CI/SfB / / (31.4) / Xh2 / / June 2006 Catalogue No. 260X. Revised PART L Explained

Transcription

1 CI/SfB / / (31.4) / Xh2 / / June 2006 Catalogue No. 260X S T E E L W I N D O W S Revised Explained

2 revised explained... Introduction With effect from April 2006 a revised Building Regulations Approved Document Part L (Conservation of Fuel and Power) was published. This supersedes the Part L document published in April The Revised Regulations exempt from the Building Regulations. Conservatories larger in area than 30 sq m have alternative requirements L1A Work in New Dwellings as follows: The three routes to compliance set out in the 2002 version Achieve a maximum whole window U-value of Part L are scrapped. In future The Target carbon dioxide of 2.0 W/m 2 K, or Emission Rate (TER) is required (see Definitions). Calculations Achieve a maximum glass centre pane value are required for both the designed and constructed of 1.2 W/m 2 K. home and the Target Emissions Rate must be the lower of the two. Heritage The revised Part L differs from its predecessor in a number of fundamental ways: The calculations (which require government SAP software) take account of solar transmittance of the glazing as well as heat loss, and so the energy aspects of the glazing Special allowance is made for buildings of historic, architectural or conservation value. (See page 5). It is published in four, rather than two parts covering New Dwellings, Existing Dwellings, New Buildings Other Than Dwellings and Existing Buildings Other Than Dwellings. It scraps the three alternative routes to compliance in the 2002 document i.e. the Target U Value Method; the are taken into account. For new dwellings the area-weighted maximum average window U-value is 2.2 W/m 2 K. the worst individual element can have a U-value of 3.3 W/m 2 K. L2A New Buildings Other Than Dwellings As with document L1A, the designer must calculate total carbon dioxide emissions for both the proposed and completed building. Elemental Method; and the Carbon Index Method. In respect of windows the new Part L makes no differentiation between different framing materials. Irrespective of the materials selected the designer must L1B Work in Existing Dwellings There are alternative methods of meeting the requirements of the revised Part L for replacement windows as follows: Windows and rooflights can have an area-weighted maximum average of 2.2 W/m 2 K. In cases where the building has a high internal heat gain there is allowance for this U-value to rise to 2.7 W/m 2 K. achieve either a specified whole window or maximum average U-value or a maximum centre pane U-value. An alternative, where applicable, is a specified Window Energy Rating. Achieve a whole window U-value of 2.0 W/m 2 K, or Achieve a glass centre pane U-value of 1.2 W/m 2 K, or Achieve a window Energy Rating of Band E The U-value of any individual window, rooflight or door should be no worse than 3.3 W/m 2 K. Curtain Walling is now included within the scope of the The revised Part L offers the designer and specifier enhanced flexibility in the manner in which they combine the attributes of the various building components and services to meet the target carbon emissions rating for the structure. In this respect, no single building component can accurately be described as complying with Part L but rather can contribute towards the level of compliance that designers must in future be able to demonstrate. The revised Part L tightens the requirements for energy efficient building components established by its predecessor. It applies to windows in new build and replacement situations. As this brochure demonstrates, designers can continue to specify steel windows with the confidence that they will form part of the building envelope demanded by the Exclusions The following are specifically excluded from the revised Part L: 1. Windows, doors and rooflights or roof windows having less than 50% glazing on the internal face. 2. Display windows, shop entrance doors and similar glazing in buildings in use classes A1, A2, A3 and D2. 3. Conservatories with a floor area less than 30 sq m. As a general rule the area of windows, roof windows and doors in extensions should not exceed the sum of 25% of its floor area PLUS the area of any windows and doors that, as a result of the building work, no longer exist or are exposed. The standard for new windows, roof windows or rooflights in extensions should be as follows: Achieve a whole window U-value of 1.8 W/m 2 K, or Achieve a glass centre pane U-Value of 1.2 W/m 2 K, or Achieve a Window Energy Rating of Band D The U-value of any individual window, rooflight or door should be no worse than 3.3 W/m 2 K. Conservatories revised regulations as follows: A limiting U-value of 2.2 W/m 2 K (area-weighted average) or 3.3 W/m 2 K (for any individual element) should be applied to the glazed area of the curtain wall. Display windows are excluded from the regulations. There is no limit on the design flexibility for display windows but their impact on CO2 emissions must be taken into account in calculations. L2B Work In Existing Buildings That Are Not Dwellings There are alternative methods of meeting the requirements of the revised Part L for replacement windows as follows: Achieve a whole window U-value of 2.2 W/m 2 K, or Achieve a glass centre pane U-value of 1.2 W/m 2 K Achieve a Window Energy Rating of Band E new regulations. Conservatories with a floor area less that 30sq m are Display windows are excluded from these requirements. 2 3

