Altair louvre windows from Breezway can be screened with various types of mesh to keep insects or intruders out.
For instance, Altair louvre windows with fibreglass mesh keep insects out, while woven metal mesh keeps intruders out and also protects against bushfire. The mesh screens can be positioned on the outside or the inside of the building.
A little known fact about Altair louvre windows with mesh is that mesh screens offer more benefits than just protection from insects, intruders and bushfires. They also offer great energy efficiency benefits in the form of shading and thermal insulation.
Shading like shade cloth
Mesh screens give similar benefits to shade cloth since they are both woven, provide shade and offer visibility to varying degrees depending on the weave. Woven mesh screens help to keep buildings cooler by reducing the amount of hot sunlight that passes through them and into the building.
Insulation like double glazing
Interestingly, due to the distance between the closed blades of an Altair louvre window and a woven mesh screen (a little over 105mm), mesh screens give similar benefits to double glazing such as trapping a layer of air between two vertical surfaces, with the air acting as a thermal buffer to reduce heat flow between the two vertical surfaces.
When outside temperatures are much higher or lower than comfortable temperatures, this insulation is very beneficial in keeping warmth in, or keeping heat out to improve the efficiency of heating and cooling systems.
How beneficial are mesh screens?
The recognised source of measures of energy efficiency of Australian window systems is the Window Energy Rating Scheme (WERS). WERS generates and publishes ratings of specific combinations of window manufacturer, window style, frame type and glazing type. Historically, screens were not considered to be ‘permanent’ parts of window systems and were therefore excluded from WERS energy ratings. WERS has changed their position and now recognises woven metal mesh screens as permanent fixtures, which should therefore contribute to energy ratings. Unfortunately woven fibreglass mesh (insect) screens are still not considered to be permanent fixtures and are ignored.
The Breezway Easyscreen Altair louvre window system was the first Australian window system to have screened WERS ratings generated. The first ratings included Crimsafe security screens, followed by InvisiGard security screens. The ratings are very good with U-values (a measure of thermal insulation) as low as 3.6, which is significantly better than many double glazed windows, and Solar Heat Gain Coefficients (SHGCs – related to shading) as low as 0.2.
Should all windows be screened?
It is not necessary to screen all louvre windows. In some situations it is very beneficial to maximise the amount of direct sunlight that passes through a window, especially on a cold winter’s day. Smart designers will intentionally allow sunlight to stream in through north-facing windows during winter when the sun is low in the sky, but will also design eaves, overhangs or other shading structures to shade those same windows during summer when the sun is higher in the sky. For this reason, screening north-facing windows may reduce this winter benefit.