Typical-year and multi-year building energy simulation approaches: A critical comparison

Building Energy Simulation (BES) tools usually make use of single Typical Weather Years (TWYs) but the increased calculation capacity now allows for multi-year simulations based on Actual Weather Years (AWYs). This research analyzes how the use of a TWY affects the prediction of the energy demand and the peak load in a residential and an office building located in Catania (Italy), if compared to a multi-year approach. Different TWYs are considered, either developed by the authors according to standard international procedures and based on recent measurements from a local weather station, or already available on the internet. Results show that the adoption of a TWY is useful to assess the mean long-term energy demand, with a preference for the IWEC procedure (mean bias error below 2%). However, TWYs would underestimate the peak heating load by 12.5% and the peak cooling load by around 18% in the residential building, while in the office building the underestimation can be even higher. In the absence of specific design weather files when the aim of the simulations consists in sizing the mechanical systems, the peak values of the AWYs distribution based on the last 10e15 years of measurement should be preferred to TWYs.