3 Historic Buildings and others of special character In cases where the building has a high internal heat gain there is allowance for the whole window U-value to rise to 2.7 W/m 2 K. Achieve a maximum whole window U-value of 2.2 W/m 2 K, or Achieve a maximum glass centre pane value of 1.2 W/m 2 K Heritage Special allowance is made for buildings of historic, It is often the case that existing buildings with steel windows are buildings of an historic nature. As with its predecessor the latest version of Part L also recognises that there is a need to conserve the special characteristics of historic buildings, taking fully into account the views previously expressed by English Heritage. energy efficiency where, and to the extent that it is, practically possible, provided that the work does not prejudice the character of the host building or risk the long-term deterioration of the building fabric or fittings. The guidance given by English Heritage in its guidance note Building Regulations and Historic Buildings first published in 2002 should be taken into account. These include conventional extensions as well as enclosing existing structures that are partially enclosed (e.g. covering over a courtyard). The revised document differentiates between large and small extensions. Where an extension is greater than 100 sq m in area and greater than 25% of the floor area of the existing building it is to be regarded as a new building and designers must refer to L2A for guidance. For smaller extensions the alternatives are as follows for new windows in extensions: Achieve a whole window U-value of 1.8 W/m 2 K, or Achieve a glass centre pane U-value of 1.2 W/m 2 K Conservatories Conservatories with a floor area less that 30 sq m are exempt from the Building Regulations. Conservatories larger in area than 30 sq m have alternative requirements as follows: architectural or conservation value. (See page 5). Definitions TER is the Target carbon dioxide Emission Rate which is defined as the minimum energy performance required for new dwellings, expressed in terms of the mass of CO2 emitted as a result of the provision of heating, hot water, ventilation and internal fixed lighting. The method of calculating the TER is specified in L1A Page 16 of the Approved Document. U-values shall be calculated using the methods and conventions set out in Building Regulations 443. Scotland The current version of the Building (Scotland) Regulations came into effect in May The Scottish Building Standards Agency was initiating a consultation in March 2006 on proposed changes to the regulations governing energy efficiency with a view to bringing those changes into effect from May Under the revised Part L special considerations apply if the building on which work is to be carried out has particular historic or architectural merit. Such buildings are defined as follows: A. Listed buildings B. Buildings of local architectural and historical interest and which are referred to as a material consideration in a local authority s development plan C. Those buildings situated in conservation areas, national parks, areas of outstanding natural beauty and world heritage sites where the local planning authority s conservation officer has advised that special considerations should apply in the particular case These definitions cover a wide range of properties, either as individual structures or within the context of their neighbourhood. When undertaking work on or in connection with buildings of special historic or architectural value, the revised documents say the aim should be to improve A balance needs to be struck between historic building conservation and energy efficiency improvements. The local authority s conservation officer should always be approached for advice in these circumstances. English Heritage is quite clear that window openings establish the character of an elevation; they should not generally be altered in their proportion or details, especially when they are a conspicuous element of the design. Particular instances where advice from the local authority conservation officer would be beneficial include: A. restoring the historic character of a building that had been subject to previous inappropriate alteration e.g. replacement windows, doors and rooflights B. rebuilding former historic buildings e.g. after a fire or in-filling a gap site in a terrace C. making provisions enabling the fabric of historic buildings to breathe, so to control moisture and potential long-term decay problems Document U-Value Centre Pane Value Relaxations W/m 2 K W/m 2 K L1A 2.2 (New Dwellings) (maximum average) L1B 2.0 (Existing Dwellings) 1.8 Conservatories 2.0 (more than 30 sq m) L2A (New Non Dwellings) (maximum average) (with high internal heat gain) L2B (Existing Non Dwellings) (with high internal heat gain) 1.8 Conservatories 2.2 (more than 30 sq m) U-Value 4 5

