Houses Survive the Freeze

Five days of freezing rain brought down power lines, leaving areas of Quebec without electricity for up to a month at the beginning of the year. Building scientists examined vacant homes to determine if residents needed to guard against frozen pipes, heaving foundations, or iced up sump pumps.

In the middle of Canada's greatest natural disaster, building scientists were called upon to offer advice. Five days of relentless freezing rain brought down millions of trees and 230 high-voltage electric transmission towers. It knocked out electricity to entire regions for up to four weeks and left Montreal and Ottawa strewn with caution tape, warning passersby away from the debris. Millions of houses had no electricity for days, or even weeks, in the middle of the winter. Even oil-heated homes were without heat, since the furnaces had no fan power. Residents wanted to know whether to guard against frozen pipes, heaving foundations, or iced up sump pumps.

To help answer their questions, the Canada Mortgage and Housing Corporation (CMHC) studied 35 random vacant houses of various ages that lost heat and power for at least two weeks. Outside temperatures during the monthlong blackout averaged 18°F. But only one of the houses had air or surface temperatures below freezing, and CMHC found no frozen pipes. Most vacant houses had indoor temperatures between 39°F and 45°F, and one remained over 50°F. Well insulated, airtight houses, particularly those with passive solar design, were warmer--the warmest home had R-20 insulation in the basement. According to residents who kept monitoring indoor temperatures of vacant homes after CMHC finished, temperatures tended to decline gradually as the blackout wore on.

The storm taught Canadians a bit about their housing. First of all, many people regretted their dependence upon electricity. Those who relied on sump pumps to combat high groundwater levels learned about manual bailing or had their basements flooded. According to Ottawa's daily paper, the Citizen, the few houses that created their own electricity with wind, photovoltaics, or fuel-fired generators were popular places to catch a hot meal or shower.

People with effective and properly installed wood-burning stoves or gas fireplaces were able to remain in their homes. However, some houses burned down when decorative masonry or metal fireplaces exceeded the operating schedules they were designed for, raising temperatures on adjacent combustibles to ignition.

Roof loads of 8 inches or more of ice threatened the structural integrity of buildings, causing some to collapse. Engineers warned that more roofs would have failed if there had been heavy snow or rain on top of the ice. Expeditious and safe ice-melting procedures are being investigated.

In the aftermath, agencies that deal with emergency measures are investigating small power generation devices: gas generators, photovoltaics, and inverters or transformers that create 120V AC from the car in the driveway. But perhaps the most important thing individuals can do is to make sure their houses are well insulated and that they have their own power source.

Don Fugler is a senior research scientist at Canada Mortgage and Housing Corporation in Ottawa, Ontario.
 
 

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