Modelling the Future The implications of climate change can be seen in historical weather records. In addition to ensuring a relevant weather file is used when designing new buildings, it is prudent to explore how climate change may continue to alter weather, and how this will affect buildings moving forward. This can be achieved through climate forecasting models. We obtained data available from the Weather Research Forecast (WRF) model commissioned by the City of Toronto in 2011. A WRF simulation

is a macro-scale computational fluid dynamics (CFD) model completed over a geographic region – in this case, the Greater Toronto and Hamilton Area (GTHA). With the GTHA model, the years 2040-49 were simulated and hourly data for this time-period was made available for this study. In Figure 2, the forecast of heating degree days from the GTHA WRF study has been added to the historical values plotted in Figure 1. The WRF model predicts continued warming, and a shift from ASHRAE climate zone 5 to zone 4. To put this in context, Washington, D.C. is currently in climate zone 4.

FIGURE 2: HEATING DEGREE DAYS, HISTORICAL AND FORECAST, TORONTO, ON.

Implications for Building Design We performed three sample building energy simulations, comparing the typical meteorological year (TMY) for Toronto CWEC, CWEC2016 and 2040s weather files. We studied a typical low-rise 5,200 m2 residential building, assumed to be constructed with market-typical architectural, mechanical and electrical systems. 14

SPRING 2018 Toronto FOCUS

The resulting projected energy use intensities, presented in Figure 3 by fuel-type, shows the reduction in total energy use is minimal. This makes sense considering the increased demands for cooling energy (electricity) will be offset by decreased demands for heating energy (natural gas), driven by the much warmer summers and milder winters predicted by the 2040s weather file.