What is Part L1 (2006)?
Part L (2006) is a facility within the Virtual Environment’s <VE> Compliance view providing facilities for testing compliance with Part L1 of the Building Regulations (2006 edition).
Part L1 (2006) applies to new dwellings in England, Wales and Northern Ireland for which construction did not start before 6th April 2006. Part L1 (2006) uses version 9.8 of the SAP methodology.
Part L (2002) applies to buildings in England, Wales and Northern Ireland for which construction started before 6th April 2006. If construction had not started before that date, the 2006 edition of Part L applies.
Data for the Part L (2006) SAP analysis is taken from the <Virtual Environment> model, supplemented where necessary by inputs specific to the requirements of Part L (2006).
Results of the Part L (2006) SAP analysis are presented in three levels of detail:
Pass/fail verdicts for the methods tested.
A summary of the checks carried out within each method and their results (an HTML file).
A report setting out the analysis in detail (an HTML file).
Certain analysis results are processed and displayed immediately data is entered, providing instant feedback to the user.
Overview of Part L1 (2006)
The requirements of The Building Regulations, Part L1 (2006 edition) as applied to new buildings are set out in Approved Document L1A[1]. This document should be consulted in the course of any submission for Part L1 compliance.
The function and scope of the approved documents is set out in the ‘Use of guidance’ section:
“Approved Documents are intended to provide guidance for some of the more common building situations. However, there may well be alternative ways of achieving compliance with the requirements. Thus there is no obligation to adopt any particular solution contained in an Approved Document if you prefer to meet the relevant requirement in some other way.”
The broad requirements of L1 are set out in the Requirement section of Approved Document L1A[1] (referred to in this document as ‘L1A’). They cover:
Reasonable provision shall be made for the conservation of fuel and power in buildings by:
a. limiting heat gains and losses through i) thermal elements and other parts of the building fabric and ii) pipes, ducts and vessels used for space heating, space cooling and hot water services.
b. providing and commissioning energy efficient fixed building services with effective controls; and
c. providing to the owner sufficient information about the building, the fixed building services and their maintenance requirements so that the building can be operated in such a manner as to use no more fuel and power than is reasonable in the circumstances.
The detailed requirements are outlined in Section 0: General guidance, under the heading Demonstrating Compliance. Five criteria must be satisfied (paragraph numbers refer to L1A):
Criterion 1: the predicted rate of CO2 emissions from the dwelling (the dwelling emission rate, DER) is not greater than the Target Emission Rate (TER) which is determined by following the procedures set out in paragraphs 19 to 23.
Criterion 2: the performance of the building fabric and the fixed building services should be no worse than the design limits set out in paragraphs 32 to 45…
Criterion 3: the dwelling has appropriate passive control measures to limit the effect of solar gains on indoor temperature in summer..
Criterion 4: the performance of the dwelling, as built, is consistent with the prediction made in the DER…
Criterion 5: The necessary provisions for enabling energy efficient operation of the dwelling are put in place…
L1A should be consulted for details of special considerations and exemptions applying to particular classes of buildings.
Some of the requirements of Part L1 cannot be tested in software (Criteria 4 and 5 fall into this category). However, IES aims to provide software covering all requirements that can be so tested.
Methods and Requirements
By contrast to L2 (2002), the 2006 regulations offer only one compliance route. This has some similarity with the Carbon Index Method in the 2002 regulations, though there are important differences. The 2006 regulations have no counterpart of the L1 (2002) Elemental or Target U-value methods.
The requirements tested by the software are Criteria 1 to 3, which are implemented in the software as follows:
