PART L ENERGY CONSULTANTS
PART L - EXPLAINED
Part L (Approved Document L), forms a series of approved documents provide general guidance on compliance with the Building Regulations. Approved Document L: Conservation of fuel and power, deals with energy efficiency requirements. Our Part L Energy Consultants are fully qualified to verify compliance with the Part L Guides. Our internal Level 5 Energy Consultants will ensure that compliance is achieved in the most efficient manner possible, providing value for money. We are unique Energy Consultants with Regional Offices throughout the UK.
Approved Document L is broken down into four sections;
- Approved Document L1A: Conservation of fuel and power (New dwellings).
- Approved Document L1B: Conservation of fuel and power (Existing dwellings).
- Approved Document L2A: Conservation of fuel and power (New buildings other than dwellings).
- Approved Document L2B: Conservation of fuel and power (Existing buildings other than dwellings).
Part L2A & 1A focus on the regulations applicable to new builds.
The regulation is stated in Schedule 1 below. Please note that the regulations (shown in green backgrounds) are mandatory, and the Approved Documents are only guidance as to how the mandatory regulation can be achieved.
Schedule 1 – Part L Conservation of fuel and power - Regulation
L1. Reasonable provision shall be made for the conservation of fuel and power in buildings by:
- limiting heat gains and losses–
- through thermal elements and other parts of the building fabric; and
- from pipes, ducts and vessels used for space heating, space cooling and hot water services;
- providing fixed building services which–
- are energy efficient;
- have effective controls; and
- are commissioned by testing and adjusting as necessary to ensure they use no more fuel and power than is reasonable in the circumstances.
Demonstrating Compliance with Part L - Guidance
In the Secretary of State’s view, compliance with the energy efficiency requirements could be demonstrated by meeting the five separate criteria set out in the following paragraphs. Compliance software should produce an output report to assist BCBs check that compliance has been achieved.
NOTE: The output report can benefit both developers and BCBs during the design and construction stages as well as at completion.
Criterion 1: in accordance with regulation 26, the calculated CO2 emission rate for the building (the Building CO2 Emission Rate, BER) must not be greater than the Target CO2 Emission Rate (TER).
Criterion 2: the performance of the individual fabric elements and the fixed building services of the building should achieve reasonable overall standards of energy efficiency.
Criterion 3: demonstrate that the building has appropriate passive control measures to limit solar gains.
Criterion 4: the performance of the building, as built, should be consistent with the BER.
Criterion 5: the necessary provisions for enabling energy-efficient operation of the building should be put in place.
NOTE: Criterion 1 is a regulation and is therefore mandatory, whereas the limits on design flexibility for Criteria 2 are statutory guidance. The calculations required as part of the procedure used to show compliance with this criterion can also provide information needed to prepare the energy performance certificate required by the Energy Performance of Buildings (England and Wales) Regulations 2012 (SI 2012/3118).
Regulation 25A – Low to Zero Carbon Energy Statements
Regulation 25A requires that, before the work starts, the person undertaking the work must carry out an analysis that considers and takes into account the technical, environmental and economic feasibility of using high-efficiency alternative systems in the building design. The following high- efficiency alternative systems may be considered if available, but other LZC systems may also be considered if available:
- decentralised energy supply systems based on energy from renewable sources;
- district or block heating or cooling, particularly where it is based entirely or partially on energy from renewable sources;
- heat pumps.
The analysis should state whether high-efficiency alternative systems have or have not been included in the building design. The requirement relates to considering, taking into account, documenting and making available for verification purposes the analysis of high-efficiency alternative systems.
NOTE: The Building Regulations are technology neutral and do not require that high-efficiency alternative systems or other LZC systems are installed.
Demonstrating Compliance with 25A - Guidance for Part L
Regulation 25A essentially states that proof of the building passing the Criterion, and proof of consideration for LZC technologies must be given in order for planning permission to be obtained.
Proof is delivered within the BRUKL document obtained from the SBEM calculation methodology, and evidence within the energy statement of alternative energy resources. The statement must explain why certain technologies have been avoided, and reasonable explanation for all.
