APPROVED DOCUMENT L2A – NEW BUILDINGS OTHER THAN DWELLINGS

Previous methods of showing compliance such as the Elemental Method and Target U-value Method have been omitted. Instead, there is now only one approach to show compliance with the energy efficiency requirements, and this addresses 5 criteria;
a)
CO2 emissions
b)
Building fabric and services performance
c)
Limit risk of summer over-heating
d)
Construction quality control to ensure insulation and air-tightness proposed are actually achieved
e)
User information


CO2 Emissions
a)
The Target Energy Rating (TER) for a notional building must be calculated initially at the design stage, usually using the Simplified Building Energy Model (SBEM).
b)
When the building has been completed, the actual Building Energy Rating (BER) as constructed must be calculated using the same method, to prove it does not exceed the TER.
It is strongly recommended that a preliminary BER is also calculated at the design stage, to give an indication as to whether it will comply on completion.

Design Limits for Envelope Standards;
a)
minimum average u – values
b)
limiting u-values
c)
air permeability
d)
Heating / boilers
e)
Insulation of pipework
f)
Mechanical ventilation standards
g)
Mechanical cooling
h)
Lighting internal / external

Limiting Solar Gains in Summer

In non-air conditioned buildings, expert advice is required to ensure the design is satisfactory. In air-conditioned buildings, an allowance is made for the additional energy consumption in calculating the Building Energy Rating.


Quality of Construction and Air Tightness
a)
Ensure continuity of insulation
b)
Adopt approved design details and prove workmanship satisfactory
c)
Developer must demonstrate that an appropriate system of site inspection is in place – e.g. checklists
d)
Air Pressure testing. All buildings must now be pressure tested, other than;
  • Buildings< 500m2, provided that a higher air permeability is used in calculating the BER.
  • Pre-assembled modular buildings (with certain provisos)
Large extensions where it is not possible to separate off from the rest of the building or large complex buildings, in which case this needs to be properly justified and a suitably qualified person appointed to ensure satisfactory construction.
e)
Commissioning certificates to be provided to Building Control

Providing Information
A Building Log Book must be provided for the owner on completion of the works.



Page last updated on: 20/09/2010