Our web site uses cookies which allow us to give you the best browsing experience possible and mean we can understand how you use our site.
You can delete and block cookies but parts of our site won't work without them. By using our web site you accept our use of cookies. More Information.

Crittall Windows
Home » Products » Part L and Steel Windows Explained

Part L and Steel Windows Explained

Meeting the latest Building regulations

Crittall Windows has played a full and active role in the Government's consultation on the revision of Part L of the Building Regulations (Conservation of Fuel and Power) that came into force in October 2010.

As a result, architects and designers can continue to specify Crittall Windows' products secure in the knowledge that they may be used in a variety of ways that satisfy the requirements of the revised Part L. (See Table below for indicative U-values of window and door components).

Heritage Buildings

Much of Crittall's work involves installation in heritage buildings. The new Regulations (Part L1B for Existing Dwellings and Part L2B for Existing Buildings Other Than Dwellings) both allow exemptions in the case of heritage buildings. These exemptions apply if compliance with the new energy efficiency requirements would alter the character or appearance of heritage buildings or even risk a deterioration of the building fabric.

Exempt from the regulations

For existing dwellings and existing non-dwellings the exempt buildings are as follows:

  • Listed in accordance with section 1 of the Planning (Listed Buildings and Conservation Areas) Act 1990:
  • in a conservation area designated in accordance with section 69 of that Act; or
  • included in the schedule of monuments maintained under section 1 of the Ancient Monuments and Archaeological Areas 1979

Also exempt are:

  • buildings which are of architectural and historical interest and are covered in a local authority's development plan or local development framework;
  • buildings which are or architectural and historical interest within national parks, areas of outstanding natural beauty etc;
  • buildings of traditional construction with permeable fabric that both absorbs and readily allows the evaporation of moisture.

Indicative U-values of window and door components

Indicative U-values of window and door components
 Approved document Whole window U-value W/m2 Centre Pane Value W/m2 Doors W/m2 Relaxations W/m2
L1A New Dwellings   2.0  n/a  2.0  n/a
 L1B Existing Dwellings*  1.6  1.2  1.8  2.7 with high internal heat gain
L2A New Non Dwellings   2.2  n/a  2.2  n/a
L2B Existing Non Dwellings*   1.8  1.2  1.8  2.7 with high internal heat gain

*WER Band C also acceptable as an alternative

Where replacement windows are unable to meet the requirements because of the need to maintain the external appearance of the facade or the character of the building, replacement windows should meet the centre pane U-value of 1.2 W/m2K or single glazing should be supplemented by low-e secondary glazing.

Where to go for guidance

Guidance issued by English Heritage should be taken into account and Building Control Officers are now instructed by the regulations to take account of the views of the local authority conservation officer.

How we can help

How we can help

In partnership with MLM Building Control Ltd, a well respected Corporate Approved Inspector, Crittall Windows offers an advisory service that gives guidance to professionals seeking planning and building control approval.

Additionally, through MLM, Crittall is able to obtain Building Control Approval for projects as a whole.

To ensure the process of obtaining Building Control Approval for replacement windows is swift and straightforward, Crittall steel windows have been "Type Approved" by MLM Building Control for compliance with the new Part L 2010 (Conservation of Fuel & Power) Building Regulation.

With this knowledge, clients can be assured that Crittall Windows are fully compliant with Part L of the Building Regulations, and can be used with confidence for both replacemt window projects and new build schemes.

Head Office

Francis House
Freebournes Road

Tel: +44 1376 530800
Fax: +44 1376 530801

Crittall ® is a registered trade mark of Crittall Windows Ltd

Window products bearing the trademark or tradename "Hope's" which are manufactured or sold by Crittall Windows Ltd. are not available in the United States or Canada

Web Site Design by mc+co