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Conservatories to Be Included in Part L

21st January 2009

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Mark Hanson, Chair of the Glass and Glazing Federation’s Conservatory Association and Marketing Manager at Ultraframe, gives an early ‘heads up’ on how Part ‘L’ will apply to conservatories from 2010.

The Department for Communities and Local Government (CLG) - and their consultants FM Nectar (FMN) - have been discussing with the conservatory and window industry the proposals for changing the Building Regulations Part L; Conservation of fuel and power, and the supporting Approved Documents, for 2010, 2013 and 2016. This work is currently at the pre formal consultation stage.
To ensure the widest possible consultation, the conservatory and window industry have established the “Fenestration Industry Thermal Performance Working Party” to discuss and feedback comments to CLG and their consultants. Members of the working party are:
Glass and Glazing Federation
Association of Composite Door Manufacturers
Steel Window Association
British Woodworking Federation
British Plastics Federation Windows Group
British Fenestration Rating Council
Council for Aluminium in Building
Network VEKA
National Federation of Glaziers

Although the Thermal Performance Working Party will review windows too, in this feature we are only going to specifically cover the proposals made regarding conservatories and how these could be covered by the Approved Documents; specifically ADs L1B and L2B.
Working Party Proposals
A conservatory is a glazed structure and so to address its thermal performance requires both heat loss and solar gain to be addressed. By definition it is also thermally separated from the house and so needs treating differently to a conventional extension. Importantly, where an energy rated window benefits from solar gain, a conservatory needs to be selective about solar gain. This requires the U value and g value for a conservatory to be specified individually.
Therefore, for 2010, the Fenestration Industry Thermal Performance Working Party have proposed an ‘elemental’ approach, with the following requirements:
Following the constructive discussions with CLG and FMN in December, we welcome the indication that the requirement for “consequential benefits” to be added as pre-condition to an otherwise compliant extension (or indeed conservatory) may well be dropped.

We endorse the proposals that for the 2010 revision, conservatories be permitted based on an elemental approach with the following requirements:
• Side Frames
Maximum U value 2.0 W/m²K (for the whole window) or
Minimum Window Energy Rating Band C with a
Maximum g value on south facing installations 0.55 (for glass only)

• Roof glazing
Maximum U value 2.0 W/m²K (for the whole glazing panel measured vertical plane)
Maximum g value 0.45 (for glass only)
• New floor slabs
Maximum U value 0.35 W/m²K
• Brick dwarf walls
Maximum U value 0.35 W/m²K
• Ventilation
Provision to be required at point of installation for appropriate non-energy consuming means of cooling, including a requirement for purge ventilation of 1/20th of the combined adjacent room and conservatory floor area. A minimum area of this ventilation is to be provided at high level by roof vents. Background ventilation and the use of custom installed blinds also require specification advice.
• Separation from main dwelling to be of external performance energy standards (doors, windows).
• Heating installed to have independent temperature control.
• Safety glazing requirements under Approved Document N.
• Electrical safety – to comply with Approved Document P.
• For installations not having separation from the main building, separate heating controls or a floor area exceeding 30 sq. metres, the responsibility for ensuring compliance would be directly upon LABC offices and treated as a normal extension.
• It is proposed that the Approved Documents make reference to a revised and updated 78 page “Guide to Good Practice in the Specification and Installation of Conservatories within the United Kingdom”. GGF members currently build to this standard ( as do members of Ultraframe’s own Ultra Installer scheme) and would lead installers into the correct method for construction thus making a good voluntary industry method for compliance.
• It is proposed that a householder guide document is produced giving guidance on how to make the best use of their conservatory. This would be distributed by installers and explain about saving energy and properly ventilating their conservatory.
• And finally, in terms of regulatory control, we would recommend conservatories (as defined with thermal separation from the main house, separate heating controls and under 30m²) should come under Schedule 1 of the Building Regulations. But that any additional LABC inspection or self certification via a Competent Person scheme will result in substantial additional cost beyond that already involved in moving to the proposed elemental standards.
The Working Party will recommend that for 2013 and 2016, that there is a further review of the targets contained in the elements listed above and of course taking into account the introduction of new technologies such as photovoltaics.

In conclusion then, given the state of the economy, it might not be the time that most retailers want to consider changes to what they do. The conservatory sector has a good track record of selling a high performance product and most professional retailers are already doing virtually everything that’s in the Working Party’s proposal. This means that our industry shouldn`t fear these changes.
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