ENERGY STAR Ask the Experts | Products | ENERGY STAR
What is a Ground Source Heat Pump?
What are heat pumps and why is the UK government pushing them? | Energy efficiency | The Guardian
Air to Water Heat Pump Systems | Economical heating as well as total solution for domestic heating and hot water supply | Air Conditioning and Refrigeration | Daikin Global
Geothermal heat pumps provide earth-friendly energy for homes - The Washington Post