Simulation Weather Files in IES VE

Climate will clearly play a key role in the performance of any building so it is important to use the appropriate location settings for any analysis.  For Apache dynamic simulations in IES VE a simulation weather file is required.  These files contain data for variables including dry bulb & wet bulb temperature, wind speed & direction, solar altitude & azimuth, cloud cover etc for each hour of the year.

Weather File Sources

The standard simulation weather files are sourced from various places and converted into the standard FWT file format. Usually the fwt will have an abbreviation that points out where the data was acquired (e.g: EWY = Example Weather Year. These are individual weather years sourced from the MET office). Most files are sourced directly from the energy plus website. You can read about different weather sources here. The weather file formats the VE can read are .fwt (proprietary format) and .epw files.


When you install the Standard Data & Weather Files as part of the IES VE installation the basic set of simulation weather files is included for the following locations.  Additional weather files can be acquired from a multitude of sources (see below) for use in Apache simulations, these will usually be in the format *.fwt or *.epw.

To access these in VE they should be copied into the weather subfolder of the Standard Data & Weather Files installation (typically C:\Program Files (x86)\IES\Shared Content). After this the new files are available to select on the Simulation Weather Data tab of ApLocate.

Getting More Weather Files...


Provides the option to submit any current simulation weather file and apply WeatherShiftTM process to generate files that represent the given location in a future time period using predicted climate change scenarios.

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CIBSE 2006 Weather Files (for UK building regulations)

CIBSE TRY & DSY datasets are required to run simulations using ApacheSim method in VE Compliance. These datasets are owned by CIBSE and each user requires a license to use them. IES acts as an agent for CIBSE and the licence to use the data may be purchased on our website.


CIBSE 2016 Weather Files

Purchase CIBSE 2016 updated simulation weather files for 14 UK Locations. Test Reference year (TRY) and Design Summer Year (DSY) available based on current weather data and future predicted climate change data (UK Climate Impacts Programme).


Weather Analytics

Options to purchase weather data for individual locations as either AMY or TMY via Weather Analytics. Data is available for any global location using a 30km x 30km grid and is provided as both .csv (data) and .epw (simulation weather file).


Energy Plus Weather Files (EPW)

A selection of EPW weather files for more than 2,100 locations can be found on the Energy Plus website. Place the .epw files in your Standard Data and Weather Files installation weather folder to read them in Apache simulations and VistaPro.

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METEONORM can produce energy plus weather files for almost any location in the world. Users can either purchase a license or ask them to generate datasets for certain location at a cost of around €80 per file.

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Prometheus Weather Files

The PROMETHEUS project has produced a number of future weather files (.epw format) which can be used to 'future-proof' buildings against predicted climate change. The files were created using the UKCP09 weather generator. The weather files are currently available for 45 locations, 3 time periods and 2 emissions scenarios.

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Agrément South Africa

Authorised weather files for use in energy compliance simulations in line with the National Building Regulations of South Africa and Agrément South Africa’s Energy Software Protocols (SANS 10400-XA Item 4.3).

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