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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.

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.

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.

Firstly, the ability of each component material to conduct heat must be identified. This is shown as a ‘K value’. This value is used along with the thickness of the given material (d) in the following equation to give the resistance of the component material:

R = (1/k) x d

A resistance value (R) must then be found for each component material.

Next, the internal and external faces of the building element must be taken into account. These are known as external and internal resistances and are fixed values. This information is then combined in the following equation to discover the U value (U):

U = 1 / (Rso + Rsi + R1 + R2 …)

Rso is the fixed external resistance and Rsi is the fixed internal resistance, whilst R1, R2… give the sum of the resistances previously worked out for the different building materials in the building element.

Current building regulations in England and Wales allow a maximum U value of 2.2 W/m2K for skylights, covering 20% of the roof surface.

Green Energy Rooflights

 

All rooflights from EOS are energy efficient and feature U values as low as 0.97 W/m2K.

The EOS Eco roof lights, which are triple-glazed and injected with Krypton Gas, have an even lower U value of 0.65 W/m2K and include a centre pane U value of 0.6 W/m2K.

The U values of these skylights are so low that official building standards permit them to make up an additional 10% of the roof area than other, less energy efficient designs – taking total potential coverage to 30%.

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.

 

Image Sources

Green house courtesy of Pixabay via CreativeCommons

4.78 Average

85 Reviews

Richard Brown

Rooflight arrived on the day promised and was a good quality product at a good price.

Posted 1 day ago

Euan Pringle

As a builder having used various different roof lights we continue to recommend and use EOS to our clients for three reasons 1. They give maximum light as the frame is minimal and this makes for a great look inside 2. They are competitively priced in the market 3. They have off the shelf stock roof lights available in 3 - 5 days and have delivered on time every time so far. 10/10 for quality and service

Posted 1 day ago

Anonymous

Great customer service and efficient delivery... really quick and fitted perfectly in our extension. Price is very competitive! definitely recommend them

Posted 1 day ago

Stephen Johnson

Simple installation of a very well made, high quality product can only leave you with a happy client, a happy client is always good for future business.

Posted 1 month ago

Hugh Jones

Very good quality product and very good service

Posted 2 months ago

Jonny Clowes

Best opening roof light on the market. Build quality is excellent. Looks fantastic and electric operation works very well. EOS were very professional from order through to delivery.

Posted 2 months ago

Anonymous

good product, no problems

Posted 2 months ago

Anonymous

Really well made.

Posted 2 months ago

Roy Summers

Excellent product which has really given our kitchen extension maximum light. It also looks very sophisticated.

Posted 2 months ago

Lars Schuy

reliable delivery, excellent quality of roof light, still looks good after two years of installation, fully recommended. You need a lot of people for the installation as the roof light is VERY heavy.

Posted 2 months ago

Anonymous

Competitive prices, efficient Staff and quick lead times!

Posted 4 months ago

Richard Jellings

Very helpful people on the telephone, prompt on time delivery and an excellent product

Posted 4 months ago

Jeff Taylor

The ordering process was very easy. Within the first phone call i was able to identify the product I required, its price and availability. The order was placed and the product received on the agreed date.

Posted 4 months ago

John Stimson

I received a very professional and responsive service from EOS. Not being trade, or having any experience of a skylight I had many questions, and EOS were very patient whilst re-assuring me on the right choices (electric glass, automatic opening/closing, blinds etc).

Posted 4 months ago

Nat Ellis

there were a few communication issues - but any problems were resolved swiftly and sensibly

Posted 4 months ago

Laurence Nagel

Efficient , Quality, Modern

Posted 4 months ago

Steve Rooney

Excellent product delivered on time and within the budget required from the client. Elliot was brilliant over the phone and extremely helpful.

Posted 6 months ago

Mark

2400 x 600 fixed roof light for one of our rental properties - Arrived well packed and fastened to a pallet; delivery guy unloaded onto driveway (even though he wasn't supposed to). Product was in perfect condition. Hole construction and fitting instructions were clear and accurate. Product installed onto what I'd constructed without a fuss (which was just as well as it was nearly 100KG). Looks great and the extra light makes so much difference to the space below. Now thinking of using EOS roof lights on a large extension we have planned for our own house. Would definitely recommend. Seriously consider the extra expense of buying the upstand from EOS (I didn't and it worked out OK, but would have been so much quicker if I'd bought the upstand).

Posted 6 months ago

David Matthews

Seems to do very thing it supposed to. Looks sleek and smart.

Posted 6 months ago

Anonymous

We found EOS staff very helpful in dealing with our enquiry. The service was prompt and the goods arrive on time and in good order. The rooflight looks very well in our new extension!

Posted 6 months ago

Anonymous

Delivered on time, rooflight was easy to fit and of a good quality.

Posted 6 months ago