April 1, 2023
How can I Cost Engineer my Architectural Glazing Project?
Written by Rebecca Clayton
April 1, 2023
Written by Rebecca Clayton
When designing a project, there are large costs associated with the materiality of the fabric of the building, including specialist glazing. A holistic and integrated approach to cost engineering with architectural glazing is advised.
For large frameless glazing panels, greater costs should be expected due to specialist oversized glazing incorporating transport, risk factors and the high specification of glass needed in these large glass panels to ensure they do not deflect.
Oversized glass panels are generally described as any glass unit over 2.4m in both directions, or if one of the dimensions exceeds 4m in length. These costing variations are due to the required toughening process all construction glass in the UK needs. There are only very few toughening plants in the UK that can toughen glass over these dimensions and therefore is defined as a specialist item. There are also transportation and installation considerations with these large glass units; heavier panels require more installation manpower to lift and fit and more specialist equipment. On smaller projects, there may be the additional uplift of crane costs if the installation opening is not accessible on foot or by car.
Glass in the UK can be specified at panel sizes of up to 6m long by 3.2m wide. This is due to the way that glass is made and cut at 6m intervals in its float state from the baths. All glass used in the UK needs to be toughened as well which also controls the size of individual glass panels.
Cost engineering the glazing on a project under these measurement parameters would be prudent. Ensuring that glass units on a project can be installed and lifted 'manually', without the need for a crane, is an effective way to reduce the overall glass package.
“Does this apply to Framed Solutions?”
These glass size parameters also apply to glass that will be installed within a frame. Although, these proportions of glass are normally only a factor to consider when you are looking at using large format sliding door systems such as the minimal windows sliding doors. These systems can take a piece of glass up to 18m2, but if you want to cost engineer the glass cost, keep at least one dimension of a sliding door pane under 2.4m. If your floor to ceiling height of the sliding glass door is over 2.4m, consider keeping each pane under 2.4m wide to make the glass rate as cost-effective as possible.
Triple glazing is more expensive compared to double glazing because it involves adding an extra layer of glass to the window unit. This additional glass increases the material and manufacturing costs.
However, triple glazing offers certain benefits that can justify the higher cost. One of the key advantages is improved thermal performance. The extra layer of glass helps to enhance insulation, reducing heat loss and improving energy efficiency. This can lead to lower heating costs and a more comfortable indoor environment. It also provides better acoustic performance compared to double glazing. The additional glass layer helps to reduce noise transmission from outside, which is particularly beneficial for city properties.
If cost is a key consideration, you may consider using double glazing instead. While it may not provide the same level of thermal or acoustic performance as triple glazing, it still offers significant improvements over single glazing and meets with Building Regulations Part L.
When cost engineering for sliding doors, there are several ways to significantly reduce the costs to a minimum, such as introducing one of the panels as a fixed frame as opposed to sliding, and changing a 4 track arrangement to perhaps a 2 track. This would mean that the panels would form two stacks rather than one with each panel stacking one behind the other. However, the cost saving is substantial. Another compromise when cost engineering sliding glass doors and windows is to maintain a height under 3m. The obvious reason for this is the weight, logistics, and installation, but another reason would be that the larger the glass, the testing for windloading would also have an affect on the overall costs.
Should energy efficiency be at the top of the design brief, then it is worth bearing in mind that with triple glazing, there is as much as 50% in energy saving with heating and cooling bills, but with an initial 10-20% outright cost. Needless to say, it pays dividends in the long term. Despite the additional weight of the glass, the benefits outweigh the cons from a thermal performance, scoring an impressive to A++ (the highest value).
If there is a design requirement for larger glazing panels IQ can source specialist 12m long glass units from the continent. There is, of course, large costs associated to this specialist ‘Supersized Glazing’ incorporating transport, risk factors and the high specification of glass needed in these large glass panels to ensure they do not deflect.
Steel framed windows are at least two to three times more expensive than aluminium. Aluminium frames is a great alternative when cost engineering your glazing project. Aluminium frames are lighter and deliver on thermal broken performance. They can also be finished in a multiitude of colours and coatings. Additionally, glass on coastal projects, or marine environments would choose Aluminium as the best framing material for salty and corrosive environments.
When looking at an architectural glazing package, there may be alternative systems or solutions which can be explored to cost engineer the glazing package.
When exploring alternative glazing options, it is important to consider the specific requirements and budget of the project. For example, an Invisio structural glass wall is a premium option that requires high-specification structural glass units. An alternative solution may be a slim framed facade system like our highline glass façade system, an aluminium facade system with a 20mm framing sightline, around the same as a structural glass junction. Although you will have a box section within the internal space of 65-85mm deep, you can create a similar external design from the single-storey facade at a lower cost.
It is possible to design a glass package within a specific allocated budget for glazing that aligns with the project's financial constraints if the budget for the glazing is clear from the outset. At IQ, we recommend the most suitable systems, as well as offering alternatives to the design or specification that might help reduce costs, such as the glass sizes or framing options.
Need some further advice?
You can also make an appointment to visit our architectural glazing showroom in Amersham where all of the glazing solutions mentioned above are available to view.
The Courtyard Showroom, Sky House Design Centre, Raans Road, Amersham, Buckinghamshire, HP6 6FT.
NOW AVAILABLE The Keller NextGeneration Sliding glass door system (NGS) – as seen at BAU
May 18, 2023