Information Guide (BG 87/2024)

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This guide partly replaces BG 9/2011 Rules of Thumb 5th Edition. It provides updated reference information on a variety of topics relating to building services.

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On the 05/04/2024 corrections were made to tables 13 and 14 on page 12 of the guide. All pdfs downloaded after 05/04/2024 reflect these corrections. Customers who downloaded a pdf of the guide before this date can request a corrected pdf. 

This guide provides useful reference information for building services projects. This includes CO2 emissions factors and criteria for compliance with Part L of the Building Regulations.

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This guide partly replaces BG 9/2011 Rules of Thumb 5th Edition. Information has been updated based on consultation with designers and manufacturers. An enhanced building services glossary has been added, defining key terms for the industry, and new information has been included on resilience classifications for data centres and noise ratings.

Three further guides have been published providing reference information, definitions and data for use at early stages of design:

BSRIA would be very pleased to receive feedback on this guide – what’s missing, what can be improved in the information and its presentation, and what else BSRIA can do to make buildings better. Please email any comments and suggestions to


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Product details

  • Published: February 2024
  • Publisher: BSRIA
  • Author: Chin Hang “Kay” Lam
  • ISBN-13: 978-0-86022-809-7