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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

4.79 Average

117 Reviews

Simon Grayson

Great company to use - very helpful with pre-order enquiries, and we’re very accommodating when organising delivery dates and details. I would be happy to recommend EoS.

Posted 1 month ago

Nuno Bernardes

Very easy transaction, great product and delivery service was fantastic. Only constructive feedback I can give is to better highlight the weight of the product and that can/will cause issues with delivery and installation. Luckily we had 6 builders on site who between them managed to move the £140kg roof light but what that meant is that we had to pay extra to re-enforce the roof with different beams

Posted 1 month ago

Anonymous

Very good product and also very good customer support I received from Elliot at EOS. I highly recommend it.

Posted 1 month ago

Pat Barry

Very easy to deal with and delivered on-time.

Posted 1 month ago

Anonymous

We were very happy with how efficiently the work was carried out.

Posted 2 months ago

Moni Liu

"Bought 2 flat glass skylights from you, You're all very helpful on the phone answering all my questions.\r\nThe skylights fit brilliantly and they are very sturdy!\r\nOur builders were surprised with their quality. \r\nPrices are very good too!\r\nThank you!"

Posted 2 months ago

Simon White-Miller

Service was good and delivery prompt and actually arrived the day they said it would

Posted 2 months ago

James Fraser

We have been dealing with EOS for over a year now and its always a pleasure. The team are always very quick to answer any questions and the information given is always accurate and really helpful. Quotes are always set out clearly and easy to understand which helps us greatly. The products always arrive well packaged and when there has been any issues at all they have been solved quickly and brilliantly. The products they produce are excellent with a customer service to match that! look forward to doing more business with EOS in the future! Thank you.

Posted 2 months ago

Altan Riccardo

Customer Service is great! Roof lights are great! Reasonably Priced!

Posted 2 months ago

Anonymous

Chris was a great help in selecting my roof lights. Quick delivery for 3 stock roof lights and the builders had them installed without a problem. The one opening roof light has not been connected so I wait to see how it works after our extension is complete.

Posted 2 months ago

Anonymous

They look fab and the customer service was great

Posted 2 months ago

Richard Coates

Very pleasant to deal with - no waiting around for someone to answer the phone - delivery process on time , so all good.

Posted 2 months ago

Ollie Chance

Order placed - Drawings received for approval - Items delivered. Quick and friendly service delivered on time and fitted without hassle. Highly recommend

Posted 4 months ago

David Whatley

Very professional and straightforward - one of the few things on our project that went according to plan and in the time frame given to us!

Posted 4 months ago

Matthew Waldren

Our rooflights from EOS look stunning and 'make' our room. Our extension is flooded with light. The electric one functions really well. We couldn't fault the service from EOS. They were so helpful, especially as we needed a bespoke size rooflight. I did a lot of research into which rooflights to buy and EOS were the most cost-effective by far, and theirs is a quality product. Thanks to the entire team at EOS. We wouldn't hesitate to recommend you.

Posted 4 months ago

Mr Walker

Great quality, looked great on top of my fibreglass flat roof.

Posted 4 months ago

Laurence Nagel

Delivered on time with in the right budget and I never have to go back to them once fitted. A superb product ...

Posted 4 months ago

Sheila Roed

Ordered online for delivery within 2 days. Not yet fully installed, but looks really nice. Contacted the office and got efficient help from Elliot

Posted 4 months ago

Anonymous

Product was delivered with good protection and installation instructions. Could help with info on manual handling the unit to move and when installing. Now installed looks great.

Posted 4 months ago

Harry

The team at EOS were really helpful and quick with answering all my questions and went the extra mile with there customer service. The product is really good so I would recommend buying from these guys.

Posted 4 months ago

Alan Pettitt

Good price, helpful on information delivered promptly and well wrapped. Delivery cost seemed steep but I don't think that was under their control.

Posted 5 months ago