Adjusting the thermostat for dollar, emissions savings

It was announced Feb. 27, to coincide with International Polar Bear Day, that indoor temperatures across campus will be raised two degrees in the spring and summer, to a target of 24 degrees C, and lowered one degree to a target of 21 degrees C in fall and winter. "And like all good energy management programs, there's an environmental benefit and an economic benefit too," said Kathryn Theede, energy and emissions officer in the Office of Sustainability.

Those benefits are expected to amount to about $200,000 annually in utility costs and a 2,000-tonne reduction in annual carbon emissions attributable to the U of S.

Theede said the new temperature initiative – referred to as two up, one down – builds on the university's Climate Action Plan that was instituted in 2012 and all procedures related to the change are expected to be in place by May when the central heating plant switches buildings from heating to cooling. Most campus spaces are currently maintained at 22-23 degrees C year round, which is within the industry standard for thermal comfort, the point at which about 80 per cent of people are happy.

"We're working toward getting everyone into this range," added Heather Trueman, sustainability initiatives liaison.

One of the first steps in making the change is to ensure thermostats are properly calibrated to read temperature accurately, said Theede. But even with accurate thermostats, campus is an extraordinarily complex environment to heat and cool consistently given the varying ages of infrastructure and the sizes of rooms. A lecture theatre, for example, is cool when empty but can heat quickly when it is filled with 200 people.

"The change would be so much easier if we were dealing with only one building," she said, "so we need to use the target temperatures as rules of thumb. There are parts of campus that are hard to heat and cool, and the facilities division deals with those on a case-by-case basis. We're also faced with areas of special need like research, animal care and technology so there has to be some variation."

Calculating the savings in both dollars and emissions is also a bit of an art, said Trueman. Because there are so many variables, the sustainability office relies on industry calculations to estimate savings, and even then, the expectations are conservative.

When last calculated in 2009-10, U of S carbon emissions were pegged at 165,000 tonnes per year with 58 per cent of that total attributed to electricity, 34 per cent to natural gas and the remainder to transportation, waste and agriculture. The savings estimate of 2,000 tonnes is a very small percentage of actuals, said Trueman, "but to be absolutely accurate we would have to be able to hold everything constant, including the weather. We have to rely on industry wisdom about what percentage we can save with each degree of temperature change."

"We have to trust in the logic," continued Theede. "If we reduce demand, our greenhouse gases will go down and we'll save money."