Solving the global cooling challenge: how to counter the climate threat from room air conditioners

Comfort cooling represents one of the largest end-use risks to our climate, and the residential sector alone is set to account for an over 0.5º C increase in global temperatures by 2100. A warming planet, rapid urbanization, growing population, and rising incomes are driving up the global demand for air conditioning, and under a business-as-usual growth trajectory, the number of room air conditioner (RAC) units in service is estimated to increase from 1.2 billion units today to 4.5 billion units by 2050. Much of this growth comes from emerging economies, which will see a five-times (5X) increase in the number of RACs between now and 2050. The most advanced commercially available, vapor compression-based RACs have achieved only about 14% of the theoretical efficiency limit;i efforts to date have focused on meeting minimum performance standards and refrigerant transitions, and not transformative innovation in efficiency. Our analysis shows that conventional solutions— such as efficient building design, improved maintenance and operations, and driving behavior change, in combination with the incremental pace of technology improvement— will only address a portion of the challenge and cannot bring us anywhere close to neutralizing the impacts of the projected increase in the number of RACs. The world needs a radical change in comfort cooling technology, one that can effectively and assuredly offset the exponential increase in cooling energy demand and put us on a path to cooling with less warming.