Comparative analysis of old and new weather files: City-based versus climate zone-based approaches

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Abstract
Weather files are fundamental for building performance applications such as estimating energy demand or predicting the risk of thermal discomfort. Often such weather files are based on specific locations with limited guidance to which file to use which can lead to non-representative climate conditions for a specific building and potentially under or over engineering of systems. Recently, a new approach to generating representative weather files for building performance using climate zones has been proposed. This work presents a comparative analysis of the two approaches. Results from examining the external climate and an example building simulation reveal substantial differences: heating degree days vary by up to 931° days, cooling degree days by up to 500° days, heating energy demand differs by as much as 60%, and overheating exposure in the bedroom exceeds 26°C for up to 45 h more. Overall, we find significant variations in heating and cooling loads can be expected if unrepresentative climate data is used highlighting the importance of selecting appropriate weather data for building performance simulation. The use of zone-based files provides a more nuanced understanding of climate conditions, improving the reliability of building performance assessments and compliance with overheating standards. Practical application: Weather files are fundamental for building performance analysis and supporting design decisions including the prediction of the risk of thermal discomfort. There is a need for these weather files to be kept up to date following the continual warming of the environment to ensure that the performance analysis represents external conditions and ensuring the analysis is fit for purpose. A significant limitation of the current approach is the uncertainty of which weather file should be used for any given location particularly in locations such as the UK. This work provides a framework for the development of climate-zones and representative weather files suitable for supporting the benchmarking of building performance across the climate zone removing ambiguity within the industry for the appropriate selection of weather data.
Funding Information
  • Innovate UK (12939)

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