(HRV) is an energy recovery ventilation system which works between two air sources at different temperatures. By recovering the residual heat in the exhaust gas, the fresh air introduced into the air conditioning system is preheated. See also Air source heat pumps Autonomous building Architectural engineering Biogas Energy conservation Ground source heat pump Green architecture Green building Hot water heat recycling Heat recovery ventilation Superinsulation Sustainability Sustainable design Mitigation of global warming Natural building Passive house Passive solar Renewable energy Renewable energy development Solar Air Heat Solar combisystem Solar hot water Solar power European Biomass Association Thermal insulation Underfloor heating Wood briquettes Zero energy building References External links Heat pumps based on R744 (CO2) FAQ Heat pumps Long Awaited Way out of the Global Warming - Information from Heat Pump & Thermal Storage Technology Center of Japan Department of Trade and Industry, 2005 study on Renewable Heat Renewable Heat combining asphalt solar collectors, thermal banks and ground source heat pumps. Energy Saving Trust information on Home Insulation The Gill report on biomass in the UK - download Solid wall insulation Cavity wall insulation Energy economics Energy conservation Heating Low-energy building Residential heating Renewable energy technology Sustainable technologies Sustainable building Sustainable architecture Sustainable energy