CHP (combined heat and power) is recognised as an established efficient and environmentally friendly technology suitable for the local generation and provision of thermal and electrical energy to the built environment. Small-scale CHP systems, which include micro-CHP systems with electrical capacity less than 5kW and mini-CHP systems with electrical capacity in the range of 5kW to 500kW, can achieve the total energy efficiencies from 75% to as high as 95% as compared to an average of 30-35% for conventional fossil fuel fired electricity generation systems. The most promising targets for the application of CHP systems lie in energy production for buildings. An up-to-date review of the various small-scale CHP technologies suitable for building application is provided in this paper. The properties of relevant technologies are briefly discussed, and the impact of CHP on building energy consumption is presented.