Climate and weather¶
Why performance is assessed against the current climate rather than a fixed benchmark, and why benchmarks themselves keep moving.
Changes in global and regional climates and in the frequency and intensity of extreme weather (rainfall, wind, humidity, heat and cold) are now occurring and are increasingly impacting the performance of long-lived structures such as buildings, and their occupants. This is because of both the gradual increase of average annual temperatures and significantly the increasing frequency and intensity of dangerous hot weather events such as heatwaves.
Building performance is typically reported relative to the ‘current climate’ - which is changing globally, with changes varying regionally and locally. The current climate is defined according to measured conditions over an agreed period of time – typically 30 years. Different time periods or benchmarks are used for different purposes and may or may not be universally used across governments and organisations.
Benchmarks are periodically updated. For example, the UK’s Met Office has recently updated UK regional benchmarks for heatwaves as a result of the changing climate (note that different regions have different benchmarks to reflect regional variations in climate).
ARC recognises that building performance is usefully assessed relative to the ‘current climate’ in any particular climate zone, climate region or even relative to the climate in a very specific locality.
Because of faster than predicted climate change, building performance now needs to be assessed relative to both current and predicted future extreme weather events, particularly extremes of heat and humidity – heatwaves.
Source: ARC Technical Criteria - 62
Overview · confidence medium · Imported 2026-09-12, not yet reviewed · next review 2026-12-12
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Citation key: climate-and-weather