As Toronto Mayor John Tory experienced the city heat this week while riding the Rocket, so too are complaints about discomfort at Toronto District School Board schools without air conditioning. As temperatures spike to unseasonable highs, warranting Environment Canada to issue Heat Warnings, finding a cool spot to rest is serious business that will start to affect the health of those living, working and learning in the buildings.
Waiting for the OBC to catch up with reality…
Our climate is changing and like it or not, we’re going to get more heat. This translates to milder winters and longer growing seasons or hotter, longer summers. More importantly, it means the size of our heating and cooling systems will be impacted. Take a 2012 report published by the City of Toronto for example. Mechanical designers use heating degree days and cooling degree days to size mechanical equipment in buildings. According to the report,
- Values below 18°C can be used to estimate the heating requirements of buildings. The occurrence of such degree days are expected to reduce by almost a third – 31%
- Values above 24°C can be used to estimate the cooling requirements of buildings. The occurrence of such degree days are expected to increase by more than five times – 560% (i.e., from 32 degree-days to 180 degree days per year)
Which gets me to my point; with the caveat that cooling loads be minimised – greater emphasis on high performance building shells in the form of high R-value, limited thermal bridging and air tight with optimised window areas that minimise solar heat gain well into the shoulder seasons – all future buildings in Southern Ontario need to have Air Conditioning systems installed in them.
If not to lower indoor temperatures (sensible heat), then at least to cut the humidity (latent heat) to safe levels in order to discourage mold growth and allow our skin to evaporate more effectively. From public and institutional buildings to social housing, they need to be cooled – install more fixed windows if you must – but with a good building envelope, ventilation system and a cooling system, we will reduce the heat stress in the city.
If you’re a designer and your client suggests they don’t want AC as part of their mechanical design – especially in a high performance building – don’t do it.
This high rise along Bloor Street West has at least 24 window air conditioners, no wonder they’re hot, with those huge windows! There’s at least 24 window units along the south side of this building. The window units are nowhere near as efficient as a central systems and are a liability when it comes to falling when removing and replacing.