7 months ago

ECOBuilder-Specifiers Journal spring2018

Considering alternative

Considering alternative glazing options for dynamic performance and user comfort The choice of glass that is used in a façade not only affects the visual appearance of the building but will also have a great influence on the overall building’s performance as well as the comfort of the occupiers. Each building’s requirements will be different, and influenced by numerous factors such as the intended use, material, finish, planning constraints, energy performance, daylighting needs, and, of course, budget. Cost, while important for the project, should be considered in the round where the selection of the glass for the façade is concerned. Using a basic clear glass with a solar coating may meet the basic project requirements but may not address associated issues which may then require additional devices to add shading or glare control, and which may have a further impact on energy usage for the building’s owners. As we move towards producing buildings that are intelligent both passively and digitally thorough their management systems, the correct selection of glazing to a façade becomes even more critical. If we take a typical glazing proposal where clear glass is used, we know that there will be glare problems at the extremes of the year when the sun is high or low. The typical solution to the problem is to use internal or external blinds to block the sunlight, with the consequence that, in some cases, artificial lighting is turned on to compensate for the loss of light. Separate shading devices will require additional work, as well as extra expense: the obvious basic costs of purchase and installation are inflated by the unseen cost of making sure that any loads inferred on the building by the device, are accommodated for in the structure. Perhaps most easily forgotten, are the maintenance costs for the client over the lifespan of the building. The solution, is to incorporate passive systems WITHIN the glazing of the façade, that are maintenance free, require no additional work during installation, and enhance the visual, as well as the building user’s comfort. Taking these into consideration, it is easy to see how comparing the basic cost of two different glazing proposals is an unrealistic comparison: potentially one is steered away from the most practical long term solution, to the ostensibly simpler and cheaper base option, where the costs of shading and maintenance are left to someone else. Having worked with specialist glazing solutions for over 10 years, I have noticed that the projects where unique solutions are selected, are where the end user is involved in the design and sees the long-term benefit of selecting a glass which offers more function. The ideal is a solution which will have the least cost to them over the life of the building but which adds to the overall architectural appearance of their building to make it a stand out project, promoting both the building itself as well the organisation’s brand. There can be little cost benefit in designing buildings where much of the glass is shaped or twisted over the façade, however we all know that buildings that use these techniques are some of the most memorable we encounter. They can create a landmark both architecturally and commercially - promoting the brand of the occupier in an easily memorable way. ©OKALUX GmbH An alternative to using shaped glass to distinguish a building, would be to look at the materiality of the façade. A building can be simple in form yet distinctive in its appearance through the use of bold frits, colours, panelling, or materials within the glass to add form and material contrast to the façade. Using natural materials such as wood, copper and aluminium can create facades that take on an altered appearance at different times of the day and in diverse lighting conditions, while at the same time providing good solar shading and glare control. 50 ECOBUILDER - THE SPECIFIER SPRING 2018

Whether it be an art gallery, where natural well balanced daylighting is crucial to best show the exhibits, a factory, university building, or office , excellent solar shading and daylighting without glare are vital with the common theme being user comfort and ease of maintenance as well as the appearance of the building: these issues are therefore critical to consider when selecting the glass solution. ©VENA Ltd ©Tim Meier Where views out from a building are not essential, but natural daylighting of the space with minimal glare is critical, then utilising a structure within the glass itself could be the solution: such structures diffuse sunlight thereby optimising it and minimising the need for artificial lighting. One of the more effective means of doing so is to use a 3 dimensional structure of capillaries that bounce light in all directions within the glass system, resulting in daylight that is effective in all directions. This effect can be clearly be seen here where a capillary glass (Okalux +) has been used alongside clear solar control glass. The direct sunlight through the clear glass creates intense areas of light which are distracting, whereas the light through the capillary glass is diffused, creating a comfortable light in which to sit and work ©Andrew Lee This type of glazing can be combined with clear glass areas, to maximise the benefits of both systems: the diffused light though the capillary glass compensates for the loss of light when blinds are drawn over the clear glass, whilst users can still see out. Glazing can not only be used for areas where light or views are required, but also to the solid spandrel areas: this enables the facade design to be simplified, by using the same framework throughout, but with glazing modules of different types and performing distinctive functions within the same system . Traditional insulating of spandrels - combined dry lining or aluminium back trays - can now be replaced using the latest vacuum panel technology incorporated within a sealed glass unit. This construction offers protection of the vacuum panel from damage during installation, and results in a thin unit dimension with very good Ug values. Utilising a 20mm cavity, an Ug of 0.23W/m2K is achieved which can be improved down to 0.11W/m2K with a 40mm cavity. The benefits of this solution are: simplified installation, reduced transport and storage costs, and ultimately, where insulation beyond the line of mullions is no longer required, increased floor area for the client to sell or rent. The message is simple – costs of the glazing alone should never be the driving factor in specifying glass. The effectiveness of how it performs across a whole range of criteria, coupled with the ability to simplify construction and minimise building life costs, should be the key influencers for selection. Moreover, its ability to improve occupier comfort thereby improving productivity and sales, may ultimately make the building more attractive to prospective buyers in the future. It’s the material that keeps the rain out, offers views to the world and lets the light in… and its correct selection is vital to a project’s overall success. John Godwin is the Director of VENA Ltd, the UK agent for OKALUX GmbH who have produced specialist glazing solutions for over 50 years. ECOBUILDER - THE SPECIFIER SPRING 2018 51

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