An SBEM is the Simple Building Energy Model, and is purposely used as a national calculation method for comparing buildings of the same type. The SBEM calculated a carbon output, called the Building Emission Rate. This building emission rate is then compared against the target emission rate, to tell if there is a pass or fail. Effectively, the calculation is in place to ensure that all buildings meet a certain level of energy efficiency in terms of carbon emissions.
JPA M&E Consultants will guide you through each stage and will carry out the Energy Statement to get through planning successfully.
Regulation 26 – BER/TER
(Part L Criterion 1)
Where a building is erected, it shall not exceed the target CO2 emission rate for the building that has been approved pursuant to regulation 25 applying the methodology of calculation and expression of the energy performance of buildings approved pursuant to regulation 24.
Demonstrating Compliance with 26 - Guidance for Part L
There are 5 criterions to pass in order for a building to be deemed suitable for constructions, which are all interpretations of the building regulations and given in the Approved Document L guidance.
To demonstrate that the requirement in regulation 26 has been met, the actual Building CO2 Emission Rate (BER) must be no greater (no worse) than the TER calculated from the NCM calculation methodology, approved by the government bodies. Regulation 26 is Criterion 1, and is the only criterion that is mandatory. The rest of the criteria are technically described as guidance.
The TER is established by using approved software to calculate the CO2 emission rate from a notional building of the same size and shape as the actual building, but with specified properties. These specified properties shall be as set out in the National Calculation Methodology (NCM) modelling guide, in the section headed ‘Detailed definition of Notional Building for buildings other than dwellings’. The key components of the notional building specification can also be seen at Table 5. The TER is set equal to the CO2 emissions from this notional building, with no further adjustment being made.
NOTE: The TER is based on a building of the same size and shape as the actual building, constructed to a concurrent specification. This concurrent specification for Part L 2013 is given in the NCM modelling guide. Developers are still given the freedom to vary the specification, provided the same overall level of CO2 emissions is achieved or bettered.
Part L Criterion 2 – Limits on design flexibility
While the approach to complying with Criterion 1 allows design flexibility, paragraph L1(a)(i) of Schedule 1 to the Building Regulations requires that reasonable provision be made to limit heat gains and losses through the fabric of the building, and paragraphs L1(b)(i) and (ii) require that energy-efficient fixed building services with effective controls be provided. The efficiencies and minimum control requirements within the Building Services Compliance Guide should be followed in order to pass this element.
Limiting U Values & Thermal Properties - Part L2A 2013
|Swimming pool basin||0.25 W/(m^2K)|
|Windows / roof windows roof-lights / curtain walling and pedestrian doors||2.2 W/(m^2K)|
|Vehicle access and similar large doors||1.5 W/(m^2K)|
|High-usage entrance doors||3.5 W/(m^2K)|
|Roof ventilators (inc. smoke vents)||3.5 W/(m^2K)|
|Air permeability||10.0 m^3/(h.m^2) at 50 Pa|
Part L Criterion 3 – Limiting the effects of heat gains in summer
This section sets out the approach to limiting heat gains as required by paragraph L1(a)(i) of Schedule 1 to the Building Regulations.
The following guidance applies to all buildings, irrespective of whether they are air-conditioned or not. The intention is to limit solar gains during the summer period to either:
- reduce the need for air-conditioning; or
- reduce the installed capacity of any air-conditioning system that is installed.
This criterion does not reflect overheating values, and is simply a limitation of heat gains through glazing percentage, transmittance (g-value) and room area. There may be instances where zoom rooms fail particularly due to zoning arrangements, therefore the guidance is to show that everything possible has been done to avoid unnecessary heat gains. If a room is shown to not be overheating in accordance with TM52, and is cooled naturally, then effectively this criterion could be argued as it does not increase the carbon emissions of the building.
Part L Criterion 4 – Building performance consistent with the BER
Buildings should be constructed and equipped so that performance is consistent with the calculated BER. As indicated in paragraph 2.15, a calculation of the BER is required to be submitted to the BCB after completion to take account of:
- any changes in performance between design and construction; and
- the achieved air permeability, ductwork leakage and commissioned fan performance.
NOTE: The following paragraphs in this section set out what in normal circumstances would be reasonable provision to ensure that the actual performance of the building is consistent with the BER. The results referred to in paragraph 2.14 would assist the BCB in checking that the key features of the design are included as specified during the construction process.
