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With competition becoming ever fiercer, quality production, quality marketing and quality assurance provide a way out of the price war.
Everybody wants quality, and everybody claims it of their building components, promoting them with various statements and labels. These may include CE marks, the "Made in Germany" tag or the RAL quality mark. The diversity and frequent lack of transparency and verifiability of the various labels not only confuses consumers, but also architects.
CE must not be confused with quality!
The CE mark is often used as a quality mark, but the CE mark was only introduced in order to facilitate free trade in Europe. It confirms that the technical parameters were determined by uniform rules and that minimum safety standards apply. Nevertheless, the notion that the CE mark stands for quality is widespread. For example, during a recent interview the question was raised as to whether it is plausible that the stricter conditions associated with the CE mark would keep low-price suppliers from other countries out of the German market. Of course this is not the case, because all manufacturers have to affix the CE mark.
The fact is that the CE mark must be displayed on the product when it arrives where it is to be used, i.e. on the building site. However, in practice building owners and architects seem to have but little interest. The mark is more relevant to market supervision, as part of law enforcement of lower and higher building control authorities, in order to establish whether the minimum construction requirements for the essential characteristics have been met. There is therefore an assumption that there is potential for successful business based on quality, safety and security that goes beyond the CE mark.
This casement in a school has fallen out. The actual boundary conditions cannot be reproduced when testing with standardised procedures.
Making quality transparent – What aids are anticipated?
When consumers buy a window they face the problem of being overwhelmed by the technical information and performance indicators, and even construction professionals find this difficult. Insufficient knowledge of the more than 20 characteristics (product standard EN 14351-1) and performance indicators of windows on the part of architects often leads to inadequate and faulty descriptions of the properties with respect to the intended use, already at the tender stage. There is a big difference between windows used in a private home, an office building or a school. In view of the fact that the product standard does not give any information in this respect, an inappropriate description of necessity leads to the building components being inadequate in service. In addition, there are often design faults as well as defects in production and installation.
However, the customer expects the architect, designer or a competent manufacturer or supplier to be able to ensure that the products meet the requirements, are durable and have a long service life – in short, what has always been referred to as "suitable for use" by the ift Rosenheim. For this reason, the ift Rosenheim has started a new initiative for a series of Rosenheim guidelines with the working title "Application-related building component quality". The guidelines start with recommendations for the design of and specification and requirements for windows in school buildings.
Window quality initiative
In cooperation with the RAL Quality Association, the ift Rosenheim has developed a graded quality scheme that can be used by architects and consumers to select one of three quality standards – Standard, Quality and Premium. All standards have in common that the quality level can be verified simply and transparently using a QR code, and that the manufacturing conditions are regularly audited on site by the ift Rosenheim. The Standard grade ensures that the minimum legal requirements are complied with by the manufacturer. The Quality grade confirms that the window is a quality product with defined quality characteristics and that its suitability for use is regularly checked (unlike with the CE mark). A Premium window is identical to a RAL window, with best quality characteristics, including professional installation amongst other aspects, and is therefore what you might call a "worry-free package".
Guidance on the assessment of energy-related properties
The technical classes and performance indicators for the energy-related properties of building components are particularly confusing. Is there anyone who really understands the meaning of values such as Uf, Ug, g, Y, tV, gtotal… and can determine their relevance in practice?
The answer is clear – building physics experts, specialist engineers and experienced architects and building energy advisors, but surely not the average architect or the building owner. A differentiation must be made between windows, facades and doors used in property development or in the refurbishment of private residential properties. The requirements in most residential buildings are similar and easy to ascertain whereas in property development, the large glazed areas, specific use conditions (internal loads) and other special requirements make it necessary to carry out a complex analysis. Furthermore, statutory instruments such as the Energy Conservation Directive (EnEV), which specifies limits for the total energy demand of buildings, are easy to apply in new buildings and property development, but have distinct limits when it comes to refurbishment. This situation is supposed to be addressed by the simplified table method (EnEV easy). However, this stipulates windows that fall below the standard of what manufacturers can now supply and sell in the market.
The Energy Labelling Directive offers a simple evaluation method, i.e. "an energy label for windows". For this purpose, extensive work was carried out as part of a European study (known as LOT 32 study). The objective of the study was to analyse the different energy labels in Europe, to evaluate their potential and to make proposals for a Europe-wide solution. The potential seems enormous because studies in the UK have shown that the introduction of the Energy Rating System (the UK energy label) to the UK market very soon resulted in the distribution and sale of significantly improved products with optimised energy characteristics.
