APPROVED DOCUMENT L1B – EXISTING DWELLINGS


Extensions
There are now 3 ways of proving compliance;
a)
Meet min fabric standards (Walls/Floors/Roofs/Windows etc.) and limit area of openings (doors/windows etc.).
b)
Ensure actual average u value of extension is less than average u value of a notional extension. This provides greater design flexibility, and can be calculated simply by using our on-line Heat Loss Calculator
c)
Ensure calculated CO2 emissions for proposed dwelling using SAP 2005 are less than calculated CO2 emissions for dwelling + notional extension. (If elements are up-graded, they must be to min standards).
d)
Heating and lighting must also meet the minimum standards.
Conservatories
As before, (thermal separation/ heating controls) but if conservatory exceeds 30m2 then elements must meet the thermal standards required for extensions, although there is no limit on the area of glazing permitted..
Substantially Glazed Extensions
e.g. Sun Rooms, can now be treated as non-exempt conservatories.
Change of Use - 2 Ways of Proving Compliance;
a)
All new thermal elements being provided must meet the required standard for extensions.
If thermal elements are renovated (>25% surface area), then they mus be up-graded to an improved standard.
If thermal elements are to be retained, then they must be up-graded (including windows) to an improved standard.
Heating and lighting must also meet the minimum standards.
b)
Ensure calculated CO2 emissions for dwelling using SAP 2005 do not exceed those for the same building up-graded in accordance with required standards (as above).

Material alterations
See Change of use
Controlled Services and fittings
a)
Replacement windows – slightly less onerous standard than for new build/ extensions.
b)
Heating and hot water systems – to be installed to minimum standards + commissioning required and notice given to LA
c)
Insulation of pipes and ducts – to min standards
d)
Mechanical Ventilation – perform to minimum standards
e)
Mechanical cooling – to minimum energy efficiency standards
f)
Lighting – minimum provision of energy efficient light fittings
Thermal Bridges/ unwanted air leakage
Report to be submitted by suitably qualified person confirming suitable detailing and construction.

Provision of Information
Operating and maintenance instructions for occupiers.



Page last updated on: 20/09/2010