Does it matter which weather data you use in energy simulations

Users of energy simulation programs often have a variety of weather data from which to choose--from locally recorded, measured weather data to preselected typical years--a bewildering range of options. In the last two years, several organizations have developed several new typical weather data sets including WYEC2, TMY2, CWEC, and CTZ2. Unfortunately, neither how these new data influence energy simulation results nor how they compare to existing typical data sets or actual weather data is well documented. In this paper, the authors present results from the DOE-2.1E hourly energy simulation program for a prototype office building as influenced by local measured weather data for multiple years and several weather data sets for a set of North American locations. They compare the influence of the various weather data sets on simulated annual energy use and energy costs. Statistics for temperature, solar radiation, and heating and cooling degree days for the different locations and data sets are also presented. Where possible, they explain the variation relative to the different designs used in developing each data set. They also show the variation inherent in actual weather data and how it influences simulation results. Finally, based on these results, they answer the question--does it really matter which weather data you use?