The proposals in the study ranged from simple approaches through to rather complex evaluation methods. The following questions were discussed:
- Should the reference size be the size specified in the standards (123 x 148 cm) or a non-standard window size?
- Should the label refer to standard values or to non-standard values?
- Is the evaluation to be based on just one climate zone in Europe or on different climate zones?
- Should the value be separated to reflect the different orientations of a building or should it be a mean value for all the building’s orientations?
- Is the energy efficiency to be verified only for heating in winter or also for cooling in summer?
- Does the energy label apply with or without solar shading?
Owing to intensive lobbying by some industrial circles, a preference for a complex and hence difficult to understand model is emerging. In the original words of a window manufacturer: "Such a model requires an individual calculation for each property with more than 9 parameters – that involves additional effort, red tape and cost." It is also intended to keep the option of accepting voluntary labels at the national level open.
For this reason, the ift Rosenheim takes the view that "it is better not to have an energy label than to introduce such a complex system". In the study, the ift Rosenheim has therefore campaigned intensively for a simple model which is easy to apply and understand, but nevertheless describes the energy properties of a window comprehensively and with sufficient detail.
For this reason, the ift Rosenheim takes the view that "it is better not to have an energy label than to introduce such a complex system". In the study, the ift Rosenheim has therefore campaigned intensively for a simple model which is easy to apply and understand, but nevertheless describes the energy properties of a window comprehensively and with sufficient detail.
The energy label takes solar shading into account as well as the properties of glass and window frames, and provides a sub-division into energy efficiency glasses from A to G for the different functions of heating and cooling, since requirements are different in winter and summer. The simple evaluation and classification provided by the ift energy label is a good basis for architects and property owners for the evaluation of energy efficiency and for the comparison of windows, and therefore is an aid to making a purchase decision. The supplier’s own declaration issued with the energy label contains the necessary information for the energy consultant to produce a detailed building energy passport.
Safety – windows that can withstand catastrophes
Climate change is upon us and its effects can be felt by all of us more and more often. The news regularly reports on various incidents – a tornado in Augsburg, flooding in Rosenheim, hail in Munich, drought in Central Germany, landslides in Austria etc. This makes it clear that a wide range of products with resistance to the effects of natural catastrophes will be required and demanded in the future, because people seek protection in their homes and immediate living environment.
Back in 2007, the Rosenheim Window and Facade Conference reported on the first effects on construction elements under the heading "Windows and facades exposed to climate change". Today, we are finding that wind loads often exceed the wildest assumptions. Broken glass (in spite of correct dimensioning), the destruction of frames by flying objects and hail and building components destroyed by flooding indicate that the requirements specified in the standards are too low for these ever more frequent climatic events. In order to keep damage within limits in the future, improved components with increased mechanical strength, impact resistance of surfaces, stronger hardware and better installation and fastening technology are required, as well as practical systems for upgrading such components.
In future, these products will not only be needed in extreme weather locations but increasingly also in European regions where, up to now, such events have not occurred. Designers will require thicker materials, new materials and material combinations and increased use of safety glass and safety hardware. Likewise, it will be necessary to define and classify the changed requirements in order to ensure that tender specifications are appropriate.
Security – burglary and vandalism
We are currently experiencing a time in which increasing and diffuse security fears are widely spread in the population. Crime statistics show that these fears are actually based on facts with respect to burglary. The rate of increase of these crimes is different in the different Federal states but reaches double-digits in some, while the rate of solving these crimes remains rather low.
(Source: Polizeiliche Kriminalstatistik PKS 2014)
However, investigations in the state of North-Rhine-Westphalia indicate that in 43 percent of cases, intended break-ins were effectively prevented because building owners used tested and certified burglary prevention devices. This success came about following an intensive publicity campaign in combination with advice and political support. This has motivated the Federal government to release funds via the KfW bank for the improvement of burglar resistance of windows and doors as part of refurbishment programmes; these funds are available either as loans or investment subsidies ("Energy-efficient refurbishment", Nos. 151/152 and No. 430, and "Age-appropriate Conversion Programme", No. 159 and No. 455).
