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A common way to prevent excessive or prolonged high temperatures in buildings is to use an active cooling system, such as:

  • mechanical ventilative cooling – where fans introduce external air to the building to give a cooling effect


  • comfort cooling – where a mechanical system cools the air in the building to a specific temperature.

The drawback of these active cooling systems is that they increase the energy use of the building, resulting in greater whole-life costs.

What are the sustainable alternatives to mechanical cooling systems?

The typical passive method of cooling is to use open windows. However, for buildings located in noisy environments (e.g. near major highways, railways, flight paths etc.) opening the windows to the extent required to give a cooling effect would also introduce a significant amount of external noise to the building. This could result in unacceptably high internal noise levels.

Here are four options for passive cooling that also reduce the level of noise introduced to the building:

  1. Balconies

    Balconies with solid balustrades can shield open windows from sources of external noise. Sound absorptive material on the underside of balconies can be used to attenuate noise reflected towards windows beneath balconies.


4 to 10 dB improvement in noise reduction compared to open windows alone.

  1. Plenum windows (noise reducing windows)

These are dual windows with absorption lined cavities and staggered openings.

Plenum Windows

4 to 11 dB improvement in noise reduction compared to standard open windows.

  1. Acoustic vents/louvres

These are large ventilation openings formed of acoustic louvres or absorption lined plena/ducts. Some acoustic vents have a small built-in fan to boost the air flow rate.

Acoustic Vents

4 to 16 dB improvement in noise reduction compared to standard open windows.

(Photo: TEK LTD)

  1. A combination of methods

Combining balconies that provide a shielding effect with either plenum windows or acoustic vents/louvres can result in a much greater level of noise reduction than would be achieved with any single method.

8 to 26 dB improvement in noise reduction compared to standard open windows alone.

In conclusion, it may prove more sustainable and cost-effective to explore the possibility of innovative passive cooling solutions than it would to specify an active cooling system.