The Fuelstretcher is a self tuning retrofit boiler controller, designed and developed by BRE, which saves significant amounts of fossil fuel in boiler powered commercial heating systems. Simple to install, it will control up to four boilers. Daily, it measures the heat demand of the building and controls the boiler to satisfy this. BRE report that it can save between 5% and 25% of the fuel used, depending on other controls present. It will operate under the general management of a BMS.