Older incandescent bulbs, such as the one above, throw more heat than energy-efficient CFL bulbs.

Questions are being raised about whether so-called energy saving light bulbs might cause cold-weather Canadians to burn more energy to heat their homes than if they were to use regular light bulbs.

CBC News has found that in some cases compact fluorescent bulbs (CFLs) can have the adverse effect of increasing greenhouse gas emissions, depending on how consumers heat their homes.

Physics professor Peter Blunden at the University of Manitoba said CFL bulbs are certainly more energy efficient than older incandescent bulbs.

But in cold-weather climates such as Canada's, Blunden said older incandescent bulbs do more than just light our homes. During the long winter months, they also generate heat. The new CFL bulbs on the other hand produce minimal heat so the loss has to be made up by fossil-fuel burning gas, oil or wood to heat your home.

“To some extent, the case [in favour of CFL bulbs] has been oversold” because of the offset in higher heating costs, he said.

In fact, a recent report by BC Hydro estimates new lighting regulations will increase annual greenhouse gas emissions in British Columbia by 45,000 tonnes annually as consumers use more energy to heat their homes after switching to more energy efficient — but cooler — lighting.

"The replacement of inefficient lights with efficient lights that produce less waste heat will lead to increased fossil fuel use for non-electric space heating," says the report, part of a submission BC Hydro made to the B.C. Utilities Commission last month.

Another study, by the Canadian Centre for Housing Technology, also concluded that actual dollar savings by using CFLs depend on the climate in which a home is located. In Canada, in winter, "the reduction in the lighting energy use was almost offset by the increase in the space-heating energy use," the study said.

But Canadians, depending on where they live and the severity of the winter, may still benefit from using CFL lighting, despite the higher cost of the new bulbs and the additional heat energy consumed, said the CCHT study, conducted in 2008.

Some proponents of the CFL bulbs claim the new bulbs use only about 25 per cent of the energy of old incandescent bulbs.

"In Winnipeg you are going to lose a significant amount of those savings," said Blunden.

Indeed, when everything is factored in, Blunden says the real energy saving for Winnipeggers using CFL bulbs is probably closer to 17 per cent. Blunden said energy saving results will vary across the country, depending on how consumers heat their homes.

If you live in Newfoundland, for example, where many people use expensive heating oil “it might even cost you money" to use the new, cooler, efficient, CFL bulbs for lighting, Blunden suggested.

"If your advertising campaign says you’re going to save money, then you’ve kind of shot yourself in the foot,” he said, noting CFL bulbs were originally designed for use in warmer climates.