The energy efficiency of heating and cooling appliances and equipment steadily increased in recent years, partly thanks to the use of smaller diameter copper tubes in heat pumps, air conditioners and refrigeration systems. Efficient appliances and building systems already are helping to draw down greenhouse gas (GHG) emissions and there is still plenty of room for improvement.

Research and development on energy efficiency were presented in 2021 at ACEEE’s Hot Water Forum and the Purdue’s International Refrigeration and Air Conditioning Conference. Both conferences took place virtually this year and high quality presentations and papers were delivered at both.

What follows are some highlights from each of these two conferences, emphasizing the energy efficiency of heating and cooling systems.