Super Spaces encounter plenty of customers, builders, and trades who find U-values a little confusing especially when it comes to understanding what the U-value actually means and how it will affect or benefit the performance of our garden rooms or a building in general, so we have compiled this blog entry as an explanation to help.


U-value definition

U-value is a sum of the thermal resistances of the layers that make up an entire building element – for example, a roof, wall, or floor. It also includes adjustments for any fixings or air gaps. A U-value value shows, in units of W/m²·K, the ability of an element to transmit heat from a warm space to a cold space in a building, and vice versa.

In other words, a U-value is used to measure how well or how badly a component transmits heat from the inside to the outside.

As the U-Value decreases so does the amount of heat transferred through the material, i.e. the lower the U-value (w/m2k), the better the insulation. The lower the U-value, the better insulated the building element.


Do Building Regulations Require U-values?

A building element’s U-value is extremely important as there are certain standards that should be reached according to Building Regulations / Standards. Part L (Requirement L1) of the Building Regulations covers ‘Conservation of Fuel and Power’ and U-value maximums have traditionally been set by these regulations.

There are limits set out in UK Building Regulations which are shown below and should never be exceeded:

  • External walls: 0.30
  • Roofs: 0.20
  • Floors: 0.25
  • Windows: 2.0 (whole window value)

These restricting parameters exist to ensure that some future-proofing is built into a home or any building you have constructed like a garden office or garden annexe.


How are U-values calculated?

Most materials have known and published values for the rate at which heat is conducted through them under specified conditions. These values are known as k-values. They are a measure of thermal conductivity. In any element, such as a wall, the k-values for each material layer are divided into the thickness of that material to obtain the R-value for that layer or the thermal resistance.

When they are added all together, the total resistance for the complete section of the wall is nearly found (the air resistances for the inner and outer face have also to be added on). The total resistance is then divided into one to obtain the reciprocal of resistance and this figure is the U-value for the wall.


So what is a good U-value?

Remember what we said earlier, the higher the U-value, the worse the thermal insulation quality is in a building. This means that the lower the u-value the more efficient the building is at keeping heat flow through the structure to a minimum. So, the rule of thumb here is that the lower the U-value the better.

If you require a comfortable, modern home, or in our case a garden room, that has relatively small heating requirements, aim to keep your U-values low.

Super Spaces build all our garden rooms with Structurally Insulated Panels (SIPS) which can achieve u-values from 0.21 down to as low as 0.13 depending on the thickness of the panels we use on your garden room. This means that your garden office will be warm in the winter and cool in the summer. Because our garden buildings are made using SIPS means our range of garden buildings are all incredibly energy efficient, drastically reducing energy bills.


Contact Super Spaces

Super Spaces offer a professional and bespoke garden building service which have low U-values throughout Sussex and Kent. We cater to your personal requirements and individual business needs. We will work with you to create a bespoke garden office that is just right for your business needs and your garden and can be used all year round.

Contact us today on 01797 223044 to find out how Super Spaces can transform your professional and personal life by supercharging your garden space.

Or why not come and visit our garden office showroom located in Rye, East Sussex – Super Spaces Showroom

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