Das Schaubild zeigt die Entwicklung von Mehrscheiben-Isolierglas seit 1986 bis heute und in die Zukunft. Nähere Informationen zur Darstellung erhalten Sie auf Anfrage unter +49 8031 261-2150.

Insulating glass units

News from the revision of EN 1279

Reading time: 1 minute

The first draft version of EN 1279 was published in the year 1994. It contained the test standards prEN 1279 Part 2, 3 and 4, which then superseded the national regulations – in Germany DIN 1286 Part 1 and Part 2.

The first draft version of EN 1279 was published in the year 1994. It contained the test standards prEN 1279 Part 2, 3 and 4, which then superseded the national regulations – in Germany DIN 1286 Part 1 and Part 2. The drafts of Parts 1 to 4 as well as 6 first published were available in 1994/1995, until the first draft version of the actual Product Standard EN 1279-5 was available in the year 2001. However, it still took some time until the publication of the harmonised product standard DIN EN 1279-5 (Glass in building –  Insulating glass units – Part 5: Evaluation of conformity) 2005. From this point in time, CE marking for insulating glass units (IGU) was possible. The coexistence phase began in March 2006, after publication of the product standard in August 2005, such that insulating glass was finally mandatory for CE marking with effect from 2007. Since the test standards had already been published in the previous years, testing according to the new standard was already possible and required. There was no equivalence with previous national rules.

Since standards (primarily harmonised product standards) must be reviewed every 5 years, the first versions of the test standards were revised in 2007. It soon became obvious that the previous versions needed to be improved with respect to their mapping and content, and that a cumbersome phase of revision was pending. In order to avoid a time delay between the test and product standards, the revision of EN 1279-5, which was due for review in 2010, was also included in the work programme. Not least due to the requirements of the new Construction Products Regulation for the design and contents of product standards with effect from July 2013, the time period got extended. The standardisation committee hopes that the new versions of all 6 parts may be published in the year 2017.

This is why the following outlines what changes are expected at present (status of the papers as at the beginning of 2016) for manufacturers of windows and facades.

Das Schaubild zeigt die Entwicklung von Mehrscheiben-Isolierglas seit 1986 bis heute und in die Zukunft. Nähere Informationen zur Darstellung erhalten Sie auf Anfrage unter +49 8031 261-2150.
Figure 1: History of insulating glass units since 1986

Changes in the European product standard for insulating glass units

In those parts of EN 1279, which describe the tests and specifications for the system description, rules for substitution and audits, some modifications and reorganisation have been undertaken, which are not discussed in detail in this report since they have no impact on the interfaces with the manufacturers of windows and facades.

The characteristics given below, which need to be considered for further use of IGU and which will be amended in the product standard, include:

  • Mechanical strength of the glass, requirements for the edge seals, tolerances for the dimensions
  • Classification of the edge sealing systems of IGUs for non-load bearing, non-UV-resistant edge seals, UV-resistant edge seals without requirements for load bearing and for the load-bearing UV-resistant edge seals
  • Specification of the g value of a glazing in addition to the radiation characteristics of the coating used
  • Specifications in the declaration of performance (DoP) and in the CE mark
Die Tabelle zeigt die charakteristische Biegefestigkeit für die verschiedenen Glasarten. Nähere Informationen zur Darstellung erhalten Sie auf Anfrage unter +49 8031 261-2150.
Table 1: Characteristic flexural strength for various types of glass, prEN 1279-5 [1], Table A.1

Mechanical Strength

Contrary to information in the CE mark so far, the thickness of the glass and the glass type will be no longer specified in the future, but the characteristic flexural strength in accordance with the following Table 1.

In the future, fabricators will use the values for dimensioning the resistance against the respective types of impact in accordance with the specifications of prEN 16612 [2]. Since this standard is also only in the draft stage so far, national regulations will be used until the final implementation. In Germany, this is the standardisation series DIN 18008, which is introduced here by the building supervisory authorities. Another note in prEN 1279-5 will be the information that edge loads of insulating glass units must be considered separately in the following cases:

  • With highly asymmetrical superstructures,
  • If very thick (= rigid) individual panes or curved glass is used,
  • If the side length of the insulating glass unit is < 60 cm,
  • If for triple glazing the inter-pane cavity is > 16 mm,
  • If small size panes (high flexural strength of the individual panes) are used.

The calculated edge load should not exceed 1.3 MPa to ensure the durability of the insulating glass units during their service life. The calculation is done in accordance with the specifications of prEN 16612 (Glass in building – Determination of the load resistance of glass panes by calculation and testing), Appendix B. To review these cases, the dimensioning diagrams of Prof. Dr. Franz Feldmeier, presented in a report for the Federal Flat Glass Association (Bundesverband Flachglas) [3] offer simple solutions.

