Weather Modeling

When a user creates a new modeled building they are asked to enter the ZIP code for its location. Based on that zip code they are assigned a default city to provide a weather data file for DOE-2 modeling. This assignment is a straightforward mapping of ZIP code location to the closest geographical location associated with a weather station, based on the distance of the ZIP code centroid to the weather stations. In addition, alternative weather stations closest to the default selection are listed. These alternatives default to the 10 closest stations, but in some regions the 10 closest stations could include locations very far away, so we limit the mapping to the closest stations within 200 miles, up to a maximum of 10.

Weather data are typical meteorologic year (TMY) data from NOAA, currently TMY3 weather data is used. A map of the TMY3 weather locations is here, for more information about TMY data see the National Solar Radiation Database.

For use in modeling water heating energy consumption, we estimate the annual average inlet water temperature (from the domestic water system) by subtracting 2˚F from the annual average dry-bulb air temperature reported in the weather data files. Inlet water temperatures in Alaska were constrained to be greater than 32˚F. These values are listed in Appendix C.

Summary weather statistics for each weather data file were calculated using the DOE-2 weather packing routines. These summary statistics include seasonal heating and cooling degree-days, winter and summer design-day conditions, and weather-station location data. DOE-2 utilizes the full TMY2 weather tape, extracting solar gains (insolation) and other needed information for use in the annual simulation.