Architecture
Stay Cool: 6 Ways to Boost Natural Ventilation in Your Home
Keep your house comfortable, your bank balance in check and look after the environment while you're at it
Natural ventilation is not only a better choice for the environment than artificial cooling such as air conditioners, it is also free. Natural ventilation makes use of outside air movement and pressure differences to cool and ventilate a house. Cooling breezes carry heat out of a building, replacing warmed internal air with cooler external air to effectively lower the temperature of interior spaces.
Strategically placed windows and doors are key to natural ventilation, as are unrestricted breeze paths. Here are six ways to boost natural ventilation in your home and reduce the need to flick the switch on your air conditioner when the temperature rises.
Strategically placed windows and doors are key to natural ventilation, as are unrestricted breeze paths. Here are six ways to boost natural ventilation in your home and reduce the need to flick the switch on your air conditioner when the temperature rises.
1. Orient windows and doors based on climate and site
A house should be oriented on a site to take advantage of prevailing breezes that vary depending on location, time of day, climate and landscape.
A house should be oriented on a site to take advantage of prevailing breezes that vary depending on location, time of day, climate and landscape.
For example, in coastal regions, breezes come from an onshore direction; in mountainous and hilly regions they usually travel downslope; and some maritime regions may have notoriously strong winds (think Wellington, New Zealand). Generally, cool breezes tend to occur in the late afternoon or early evening.
Fences and planting outside a house can help funnel breezes through a window or door, as well as filtering stronger winds.
Fences and planting outside a house can help funnel breezes through a window or door, as well as filtering stronger winds.
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2. Choose window types to direct or deflect air flow
The design and size of openings can affect airflow patterns and how air movement is directed or deflected.
Casement windows are the most traditional window type, with hinged frames that open inwards or outwards like a door. They offer maximum ventilation when fully opened, and can limit air flow inside when not opened fully.
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The design and size of openings can affect airflow patterns and how air movement is directed or deflected.
Casement windows are the most traditional window type, with hinged frames that open inwards or outwards like a door. They offer maximum ventilation when fully opened, and can limit air flow inside when not opened fully.
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A louvre is a small rectangular glass panel that can pivot open to facilitate air flow. Louvre windows have a series of these panels and the amount they are opened will affect the breeze that can flow into a room. Opening and closing louvre windows – fully or partially – can vary ventilation paths and control air speed.
3. Position openings for cross ventilation
While we may think wind blows through a building, it is in fact sucked towards areas of lower air pressure. Openings should therefore be placed to draw breezes through. This means positioning openings on at least two sides of a room, on either opposite or adjacent walls, for cross ventilation.
While we may think wind blows through a building, it is in fact sucked towards areas of lower air pressure. Openings should therefore be placed to draw breezes through. This means positioning openings on at least two sides of a room, on either opposite or adjacent walls, for cross ventilation.
There should be multiple wind-flow paths through a room or house. Cooling breezes work best in narrow or open-plan layouts. Internal windows can help in deeper plans, but there still needs to be cross ventilation.
4. Install natural ventilation systems that automatically adjust openings
Automatic ventilation systems can open and adjust window openings depending on internal temperatures. This releases and regulates heat and allows airflow inside – particularly useful if you are out of the house all day. In houses with large swathes of northern glazing, an automated system can help prevent overheating.
Automatic ventilation systems can open and adjust window openings depending on internal temperatures. This releases and regulates heat and allows airflow inside – particularly useful if you are out of the house all day. In houses with large swathes of northern glazing, an automated system can help prevent overheating.
“The energy to open and occasionally adjust a window can, in some cases, be as little as 1/400th of that needed to run a heat pump on cooling mode to achieve the same ambient temperature,” says Richard Wright of Solar Homes in New Zealand. The company installs Soho Ventpac natural ventilation and solar-heat harvesting systems.
Wright explains that a typical automated Ventpac system uses about the same wattage as an incandescent lightbulb, and on normal settings it costs less than $100 a year for electricity to run the fan, window openers and programmable logic controller. When applied to a house designed on correct passive design principles in a temperate climate zone, active solar systems such as these remove the need for refrigerated cooling and minimise the need for supplementary heating. This adds up to home comfort at a far lower cost compared with air conditioning and heat pumps.
Wright explains that a typical automated Ventpac system uses about the same wattage as an incandescent lightbulb, and on normal settings it costs less than $100 a year for electricity to run the fan, window openers and programmable logic controller. When applied to a house designed on correct passive design principles in a temperate climate zone, active solar systems such as these remove the need for refrigerated cooling and minimise the need for supplementary heating. This adds up to home comfort at a far lower cost compared with air conditioning and heat pumps.
5. Encourage convective air movement
Convective ventilation, or stack ventilation, uses temperature differences to move air. Warm air is more buoyant so rises to escape through higher openings, drawing in cooler air from lower openings as it does so.
Convective ventilation, or stack ventilation, uses temperature differences to move air. Warm air is more buoyant so rises to escape through higher openings, drawing in cooler air from lower openings as it does so.
Clerestory windows, operable skylights, roof ventilators and vented ridges work on the basis of convective air movement and help improve cross ventilation.
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Browse beautiful homes on Houzz
6. Take advantage of cool night air
Houses typically cool at night time when hot air radiating from a building is replaced with cooler night air. Leaving windows open at night will help purge warm air to ventilate interior spaces for the next day.
Double-hung windows and clerestory windows are ideal for this purpose as the hot air escapes through higher-level openings.
Houses typically cool at night time when hot air radiating from a building is replaced with cooler night air. Leaving windows open at night will help purge warm air to ventilate interior spaces for the next day.
Double-hung windows and clerestory windows are ideal for this purpose as the hot air escapes through higher-level openings.
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Have you managed to keep your home cool naturally? Tell us how in the Comments below, like this story, save your favourite images and join the conversation.
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Doreen Mellor