In Canada, home air conditioning is less common than in East Asia and the United States, but it still quite prevalent. This is especially true of the Great Lakes regions of southern Ontario and Quebec, where there are especially high humidity levels. While window and split units are common in these regions, central air systems are the most widespread in Western Canada. Most Western Canadian homes are built with already-compatible central forced air natural gas heating systems, making installing a central air system very simple. In Central Canada separate room-based hydro powered heating is more common, leading to the higher cost of retrofitting a central air system. The majority of modern urban high-rise condominiums built in Canadian cities have air conditioning systems. It is also offered as a relatively low-cost option on most new built homes. While energy is comparatively very cheap in Canada, the large size of the average Canadian home and cold winters make heating and cooling one of the largest household expenses. Canadian summers are uncomfortably hot, but rarely reach the dangerous temperatures experienced in the United States or Asia. As such, many Canadians, especially in older homes, simply choose to forgo air conditioning in lieu of simple fans and evaporative coolers. Cost of operation (as a factor of efficiency) of air conditioning is often considered an environmentally unfriendly mitigation to poor thermal design. There have been a number of advances in more environmentally friendly technologies, including insulation advancement, geothermal cooling, and the Enwave deep lake system in Toronto that cools a number of office towers using cold water from Lake Ontario.
