Getting Natural Ventilation Right: Windows
When a home is naturally ventilated, air from outside the building is invited inside without any help from electrical or mechanical hardware.
Natural ventilation is important because it improves your home’s indoor air quality and encourages “passive cooling” during the summer months. By refreshing and cooling your home without relying on electrical means, natural ventilation lowers your electricity bill to save you money. This also makes it great for the environment.
The main way to encourage and enjoy natural ventilation in your home is through the selection and placement of your windows.
The placement of your windows will determine whether you need panes with larger or smaller openings. While your architect will advise you on this, it’s still up to you to choose the most appropriate windows.
Different rooms in your home will also have different ventilation needs. Because of this, it’s important to understand how each type of window offers or limits ventilation. You can then use this information to inform your choices as you plan your new home or renovation with your architect.
Because sliding windows don’t protrude when they’re opened, they’re ideal for encouraging ventilation in areas with limited inside and outside opening space. They’re also easily combined with insect or safety screens for improved security without compromising your ventilation.
In rooms that require adequate ventilation (such as bathrooms), sliding windows can be ordered with a vent lock. This allows you to lock the window at different opening points along the track for security and total control over your ventilation.
However, it’s important to keep in mind that for sliding windows, only half (sometimes less) of the window can be opened for ventilation, which obviously restricts the volume of natural air flow.
Like sliding windows, awning windows can be placed in areas with limited opening spaces. They can also be combined with insect or safety screens for secure ventilation.
The similarities end there, however. In most cases, awning windows have significantly smaller openings than sliding windows – especially if they’ve been placed on an upper story, where their openings are restricted for safety. Because of this, awning windows are most appropriate for rooms that require less ventilation. They’re also ideal for areas where your home’s design requires windows with smaller openings to encourage the ventilation process. (You can learn more about the science behind the placement of smaller opening windows here.)
That said, because they can be left open during light rain, awning windows can provide ventilation in situations where other windows cannot. In other words, they still have their place in a naturally ventilated home
Double Hung Windows
Double hung windows offer particular control over your ventilation. That’s because you can choose to invite air into your home through the top of the window, the bottom, or both by moving each of the two window sashes as desired.
Like sliding and awning windows, double hung windows are ideal for restricted opening spaces. They can also be combined with insect or safety screens for increased security without affecting air flow. (However it’s worth noting that this makes them difficult to clean, as the fixed screens cannot be removed.)
The main restriction on natural ventilation from double hung windows comes with upper story windows, as the bottom panel of these windows may need to be completely fixed for safety.
If you want maximum ventilation, you can’t look past bi-fold windows. These windows fold all the way back to provide a large opening area that’s almost the size of the window frame itself.
Keep in mind, however, that unlike the other window options we’ve discussed so far, there are limited screening options for bi-fold windows. Because they protrude to the width of each panel on the outside, bi-fold windows can only be installed in areas with room for large opening spaces.
Casement windows are another fantastic window for maximising ventilation in your home.
Thanks to their wide opening arc and the manner in which they open, casement windows allow you to control and divert breezes from different directions into your home. In fact, it’s these two features that account for why they’re one of two window types recommended by the Australian government for maximising air movement in your home.
The only downside? Casement windows are difficult to screen, and they cannot be safety screened.
The other window type recommended by the government for encouraging airflow in your home is louvre windows.
With the ability to open out to be as much as 95% open, louvre windows are great for encouraging ventilation in your home. Their variable opening angles also allow you to control and direct this ventilation as desired and required. Importantly, while second storey louvre windows have restricted openings for safety (much like most other types of windows), they still invite plenty of ventilation into your home.
The main challenge with louvre windows is that you cannot use them in areas with a bushfire rating over BAL-19.
As you probably guessed, due to their fixed nature, fixed windows do not contribute to natural ventilation in your home. While they’re ideal for light, views, and architectural accents, they’re not useful for ventilating your home.
Make Informed Choices
Choosing windows is a task that should be done in consultation with your architect, or with a consultant at Bradnam’s Windows & Doors. But now that you know all about different windows and their ventilation potential, you’ll be able to make better informed choices.
Want to learn more about natural ventilation? Visit one of our showrooms for an informative tour with one of our experienced representatives, we’d love to see you soon!