Avoiding the ill-effects of poor fenestration design

Fenestration plays a key role in determining how much energy is lost through the building envelope, and with the NHS now facing a challenging task to decarbonise its estate, it’s time to take a new view on the specification process. So says Andrew Cooper, National Specification manager at Senior Architectural Systems, the UK’s largest privately-owned aluminium fenestration solutions provider, who here takes a look at some of the key things to consider.

From enhancing wellbeing to reducing heat loss and energy bills, there is more to good fenestration design than meets the eye. The term 'fenestration' itself encompasses a wide range of systems that each have more than one purpose, and the size, style, and positioning of all glazed units need to be carefully considered. Windows provide both daylight and ventilation, but must also limit heat loss to prevent damp or draughty interiors. Doors must be safe and secure, but also easy to operate and maintain. Curtain wall systems, widely favoured for aesthetic reasons in the commercial sector, can also help 
improve the overall thermal performance of the building envelope. Balancing performance with practicalities and style together with sustainability can be a challenge, but this need is also what has driven innovation in the industry, and in terms of sustainability, aluminium systems are leading the way.

Popular on new-build developments, aluminium fenestration systems are also the ideal choice for replacement and retrofit projects. As the development of thermally efficient aluminium windows systems has come on leaps and bounds over the last decade, this means that many older healthcare buildings don't come close to complying with the 
current regulations. The reality of this is that these buildings are also more expensive to heat. With energy costs at an all-time high, replacing and upgrading windows to a system that is not only easy to maintain, but which also gives exceptionally low U-values by retaining more heat, is a wise investment for the healthcare sector. The added benefit of switching to an aluminium window system with a high performance thermal barrier is that they are built to last and require little or no maintenance throughout their lifespan. The durability of aluminium windows can be further enhanced by powder coating, which enables new windows to be colour matched to any existing fenestration systems that are to remain in place. Upgrading to more energy-efficient windows which don't create any cold spots or draughts can also create more adaptable interior spaces by enabling radiators to be 
moved from their conventional positioning under the windows.

When we talk about the thermal performance of fenestration, what we are really concerned about are U-values. Put simply, when it comes to U-value ratings, less is more, and the lower the figure, the more heat is retained. The U-value of a window system is dependent on a number of factors, including the frame material, the type of glazing, and the use of a warm edge spacer bar which provides the space and insulation between the two or three panes of glass.

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