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  1. Building Regulations (cy)
  2. Approved documents
  3. Approved Document L (Conservation of fuel and power)
  4. Frequently Asked Questions

Frequently Asked Questions

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Part L and the Energy Performance of Buildings Directive - Frequently Asked Questions (April 2007)

General Questions
1. Why was Part L amended in April 2006?
2. What were the main changes in April 2006?
3. What do builders have to do to achieve compliance?
4. What are the improvement's in energy efficiency resulting from the changes in 2005 and 2006?
5. How will industry comply?
6. What further guidance is available?
7. What are the transitional provisions?
8. How will Government promote self-certification?
9. What are SAP and SBEM?
10. Where can I find out about the availability of approved SAP and SBEM software?

Technical and Legal Questions
11. What will be the application of consequential improvement in buildings with floor areas under 1000² which, when extended, have an area greater than 1000m²?
12. What are the minimum energy benchmarks for new buildings?
13. Have energy efficiency benchmarks been published?
14. Who is approved to carry out pressure testing?
15. What is the position when generating equipment is changed commissioning?
16. Clarification of the thermal value of mineral/cellulose fibre quilt?
17. Is it OK to use manually controllable normal internal window blinds as a method of reducing design solar load?
18. Do the new regulations mean that 30% of all lighting needs to be low energy or 30% of energy consumption needs to go to low energy lighting?
19. What is the position regarding use of lighting approved by the energy Savings Trust?
20. Is it unlawful to install a non-condensing boiler?
21. Is it acceptable to fit a condensing boiler in a bathroom cupboard?
22. What are the rules regarding the proximity to neighbouring property of flue from condensing boiler, and what are the possible remedies for nuisance?
23. Do single pipe systems have to be replaced with double pipe systems?
General Questions

Q1. Why was Part L of the Building Regulations (Conservation of fuel and power) amended in April 2006?
A. i) To reduce CO2 emissions from buildings in line with the commitments made in the 2003 Energy White Paper ; and
ii)  To implement part of the Energy Performance of Buildings Directive (EPBD).

Q2. What are the main changes to Part L that came into effect in April 2006?
A. i) The 3 methods for demonstrating compliance in the 2002 Approved Documents replaced by a single calculation method (which sets maximum carbon dioxide emissions for whole buildings);
 ii) The CO2 emissions standards for new buildings have been raised by between 20% and 28% compared to 2002 standards, depending on the type and size of buildings;
 iii) Standards for work on the existing stock of buildings will be generally higher than in 2002:
- when building work is carried out on buildings with a floor area greater than 1000 m2, "consequential improvements" must also be made to the whole building where practical and cost-effective.  Consequential improvements are improvements to the fabric of the rest of the building to improve its energy efficiency;
- where more than 25% of the surface area of a "controlled element" (such as a wall elevation) is renovated, the energy efficiency of the whole element should be improved;
- as part of a material change of use, any retained element or fitting whose thermal performance is worse than a defined threshold should be upgraded;
- as part of a material alteration, any element that becomes part of the external envelope, where previously it was not, should be upgraded if its thermal performance is worse than a defined threshold.
 iv) The changes implement Articles 3 to 6 of the EPBD:
 Article 3 – the adoption of a methodology for calculating the energy performance of buildings;
 Article 4 – that minimum building energy performance standards should be set using this methodology;
 Article 5 – that new buildings meet these minimum performance standards, and that for buildings over 1000 m2 the viability of 'Low or Zero Carbon' (LZC) systems should be evaluated;
 Article 6 – that the energy performance of buildings over 1000 m2 undergoing major renovation should be upgraded where practical and cost-effective.

Q3. What will builders have to do to achieve compliance with the new Part L requirements?
A. Compliance involves demonstrating that:
1. the CO2 performance target has been met;
2. elements of the design do not fall outside energy efficiency limits unless there are exceptional circumstances;
3. the building will not suffer from excessive solar gain;
4. the building as constructed matches the design intent;
5. information is provided to enable the building to be operated efficiently.

Q4. What improvements in energy efficiency can be expected following the revisions to Part L in 2005 (boiler amendment) and 2006?
A. The commitment in the Government's February 2003 Energy White Paper was for a further substantive uplift in the energy efficiency of new buildings. The revisions made in 2006 are cost-effective, taking into account for the first time the social cost of carbon emissions, valued by the Treasury at around £75 per tonne of carbon emissions.
 The energy efficiency standards in the previous Building Regulations (Part L1 for dwellings and Part L2 for other buildings) came into effect on 1 April 2002. The changes were significant, so that, for instance, for new dwellings energy performance was expected to be 25% better than before.
 The cumulative effect of the 2002 and 2006 changes remains substantial at around a 40% improvement in the energy efficiency of buildings.

