Is it time to rethink windows?

Windows are an essential part of our homes and buildings, providing natural light, ventilation, and a connection to the outside world. However, they also come with costs that we often overlook. In this blog, we'll explore the historical background, cost of windows in terms of energy flows, the price of high-performance windows, the extra cost of complying with energy efficiency requirements for large windows, why we have windows and glazed doors in the first place and what we can do to keep the benefits but minimise the costs.

Why We Have Windows and Glazed Doors

​Despite the costs associated with windows, they remain a crucial element of building design. Windows and glazed doors provide natural light, which can improve mood. They also offer ventilation, helping to maintain indoor air quality. Additionally, windows can connect us to the outside world, providing views and a sense of openness and oneness with nature. These benefits make windows an indispensable part of our homes and buildings, even as we work to improve their energy efficiency.

Historical background

​If you consider homes built in Australia built before the fifties, they had small windows because the predominant form of heating was open wood fires. Because they are not an effective form of heat and insulation was rare, windows were as small as possible to reduce heat loss so the rooms could be heated to a moderately comfortable temperature. The small windows also minimised summer heat gain. Because house comfort levels were so poor, most people were aware of the comfort cost of windows.

Frank Lloyd Wright (1867-1959) an American Architect is generally attributed with developing the concept of large glass windows connecting to the outside which has been embraced in Australia. The early Australian exponent of this concept was Robin Boyd (1919-1971).

However, you need to recognise Frank Lloyd Wright was designing for the wealthy who could afford the high heating costs of the buildings, and he experimented with early air conditioning systems to try and keep them cool. Although he later embraced the use of shading to maximise winter warmth and minimise summer heat build-up, these techniques are insufficient in South Australia to achieve comfort all the time.

It should be noted that even Frank Lloyd Wright implicitly recognised his homes didn’t give year-round comfort and he later lived in Chicago in the summer, and Arizona in the winter.

During the 1970’s builders in Australia realised that the construction cost of a square meter of brick veneer wall and a square meter of single glazed aluminium sliding windows was the same. This meant a show home could be built with large windows facing a landscaped garden to give the wow factor that closed the sale. Because the show home could have air conditioning and people were less likely to go out on an extremely hot or cold day (cars didn’t have air conditioning) people didn’t notice the problems until after the house was built.

The problems with excessive windows include:

• High cost of compliance with the National Construction Code
• the high cost of window treatments
• poor comfort in hot and cold weather (even with window treatments)
• high heating and cooling costs

Because expectations in Australia have moved to large, often floor to ceiling windows, to achieve the star rating can be expensive. We need to minimise these negatives while still retaining the positives of light and the connection to the outside.

The Cost of Energy Flows Through Windows

​Windows can be a significant source of energy loss in a building (up to 40% of energy loss in existing homes that I energy audit). During the winter, heat escapes through windows, leading to higher heating costs. In the summer, windows let in unwanted heat, increasing the need for air conditioning. It's essential to consider these energy flows when designing or renovating a building to ensure energy efficiency.

​You also need to spend money on curtains or blinds, even in a 7-star home, so avoiding excessive windows also reduces this cost.

The Extra Cost of Complying with Energy Efficiency Requirements

Large windows can be a beautiful feature in a building, providing ample natural light and stunning views. However, they also come with additional costs to comply with energy efficiency requirements. 

High-performance windows are designed to minimize energy loss and improve a building's overall energy efficiency. These windows often feature multiple panes of glass, low-emissivity (Low-E) coatings, and Argon gas between the panes to reduce heat transfer. They also have high performance window frames. While high-performance windows are more expensive upfront, they lead to significant energy savings over time.

In fact, if you have a lot of glass, you won’t be able to achieve a 7-star rating without high performance glass. This is the main driver of increased costs for 7-star homes. However careful design can minimise this cost. The Australian Glass Window Association research has shown the average premium is $4,300, not the $40,000 plus premium touted by the Housing Industry Association (although this latter figure is possible, if you don’t consider windows, orientation and building form carefully).

However, it is possible to achieve the benefits of windows with substantially smaller windows that are common today, but you need to start considering these ideas when considering the block and house concept, not when you have detailed designs as the costs will already be locked in. See How early design decisions impact the cost of achieving energy efficiency in homes - YOUR LOW ENERGY HOME and Optimal House Orientation in Adelaide: More Than Just Facing North
- YOUR LOW ENERGY HOME

A future blog post will address how we can achieve this and achieve a lovely home at an affordable cost.

In the meantime, contact us to get started on the energy efficiency planning for your home as early as possible.

Conclusion

​While windows offer significant benefits, they come with costs in terms of energy flows, comfort,  window treatments and the cost of compliance with energy efficiency requirements. By careful design we can achieve the benefits with smaller windows than is common today, minimising the cost of high-performance windows, and we can enjoy the advantages of windows while minimizing their impact on our hip pocket.
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​Contact us to get started on the energy efficiency planning for your home as early as possible.

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