The actual savings will depend on specific circumstances, such as the existing heating appliance and the type of delivery system. With a one-on-one replacement of a typical condensing boiler, in combination with a high-temperature heating system, approximately 30% less gas will be required, compared to the existing condensing boiler. The emission of CO2 is also 30% lower. When replacing non-condensing appliance, or in combination with heating systems for lower temperatures (such as underfloor heating), the savings increase up to 40%. In combination with insulation of the house, much higher combined savings can be achieved.