WEP - Window Energy Performance Scheme

NSAI Agrément has introduced an independent Window Energy Performance (WEP) Certification scheme for the Irish consumer market.

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.

ENERGY PERFORMANCE CRITERIA

THE THERMAL TRANSMITTANCE ⁽⁴⁾ (U_window or U_w) 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⁾ (g_window) 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⁾ (L_factor) 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 600Pa 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 (U_g) 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⁾ (g_window) in order to make allowances for overshading and inclination of the sun.

The Rating Index for each window assembly is derived by combining U_window, g_window and the L_factor. 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 -30 to -20 kWh/m²/year.

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

For detailed information download: NSAI Window Energy Peformance (WEP) Scheme Booklet.


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 Band	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/W003/001	Senator Windows	Senergy Plus Window	PVC U	A	A3	1.65
IAB/W003/002	Senator Windows	Senergy Premium Casement Window	PVC U	A	A3	5.08
IAB/W003/003	Senator Windows	Senergy Elite Casement Window	PVC U	A	A2	10.33
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	A	A3	1.92
IAB/W007/002	Grogan & Currid uPVC Ltd.	Ecospec+	PVC U	A	A2	17.47
IAB/W008/001	S. Doyle & Sons Ltd	Energy Plus Int	PVC U	A	A3	0.55
IAB/W008/002	S. Doyle & Sons Ltd	Energy Plus Ext	PVC U	A	A3	-0.14
IAB/W008/003	S. Doyle & Sons Ltd	Energy C70	PVC U	A	A3	0.55
IAB/W008/004	S. Doyle & Sons Ltd	Ecotherm 70	PVC U	A	A3	0.28
IAB/W008/005	S. Doyle & Sons Ltd	Ecotherm 70 Passive	PVC U	A	A1	25.53
IAB/W008/006	S. Doyle & Sons Ltd	V/S Supremacy	PVC U	A	A3	3.29
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	A	A3	6.16
IAB/W010/001	Global Home Improvements	Heat Therm 30 A	PVC U	A	A3	0.28
IAB/W010/002	Global Home Improvements	Heat Therm 30 Plus	PVC U	A	A2	12.38
IAB/W010/003	Global Home Improvements	Heat Therm 30 VS	PVC U	A	A3	3.29
IAB/W010/004	Global Home Improvements	Heat Therm 30 A 828	PVC U		A3	9.45
IAB/W010/005	Global Home Improvements	Heat Therm 30 A 836	PVC U		A2	18.25
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/W013/001	Fox & O'Rourke Aluminium	Fox & O'Rourke 'A' - Rated Window	PVC U	A	A3	0.42
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	A	A3	-0.14
IAB/W014/002	Kells Window Restoration Systems	Kellwin Heritage Eco	Timber	A	A3	2.73
IAB/W015/001	Wright Window Systems	Eco-Wright Gold	PVC U	A	A3	-0.27
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/W016/001	Dalgan Windows	Dalgan Ultratherm 1	PVC U	A	A3	8.77
IAB/W016/004	Dalgan Windows	Dalgan Ultratherm 4	PVC U	A	A3	4.39
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/W019/001	Forde Bros Ballinlough	Forde Bros A-Rated Window	PVC U	A	A3	-0.27
IAB/W020/001	Michael Harrington uPVC Ltd	Premium Energy	PVC U	A	A3	0.15
IAB/W021/001	Fingal Joinery	Fingal Joinery A-Rated Aluminium	Aluminium		A3	2.31
IAB/W022/001	Joseph O'Halloran & Sons Ltd	S/F 70 Passive	PVC U	A	A1	25.53
IAB/W022/002	Joseph O'Halloran & Sons Ltd	S/F 70	PVC U	A	A3	1.92
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/W025/001	Star Elm Frames Ltd	Profile 22 60mm	PVC U		A3	2.60

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