In terms of sustainability, windows are often overlooked. They can serve as crucial, constant heat escape zones in many regions of the world. However, this can often depend on the climate of the country, its glazing, and what materials are used. It’s important to consider whether they will be worth the cost.

In the UK, wooden double glazed sash windows cost more than standard uPVC casement windows (the cheapest sustainable material) but also make a return on investment in the savings on heating and the extra lifespan of the material. Consequently, the climate can make both the design and the choice of material worth it. The winters can be harsh and snowy in the UK, which is less likely to be the case in Cyprus.

So, is there still value in certain types of windows for both consumers and the environment?

What are sustainable windows?

Sustainability is a buzzword that’s thrown out a lot, so it’s important to clarify it, especially for people who don’t know how an item such as a window can play a role. Sustainable windows are often made of materials that are eco-friendly and prioritise energy efficiency at home by keeping in the heat or cold and minimising your air conditioning usage.

In effect, they aren’t just better for the environment, they are also better for your energy bills. They can seal up heat or cold escape zones and thus decrease the strain on your heating or cooling system by preventing air diffusion. In doing so, they can also decrease the strain on the energy grid, making them more environmentally friendly.

Another factor that adds to sustainability is the recyclability of the materials that make up the frame. Some materials have limited recyclability while others are infinitely recyclable as long as they are in a decent condition. One thing worth noting is that not all window panes are recyclable since most use very different types of glass.

Testing glazing in Cyprus

Researchers at Aswan University examined the impact of various types of window glazing, window orientations, and Window to Wall Ratios (WWR) in a typical office room located in Aswan, Egypt (which has a similar climate to Cyprus).

The findings indicated that a setup with a nanogel layer embedded between two argon layers and two single transparent glazing layers, with a WWR of 10%, substantially lowered the annual energy consumption across all directions (North, West, South, and East), with savings of 3.66%, 12.71%, 6.51%, and 4.18%, respectively.

Compared to a standard single clear glass layer (3 mm), these resulted in better thermal efficiency and cold capture. Additionally, the study found that the energy efficiency of using a nanogel layer with a WWR of 20% is roughly equivalent to that with a WWR of 10%. The configuration using the nanogel layer was the most effective.

Electrochromic glass has also been shown to improve energy efficiency and the flow of light. Both of these options greatly reduce costs from multiple sides. Smart glazing and tinted glass were both good additions to the office buildings simulated in both studies, creating better energy efficiency and saving on costs.

Keep in mind that office buildings often have 100s of windows. If each one can prevent temperature changes by a small percentage it can lead to incredible cumulative savings. This also indicates that there are benefits to double glazing within the region.

Which materials work best?

Let’s examine which materials are the best in Cyprus based on the metrics above.

Wooden windows are by far the best in terms of home heating and recyclability, but their material sustainability can vary. The highest sustainability comes from soft woods since they grow faster but they have a slightly shorter lifespan because they are comparatively brittle. Wooden windows might be less feasible at scale because of the cost per unit.

Aluminium windows are another contender that have great thermal efficiency. While aluminium was not always considered a good option, the invention of thermal breaks made them far more suitable for sustainable operations. They are highly recyclable and, unlike wood, require a lot less maintenance. While wood can require polishing and treating against pests, aluminium windows are often treated against environmental hazards and other such issues in the manufacturing stage.

Additional benefits

Aside from the sustainability and energy savings they can provide, the windows listed can have some additional benefits. Materials like wood can often outlast most other materials (they can last up to 75 years if well-maintained) and provide better noise reduction as well.

Similarly, materials like aluminium can be strong even at low volumes. This allows for stylish designs with wide windows that allow for great lighting due to the slim frames that provide extra space for glass. This can save a lot in terms of annual lighting costs as well.

In conclusion, more sustainable windows can be a good addition to your home or office under the right conditions. In hotter regions where the cold needs to be kept in, they can mitigate your air conditioning costs. They may cost more than non-sustainable materials but they could be useful in providing better financial maintenance in the long run.