Technical Booklet F2 Conservation of Fuel and Power in Buildings Other Than Dwellings·Page 66·3.85
Fabric improvements when heating system capacity is increased
When heating system capacity per unit area is increased, thermal elements exceeding specified U-values must be improved, and windows, roof windows, rooflights and doors with U-values greater than 3.3 W/(m².K) must be replaced.
Where the installed capacity per unit area of a heating system is increased –
(a) the thermal elements (within the heated area served) that have U-values greater than those given in column (a) of Table 3.4 should be improved in accordance with paragraphs 3.75 and 3.76; and
(b) existing windows (excluding display windows), roof windows or rooflights or doors (excluding high usage entrance doors) within the area served, and which have U-values greater than 3.3 W/(m2.K), should be replaced by fittings complying with paragraphs 3.57 to 3.63.
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