Even the permissible thickness tolerances, primarily of triple layer structures using LSG and SSG may lead to situations where a special agreement becomes necessary between the manufacturers of the insulated glass units and the manufacturers of the windows in order to ensure leak tightness of a glazing.

Regarding the tolerances of the dimensions it must be observed that apart from the permissible deviations in the width and height, even an offset of the individual panes of 2 mm to 5 mm is considered permissible. The extent to which this may affect the durability and lead to glass breaking due to the edge strength being exceeded, especially with large and heavy panes should be estimated in each individual case and corrected with the help of agreements.

UV resistance of the edge seals

The insulating glass unit system, which is illustrated in Figure 2 as Type C (right) must be designed to additional technical rules (EN 13022-1 [4]) and should be manufactured only with adhesives that comply with EN 15434 [5]. Such bonded systems that are not linear in shape in the closed condition, also require a national or European approval. The systems in Type B (centre) must be dimensioned as standard insulating glazing. The bonding of the stepped glazing to the frame is subject to the specifications of the ETAG 002 [6].

Das Bild zeigt drei verschiedene Randverbundsysteme. Nähere Informationen zur Darstellung erhalten Sie auf Anfrage unter +49 8031 261-2150.
Figure 2: Edge sealing systems of type A, B and C

Specification of the g value

Apart from the solar energy values in accordance with EN 410 [7] for individual panes, in future, even the total solar energy transmittance g must be specified for the entire package. Provided that fittings are used in the inter-pane cavity, the values of the fitting must be determined and specified in accordance with EN 13362-2 [8]. This regulation enables the planner to make a more accurate assessment of the building component with respect to the penetration of energy into the building with different alignment.

Conclusions

Based on the definition of insulated glass units, which is formulated more clearly in the new version:

"Arrangement that consists of at least 2 panes, separated by one or more spacers that are hermetically sealed, mechanically robust and durable on all sides, according to the specifications in Section 6.1"

systems, whose sealing has been verified in accordance with the specifications of prEN 1279-2 and 1279-3, can be defined as insulating glass units. If the test cycle has been completed successfully, this is also valid for breakages in the edge seals (e.g. due to cabling).

Vacuum insulated glass units are explicitly excluded from the set of standards. Thus, it remains an unregulated construction product and so far, it could be used only in the course of case-by-case approvals (Zustimmungen im Einzelfall, ZiE). 

Literature

  1. prEN 1279-5:2016
    Glass in building – Insulating glass units – Part 5: Evaluation of conformity
    Working paper unpublished at the point in time of the manuscript preparation
  2. prEN 16612:2013-06
    Glass in building - Determination of the load resistance of glass panes by calculation and testing
    Beuth Verlag GmbH, Berlin
  3. Feldmeier, F.
    Report G1109-3: Beanspruchung des Isolierglasrandverbundes durch interne Lasten, September 2011
    on behalf of the Federal Flat Glass Association (Bundesverbandes Flachglas e.V.)
  4. DIN EN 13022-1:2014-08
    Glass in building - Structural sealant glazing – Part 1: Glass products for structural sealant glazing systems  (SSG)  Glass products for structural sealant glazing systems for supported and unsupported monolithic and multiple glazing;
    Beuth Verlag GmbH, Berlin
  5. DIN EN 15434:2010-07
    Glass in building – Product standard for structural and/or ultra-violet resistant sealant (for use with structural sealant glazing and/or insulating glass units with exposed seals)
    Beuth Verlag GmbH, Berlin
  6. ETAG 002-1: 2012
    Supported and unsupported systems
    Guideline for European Technical Approval of Structural Sealant Glazing Systems – SSGS)
  7. EN 410:2011-04
    Glass in building – Determination of luminous and solar characteristics of glazing
    Beuth Verlag GmbH, Berlin
  8. DIN EN 13363-2:2005-06
    Solar protection devices combined with glazing – Calculation of solar and light transmittance – Part 2: Detailed calculation method
    Beuth Verlag GmbH, Berlin

Karin Lieb

ift Rosenheim

After graduating from high school, education in carpentry and studies at the Rosenheim University of Applied Sciences as a graduate engineer (FH) in the area of wood technology, Karin Lieb has been working in the testing division of ift Rosenheim since 1989. Since then she has been involved with materials testing, which at ift Rosenheim means dealing with all the individual parts that can occur in building components. This activity has built up over time from the position of Test Engineer, to Head of Testing Department, to Product Management. There she is now available to customers for enquiries of all types regarding the services provided by ift Rosenheim. She also works as an expert for the ift Centre of Technical Experts.

These activities have always been accompanied by technical cooperation in national and European standards committees as well as working groups for various associations.

Solutions related to this topics

Articles related to this topics