Energy Efficient Windows and Doors

What is U-value?

U-value is also often referred to as «thermal transmittance», which refers to the rate at which a structure allows the transfer of heat energy, divided by the temperature difference on either side of the structure.

Therefore, U-values are essentially a measure of the effectiveness of a material’s insulation. When this value is lower, it means that the material is considered as performing more efficiently as an insulator against heat loss from an internal space, than when it is a higher value.

U-value is measured in W/m²K. The average cavity wall will have a U-value of around 1.6 W/m²K, whereas a wall built of solid brick will be lower at around 2.0 W/m²K. For a window, this can rise to around 2.8 W/m²K. This is typical for existing dwellings, but many countries now have guidelines regarding the maximum allowed U-value that a new build window may have.

What’s the difference between U-value and R-value?

These two things are essentially the same, but with different applications. When talking about insulation within walls or ceilings, the industry favours R-value. When we talk about windows, we talk about U-value. R-values that are high are considered better insulators, whereas for U-values, the insulation is better the close the number is to zero.

How does U-value rating affect your home?

As U-value refers to the rate at which heat is lost through your windows, it is essentially a measure of your home’s energy efficiency. If your windows have a poor (high) U-value, then you are wasting energy that could be saved through the installation of better quality windows.

By installing new-build windows such as those manufactured by Blue Sky Windows, you can improve your U-value and as a direct result, your home’s ability to retain heat, which means that it will cost you less to heat your home. This will in turn lead to a reduction in energy bills for heating.

How Can I Improve my U-Value?

Blue Sky Windows only use the highest quality components from German manufacturers in producing doors and windows to your specification. Windows in old-builds often have an average of 8 to 10 W/m²K, which means that you’ll be losing a great deal of heat through your windows. Due to industry requirements, it is not typical to have a U-value any higher than 1.6 W/m²K in newly-installed windows.

All windows built by Blue Sky Windows are optimised to have as low a U-value as possible, which means you’ll immediately be improving the energy efficiency within your home. As a bonus, you’ll also be better insulting yourself against disruption from noise outside the home, for example traffic, railways or noisy neighbours, and protection against extreme weather.

FAQ

What is 7 start energy rating?

A 7-star energy rating indicates a high level of energy efficiency, used in Australia to measure the performance of buildings and their components. This rating is part of the National House Energy Rating Scheme (NatHERS) and is applied to residential buildings, including homes and apartments.

7-star homes need approximately 20 to 25% less energy than 6-star homes for heating and cooling, lowering heating and cooling energy costs.

Are uPVC windows and doors 7 start suitable?

When aiming for a 7-star energy rating for your new home, uPVC windows and doors are your best choice. At BlueSky Windows, we prioritise the value of your investment by offering products that deliver exceptional energy performance.

Our uPVC windows and doors provide unmatched energy efficiency with a low U-value of 1.4. In comparison, aluminium windows typically have a U-value of 3.5 for double glazing or 5-6 for single glazing. This means our uPVC products significantly reduce heat transfer, helping you achieve superior energy savings and comfort in your home.

Choose BlueSky Windows for your next project and experience the benefits of advanced energy efficiency and long-term value.

What types of windows and doors are suitable for a Passive House?

BlueSky Windows proudly holds the distinction of having certified the very first Passive House in Australia. As leading and certified Passive House consultants, we value the trust you place in our expertise.

When selecting uPVC windows and doors for a Passive House, key factors to consider are airtightness, U-value, and Solar Heat Gain Coefficient (SHGC). Our range of high-quality products—including Hinged and French doors, as well as Tilt-and-Turn, Tilt-and-Slide, and Lift-and-Slide systems—are designed to help you achieve Passive House standards.
There are other aspects for your project to consider such as – glazing, spacers, insulating taping etc.

For a comprehensive consultation on achieving your Passive House goals, contact one of our specialists today.