Approved Document Part L1a – New Dwellings
- Design Stage SAP to Building Control “No later than the day work starts”
- Approx 25% reduction in CO2 emissions compared with a 2006 compliant dwelling
- Maximum average fabric u-values have decreased (eg Walls from 0.35W/m2K to 0.3W/m2K)
- Carbon emissions for electricity from grid increase by 22.5% (Partly compensated for by a new Emissions Adjustment Factor, which increases the TER)
- Increased no. air pressure tests. Three per plot type for developments above 6 units (Any dwelling not tested must add 2m3/hm2 to the air leakage rate for a tested plot of same type)
- Party walls having a cavity must be sealed and insulated or else incur a CO2 penalty
- Accreditation scheme for cold bridging details to replace the ‘y-value’ in future
- To exclude Conservatories from CO2 calculations they must be fully thermally separated
Conservation of Fuel and Power in New Dwellings
5 Criteria in the Approved Document Part L1a 2010:
ADL1 Section 4
Criterion 1:
- Achieving the TER (& definition of DER)
- Design Standards
Criterion 2:
- Limits on design flexibility
- Fabric standards & System efficiencies
- Domestic Building Services Compliance Guide
Criterion 3:
- Limiting the effects of solar gains
ADL1 Section 5
Criterion 4: Quality of construction & commissioning
- Building performance
- Party walls and other thermal bypasses
- Thermal bridges
- Air permeability and pressure testing
ADL1 Section 6
Criterion 5: Providing information
- Energy Efficient Operation
- Provision of information on system operation
- Current spec and further improvements in EPC
Posted on October 4th, 2010
Author: Richard Hodkinson
Related services: Code for Sustainable Homes, SAP,