Of course it is important to know which products are really effective in preventing break-ins and how this should be defined. In the conditions for funding issued by the KfW bank (No. 151/152 and No. 430), it simply states "burglar resistant doors and door constructions, windows and window frames…". In this context it is important that the clearly defined products specified in EN 1627 "Pedestrian doorsets, windows, curtain walling, grilles and shutters – Burglar resistance – Requirements and classification" for new windows, and in EN 18104 Parts 1+2 for "Mechanical security devices" for upgrades, are used and are installed by recognised and certified installers. This would make it possible to ensure that the measures undertaken are effective, and that funding for the use of products that are not tested and mostly not effective is avoided.
The results of hundreds of tests show again and again that the success of burglary prevention is governed by the principle "every chain is only as strong as its weakest link". The standardisation of burglar resistant building components and the resistance classes have been defined in accordance with this principle and the experience of the criminal investigation department. Only the combination of the various measures, i.e. the combination of window profile, glazing, hardware and installation will lead to the desired success – to effective burglar resistance of the whole construction element.
For this reason, products of resistance class RC1 or lower are not really "burglar resistant" in the true meaning. In certain cases, RC1 may mean improved mechanical strength and it may also make sense to a certain extent to use products of this class in the upper storeys of multi-storey buildings. However, areas to which burglars have easy access require security glass, burglar resistant hardware, strengthened frames and special installation. All this is included in resistance class RC2 in accordance with DIN EN 1627. This recommendation also applies to roller shutters and other products that are intended to prevent burglary. With respect to the principles of government-assisted funding and building control instruments, it would seem urgently necessary to include mandatory minimum requirements for burglar resistance in accordance with these standards.
Obviously, the requirement for burglar resistance also affects the construction of the component. When safety glass is used, the component will be heavier which leads to the familiar problems of transport, safety in use, the selection of hardware with structural strength, etc. It also affects the element’s suitability for use. For this reason, the necessary components used in burglar resistant windows and doors must be tested, for example as part of a mechanical durability test.
There are specific effects and recommendations that relate to laminated safety glass (LSG) as part of triple glazing. The laminated safety glass should be used as the central pane in order to avoid asymmetrical loading and deflection of the external panes and in order to reduce the exposure to high temperatures of the sensitive films in laminated glass units. When laminated safety glass is used in triple glazing there is often an increased risk of breakage; as a result, it is currently being discussed whether P4A safety glass can also be produced with heat strengthened glass with its greater stress resistance, rather than with float glass.
The dimensioning of glass
The issue of dimensioning glass leads to the intensively discussed subject of glass designing in accordance with DIN 18008-2. This DIN 18008-2 has not introduced significant changes for linearly supported glazing in terms of practical effect compared to the technical regulations applicable up to now (TRLV – Technical rules for linearly supported glazing units). However, the new design concept means that the glass of smaller panes has to be thicker or that different types of glass with greater strength (toughened glass or heat-strengthened glass) have to be used. For this reason, the relaxation of rules for providing documentary evidence has been adopted for glass panes of less than 1.6 m² (Table 1) as it was in the previously applicable technical rules for linearly supported glazing units.
It is not new that small-format glass units, especially with asymmetrical configuration, have an increased risk of breakage. This was also reflected in the technical rules (TRLV) for the dimensioning of glass units; nevertheless, following the introduction of DIN 18008-2, this is now considered to be controversial, in spite of the fact that nothing has really changed much, and experienced manufacturers know which applications need special attention. As a practical aid, the ift – together with Prof. Feldmeier – is currently drafting an ift Guideline for the simple design and dimensioning of common glazing unit constructions using design diagrams.
Summary
Safety, security and quality are wanted by everybody, but are difficult to describe since they depend heavily on personal expectations and the intended function of the unit. Both these properties can definitely not be expressed by the CE mark or the declaration of performance.
The expectations and the understanding of window purchasers regarding quality are increasingly also affected by current developments such as climate change and security consciousness. Without doubt, quality is not always straightforward, and cannot be specified as an unchanging requirement profile. For this reason it is difficult to describe this characteristic using technical classes, requirements and performance indicators. Therefore the essential key to success will be a correct combination of customer requirements, the requirements of the property and the technical characteristics of the building component. This requires competence, experience and sustainable and systematic commitment to quality. The ift Rosenheim will continue to support quality-minded manufacturers, designers and building owners with suitable services, and drive the development of modern and easy-to-use online tools.
