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

O N L I N E V E R S I O N AC Table C1 Continued Proposed works Target Typical construction Comments (reasonableness, practicability U-value and cost-effectiveness) W/(m2·K) Ground floor constructions Renovation of a solid or See Solid floor – replace The cost-effectiveness of floor insulation suspended floor involving the comment screed with an is complicated by the impact of the size replacement of screed or a insulated floor deck and shape of the floor (ratio of perimeter timber floor deck to maintain existing to area). In many cases, existing uninsulated floor level floor U-values are already relatively low when compared with wall and roof U-values. Suspended timber Where the existing floor U-value is greater floor – fit insulation than 0.70W/(m2·K), added insulation is likely between floor joists to be cost-effective. Analysis shows that before replacing the cost–benefit curve for the thickness of floor deck added insulation is flat; therefore, a target U-value of 0.25W/(m2·K) is appropriate, subject to other technical constraints (adjoining floor levels, etc.) BBuuiillddiinngg RReegguullaattiioonnss 22001100 AApppprroovveedd DDooccuummeenntt LL VVoolluummee 11,, 22002211 eeddiittiioonn 8833 O N L I N E V E R S I O N