Topic 1 – Weather Data: Understanding TMY & TRY
A free BEMRG learning resource explaining Typical Meteorological Year (TMY) and CIBSE Test Reference Year (TRY) weather data for building energy modelling. The video introduces what TMY and TRY files represent, why weather data affects simulation results, and how to select suitable weather data for different building performance studies. This video is free to watch. More free BEMRG educational videos will be published regularly.
Understanding TMY & TRY Weather Data
Weather data is a fundamental input to building energy modelling.
The weather file selected for a simulation can directly affect predicted:
Heating demand Cooling loads Annual energy consumption Indoor temperatures Solar gains Ventilation and infiltration Overall building performance
Selecting an appropriate weather file is therefore an important part of reliable building performance analysis.
What This Video Covers
In this free BEMRG teaching video, we explain:
The difference between weather and climate Why building simulations use hourly weather data What a Typical Meteorological Year (TMY) is How a representative weather year is created from long-term weather records What a CIBSE Test Reference Year (TRY) is The similarities and differences between TMY and TRY The difference between TRY and Design Summer Year (DSY) How to choose weather data for different simulation purposes TMY and TRY
A Typical Meteorological Year (TMY) is a representative year constructed from longer-term weather records. It is widely used internationally for building energy and environmental simulation.
A CIBSE Test Reference Year (TRY) is a representative weather year used within the CIBSE weather-data framework for UK building performance analysis.
TMY and TRY have a similar purpose, but they come from different frameworks and methodologies.
When selecting weather data, always consider:
Location Data source Climate period Weather-file methodology Intended application
The appropriate weather file depends on the purpose of the analysis.
For example, annual energy assessment and overheating analysis may require different weather datasets.
Free BEMRG Learning Resource
This video is provided as a free educational resource for students, engineers, researchers and building-performance professionals.
No BEMRG membership is required to watch this video.
BEMRG will continue to publish free educational videos covering topics such as:
Building energy modelling Weather and climate data Heating and cooling load calculations Energy efficiency Building performance Building services engineering Decarbonisation Net Zero Carbon buildings Practical engineering and modelling tools
Our aim is to provide clear, practical technical learning resources that support better building-energy analysis and engineering practice.
More free BEMRG learning videos will be added regularly.
🌐 Building Energy Modelling Research Group (BEMRG) https://www.bemrg.com/