Q5.  How are you going to ensure that the industry will comply with the new measures?
A.  The Government said in the Energy White Paper that it would work with local authorities to see how compliance with the Building Regulations could be improved. Measures being implemented or under consideration include:
1 A simplified single approach to showing compliance.
2 A substantial dissemination and training campaign targeted at building control bodies and industry - this started in 2005 and ran into 2006.  An e-learning pack was sent to all building control bodies in England and Wales.
3 Simplified technical guidance in the new Approved Documents backed up by reference documents that contain technical details developed in conjunction with the relevant industries.
4 The setting up of a number of new competent person self-certification schemes allowing registered individuals or companies to self-certify compliance of certain elements of works with the Building Regulations.

Q6. What further guidance is available?
A. Publication of the National Calculation Methodology will be published shortly.  All the new technical guidance supporting the Approved Documents have already been published.  The new technical guides have been published as priced Department for Communities and Local Government documents but they will also freely available on the DCLG web site for downloading.  An e-learning pack that walks through the new Part L as applied in an example building situation has been circulated to all local authority building control officers and approved inspectors in England and Wales.  The technical guides are:
• Low or Zero Carbon Energy Sources: Strategic Guide
• Domestic Heating Compliance Guide
• Non-Domestic Heating, Cooling and Ventillation Compliance Guide
• The thermal performance of multi-foil insulation
• Accredited Construction Details.
All of these can be viewed or downloaded by visiting the following page on the Planning Portal website:

Q7. What are the transitional provisions?
A.  Part L 2006 applies from the 6th of April 2006.  Transitional arrangements are set out in Annex H of the ODPM Circular issued on the 15th March 2006.  This can be viewed or downloaded from the DCLG website via the following link:  http://www.communities.gov.uk/index.asp?id=1164205. Further guidance is contained in the Circular letter dated 30 March 2006. This can also be viewed or downloaded via the link:  http://www.communities.gov.uk/index.asp?id=1165013.

Q8. How will Government promote the development of self-certification schemes to improve regulation?
A. The current system of Competent Person schemes allows members to self-certify that their work meets the requirements of the Regulations.  A number of new schemes have been authorised, mainly in the heating, plumbing, ventilation and air-conditioning sectors to help deliver compliance with the standards in Part L.  Schemes have been authorised for pressure testing and CO2 emission rate calculations. 

Q9. What do “SAP” and “SBEM” mean?
A. SAP 2005 (Standard Assessment Procedure for The Energy Rating of Dwellings) is the approved calculation tool for the calculation of the energy performance of dwellings. 
SBEM (Simplified Building Energy Model) is an approved calculation tool for the calculation of the energy performance of buildings that are not dwellings.

Q10. Where can I find out about the availability of approved SAP and SBEM software?
 A. A list of approved software is maintained on the SAP website at www.bre.co.uk/sap2005 . The website also contains details of approved commercial software applications of SAP 2005.  Information on SBEM approved software can be found on the National Calculation Method website at: http://www.ncm.bre.co.uk/ .


Q11. When a building is to be extended, Regulation 17D requires a consequential improvement to be made if the building is greater than 1,000m² total useful floor area. Does this apply to the area of building as it was, or as it will become?
A. The threshold for consequential improvements relates to the size of the existing building before the planned work takes place. Therefore, if an existing building with a total useful floor area of 800m2 is to be extended by 300 m2 for instance, the construction of the extension itself would have to comply with the energy efficiency requirements, but there would be no requirement for a consequential improvement.  See Page 10 of ADL1B.

Q12. What are the minimum energy benchmarks for new dwellings?
A. With effect from 06 April 2006 performance standards for new dwellings are set on the basis of annual carbon dioxide emissions comparing the proposed design with a notional building having the same size and shape etc built to comply with the specifications in Annex N to SAP 2005.  Appendix N is based on the performance standards given in the Elemental Method in Approved Document L1 published in 2002.  The proposed building must be 20% better than the notional building.  This system provides design flexibility but there are limits on this flexibility which are given in Approved Document L1A as applicable in normal circumstances.

Q13. Have benchmarks for energy efficiency been published in parallel to the revised Building Regulations?
A. No. General benchmarks for overall energy efficiency have been published as such. However, the notional building used as the basis of setting the CO2 target provides a specific benchmark, in that it represents the performance of a building of the same size, shape and usage pattern as the actual building constructed to the elemental standards set out in the 2002 editions of the Approved Documents for Part L.  The proposed building must be 20% better than the notional building in the case of new dwellings and from 23.5% to 28% better for other buildings dependent upon whether air conditioning etc is proposed.   See Table 1 in ADL2A.

Q14.  Who is approved to carry out pressure testing?
A. Someone approved under the appropriate scheme with the British Institute for Non Destructive Testing (BINDT), or someone whom the the local authority has satisfied themselves that they meet the requirements.

