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WEP (Window Energy Performance) Scheme

NSAI Agrément Window Energy Performance certification WEPNSAI Agrément provides an independent Window Energy Performance (WEP) Certification scheme for the Irish consumer market.  Search the list of certified window systems and their manufacturers.

How to Apply for WEP

Manufacturers who wish to have a NSAI Agrément Window Energy Performance certification their products should review the application process which outlines the terms and conditions of the WEP scheme and WEP application forms


WEP Explained

The WEP rating is provided for a standard window to represent typical window sizes.  This enables a comparison between different products. Each WEP rating label is specific to a unique window frame and glazing assembly from a single manufacturer.  This WEP label is non-transferable and both the window assembly name (1) and the manufacturer (2) will appear on the WEP Certificate.  The WEP Certificate Energy Index(3) combines the following characteristics to allow consumers to determine how well each window assembly will perform.

sample of Window Energy Performance labelEnergy Performance Criteria 

THE THERMAL TRANSMITTANCE (4) (Uwindow or Uw) is a measure of the insulation properties of the window assembly and allows the consumer to compare how effective each window assembly is at containing and conserving heat within a building in the winter. The lower the U-value of the window assembly, the greater the thermal performance of the window. The published U-value combines the thermal transmittance for both the glazing and the window frame.

THE SOLAR FACTOR (5) (gwindow) or Solar Heat Gain Coefficient (SHGC) measures how well a product blocks heat caused by sunlight.  Heat gain can be beneficial in winter months but can also present consumers with additional cooling loads in summer months.  The Solar Factor is expressed as a number between 0 and 1. A lower Solar Factor means less heat gain.

THE AIR LEAKAGE (6) (Lfactor) is a measure of the air tightness of a specific window assembly.  The weakest point in any window arrangement will tend to be around the seals on an opening section of window.  To qualify for the NSAI WEP Scheme, manufacturers must first demonstrate that their window arrangements achieve a Class 4 air tightness rating when tested at 600 Pa to I.S. EN 12207:1999 Windows and doors - Air permeability - Classification.  As a result well-made windows should have little or no air leakage. The lower the air leakage value of the window assembly, the greater the overall efficiency of the window assembly.

 

Additional Information

(7) The certificate identifies if the window assembly has a double or triple glazed unit.
(8) The thermal transmittance of the glazing unit (Ug) is published on the certificate.
(9) The material from which the window assembly is manufactured is identified on the certificate i.e. uPVC, Timber or Aluminium.
(10) The Solar Energy Transmittance (g) is measured perpendicular to the glazing units. The solar energy transmittance (g) is then converted to the Solar Factor (5) (gwindow) in order to make allowances for overshading and inclination of the sun.

The Rating Index for each window assembly is derived by combining Uwindow, gwindow and the Lfactor.
The WEP Rating Band is based on the Rating Index.
For example:-

  • An A1 rated window has a rating index greater than +20 kWh/m²/year.
  • An A3 rated window has a rating index in the range of 0 to +10 kWh/m²/year.
  • A C rated window has a rating index in the range of -20 to -30 kWh/m2/year.


A positive (+) WEP rating represents a better energy performing window.

For further information download:


Click on window type links below to view energy rating label of each certified window.

