Constructing a future weather file for use in building simulation using UKCIP CP09 projections

In the future with climate change, building designers may need to demonstrate to clients that their buildings will continue to provide a comfortable environment under future weather conditions. Building simulation modelling can be used to this end provided that suitable weather files can be constructed. This article describes the use of the latest climate projections from UKCIP (UKCP09 data) and a method of constructing an hourly weather file for the following parameters: dry-bulb temperature, relative humidity, cloud cover, solar irradiation (direct and diffuse), wind speed and wind direction. For a given future scenario, the approach used first selects appropriate months from 3000 years of UKCP09 data to construct a Test Reference Year (TRY). Unfortunately, the UKCP09 hourly data has no wind or cloud data, and the solar irradiance is uncorrected at low sun angles. This article describes algorithms for calculating wind speed and cloud cover from the UKCP09 data. From this data, a TRY can be constructed and formatted to be suitable for use with commonly used simulation packages.

Practical applications: Building professionals increasingly seek reassurance on how a proposed building will perform under a future rather than historical climate. This article describes a method of processing the latest future climate projections (UKCP09 data released in June 2009) and generating a Test Reference Year (TRY) with the full complement of weather parameters suitable for use by commonly used building simulation programmes.