Conservation of fuel and power: Approved Document L, Volume 1 — Dwellings

O N L I N E V E R S I O N L1(b), L2 Underfloor heating systems Zoning and controls 6.28 New underfloor heating systems should meet all of the following, in addition to the general requirements for heating and hot water systems in Section 5. a. All underfloor heating systems should have controls to adjust the operating temperature. b. Room thermostats for electric underfloor heating systems should have a manual override. c. Heating systems for screed floors that are greater than 65mm thick should automatically reduce the room temperature at night or when the room is unoccupied. d. Heat loss should be minimised by following the guidance in paragraphs 6.29 to 6.32. Minimising heat losses 6.29 Ground floors and those in contact with the outside of the dwelling should be insulated to limit heat losses to not more than 10W/m2. The heat loss from the floor should be calculated using the sum of the thermal resistance of the floor finish and the underlying heated layer, multiplied by 10. 6.30 Underfloor heating systems intended for intermittent or cyclical operation and/or installed over unheated rooms should be separated from the structural floor by a layer of insulation with a thermal resistance of at least 1.25(m2·K)/W. 6.31 The intermediate floor should have a layer of insulation to reduce downwards heat transmission with a thermal resistance of one of the following. a. The performance in paragraph 6.29. b. As specified in BS EN 1264-4, as follows. i. For electric systems, not less than 0.5(m2·K)/W. ii. For wet systems, not less than 0.75(m2·K)/W. 6.32 Distribution pipework which does not provide useful heat to a room should be insulated to the standards detailed in paragraph 4.26. Specific standards for electric underfloor heating 6.33 Electric cables for underfloor heating should be installed within screeds as follows. a. For direct electric systems, within screeds not exceeding 60mm. b. For night energy storage systems, within screeds of at least 65mm. 6.34 Where electric cable underfloor heating night energy storage systems are used, both of the following should be met. a. A minimum of 20% of the floor area of the dwelling should have fast-response systems, such as panel heaters. b. Controls should be installed which modify the input charge in response to both of the following. i. The room thermostat. ii. Floor temperature sensing. 46 Approved Document L Volume 1, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N