Glass is a wonderful building material. It enhances building design like no other. But poor design using this remarkable material can turn it into a liability, resulting in unhappy clients and building occupants.
Here are some fundamental building glass design stuff ups (mistakes) to avoid.
Using louvre windows
Louvre windows can be problematic. Other than the fact that louvres provide some low-level security barrier while open, they provide no design advantage.
Problems can include: they have a dubious operating mechanism with poor sealing qualities; you can’t stick your head out the window to get a better look at outside; they are difficult to fit security and insect screens to; their largely unframed condition leaves them susceptible to breakage from impact or pressure.
Louvre windows are also very difficult to clean. Louvre panes open to a non-vertical position, so the glass collects dirt and dust quickly, and each pane is awkward and time consuming to clean. This natural cleaning difficulty becomes a cleaning problem with large banks of louvres.
Very large window panes
Large windows enhance views, let more natural light into a building, and create an open atmosphere inside, but very large unframed window panes can have problems.
Large panes can be proportionally very expensive as the glass has to be thicker to handle normal stresses, and thicker glass is very expensive both in up-front material cost and in handling costs. This expense is doubled if the pane suffers breakage and needs to be replaced.
Large panes are not necessary to capture a view, as views through large windows which are divided into smaller framed sections don’t detract from the view.
Large uninsulated glass areas tend to have poor thermal insulation qualities.
Large window panes that extend up from floor level can lead to pedestrian impact where the pedestrian thinks there is an opening to go through. This danger can exist even with motif strips printed onto the glass. A mid-height transom frame eliminates this danger.
Large window panes also represent potential danger to flying birds.
Glass danger to birds
Badly designed building glass can create situations where flying birds impact the glass due to its invisibility. Americans have now acted on this with the recent passage of the Bird Safe Building Act 2020.
Bird-friendly building glass design features include, large expanses of glass broken into smaller sections by framing, and also using tinted, patterned or reflective glass (including and especially for glass balustrades and pool fences) to increase glass visibility.
Using double glazing unnecessarily
Double glazing is a great solution to provide window acoustic or thermal insulation. However it may be best used only when necessary, mainly because if one of the panes breaks, the whole framed window unit (including the un-broken pane) needs replacing. Double glazing is expensive. An alternative, where design performance allows, can be to use thick laminated glass which is strong, is cheaper than double glazing, and has notable acoustic and thermal insulation properties (albeit not as good as double glazing).
Large sliding/folding glazed door openings
A trend in house design is using large sliding/folding glazed doors to create whole external wall openings. While this can create a great indoors-to-outdoors environment, it comes with design compromises including: the opening can not be insect screened; the opening has no intruder security; the surprise of sudden storms may result in wind and water internal damage; it lets a lot of dust inside, has complex operating mechanisms which are expensive to purchase and install: and it creates a weakened thermal and acoustic insulation barrier.
Odd shaped windows
Odd shaped windows are not square or rectangular. Odd shaped windows are comparatively expensive because the glass needs to be cut down from larger panes to form the odd shape, and then requires customized framing.
Odd shaped windows also are very difficult to furnish with curtains or blinds.
Large windows in Australia should not face east or west as that is the direction hot summer direct sunlight can enter a building through windows.
Large north facing windows should be used to capture warming winter direct sunlight to passively heat a building.
A problem with north facing large windows, however is the risk of allowing warm day autumn and spring sunlight into the building. The most practical way to counter this risk is use of external adjustable sun shading. Shading adjustment is needed during autumn and spring to block direct sunlight during hot days and allow it in on colder days.
Some commercial buildings use non-opening windows because it is cheaper and it is expected that air conditioning will be used continuously in the building. This is not only results in excessive energy consumption, but also may create occupant health risks through the promotion of mould growth, poor quality air, and negative psychological effects.
Glass is an amazing building material. Don’t allow a building design to suffer because appropriate consideration was not given to glass design. It deserves utmost design attention.
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