buildwiz.uk
Part O

Overheating

Building regulations introduced in June 2022 limiting summer overheating in new residential buildings in England. Applies primarily to new dwellings and material change of use to residential, not generally to extensions of existing dwellings. Sets two compliance routes: a simplified method based on glazing area, ventilation openings and shading, or a dynamic thermal modelling method (CIBSE TM59). Building control checks Part O at design stage for in-scope projects.

Read on gov.uk All Approved Documents

Also known as

Part OApproved Document OAD OBuilding Regs Part OOverheating

Pages where Part O comes up

Part O is in the graph but no published guide currently links to it. As leaves get authored or expanded the cross-link sweep will pick them up here automatically.

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The buildwiz build guides walk through a UK extension in sequence and link to Part O (and every other Approved Document) at the exact stage it bites. That is usually a more productive way to use this material than reading the document cover to cover.