4 Crittall Products For residential projects Crittall offers: Crittall offers the designer and specifier a range of steel windows, any of which can be used with confidence in contributing to a design that meets the requirements of the revised Part L of the Building Regulations which came into force in April FAQs All products are hot-dipped galvanised and Duralife polyester powder coated to the specifier s colour choice. Q. When did the revised Part L come into effect? Steel-framed windows also offer a slim profile and unmatched strength for added security. A. On April 6, ALL CRITTALL STEEL WINDOW PRODUCTS MEET THE CENTRE PANE U-VALUE OF 1.2 W/m 2 K. Q. Will it apply to building work started before this date? A. It will not apply if work started before April The range of Crittall products include: with full building plans approval. If plans have been fully approved but work has not started before this date, it Corporate 2000 Range Corporate W20 Range Homelight Range must start by April , otherwise the new regulations will apply. A high performance steel window and door range particularly suited to new build projects. Extensively used in refurbishment projects and versatile in design. These offer the same size and styles as the original imperial range of steel windows. Q. Are Part L regulations mandatory? A. Yes, they are. Indicative U-value range of 1.9 W/m 2 K 2.5 W/m 2 K Indicative U-value range of 1.7 W/m 2 K 2.4 W/m 2 K Indicative U-value for Homelight L 1.7 W/m 2 K 2.1 W/m 2 K Q. Do they apply throughout the UK? Centre Pane U-value 1.2 W/m 2 K using 4mm float, 4mm low E soft coat and 20mm air gap (argon gas). Centre Pane U-value 1.2 W/m 2 K using either 4mm float, 4mm low E soft coat and 6mm air gap (xenon gas) or 4mm float, 4mm low E soft coat and 8mm air gap (krypton gas). Centre Pane U-value 1.2 W/m 2 K using 4mm float, 4mm low E soft coat and 6mm air gap (xenon gas) DG Range; or 4mm float, 4mm low E soft coat and 16mm air gap (argon gas) L Range. A. No. They will apply in England and Wales. See separate paragraph on Scotland. In Northern Ireland, amendments to Part F of the Building Regulations (Northern Ireland) came into force in June Full details on each product range with steel performance technical information are available from Crittall on: Q. Which part of the regulations apply if a new building is constructed with areas used for accommodation and for commercial purposes? A. Approved Document L1A should be used for guidance in relation to individual dwellings within the building Or contact: and Approved Document L2A for the non-dwelling parts of a building e.g. in the case of a mixed use Technical Department, Crittall, Springwood Drive, Braintree, Essex CM7 2YN. Tel: Fax: hq@crittall-windows.co.uk development, for commercial or retail elements. NB: the term dwelling refers to self-contained dwelling units. Buildings that contain rooms for residential purposes e.g. in nursing homes, are not considered to be dwellings per se and so Approved Document L2A would apply. Crittall is a member of FENSA. 6 7

5 Crittall Windows Limited, Springwood Drive, Braintree, Essex, CM7 2YN Tel: +44 (0) Fax: +44 (0) Crittall Windows Limited, Scottish Regional Office 39 Durham Street, Glasgow G41 1BS Tel: +44 (0) Fax: +44 (0) Further Information Building Regulations Approved Document Part L (Conservation of Fuel and Power) Building Regulations 443 (2002) (U-values) NB: currently under review Available from Department for Communities and Local Government (formerly the Office of the Deputy Prime Minister). Copies and supporting information can be downloaded from the ODPM website at: Building Regulations and Historic Buildings: An interim guidance note on the application of Part L Published by English Heritage (2002 reprinted 2004) can be downloaded from the English Heritage website at: This publication gives a general description of the product and materials. It is the responsibility of the user of this document to ensure that their use is appropriate for any particular application and that such application complies with all relevant local and national legislation, standards, codes of practice and other requirements. Crittall Windows Ltd hereby disclaim all liability howsoever arising from any error in or omission from this publication and all consequences of relying on it. Crittall Windows Limited also reserve the right to modify the details in this publication as products and specifications are updated and improved. Crittall, Homelight, Corporate, and Duralife are registered trademarks.