This is the third in a series of articles considering how better design and thoughtful public policy can help to improve the energy efficiency of my 1920s Queenslander home. Improvements to a home’s energy efficiency creates a healthier, more comfortable home, and can save us money on our energy bills – things many of us will be thinking about during a hot and sweaty summer.

A home with good ventilation will be healthier and more energy efficient than a poorly ventilated home. Simply put, home ventilation means the exchange of indoor and outdoor air. This can be done naturally, through windows, doors, and other openings, and mechanically by small exhaust fans or large whole-house ventilation systems. Natural ventilation is the most common method. The movement and exchange of air inside and outside a home is important to keep our homes healthy and can also help to reduce our energy bills. The health aspects of ventilation are really important, but they won’t be the focus of this article. For more information about indoor air quality and the health benefits of good ventilation, check out this LINK.

Natural ventilation is critically important when designing a home for a warm climate. For existing homes, retrofitting to improve natural ventilation will be possible in most situations. The original Queenslander homes were built to encourage cross-ventilation and raised above the ground to allow for good ventilation through the sub-floor area. Ventilation was needed to offset the poor thermal insulation provided by the timber structure, and the high heat conductivity of the tin roof.

In my home, the street facing veranda has been enclosed to create an additional room, and one of the original front windows has been removed and replaced by a solid wall. The (reasonably) modern extension at the back of the home has also blocked some of the original front-to-back ventilation that would have been enjoyed under the original design. These and similar changes found in other homes are typical and reflect changes in society and culture (demand for bigger houses, additional privacy, etc.). With a little thought and investment, it is possible to recover what has been lost (natural ventilation) and retain the things that modern homes need.       

During the middle of summer, direct afternoon sunlight hits the entire western wall of my home. This can make parts of the house unbearably hot. To make things worse, as the hot air inside the home rises it becomes trapped at the top of the three-metre-high internal ceilings. Using ceiling or other fans helps to cool us down but doesn’t actually deal with the hot air problem. Many people will understandably turn to air-conditioners to cool down, although we don’t have this option. These mechanical cooling options mean more energy is used, and unless you have a large solar PV system, more cost.  

For the layout and orientation of my home, installing north-facing glass louvre windows in the place of the solid section at the top of the north-facing wall will improve ventilation and allow the hot, rising summer air to be purged outside. Glass louvres are a practical and attractive option, especially in a warm climate such as Brisbane. Research has found that cooling a house using natural ventilation results in energy savings of 40 per cent when measured against the mechanical cooling of an air-conditioner. Glass louvres also increase the natural light entering the home, particularly important during the winter months when northern sunlight helps to warm a chilly home. The downsides of extra northern sunlight at other, warmer times of the year, can be managed using manually operated blinds or curtains, or by choosing high-performance low-E glass. 

Improving ventilation to help purge hot air from inside the home only addresses one part of the energy efficiency and thermal comfort puzzle. In my situation, I also need to consider what I can do to block the direct sunlight from hitting my home. This will be tackled in a future article and emphasises how each of these retrofit solutions are interconnected. Done as individual fixes they will provide some improvement.

What is better is to bundle these interconnected parts together and treat the house as a system, which will produce effective and lasting solutions.

Images, Shutterstock

More from Ben Powell below:

Are our homes just glorified tents?

Energy: Gaining more by using less.