What U-value should I use where?

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We’ve talked about how a U-value gives you the thermal conductivity for a particular construction and how you can calculate it (by using our online U-Value calculator). But what U-value should you be aiming for and why?

Building Regulations and Standards

England, Scotland and Wales all have their own separate set of Building Regulations (for England and Wales) and Standards (for Scotland) which specify the required U-value for new build and refurbishments applications for domestic and non-domestic buildings. These differ for walls, floors and flat/pitched roofs. These are specified by the government or assembly and can be found on the internet. For example for England, the Approved Documents which describe all the building regulations can be found on https://www.planningportal.gov.uk/buildingregulations/approveddocuments/. Part L of these documents applies to insulation.

Our Building Regulations/Standard Guides

To make life easier we have produced guides to all of the regulations and standards as they apply to insulation. We’ve separated them out into guides for England, Scotland and Wales as well as new build or existing dwellings for both domestic houses and other buildings. These give a simple overview to the parts of the regulations which are relevant to building fabric insulation and showing how these regulations can be achieved using Kingspan Insulation products. These can all be found on the Building Regulations page of our website, along with a summary table of the U-values which act as a quick reference.

If you are still not sure what you need your U-value should be, or if you are building a more complicated construction then you can ring our Technical Services department and they will be able to talk you through your options.

What to check

You should always make sure that your intended solution will meet or exceed (be lower than) the required U-Value for that application. We always suggest that you check to see what your U-value should be and that the insulation solution you have chosen for your build up will result in a U-value that meets this before ordering your insulation. For new builds the standards are higher than for refurbishments.

The Building Control Officer will want to know that you are complying with the Regulations/Standards and how you are intending to do this. Our U-value calculator can email you a PDF of the build-up you have selected and the U-value that this will achieve which you can show them to demonstrate how you are intending to comply with the Building Regulations/Standards.

Other standards

There are other standards which can be used when building a property which are more stringent than the Building Regulations, for example when constructing a house to Passivhaus standards there is a requirement to have a space heating demand of ≤ 15kWh/m2/yr. To achieve this then it is likely that a lower U-value for the elements of the building will be needed than that specified by the Building Regulations or Standards.

If you need to achieve a lower U-value then by using our online calculator you can select your construction build up and then alter the U-value to be the number you require. The u-value calculator will then show you the type and thickness of insulation required to achieve this.

Lower = Better

The key fact to remember with U-Values is that the smaller the number they are, the better they are. The lower the U-value you achieve, the better insulated the building is, the less heat will be lost and the more thermally efficient the building is, which should result in lower heating bills and a more energy efficient building.

So when you’ve looked up your U-value, try out our online U-Value calculator at www.uvalue-calculator.co.uk

To find out more about the u-value calculator and how it works check out the rest of the posts in this series which are linked below.

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Kingspan Insulation is a market leading manufacturer of optimum, premium and high performance rigid insulation products and insulated systems for building fabric and building services applications.

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