WEP
Certificate Number
Manufacturer
[website listed]
Window Type Description WEP
Rating New
Rating Index
IAB/W001/009 TJ Grady Ltd Elegance ZE2 Plus PVC U A3 4.95
IAB/W001/011 TJ Grady Ltd Elegance ZE3 Plus PVC U A2 18.29
IAB/W001/012 TJ Grady Ltd Elegance ZE3D Plus PVC U A1 27.03
IAB/W003/007 Senator Windows Senergy Plus PVC U A3 5.47
IAB/W003/008 Senator Windows Senergy Premium PVC U A2 11.41
IAB/W003/009 Senator Windows Senergy Elite PVC U A1 21.68
IAB/W004/003 O'Grady uPVC Ltd Eco-Elite Plus PVC U A3 0.15
IAB/W004/004 O'Grady uPVC Ltd Eco-Elite Triple PVC U A3 5.53
IAB/W005/004 Amber Windows Ltd Earthkind A Plus PVC U A3 7.72
IAB/W005/005 Amber Windows Ltd Earthkind A PVC U A3 -0.14
IAB/W007/001 Grogan & Currid uPVC Ltd. Ecospec PVC U A3 1.92
IAB/W007/002 Grogan & Currid uPVC Ltd. Ecospec+ PVC U A2  17.47
IAB/W008/007 S. Doyle & Sons Ltd Odyssey C70 28 PVC U A2 9.58
IAB/W008/008 S. Doyle & Sons Ltd Odyssey C70 36 PVC U A1 19.76 
IAB/W008/009 S. Doyle & Sons Ltd Odyssey C70 44 PVC U A1 31.40 
IAB/W008/010 S. Doyle & Sons Ltd Energy Plus External PCV U A3 -0.27 
IAB/W008/011 S. Doyle & Sons Ltd Energy Plus Internal  PVC U A3 -0.27 
IAB/W009/005 Maher Windows Maher Eco Rated PVC U A3 6.16
IAB/W009/006 Maher Windows Maher Eco Triple PVC U A3 -0.31
IAB/W012/009 Profile Systems C70 A3 1.40 PVC U A3 -0.40
IAB/W012/010 Profile Systems C70 A2 1.0 PVC U A2 18.39
IAB/W012/011 Profile Systems C70 A3 1.42 PVC U A3 0.42
IAB/W012/012 Profile Systems C70 Triple Seal Passiv PVC U A1 31.40
IAB/W013/002 Fox & O'Rourke Aluminium Fox & O'Rourke C70 A-Rated PVC U A3 0.55
IAB/W014/001 Kells Window Restoration Systems Kellwin Energy Plus Timber A3 -0.14
IAB/W014/002  Kells Window Restoration Systems  Kellwin Heritage Eco Timber  A3 2.73
IAB/W015/002 Wright Window Systems Eco-Wright Diamond II PVC U A3 0.42
IAB/W015/003 Wright Window Systems Eco-Wright Platinum PVC U A2 12.91
IAB/W015/004 Wright Window Systems Eco-Wright Platinum II PVC U A3 7.85
IAB/W015/005 Wright Window Systems Eco-Wright Passive PVC U A1 31.40 
IAB/W015/006 Wright Window Systems Eco-Wright Platinum 1 PVC U A2 17.02
IAB/W015/007 Wright Window Systems Eco-Wright Natural 1.3 PVC U A3 5.21
IAB/W015/008 Wright Window Systems Wright Legacy 1.2 PVC U A3 1
IAB/W015/009 Wright Window Systems Wright Legacy 0.8 PVC U A2 14.60
IAB/W017/002 Moloney Windows Platinum 36 PVC U A2 9.90 
IAB/W017/003 Moloney Windows Platinum 28 PVC U A3  1.23
IAB/W019/002 Forde Bros Ballinlough Forde Windows A-Rated PVC U A3 0.42
IAB/W019/003 Forde Bros Ballinlough Forde Bros 1.2 Window PVC U A3 2.66
IAB/W020/001 Michael Harrington uPVC Ltd Premium Energy PVC U A3 0.15
IAB/W021/001 Crystal Industries Ltd T/A Crystal Windows Fingal Joinery A-Rated Aluminium Aluminium A3 2.31
IAB/W022/003 Joseph O'Halloran & Sons Ltd Europlus II A PVC U A3 -0.14
IAB/W024/002 Larkin Aluminium Ltd Larkin Double A Rated Window  PVC U A3 6.03 
IAB/W024/003 Larkin Aluminium Ltd Larkin Triple A Rated Window PVC U A2 12.64
IAB/W026/001 TSL Windows TSL A Rated Window PVC U A2 10.27
 

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