How Much Does Energy Use Vary with 'Actual' Weather from Year to Year?

Historically, building simulation users have used ‘typical’ year weather data to represent climatic conditions for a location or region. With advent of increasingly powerful computers, using a single year of data is no longer necessary. Prior studies have shown that a single year of data often does not well represent the range of climate conditions over a period. We demonstrate how several sets of international typical meteorological data sets compare to the actual period of record that they represent, and demonstrate the inter-annual variability of energy use due to real weather data in comparison to TMY-type data.