Technical Booklet F1 Conservation of Fuel and Power in Dwellings·Page 44·3.29
Change of energy status for previously exempt conservatories and porches
A previously exempt conservatory or porch is considered a change of energy status when thermal separation is removed, heating or cooling systems are extended into it, or fixed combustion or cooling appliances are installed.
Where a previously exempt conservatory or porch is no longer exempt and energy is used to condition the indoor climate this is a change of energy status. This is the case where – (a) the thermal performance of the dwelling is not retained (e.g. if any part of the thermal separation between the dwelling and the extension is removed and not replaced); (b) the dwelling's heating or cooling system is extended into the extension; or (c) a fixed combustion appliance or a fixed cooling appliance is installed in the extension.
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