1.2.1 This section gives guidance on the minimum level of renewable technologies to be provided to show compliance with Regulation L (2(b). The following represents a reasonable minimum level of energy provision from renewable energy technologies in order to satisfy Regulations L2 (b):
10 kWh/m²/annum contributing to energy use for domestic hot water heating, space heating or cooling, or
4 kWh/m²/annum of electrical energy, or
A combination of these which would have equivalent effect.
For the purposes of the section, “renewable energy technologies” means technology products or equipment that supplies energy derived from renewable energy sources, e.g., solar thermal systems solar photo-voltaic systems, biomass systems, systems using biofuels, heat pumps, aero generators and other small scale renewable systems.
1.2.2 Where a building or development contains more that one dwelling, reasonable provision would be to show that:
Every individual dwelling should meet the minimum provision from renewable energy technologies specified in Paragraph 1.2.1 above or
The average construction of renewable technologies to all dwellings in the building or development should meet that minimum level of provision per dwelling.
Where the latter approach is used, common areas on the building are not included in this calculation.
1.2.3 In the case of electrically powered heat pumps, only energy in excess of 2.5 times the electrical energy directly consumed by the heat pump can be counted towards meeting the minimum level of energy provision from renewable technology. In the case of systems based on biofuels of biomass, appliances must be designed to run on these fuels only, i.e. incapable of providing thermal energy from fossil fuels, to be accepted as renewable technology for the purposes of this regulation. For example a boiler which could operate on either oil or a biofuel mixture would not be considered to be a renewable technology. Similarly a boiler capable of utilizing coal or peat, in addition to a biomass fuel would not be considered a renewable technology.
1.2.4 The use of centralised renewable energy sources contributing to a heat distribution system serving all dwelling units in a development or part of a development e.g. an apartment block, may prove to be more practicable than providing separate renewable energy for each dwelling individually.
1.2.5 As an alternative to providing 10kWh/m²/annum thermal energy (or 4kWh/m²/annum electrical energy) from renewable technology sources, the use of a small-scale combined heat and power (CHP) system which contributes to the space and water heating energy use would be acceptable. This approach may be appropriate in some high density developments e.g. apartment and mixed use developments.
1.2.6 Part D of the Building Regulations requires that all works be carried out with the proper materials and in a workmanlike manner. “Materials” includes products, components and items of equipment and guidance is provided on how products, components and items of equipment can be shown to be “proper material”. Renewable technologies should satisfy the requirements of Part D in the same way as other construction products and materials. A range of standards applicable to renewable energy technologies are given in the “Standards and Other References” Section in this document. For specific renewable technologies, it is intended that SEI will maintain databases of acceptable products together with information on relevant performance characteristics. Products listed in these databases may be assumed to be “proper materials” for the purposes of this Part of the Building Regulations. It is intended to establish databases for
1.3.4.1 To avoid excessive heat losses, reasonable care should be taken to limit the air permeability of the envelope of each dwelling. In this context, envelope is the total area of all floors, walls (including windows and doors), and ceilings bordering the dwelling, including elements adjoining other heated or unheated spaces.
1.3.4.2 The following represents a reasonable approach to the design of dwellings to ensure acceptable levels of air permeability:
Identify the primary air barrier elements (e.g. sheathing, plaster, vapour control layer, breather paper) at early design stage;
Develop appropriate details and performance specification to ensure continuity of the air barrier and communicate these to all those involved in the construction process;
Provide on-site inspection regime and related quality control procedures so as to ensure that the design intention is achieved in practise.
1.3.4.3 Achievement of reasonable levels of air permeability can be facilitated by adopting the standard details referred to in Paragraph 1.3.3.2, together with an appropriate performance specification and the on-site inspection regime and related quality control procedures, referred to in that paragraph. Alternative approaches to element design details and quality control procedures may also be acceptable, provided it can be shown that these approaches provide an equivalent level of performance, as if the standard details, performance specification and quality control procedures referred to above were adopted.
1.3.4.4 Air pressure testing should be carried out on a proportion of dwellings on all development sites. See sub-section 1.5.4 for details of the test procedure, extent of testing, use of test results in DEAP calculations and appropriate measure to be undertaken where the limit set is not achieved. When tested in accordance with the procedure referred to in Sub-section 1.5.4 a performance level of 10m³/ (h.m²) represents a reasonable upper limit for air permeability.
1.5.4.1 Air permeability can be measured by means of pressure testing of a building prior to completion. The procedure for testing is specified in IS EN 13829:2000 “Thermal performance of buildings: determination of air permeability of building: fan pressurisation method”. Additional guidance on testing procedure is given in Sections 2 to 4 of the BSRIA Guide “Air tightness testing for new dwellings” and CIBSE Technical Manual TM 23 “Testing Building for Air leakage”. Permeability is calculated by dividing the air leakage rate in m³/hr by the envelope area in m². The performance is assessed at 50 Pascals pressure difference. It has been empirically determined that for dwellings generally the permeability at 50 Pascals pressure difference is approximately 20 times the air change rate at normal conditions. Guidance on appropriate extent of testing is given in Paragraph 1.5.4.3
1.5.4.2 Subject to the guidance in Paragraph 1.5.4.7, air pressure testing should be carried out on a proportion of the dwellings on all development sites, as outlined in Paragraphs 1.5.4.3 to 1.5.4.6. The tests should be carried out by a person competent to carry out this work. This test report should contain at least the information specified in Section 7 of IS EN 13829.
1.5.4.3 On each development, an air pressure test should be carried out on at least one unit of each dwelling type. One dwelling from the first four units of each dwelling type planned for completion should be tested. The basic number of tests for each dwelling type is presented in Table 4. The total number tested is related to the number of units of that type in the development and to the results achieved in any earlier test carried out. Where a number of apartment blocks are constructed on the same site, each block should be treated as a separate development irrespective of the number of blocks on the site.
Number of units
Number of tests
4 or less
One test
Greater than 4, but equal to or less than 40.
Two tests
Greater than 40, but equal or less than 100.
At least 5% of the dwelling type
More than 100
where the first five tests achieve the design air permeability
where one or more of first five tests do not achieve the design air permeability
At least 2% (for dwellings in excess of first 100 units)
At least 5% of units, until 5 successful consecutive tests are achieved, 2% thereafter.
