Important Considerations in choosing new windows

• For single sided ventilation, it is best to opt for windows which provide top and bottom level openings. 

• Two openings; one high and one low provides better air flow than one large opening. 

• The turn window is not well suited especially in winters because of cold air gusts directly to the occupants.  

• For cross ventilation, it can be beneficial to install double vertical slide windows so that the top level and bottom level openings can be adjusted according to weather conditions.

• If it is desired to keep windows open for longer periods with trickle effect while keeping the space thermally comfortable, awning windows and tilt windows are the best choice.

• For quick exchange of air, the horizontal pivot window by far provides best flow rates. If availability is an issue, windows with an upper and lower opening are ideal.

• Factors like safety, rain protection, aesthetics and seating arrangement can be taken into further consideration when opting for a window replacement or installation. 

 It is important to consult with a qualified engineer to determine the best option for a specific application, as the choice of specifications will depend on the specific needs and characteristics of the space. 

Horizontal Pivot Window, Double Vertical Slide Window, Vertical Pivot Window

Horizontal pivot window provides highest flow and quick replacement of stale air. Double vertical slide window is best for cross ventilation with adjustable lower and higher-level openings.

When opened all the way through, the flow rate offered by the horizontal pivot window is 17% higher than the other two window types. Hence best suited for quick replacement of stale air with outdoor fresh air.

Turn Window, Awning Window, Tilt Window

Awning and tilt windows are beneficial when it is possible to open windows constantly as they provide the trickle effect all day around. While for quick exchange of air, a turn window performs better

Required opening areas

The table below provides approximate opening sizes required to provide adequate air flow to occupants when wind speeds are very low. Given varying outdoor conditions it is advised to use CO2 monitors to help you balance providing adequate fresh air and minimise energy cost. 

Choosing a Ventilation Expert

In order to choose a qualified ventilation expert it is recommended to consult the Building Engineering Services Associate Find a Member list. Filtering by Air Conditioning will usually find companies with expertise in ventilation too.