A clear view

The CIBSE facade engineering group attracts members from across the supply chain, including architects, engineers and manufacturers of glazing and window frames. This reflects the kind of teamwork required to make a facade work, particularly in the light of the new Part L legislation which is looming.

With the increasing demands being made on facades, several groups have developed software to help specifiers make the right choices. As well as the TM35 toolkit (see ‘All wrapped up’), glass specialist Pilkington is also launching a system to aid correct product choice. Spectrum is due to be launched in 2004 and will be available in CD form and on the Pilkington website (where regular upgrades will also appear).

Phil Brown, Pilkington’s European standards development manager, explains: “Spectrum was developed with our r&d division because they measure the performance of a great number of product samples. Transferring that data into files which can then be managed and sent out to marketing communications and other departments can be a laborious process. The Spectrum program was initially developed for this use.”

It became clear that this type of information would be useful to Pilkington customers who need to calculate light transmission, solar transmission and other aspects related to specifying glass. This will be available from the Pilkington website and customer service team from this month.

Software such as Spectrum is increasingly necessary as the properties of glass for buildings become more advanced. Pilkington is researching technologies such as electrochromic or photochromic glass. “These technologies are already in existence, but they aren’t really practical at the moment. We’ve been looking at those kind of technologies for a number of years. The big hurdle to tackle will be to produce something which rather than just being a prototype r&d product is one which can be produced in similar ways to existing glass, so it can be toughened or laminated made into units and on a large scale. That’s where the challenges will be.”

There are other areas which haven’t yet been fully explored but can have an impact on building energy efficiency and hence CO₂ emissions. One example is internal blinds. Andy Dyer, of Dutch manufacturer Verosol, says that in the Netherlands and Germany blind manufacturers have been working to much tougher regulatory standards, resulting in superior product performance. “Glare on vdu screens has increased and more people are planned into a space due to rising rents.The users and facilities managers are more aware of what they don’t have to put up with in terms of glare and heat which can be caused by ineffective, or non-existent, blinds,” says Dyer.

A European research project carried out by institutes, universities and some manufacturers including Verosol, resulted in the Window Information System (WIS) which is a calculation tool for engineers to work out heat gain into buildings using different types of glass, cavities and window coverage. “Our engineers have created a simplified version of this which can be used as a tool for demonstrating the effects of using different types of metalised blinds with types of glazing,” explains Dyer. The software is not designed for customer use, but is a demonstration tool. “We can add particular information for products which they may want to check,” says Dyer.

The software shows the cost of compensatory heating and cooling to neutralise heat gains and losses both with and without blinds. Dyer adds: “We can’t show the costs for every aspect of the building, so we show the benefit of blind use in terms of energy cost savings and CO2 emissions reductions.” See table for example of information outputs.

Dyer says that with Part L2 legislation putting more pressure on designers to meet strict energy use targets for the whole building, greater thought is needed for what used to be seen as small elements: “For many years the perception was that blinds were an afterthought rather than something which can bring energy savings”

Brown agrees. “Closer co-operation will happen more often. Facade design and engineering will be a more complicated process than just specifying a window that needs a U-value of x. It will mean that the building needs an energy performance of x. So the manufacturers will have to be involved much earlier to design a solution for the whole building.”

• For more information see www.verosol.co. uk and www.pilkington.co.uk