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Rooflights: What Are U Values and Why Are They Important?

Increasingly, new build projects as well as existing buildings are maximising the use of natural light together with the thermal properties of modern glass, to create a revolution in how we look at heat retention and accessing light sources.

When you consider the costs involved in paying for artificial light and heat, especially at a time when energy prices are soaring so significantly, rethinking our approach to and reliance on these basic needs makes a lot of sense.

A U value tells us how much heat is lost from a building through different elements, such as windows, walls and floors.

It is a measurement of heat transference, also known as the “overall heat transfer co-efficient”, meaning the higher the number value, the more heat is being lost, and the less environmentally friendly the building is. A lower value therefore indicates greater insulating properties and is more energy efficient.

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Calculating the U Value

The U value of a building element is calculated by working out heat loss for each component of the building. This is determined by the material used, its thickness, and its positioning.

Current building regulations in England and Wales allow for all non-domestic applications, the worst acceptable standard for the thermal performance (U-value) of rooflights in new build work is stated as 2.2 W/m2k. For refurbishment or domestic applications, this figure is reduced to 1.8 W/m2k.

Rooflights are made up of a number of different component materials that each have different properties when it comes to heat transference. Therefore, to find out the U value of this type of element, a number of factors need to be determined.

It is simply not enough to state the glass centre pane U value of the glass unit as this does not represent the U value of the entire rooflight product.

Equally, thermal comparisons between competing rooflight products can only be made when U values for the whole rooflight are considered. A poorly designed triple glazed rooflight product may in fact perform worse than a well-designed double glazed product albeit the centre pane U value of the triple glazed glass unit may be better than that of the double glazed glass unit.

Energy Effecient Rooflights.

Energy efficiency is at the core of our product range at EOS, each of our rooflights boasts U Values significantly lower than current and future building regulations. Our standard fixed products boast a 0.97 W/m2K U Value whereas our ECO Range is tested to a market leading 0.65Wmk system U Value.

In fact our U values are so low that official building standards permit you to increase the amount of glass within your roof area.

So, as well as flooding a building with daylight to naturally enhance the indoor environment, EOS rooflights ensure green energy efficiency by reducing the need for CO2-emitting artificial lighting, whilst guaranteeing that heat isn’t lost unnecessarily.

For green efficient skylights with low U Values, speak to the EOS Rooflights team today

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4.85 Average

250 Reviews

SeanOwen

Looks great. Very solid, good quality. Service was wonderful, delivered in a couple of days as promised

Posted 1 week ago

Andy

We purchased a flat roof light last year and we're so glad we did. It's made such a difference to the light we get into the room and looks amazing too. Top product and great results. Our builder was impressed with it too and how quickly his question was answered when he was installing it.

Posted 1 week ago

Anonymous

As part of my build project I researched many companies looking for good quality skylights and a company that could offer both opening and fixed skylights. EOS fitted all my requirements. Both Elliot and Chris were consummate professionals in dealing with my queries and ensuring I got my delivery on time. The skylights were solidly constructed and we love them. The only thing I will say is that if you order a bespoke size, make sure you can wait 6 weeks from order to delivery.

Posted 1 month ago

IanGriffiths

Very pleased with rooflights . Easy to fit . Great communication both when ordering and delivering. Would definitely buy again.

Posted 1 month ago

PeterJaggard

Brilliant company to work with, always ready to assist, and very good communication. Excellent product, of great quality and looks brilliant, well pleased. Thanks to all at EOS

Posted 1 month ago

MadeleineBradbury

Delighted with our rooflights. EOS did everything they said they would do when they said they would do it. We were a bit nervous about doing our own fitting but we got precise, practical instruction diagrams and all went very smoothly

Posted 2 months ago

JeffereySmith

Excellent rooflights and easy to fit

Posted 2 months ago

AndrewHamilton

Excellent product, delivered on time. Would certainly use this company again,

Posted 2 months ago

Anonymous

Rooflights are high quality and fixing instructions clear.

Posted 2 months ago

PaulSeabright

A great product. The speed and efficiency of the online purchase and then the delivery of the items made the process a hassle free pleasure that is all to rare these days.

Posted 2 months ago

KevinTimmins

From ordering to receiving our rooflight everything went great, we built the upstand ourselves from the drawings supplied and the light fitted perfectly. Excellent product at a great price. Wish everything on our extension went that well. 5 stars all round.

Posted 2 months ago

ShafiqCaan

Hi, excellent service and they added solar control without additional charge.

Posted 3 months ago

Anonymous

Clearly a top quality roof light which is beautifully made. I looked at several manufacturers and the EOS had the best insulation among those I looked at. The frame is substantially made and the glass perfectly set into it. It was really simple to fit and the superb drawings allowed me to construct the kirb with confidence and accuracy. Delivery was fast and the unit well supported and protected on a pallet.

Posted 3 months ago

Jeremy

Very impressed with dealing with EOS, great quality product, courteous and good communication which helped make my decision to purchase the 2 Roof lights I needed from them. Thanks for your help.

Posted 3 months ago

Michael

Roof lights turned up day we asked for van driver was very helpful and in position look great !!!

Posted 3 months ago

Joe

Great product and customer service

Posted 3 months ago

Ray

I was really pleased with the quality of the roof lanterns I ordered 2mt x 1mt and 1.5mt x 1mt. We have all heard the old saying you only get what you pay for and this product is spot on ,great build quality would highly recommend

Posted 3 months ago

Richard

I always get my sky lights from EOS. They are reliable, friendly and very good quality. There technical help is invaluable. Richard Abbey Building

Posted 3 months ago

Andy

We recently bought an opening roof light 1 metre x 1500 and a fixed roof light 1 metre x 1500 and we have found EOS Rooflights very competitive in price and of high quality also technical advice was very good.

Posted 3 months ago

Nicola

In the middle of Covid 19 lockdown they were able to advise, honestly estimating the future timing of delivery. I had to wait, which was not surprising, but their service was very personal.

Posted 3 months ago

Paul

Very good quality flat roof windows , good seling-advice service , fast delivery.

Posted 3 months ago