Preventing Window Size Reductions in New Buildings

Facades made entirely out of glass only interrupted by small joints cover strips are in great demand, not just in Germany but all over the world. The issue of summer heat protection must be addressed at each location.

Thanks to their involved commitment the German Flat Glass Manufacturers’ Association and the Association of Window and Façade Manufacturers (Bundesverband Flachglas e.V. / BVF and Verband der Fenster- und Fassadenhersteller e.V. /VFF respectively) are preventing window panes and glass facades having to be made smaller in new buildings in Germany in future.

Germany’s Energy Saving Ordinance for 2009 gave the German glass and window sector a start in spring 2008. This is because the bill tabled in April also contained a previously undiscussed amendment reducing the permissible level of sunlight transmission by 30%. Had this amendment gone though it would have had far-reaching implications on new buildings in terms of the restrictions placed on the size of windows and glass façades. The aim of this amendment was to improve protection against heat from the sun during summer.

The logic behind the policy went as follows: by reducing the area of windows and glass facades you allow less solar energy to penetrate the building and therefore reduce the energy required for cooling it. “The kind of glass architecture used today in the construction of commercial properties and office buildings would have simply no longer been possible and even with residential properties windows and glass areas would have had to be smaller,” said Ulrich Tschorn, Managing Director at the Window and Façade Manufacturers’ Association (VFF), explaining the possible consequences of the planned new regulation.

However, through representations to the ministries and background talks the associations were able to induce the politicians to remove the controversial reduction of sunlight clause from the bill. “A demand of this kind would not have brought about any energy advantages. On the contrary, it would have prevented solar energy gains as well as heavily limiting the possibilities for modern architecture with glass facades, especially in non-residential buildings,” said Jochen Grönegräs, Chief Executive at the German Flat Glass Manufacturers’ Association, summarising the associations’ arguments here. Energy from solar radiation, he said, is in fact desirable as a form of regenerative energy when it is handled properly and a number of points are taken into consideration in building design.

Study to provide Insight

Ensuring that restrictions of this kind – considered counter-productive by the glass and window sector – are nipped in the bud the German Flat Glass Manufacturers’ Association and the Association of Window and Façade Manufacturers say they are now preparing a study on the summer behaviour of “glass buildings”. This is aimed at providing policy makers with reliable data in good time ahead of any future ordinances (the next tightening of the Energy Saving Ordinance (EnEV) is planned for 2012). As part of this study a manual is also planned with guidelines on what should be taken into consideration with glass-oriented construction.

Practical Aid for Planners and Users

Under the Energy Saving Ordinance it will be obligatory for buildings to provide proof they have adequate heat protection in summer making it possible to create a comfortable climate in summer. Within this context a VFF working group already presented a revised Memorandum (ES.04) in mid 2008. Alongside detailed explanation of the proof of summer heat protection clause in line with DIN 4108-2 the paper will also for the first time give key pointers for planners and users of buildings with a large area of glass facade. This is because the simplified hypotheses of the norms are not always sufficient. The aim is to optimise summer and winter measures to guarantee comfort all year round with the lowest energy consumption levels.

Memorandum ES.04 was compiled in collaboration with the Federal Association of German Prefabricated Building Manufacturers (Bundesverband Deutscher Fertigbau), the German Flat Glass Manufacturers’ Association (Bundesverband Flachglas), the German Roller Blind + Sun Shade Association (Bundesverband Rollladen + Sonnenschutz), the Head Association of Germany Woodworking and Plastic Industries (HDH) and other competent specialists. Association members receive a free copy. Non-VFF members can order the Memorandum via the online shop at www.window.de for a token fee of Euro 6.00 plus a flat shipping fee.

Exhibition at glasstec 2008

The glass industry has a wide range of functional glass on offer to counter heat penetration of residential and office properties in intense sunlight. Wafer-thin, invisible, sun protective coatings, switchable glass and in-glass sunblinds are just some of the solutions on offer here. From 21 to 25 October 2008 numerous other product innovations will be on display at glasstec that will make it possible to use large areas of glass in both residential and administrative buildings in future, too.