What is a U-value?
"A U-Value is the measure of the rate of heat loss through a material" - SEI (Sustainable Energy Ireland)
The U-value of a window is a measurement of the rate of heat loss indicating how well your windows are keeping valuable heat in. The lower the U-value the better the thermal performance of the glass also the lower the U-Value the less energy you will require to heat your home
- Significantly reduce energy usage, thus drastically reducing fuel bills (up to 30% of the heat lost from a home is lost from the windows)
- Poor quality windows and doors can result in 50% heat loss in your home
The U-Value of a McGorman Window manufactured with Spectus profile and using Low Iron Vista Therm Elite (Diamant) with Super Warm Spacer bar is U Value = 1.4 and G - Value = 0.43.
VistaTherm Elite Low Iron Glass
The latest innovation in insulated glass:
- Greater comfort and lower energy costs for your home
- High performance insulating glass up to 136% better than standard double glazing
This is achieved through eliminating heat loss during cool months, thus helping to cut energy bills and making your home more comfortable
Building Enery Rating (BER) & Window Energy Rating (WER)
As part of the introduction of the Building Energy Rating (BER) requirement, windows will in future come with a WER (Window Energy Rating).

"Specifying and using energy rated windows will increase the value of your property and also reduce your heating bills."
"Energy efficiency in windows is basically a windows ability to keep heat in/cold out, and allow the sun's solar radiation (heat) to enter your home."
When a company receives accreditations they will receive a WER label, with the information contained on the label, builders and consumers can reliably compare one product with another and make informed decisions regarding the energy performance of window products.
Above you can see McGorman Windows WER Label. The Irish Building Regulation U-Value for a Window is 2.2. We can offer an A-Rated Window with WER 1.4 W/m2 K (see above images)
Triple Glazed Option
McGorman Windows can also offer a Triple glazed option of a 36mm unit as opposed to our standard 28mm - click here to view our PDF brochure.
Energy Rated
PVC windows will Improve the energy efficiency of your entire home! They will lower your fuel bills and can drastically cut the amount of warm air leaving the room.
Sustainable
Unlike other material used in window and door frames, PVC performs extremely
well in terms of sustainability because if offers excellent thermal
performance over a long lifetime. The sustainable features of PVC are:
Leadfree Material
The PVC material we use is without risk to humans or the environment. Our range of windows is lead-free, unlike a lot of other PVC providers, with the use of lead phased out and replaced with Calcium Zinc stabilisers.
Long Life Span
Our PVC is very durable, weather resistant and will keep their finish for a number of years. PVC windows are low maintenance and will last for over 20 years. You can be confident that windows or doors won´t warp, rot or peel and won´t need either preservatives or paint
Recyclable
Our PVC suppliers have made major advances in this area from collection to recycling of manufacturing and end of life cycle waste. PVC is a thermoplastic is made up of mainly salt therefore it can be recycled many times.
Thermal Performance
Our range of PVC windows are designed to give the highest thermal performance at affordable prices. All our windows meet with the criteria of the Building Energy Ratings (BER) U-Value System and the BFRC´s Window Energy Ratings Scheme.
Thermal efficiency for your home
- eliminate heat loss during cool months
- eliminate heat gain during warm months
- help cut your energy costs/fuel bills
- make your home more comfortable
- eliminate uncomfortable cold spots close to window
Spectus PVC-U systems
Spectus PVC-U systems can achieve a Windows Energy Rating of band A.
Through continuous evaluation and improvements in design and quality testing, we have devised a suite of products that maximises the retention of solar heat gain within the property, whilst minimising any thermal and air loss.
And because our systems are designed to provide high levels of energy efficiency, you'll benefit from reducing your carbon emissions and the ability to lower your heating bills.
McGorman Windows manufacture their own products completely on their own site. This ensures full control of the make up and quality of the product.
When combined with energy efficient double glazing units, McGorman Window's A-Rated Windows either meet or exceed all current building regulations and provide excellent thermal protection against the loss of heat from your home.
Spectus' technically-advanced multi-chamber system (See Fig 1.1) allows the fabrication of windows capable of achieving a wide spectrum of energy
performances, including the sought after 'A' Window Energy Rating (WER).
Energy Efficient Windows:
So exactly what are Energy Efficient Windows?
They are windows that help to contain and conserve heat within the home keeping out wind and rain, resisting condensation and yet allowing natural "free" energy - the warmth of the sun - to heat the home.