This report reviews the environmental effects of heat pumps for single family houses in Sweden. The heat pumps are grouped in the major groups; ground source heat pumps, air-to-water heat pumps, air-to-air heat pumps and exhaust air heat pumps. Environmental effects from material use, manufacturing, operation and scrapping have been studied via a literature survey and discussions with people in the heat pump business. Clearly, the largest effect on the greenhouse effect is from the operation of all the heat pump types. This effect also differs a lot depending on which type of electricity mix that is assumed for the operation. For ground source heat pumps with energy well, the installation causes acidification through the use of diesel oil when the well is drilled. The consumer should carefully examine the efficiency and the capacity when buying a heat pump. These factors are affecting both the energy cost as well as the environment through the greenhouse effect. Buying a high efficiency heat pump with a high capacity therefore is a win-win situation for the consumer and the environment. Keywords: heat pumps, environmental effect, efficiency