Bounding long-term building energy performance with single-year extreme weather files

A decarbonized built environment is key to climate change mitigation and adaptation, yet buildings still consume 29% of the global primary energy, mainly due to space conditioning demand. As the climate changes, there is a need to map closely and rigorously the boundary conditions of buildings to facilitate learning from typical and atypical weather events.

The representation of typical weather conditions is well understood, but resilient design and operation of buildings is also influenced by responses to extremes. This could be assessed through multi-year weather files, but such an approach is computationally intensive and onerous for conceptual design. Instead, we focused on advancing the proposal of eXtreme Meteorological Years (XMY), weather files that bound the building energy performance for space heating and cooling with a single, composite year.

The representation of climatic data for building performance simulation as XMYs was first introduced by Crawley & Lawrie (2015). Conceptually, XMYs build on the well-established approach of Typical Meteorological Years (TMYs), which successfully represent prevailing meteorological conditions present over long periods of times using a single, composite-year weather file. However, XMYs purposely select more extreme weather periods (e.g., months, seasons) to bound the performance present in the same multi-year period of record they are based on.

Past XMYs formulations have been shown to work for a wide range of climates but not all. Building on them, this work set out to evaluate new selection rules for XMYs that can be applied to any location in the world, regardless of climatic characteristics. These selection rules were then evaluated over a representative sample of locations that span Koppen-Geiger climate zones under the presence of different geographical features, using the Commercial Reference buildings by the US Department of Energy as testbeds.

Results show that it is possible to bound the energy performance for space heating and space cooling within ±5 kWh/m2-y in every location when compared to the reference provided by multi-year simulations. The selection rule was based on quantiles for temperature-based metrics. Performance obtained demonstrate XMYs are promising to evaluate resilience of space conditioning systems.