Part L
The new Approved Document L (Conservation of
fuel and power), effective from 6 April 2006, supports the
implementation of the Energy Performance of Buildings Directive and
the
Energy White Paper published in 2003.
Government recognises global warming as a
reality and aims to set a path for cutting the UK’s
CO2 emissions by 60% by 2050, with real progress by 2020. Half
of all CO2 emissions come from buildings, therefore significant
improvements in Building Regulations addressing energy efficiency
is seen as a major contributor to meeting these targets.
The new Part L comprises four documents:
Approved Document L1A (ADL1A) New
dwellings*
Approved Document L1B (ADL1B) Existing dwellings*
Approved Document L2A (ADL2A) New buildings other than
dwellings**
Approved Document L2B (ADL2B) Existing buildings other than
dwelling**
* ADL1A and ADL1B together replace the
exitsing ADL1 (2002 Building Regulations)
** ADL2A and ADL2B together replace the exitsing ADL2 (2002
Building Regulations)
Part L1A – New dwellings
In the context of Part L1A, ‘new dwellings’
refers to new-build houses and flats / apartments. It does not
refer to buildings containing rooms for residential purposes such
as nursing homes, student accommodation, etc.
Part L2A covers these new-build buildings (new
buildings other than dwellings) see later*
* For flats and other
residential buildings with heated common areas then ADL2A applies
to the common areas
This revision of Part L brings a fundamental
change to the way in which compliance is achieved. Along with the
previously available options of the ‘Target U-value method’ and the
‘Carbon index method’, the ‘Elemental method’ of choosing
individual components of the building to a given standard has been
the default method of designing residential dwellings.
The new Approved Document Part L1A (ADL1A)
makes compliance based on the carbon performance of the whole
dwelling.
A whole building measure is given through the
use of a SAP2005 calculation.
This directly addresses the major concern of
the regulations and allows for clear and objective aims.
The withdrawal of the use of the ‘Elemental
method’ of compliance allows greater design flexibility.
Of all the factors that the SAP methodology
takes into account, some factors influence the SAP calculation far
more than others. The factors with the most significant effect are
typically, water storage, ventilation and air-conditioning systems,
heating (including lagging of pipes, ducts, vessels) lighting,
position and orientation, solar gains, occupancy and use, and air
permeability.
U-value calculations and SAP calculations are
separate operations - indeed the U-value calculations of the
external envelope components make up only part of the total SAP
calculation.