An adaptive control algorithm (ACA) has been developed as an alternative to fixed temperature setpoint controls within buildings. This paper describes both the theory behind the ACA and the findings from an EU-funded research project, smart controls and thermal comfort (SCATs), from which the form of the ACA was developed. The ACA was also tested in two air-conditioned buildings as part of the SCATs project and the results are presented. The results show that use of the ACA has potential for energy savings in the climate-control services of a building with no reduction in the perceived thermal comfort levels of that building's occupants. Further refinement and testing of the ACA is required before it can be marketed.