All buildings that are not dwellings (including extensions which are being treated as new buildings for the purposes of complying with Part L) must be subject to pressure testing, with the following exceptions:
- Buildings less than 500 m2 total useful floor area; in this case the developer may choose to avoid the need for a pressure test provided that the air permeability used in the calculation of the BER is taken as 15 m3/(h.m2) at 50 Pa.
NOTE: Compensating improvements in other elements of the building fabric and building services will be needed to keep the BER no worse than the TER.
- A factory-made modular building of less than 500 m2 floor area, with a planned service life of more than two years at more than one location, and where no site assembly work is needed other than making linkages between standard modules using standard link details. Compliance with regulation 43 can be demonstrated by giving a notice to the local authority confirming that the building as installed conforms to one of the standard configurations of modules and link details for which the installer has pressure test data from a minimum of five in-situ measurements incorporating the same module types and link details as utilised in the actual building. The results must indicate that the average test result is better then the design air permeability as specified in the BER calculation by not less than 1.0 m3/(h.m2) at 50 Pa.
- Large extensions (whose compliance with Part L is being assessed as if they were new buildings – see Approved Document L2B) where sealing off the extension from the existing building is impractical. The ATTMA publication gives guidance both on how extensions can be tested and on situations where pressure tests are inappropriate. Where it is agreed with the BCB that testing is impractical, the extension should be treated as a large, complex building, with the guidance in paragraph 3.12d applying.
- Large complex buildings, where due to building size or complexity it may be impractical to carry out pressure testing of the whole building. The ATTMA publication indicates those situations where such considerations might apply. Before adopting this approach developers must produce in advance of construction work in accordance with the approved procedure a detailed justification of why pressure testing is impractical. This should be endorsed by a suitably qualified person such as a competent person approved for pressure testing. In such cases, a way of showing compliance would be to appoint a suitably qualified person to undertake a detailed programme of design development, component testing and site supervision to give confidence that a continuous air barrier will be achieved. It would not be reasonable to claim air permeability better than 5.0 m3/(h.m2) at 50 Pa has been achieved.
NOTE: One example of a suitably qualified person would be an ATTMA member. The 5.0 m3/(h.m2) at 50 Pa limit has been set because at better standards the actual level of performance becomes too vulnerable to single point defects in the air barrier.
- Compartmentalised buildings. Where buildings are compartmentalised into self-contained units with no internal connections it may be impractical to carry out whole building pressure tests. In such cases reasonable provision would be to carry out a pressure test on a representative area of the building as detailed in the ATTMA guidance. In the event of a test failure, the provisions of paragraphs 3.13 and 3.14 would apply, but it would be reasonable to carry out a further test on another representative area to confirm that the expected standard is achieved in all parts of the building.
What happens if you fail the air permeability test?
If satisfactory performance is not achieved, then remedial measures should be carried out on the building and new tests carried out until the building achieves the criteria set out in paragraph 3.13.
NOTE: If the measured air permeability on retest is greater than the design air permeability but less than the limiting value of 10 m3/(h.m2) then other improvements may be required to achieve the TER. This means that builders would be unwise to claim a design air permeability better than 10 m3/(h.m2) unless they are confident of achieving the improved value.
Further evidence for satisfaction of Criterion 4 includes for commissioning plans to be followed and in accordance with CIBSE recommendations.
Part L Criterion 5 – Provisions for energy-efficient operation of the building (The Log Book) - Regulation
In accordance with regulation 40, the owner of the building should be provided with 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
Building log book
A way of showing compliance with regulation 40 would be to produce information following the guidance in CIBSE TM 31 Building log book toolkit. The information should be presented in templates as or similar to those in TM 31. The information could draw on or refer to information available as part of other documentation, such as the Operation and Maintenance Manuals and the Health and Safety file required by the Construction (Design and Management) (CDM) Regulations.
NOTE: Further advice is provided in BSRIA BG 26/2011 Building manuals and building user guides.
The data used to calculate the TER and the BER should be included with the log book. The occupier should also be provided with the recommendations report generated with the ‘on-construction’ energy performance certificate. This will inform the occupier how the energy performance of the building might be further improved.
NOTE: It would also be sensible to retain an electronic copy of the TER/BER input file for the energy calculation to facilitate any future analysis that may be required by the owner when altering or improving the building.
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