High-efficiency or condensing boilers reduce utility bills and increase energy efficiency compared to ageing boiler units. They are also smaller and lighter than traditional boilers.

Condensing boilers can be controlled via a thermostat and achieve savings between 10 % and 30 %.

Where a single 200 kW boiler, heating an office with a single-shift system, uses around 300 000 kWh of gas a year, a 10 % saving rate corresponds to € 845 (£ 750) a year with gas prices at € 0.03 per kWh (2.5 pence). The extra cost of a condensing boiler would be around € 1 690 (£ 1 500), giving a payback in around two years.