Why Part O exists
Approved Document O was introduced to tackle overheating in new homes — a growing problem as dwellings become more airtight and better insulated to meet Part L, and as the climate warms. To satisfy Part O, a dwelling must be modelled to show either that there’s no overheating issue, or that mitigation measures address the risk.
Mitigation is often simpler than people expect: shading from overhangs, louvres on vulnerable windows, or adjustments to glazing and ventilation strategy.
Two routes to compliance
The simplified method — a straightforward calculation suitable for simple buildings without large areas of south- or west-facing glazing.
Dynamic thermal modelling — a full simulation accounting for location, solar radiation, ventilation, building fabric and shading. Required for more complex or glazed designs, and often the route that finds a pass where the simplified method can’t.
We assess which route suits your design, run the modelling, and deliver a report Building Control will accept — with practical mitigation recommendations where they’re needed, tailored to your project rather than generic.
Get it checked early
Overheating problems are cheap to fix on paper and expensive to fix on site. Send us your drawings at design stage — get a quote or call 01202 623236.