Q15. If a renewable generator is put into a building and this is taken into account for CO2 emissions when it is built, what would then happen if, when the building was up and running, the renewable generator did not work as expected and they were not able to use this.  Would they be inspected again as a follow up?
A. Three points are relevant in this context:
 1. Renewable energy technologies taken into account in the calculation of CO2 emissions are limited to types included in the various Appendices of the Standard Assessment Procedure for the Energy Rating of Dwellings, especially Appendix M: Energy from photovoltaic technology and Appendix N: Micro-cogeneration (also known as Micro-CHP), or supported by specific performance data, as detailed in Appendix Q: Special features and specific data.
 2. Criterion 2 of ADL1A sets limits on design flexibility, including thermal insulation, which effectively reduces the extent of reliance on low carbon technologies for achieving the target for CO2 emissions.
 3. Criterion 4 requires that heating and hot water systems be adequately commissioned.
 Together, these points should tend to ensure that only well tested technology is used, that overall performance is not excessively dependent on the performance of the technology, and that it should be working at the time the building control process is completed.  Further guidance on suitable systems is given the DCLG publication: Low or Zero Carbon Energy Sources: Strategic Guide.  This can be viewed or downloaded via the following link: http://www.planningportal.gov.uk/buildingregulations/approveddocuments/partl/bcassociateddocuments9/further .  Long term performance is not guaranteed, however, and there is no mechanism for intervention by building control to assess it.

Q16. Can you clarify the requirement in AD L1B table A1 for 250mm mineral/cellulose fibre quilt to provide a thermal value of 0.16 W/m2K for pitched roof construction?
A. The entry in Table A1 refers to "quilt laid between and across", which means that there are at least two layers of insulation and that there should be 150 mm insulation on top of the joists to minimise the thermal bridging effect.  If the thermal conductivity of the mineral wool is 0.04 W/(mK), the overall U-value of the roof should meet the target value of 0.16.  If the thermal conductivity is higher (0.044 W/(mK), it is necessary to increase the thickness of the second layer to 170 mm.  Manufacturers may be erring on the side of caution in some cases.

Q17. Is it OK to use manually controllable normal internal window blinds as a method of reducing design solar load?
A. Yes.  In some cases only.  Paragraph 25 on page 19 of ADL2B states that:
 If the area of windows, roof windows (but excluding display windows) within the areas served exceeds 40% of the façade area or the area of roof-lights exceeds 20% of the area of the roof and the design solar load exceeds 25W/m2, then the solar provisions should be upgraded such that at least one of the three following criteria is met:
 the design solar load is no greater than 25W/m2
 the design solar load is reduced by at least 20%
 the effective g-value is no worse that 0.3.
 This will reduce the solar gain and hence the space cooling demand. The calculation of the effective g-value is explained in CIBSE TM37.  It would therefore suggest that if the triggering criteria are met then it would be acceptable to use internal blinds if they meet any one of these requirements.  It will naturally depend on the size and orientation of the windows and the type of the blinds specified.

Q18. Do the new regulations mean that 30% of all lighting needs to be low energy or 30% of energy consumption needs to go to low energy lighting?
A 30% of the fixed lighting fittings must be low energy fittings and the SAP procedure calculates the lighting energy according to the correction factor in Appendix L.
 A light fitting may contain one or more lamps. Installing mains frequency fluorescent lighting in garages may cause dangers through stroboscopic interaction with vehicle engine parts or machine tools.  Fluorescent lamps with high frequency electronic ballasts substantially reduce this risk.  Lighting fittings in less frequented areas like cupboards and other storage areas would not count.
 GIL 20 gives guidance on identifying suitable locations.  SAP 2005 Appendix L uses the ratio of fixed low energy lighting outlets to the total number of fixed lighting outlets to correct the lighting energy consumption. 

Q19. With regard to energy efficient lighting, the regulations say that a certain type of cap on the lamps is to be used in order to be approved by the regulations.  What is the situation with lamps that are approved by the Energy Savings Trust and show approved stickers? Are these actually approved?
A. The guidance on fixed internal lighting is given in paragraph 42 of ADL1A which states that: "A way of showing compliance would be to provide lighting (including lamp, control gear and an appropriate housing, reflector, shade or diffuser (or other device for controlling the output light) that can only take lamps having a luminous efficiency of greater than 40 lumens per circuit-watt."
 A further sentence states: "Light fittings for GLS tungsten lamps or with bayonet cap fittings or Edison screw bases, or tungsten halogen bases clearly would not" [meet this standard.]   This is despite the fact that compact fluorescent lamps are available with such fittings and that they are widely promoted by the EST and others as replacements for GLS lamps.  The restricted type of fittings required in ADL1A are intended to discourage householders from reverting to tungsten GLS lamps.
 The guidance applies to the installation of fixed lighting circuits in areas affected by building work or new dwellings, covering at least 25 % of the relevant floor area.  It does not apply to homeowners buying replacement lamps for existing circuits, in which bayonet cap fittings are predominant and for which the energy efficient lamps he refers to are well suited.

