Timescale
The weather files for each decade cover a 30-year climatic period around that decade.
For example, 2020s weather files cover the period 2010 to 2040. 2020s are in the middle of the three decades (10s / 20s / 30s).
NC – 2020s and 2050s
New Construction projects assessed under the relevant standards should continue to use the 2020 weather files for mechanical ventilation, and the 2050 weather files for natural ventilation.
CIBSE weather files are available here: CIBSE Weather Data
RFO – 2030s and beyond
When published, the original intent for RFO projects was for future thermal comfort to be based on projected climate change 15 years after completion.
- For projects completed between 2015 and 2025, the 2030s data may still be used. This can be found here: Prometheus weather data.
- For projects completing after 2025, use CIBSE weather data covering the 2040s (included within the 2050s data): CIBSE Weather Data.
08-Jan-2024 - Added clarification on RFO 2030s data. 18-Dec-2024 - Merged with KBCN000006. Prometheus link updated. Title updated. 04-Jul-2024 - Clarified that 2020 and 2050 weather files are still valid for the applicable standards and guidance applied to all relevant UK standards. Applicability to international standards removed and link to CIBSE weather data added.
