Technical Booklet F1 Conservation of Fuel and Power in Dwellings·Page 28·2.32
DER and TER comparison for buildings with multiple dwellings
Multi-dwelling buildings must either have each individual dwelling's DER less than its TER by a specified margin, or achieve the same margin on average using floor area weighted averages. Block averaging is only permitted within the same building, not across multiple buildings.
Where a building contains more than one dwelling (such as in a terrace of houses or in a block of flats), either each individual dwelling should have a DER that is less than its TER by at least the margin provided in paragraph 2.48, or the average DER is less than the average TER by at least the margin provided in paragraph 2.48. These are floor area weighted averages. Block averaging is only permitted for multiple dwellings in the same building. It is not permitted across multiple buildings on the same development.
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