Energy Efficient windows

With rising energy costs and CO2 emissions damaging our atmosphere, a growing concern for the environment is being undertaken. High-tech windows allow a lot of light and warmth into your home,  while letting very little heating energy to escape. The ideal characteristics of our energy efficient windows are reflected by excellent technological light and emission values.

Top-of-the-line glazing captures a large amount of heat radiation produced by a heating system, at the same time allowing large amounts of sunlight into the living space. In doing this, free energy from the sun acts as an “additional heater” further decreasing heating expenses. The better the heat insulation of insulation glazing is, the higher the surface temperature on the inside of the window will be. The cold emission of the glazed surface is reduced – this facilitates a balanced room temperature and even provides a cosy feeling in the direct vicinity of the glass. Highly heat-insulating windows are especially important for large glass surfaces – otherwise you feel chilly near the window and waste money trying to heat your home.

Our Katzbeck range really can achieve any projects needs. From windows to tilt and slide doors, call us on 01793 766 085 to discuss your housing project, design or thermal upgrade.

What are U-Values?

The U-value is an absolute measure for the thermal loss of a structural element – in this case a triple glazed timber window. The lower the U-value of a window is, the smaller the amount of heat is that escapes to the outside. Therefore, a low U-value means a high level of heat insulation and low heating costs. Two types of U-values are distinguished for windows – depending on which part of the window is being described:

Ug: heat insulation value of the glazing
(g = glass, glazing)

Uw: heat insulation value of the entire window (glass and frame)
(w = window)

Thermal heat loss graphic Our U-Values:

Window Glazing U-Value Window U-value glass
Passiva Triple Uw 0.72 Ug 0.5
Massiva 80 Triple Uw 0.80 Ug 0.5
Double Uw 1.20 Ug 1.1
Massiva 96 Triple Uw 0.75 Ug 0.5


Our installation:

Unlike many installers, we no longer use expanding foam for the installation of any of our windows, not only our thermally efficient range. Experiments made by ISO Chemi show expanding foam to be very ineffective, especially when not applied correctly (tests also show that in some situations old fashion methods such as newspaper are more effective).

When we install we use innovative insulation materials and methods. Have a look for yourself at the quality standards to which we install:

Passive Housing

What is Passive Housing? ‘Passive Housing’ derived from the German term “passivhaus” is an ecofriendly standard of house build, outperforming building standards as we know them. To meet the recommended standards, it is often advised to achieve a “U” value below 0.8 overall. STW can supply Passive House Standard windows as low as 0.72. Our Katzbeck range does just that, but all so much better.

Katzbeck Windows

Did you know?

The Prince Charles House in Watford is a eco-friendly, low energy product undertaken by the BRE. All the energy efficient windows in this house were donated by Katzbeck – we like to think of this as an unofficial Royal approval!