Q20. During a building refurbishment a boiler was installed which is not a condensing boiler and therefore it doesn't comply with legislation.  Is this is a breach of legislation and a legal offence?
A. Upon completion of the installation, a CORGI-registered gas installer should have notified CORGI under the Gas Work Notification procedure, and CORGI should then have sent a commissioning certificate to the householder a few days later.  This requirement applies to both condensing and non-condensing gas boilers installed since 1st April 2005.  If the installer didn't do that, there may have been a breach of the Building Regulations.
 A non-condensing boiler would be justified if the installer carried out the boiler installation assessment procedure (Appendix G of Approved Document L1) correctly, found that the property qualified, signed the form, and gave one copy to the householder.  If he didn't, there may have been a breach of the Building Regulations. 
 If there is a breach of Regulations the remedy becomes a legal question therefore a Building Control Officer or other advisor concerned with enforcement should be consulted.

Q21. Would fitting a combination boiler (including controls) in a bathroom cupboard be acceptable within Part L of regulations?
A. Part L does not introduce specific restrictions on where the boiler can be fitted. The bathroom must be considered along with all other locations if assessing the case for a non-condensing boiler - see Appendix A of the Domestic Heating Compliance guide. (This guide is referred to in the Approved Documents ADL1A and ADL1B).   The Guide can be viewed or downloaded via the following link:
 The boiler position must meet the requirements of manufacturers’ instructions, Building Regulations Parts J and P, the Gas Safety (Installation and Use) Regulations and relevant standards such as BS 5440.  A particular consideration for bathroom installations is the electrical safety requirements in Part P. The installation of a boiler and controls in a bathroom cupboard is an accepted way of dealing with some of these more difficult requirements.

Q22. What is the situation where the plume from the flue of a neighbouring property is causing a nuisance?
A. Part J of the Building Regulations and the Gas Safety (Installation and Use) Regulations include requirements for the safe location of flue terminals with respect to property boundaries.  Approved Document J gives guidance on what would be reasonable distances for safety.  In some cases it is possible that the flue installation complies with the Building Regulations health and safety requirements but represents an unwelcome nuisance.  In these circumstances the Building Regulations cannot be used to obtain redress. 
 Part III of the Environmental Protection Act 1990 addresses statutory nuisance and clean air.  It considers whether fumes or gases emitted from premises constitute "statutory nuisances".  Under the Act it is the duty of every local authority to take such steps as are reasonably practicable to investigate any complaint.  If is felt that a local authority have not discharged their responsibility properly in relation to a complaint under the Environmental Protection Act, it is open to the complainant to take his/her case to the Local Government Ombudsman.
 Also, under Section 82 of the Environmental Protection Act 1990 a person can take action if affected by fumes/gases amounting to a nuisance by bringing the circumstances of the matter direct to a Magistrates’ Court.
 If it is certain that there is only one position for the boiler, a vertical extended flue may be possible.  This would allow the flue products to disperse at a high level and reduce the possibility of nuisance. Note also that modern boilers are relatively small and can be fitted on internal walls, loft areas, etc with relatively small diameter extended horizontal and vertical flues, therefore other boiler positions may be possible.

Q23. With regard to heating systems do single pipe systems have to be replaced with the twin pipe systems?
A. When a boiler is replaced the system must comply with Part L.  In practical terms meeting the minimum requirements given in the Domestic Heating Compliance Guide* will achieve this.  It covers the water circulation and control requirements of space heating and hot water systems. This is usually interpreted as: 
 - Upgrade to fully pumped from gravity circulation if required  
 - Install time controls  
 - Install interlock (room thermostat AND cylinder thermostat + motorised valve(s) for a regular boiler system and room thermostat for a combination boiler system)  
 - Install bypass where necessary
 Whilst it is preferable to use a two-pipe system, there are no specific requirements in the Building Regulations that a one-pipe system should be upgraded when replacing a boiler.  A condensing boiler can usually be connected to a one-pipe system, unless the boiler manufacturers’ instructions say otherwise.  A two-pipe system would normally be necessary if it were also intended to install thermostatic radiator valves.  This is preferable but, it is not deemed to be ‘reasonable provision’ to force a customer to install thermostatic radiator valves on an existing system. It would be considered good practice for the installer to quote for the work requested from the customer and then split the quote to cover the aspects of the installation they recommend needing to be undertaken to fully comply with the requirements of the Building Regulations.