The sustainable strength of windows

Over the past 50 years windows have undergone some radical changes. EDGE Architectural’s superior thermally broken and double glazed framing systems, means glazing systems no longer need to be viewed as a weakness in building design.

We often take framing systems for granted. Sure, we expect to see windows in architectural design, and sure, we look out through windows every day, however for all the expectations and looking, we mostly ignore the plentiful benefits of window systems. Sustainable design is no longer a fad, or something for progressive designers. Sustainable design is a social responsibility. It’s imperative architects and clients embrace environmentally sound design strategy. It’s not enough to specify recyclable, low VOC and low embodied energy building materials. These remain vital product selection criteria, but parallel to sustainable product attributes, is sustainable application. Materials must be applied to benefit building life cycle performance. Windows, once thought to hinder sustainable design, through thoughtful application is actually one of the most powerful green building technologies. EDGE Architectural’s range of thermally broken and double glazed framing systems, combined with intelligent architectural design, provides incredible benefits for building performance and user enjoyment.


Thoughtful placement of windows, external fixed shading systems and interior materials, can effectively heat interior space during winter. Make use of North facing windows by incorporating façade design encouraging of winter sun. Use windows in conjunction with external fixed shading devices to allow winter sun into interior space. Combine this design strategy with high thermal mass materials inside. When rays meet internal surfaces, the materials will begin to heat. Thanks to interior thermal mass and thermally broken windows, an interior can remain warm into the night. As an alternative to continually running gas and electric heating systems, making use of external windows stands in a sustainable league of its own.

Sun shadingCooling

Glazing systems often get a bad reputation for being areas of weakness in buildings because they allow internal heat to escape. In winter when you want warmth to stay inside, specify thermally broken U-MAX™ frames, quality glass and interior window dressings with thermal properties. Alongside not wanting to lose interior heat, we must also consider wanting to lose interior heat. Similar to using windows for heating, glazing systems can also be used to cool an interior. Employ the following design techniques and avoid needing continual artificial cooling in summer:

  • Follow the formula in the diagram above to design fixed shading devices for North facing windows. The shade will block Summer sun from entering interior space, while still welcoming winter sun.
  • Use celestial window frames, fitted with operable louvres. Hot air rises, allow heat to escape  by opening high level louvres. These windows are especially effective for night purging.
  • Use trees and other plants outside South facing sashes. Plants cool down summer breezes. Air will travel past external landscaping, cooling down before travelling inside.
  • Use East facing operable aluminium louvres to work with or against the sun (depending on time of year). See image below.
  • Allow cross ventilation, use operable sashes on opposite façades.

East facing window
Quality of life

Not directly related to sustainability, but an incredible benefit provided by architectural glazing systems, is an improvement of end user building experience. Windows allow access to natural light and fresh air. We spend almost 80 percent of our lives inside. Poor ventilation and too much artificial light can impact negatively on mood, productivity, thought process and overall health.

The savings

Windows are effective tools for sustainable heating, cooling and lighting. Not only does solar temperature control benefit the environment, it also provides financial benefit for owners and end-users. Natural light reduces use of artificial lighting, meaning lower electricity bills. Use window systems to reduce your footprint and overall building running costs.

Windows, a buildings weak spot? I don’t think so!

For more information on passive design, visit Your Home here.