I don't know it as a percentage; I do know it's certainly not trivial. With this proposal, which is a limited proposal, we used the metrics put forward by the Toronto atmospheric fund, which assisted in getting the coalition going. According to that, the savings would be 85,000 tonnes of the measure of greenhouse gas. That is the equivalent of 145, more than 12%, of Toronto's high-rise apartment towers not emitting any greenhouse gas. I know it's countrywide, as opposed to Toronto, but it's a significant amount of greenhouse gas that would be saved.
On March 5th, 2013. See this statement in context.