Choosing the right U-value for your windows and doors

The term U-value or thermal transmittance is used as a standardized measure of how easily a component passes through heat. So here are U values explained… U-value is measured in W/m²K and indicates how much heat per unit of time that flows through an area of 1m² at a constant temperature difference of 1K (1°C) between warm and cold side of the structure. And in simple terms… if it’s cold outside and warm inside, U-value measures how quickly the heat from the inside leaks to the outside. A well insulated building component has a low U value.

Both the glass and the frame are taken into consideration when calculating a product’s U-value. Broxwood’s entry level U-value is 1.4. Broxwood offers six U-values including high-tech ‘Passive House’ compatible products in ultra-low U-values of 0.7 and 0.6 respectively.

When choosing for your project consider the overall energy efficiency of your home. Look at the type of walls, floors, doors, roofing and insulation. A period property with little or no wall insulation is likely to leak more energy than a property built in the last 10 years. Therefore with a property of this type, a U-value of 1.4 or 1.2 will be appropriate as the overall heat loss from the property can only be countered so far with energy efficient windows. Similarly, fitting high-spec triple glazed windows to a standard new build project will cost up to 50% more but will only reduce overall house heat loss by around 5%, and so would be a false economy compared to fitting 1.0 U-value windows. If in doubt what U-value to choose contact Broxwood for advice.

Broxwood windows and doors have the following U-values:

Comfort, Broxwood’s entry level product, out performs the
UK building standard requirement for new build projects.
They are exceptional value and are suitable for new build
and renovation projects.

Our EnerSave windows provide real savings and are ideal for
new build or replacing windows in an older style property.

How well insulated is the rest of the building?
Our EnerPlus windows are suitable for replacing windows in a
properly insulated property or for a new build project.

Broxwood’s technically advanced product is compatible
for use in a Passive House project or a building where your overall
intention is to be as carbon neutral as possible.

If you’re looking for the ultimate windows and doors, Broxwood’s 0.6
U-value AlpineMax range is the answer to your dreams. A hand finished,
technically advanced premium product. Compatible for use in a Passive House
project, the attention to detail makes this range more akin to fine furniture.

It is worth noting that the more ‘break points’ you include in your choice of window design the less energy efficient it becomes. So if you include astragals or vents in your window options for example, you may slightly reduce overall energy-saving properties.

We want you to buy the right product. As ever, common sense should prevail but, if you are in any doubt please contact Broxwood for independent technical advice.

See the relationship between U-values and home energy costs with the Broxwood Energy Saving Calculator.