Weather Data for Simulation
Users of energy simulation programs have a wide variety of weather data from which to choose – from locally recorded weather data to preselected 'typical' years –, often a bewildering range of options. Many locations are available on this site – but users may have special needs for different locations. This page lists sites that may provide those other user locations. Before tapping the resources below, users should check if an existing EnergyPlus Weather Format (EPW) file is within 20-30 miles (30-50 km) and within a few hundred feet (100 m) of elevation.
There are a few things to consider before jumping to obtain weather data merely because your location is not supplied. Users of energy simulation programs should avoid using single year, Test Reference Year-type (TRY) weather data. No single year can represent the typical long-term weather patterns. More comprehensive methods that attempt to produce a synthetic year to represent the temperature, solar radiation, and other variables within the period of record are more appropriate and will result in predicted energy consumption and energy costs that are closer to the longterm average. Both Typical Meteorological Year 2 (TMY2) and Weather Year for Energy Calculations 2 (WYEC2) use this type of method, are based on improved solar models, and more closely match the long-term average climatic conditions.
More information on selecting weather data appropriate for energy simulation is described in this paper Drury B. Crawley. 1998. "Which Weather Data Should You Use for Energy Simulations of Commercial Buildings?" in ASHRAE Transactions, pp. 498-515, Vol. 104, Pt. 2. Atlanta: ASHRAE.
Some private sources that supply simulation appropriate weather data:
- Weather Bank - WeatherBank maintains hourly and daily historical data records from every National Weather Service reporting station in the United States, as well as other locations around the world. They archive weather data on a real-time basis and certain updates are made hourly. This hourly archiving began in late November, 1994.
- National Climatic Data Center - NCDC is the world's largest active archive of weather data. NCDC produces numerous climate publications and responds to data requests from all over the world. NCDC operates the World Data Center for Meteorology which is co-located at NCDC in Asheville, North Carolina, and the World Data Center for Paleoclimatology which is located in Boulder, Colorado.
- Weather Source - Weather Source provides historical and real-time digital weather information for more than 10,000 locations across the United States and around the world.
- Weather Analytics - Site specific weather files in EnergyPlus format based on the latest 30 years of hourly data are now available from the private sector company Weather Analytics for any official weather station on more than 600,000 35-km grid tiles across the globe. These files are built by integrating hourly weather station observations and the new NOAA reanalysis data sets. Both Typical Meteorological Year (TMY) files and individual, Actual Meteorological Year (AMY) files are available, as are files constructed from the previous 12 months.
- Meteonorm - Files for specific locations can be purchased in EnergyPlus format from Meteonorm company. Meteonorm extrapolates hourly data from statistical data for a location. Where statistical data aren't available, Meteonorm interpolates from other nearby sites. Generally, a statistical approach is a last resort ‐ weather files generated from statistics will not demonstrate the normal hour-to-hour and day-to-day variability seen in measured data.
- White Box Technologies - WBT provides instant web access to the following weather data sets:
- ASHRAE IWEC2 (International Weather for Energy Calculations) "typical year" weather files for 3,012 international locations outside of US and Canada. Individual IWEC2 files cost $35 each; country sets also available for $75-$150 depending on the number of files. IWEC2 weather files were developed in a 4-year ASHRAE research project (RP-1477), and distributed by WBT on agreement with ASHRAE.
- Historical year weather files from 2006 through 2012 for over 10,000 stations around the world, including over 1,500 US and 300 Canadian stations (earlier years are also available upon request). These historical year weather files cost were developed using the same raw data and processing technique as the IWEC2 files, and cost $50 each.
Both IWEC2 and historical year weather files come in three formats - *.CSV, *.BINM, and *.EPW (+ *.DDY). Selection can be done using either the GoogleEarth Ap or the "Select Data" button to select by list. Both types of weather files utilize actual recording from thousands of official weather stations around the world going back up to 25 years and archived in the Integrated Surface Hourly Database (ISD) maintained by the (US) National Climatic Data Center (NCDC). Extensive processing equivalent in scope to the TMY3 files has resulted in complete weather files with solar radiation, daylight illuminance, and precipitation, in addition to the standard parameters of temperature, humidity, pressure, wind speed and direction, etc.