Building regulations specify minimum levels of thermal performance for roof, floors and external walls, for new buildings. New Regulations have increased the Thickness of insulation required. See link:
TYPICAL HEAT LOSS IN THE HOME
Who can provide these calculations?
Any competent person will be able to complete a DEAP calculation using the SEI spread sheet to calculate the CO2 emissions for a design that will satisfy building control; however only 'Independent accredited assessors
' that have passed an exam of competency and are continually monitored under an accreditation scheme can produce a BER Energy Rating for a building. These assessors are listed on the SEI website.
Typical Example (Semi-Detached)
The example Semi-Detached dwelling (below) is calculated using the default figures for the notional building; the resultant CDER for the actual building closely matches the MPCDER - demonstrating that the building complies with the requirements under Part L, but with no 'margin of error' should performance of air permeability or thermal bridging be less robust than calculated for at design stage. It also means that any small trade off in thermal performance in wall, floor, roof or glazing performance will automatic lead to a failure. Reducing performance in any one component of the Energy Efficiency systems will reduce the resultant energy label.
*Air changes approx 1/20 of air permeability result as used in UK regs eg, 10m3/(hr.m2) @ 50Pa (UK worst acceptable) is equal to 0.5 air changes.
as notional values above 'C2' Label
Heat recovery & vent.
improvement to achieve 'B1' Label