 The drop in efficiency means their electrical load increases steeply as temperatures drop.A study in Canada's Yukon Territory, where diesel generators are used for peaking capacity, noted that widespread adoption of air source heat pumps could lead to increased diesel consumption if the increased electrical demand due to ASHP use exceeds available hydroelectric capacity.Notwithstanding those concerns, the study did conclude that ASHPs are a cost-effective heating alternative for Yukon residents.