A
Brief History of EN 1279
General Comparisons between BS5713 and EN1279 Part
2 - Test Type Requirements
(Table)
EN
1279 The New IG Standard - What you must do
Technical
Description of EN1279 Part 1
A
Brief History of EN 1279
In 1988 members of the Glass and Glazing Federation were appointed by
BSI to represent the United Kingdom in the negotiations to develop a new
European Standard for insulating glass units. This standard was to meet
the requirements laid down in the legislation covering harmonisation of
technical standards in the construction industry.
The initial meetings in 1989 began with each country submitting its own
standard. It was obvious from the outset that BS 5713 would not be considered
as onerous as the standards prevailing in other European countries. Rather
than use one country's standard, it was decided to take the best of each
and develop a truly European Standard. Submissions included the following:
• BS 5713
• BSI A new approach (an improved version of BS 5713)
• Dutch Standard NEN 3567
• ltalian Standard UNI 7171
• GEPVP proposed basic document
• UEATc Directive for lnsulating Glass
• Spanish Standard UNE 43-752-85
• German Standard 1286 parts I and 2
• French CEBTP standard
• Description of the proposed Norwegian standard
Also the committee considered relevant ISO standards.
The BSI new approach was the revision of BS 5713 that had been started,
but under CEN rules could not be proceeded with. It was however useful
to signal that the UK delegates were aware of the European Standards,
and the new approach acknowledged this.
There were a number of issues that had to be resolved such as unit size,
test temperatures, the necessity for cycling and heat soaking, and the
requirements for UV testing. In addition it has to be remembered that
only the UK delegates were in favour of retaining hot melt butyl sealants
as part of the European system.
The necessity and reasoning for the type of test and its requirement is
covered in the detailed description, but highlighting a few of the issues
will serve to enable people to understand the time taken to reach the
completion of the documents. The committee had a remit to ensure that
no one country had to bear excessive costs, and no currently successful
product could be eliminated. Developments after 1990 would have to catch
up to be included, or the manufacturers would have to demonstrate how
compliance could be achieved.
Firstly there were the regulations from CEN and the European Commission
that had to be
taken into account. These changed over the period of negotiations and
are the reason why the standard is now in six parts. Also the Commission
did not reach a decision on the level of attestation until March 2000,
despite the fact that the decision was required in 1995.
Technically the most significant advance was the move to moisture penetration
index from dew point tests. It had been shown that the dew point test
was inefficient when trying to differentiate between good IGUs and those
just achieving a pass. Secondly the new products based on using the desiccant
dispersed within a polymer matrix made dew point testing obsolete, as
the older standards had not envisaged this development. (These products
are slow to give a final dew point, and retain a low dew point longer,
making result translation difficult). Thus the Karl Fischer test was introduced.
There was also the acknowledgement that different desiccant manufacturers
presented their product data in different forms, making comparison difficult.
A second significant step was to drop asymmetric testing, as this rarely
gave failures and did not replicate natural ageing of the IGU. An unpublished
survey by BSI showed that less than 1% of the BS 5713 failures was due
to the cycling procedure.
Many countries had examined ways of testing IGUs, with various degrees
of success. In Norway a large (1 m x 0.5m) unit was tested for creep at
50degC to replicate creep problems that had been noted. In Germany the
units were subjected to intense UV radiation, as there had been fogging
failures using certain glass/sealant combinations. Sweden had experimented
with impact testing to replicate the opening and closing of windows in
the winter. Some countries had a 'test to failure' philosophy, which had
given rise to the hot water/UV combination test. The UK's view was that
the testing had to be meaningful.
Another part of the debate has been the role of independent test houses
and assessors. These arguments have often been heated as the two opposing
views were brought to a compromise middle ground. On the one hand was
the Benelux view of quarterly audits and full third party intervention.
On the other was the opposing view of self-certification with a legally
enforceable standard. The UK view was to follow the BSI third party certification
scheme, with testing by accredited laboratories made compulsory.
Finally, the committee decided to follow the car manufacturers' philosophy
of making the product 'right first time', with well-controlled raw materials
and processes. Thus the document has a clearly defined Part 6 (factory
production control) and sealant testing (Part 4), with little in house
testing. Part 4 would also make the comparison of sealants more transparent.
The whole standard had to be written in such a way that it could be translated
into at least German and French without altering the meaning. It is this
latter point that has caused some of the delays, as the technical detail
was worked out as early as 1996.
General Comparisons between BS5713 and EN1279 Part 2 - Test Type Requirements (Table)
EN 1279 The New
IG Standard - What you must do
1. Prepare a system description
a. detail spacer sealant and desiccant
b. indicate seal depth level of fili, etc
c. indicate cutting tolerances
d. obtain data on standard characteristics of all products used
2. Have your units tested to part 2 by an independent accredited test
house
a. units must be manufactured as per the system description
b. show certificates of conformity for all products used in the unit manufacture
3. If gas filling, submit units to part 3 at the independent accredited
test house
4. Either carry out tests, or obtain data to show the sealant conforms
to part 4
5. Comply with part 5
6. Have a factory production control scheme operational
a. based on part 6
b. kept up-to-date
c. available for inspection at all times
7. If you are ISO 9000 Quality Management Systems accredited, ensure your
process manual is updated to take EN 1279 into account
8. Prepare a test regime for changing sealant, desiccant or spacer as
specified
Technical
Description of EN1279 Part 1
Part 1 : Generalities, dimensional tolerances and rules for the system
description. Our first step must be to attempt to understand the title
and the contents of this standard.
Although the document may change slightry between the "pr",
(provisional stage) and the final
document, these changes will be minor editoria) changes, rather than any
significant change to
the technical content of the standard.
When the document is finalised, and adopted as a European Standard it
will become BS EN 1279, a British and European Standard. This may happen
in 2003.
Copies will be available from British Standards, who hold the copyright
for the standard. The l279 number refers to a numerical reference for
this standard, which relates to insulating glass units for building.
The provisional standard has been issued in six parts; details of each
part follow.
Before proceeding with the explanation of this part of the standard, it
is important for the
reader to understand the meaning of the terms "Normative" and
"lnformative", as used in European Standards.
'Normative' means that there is a legal requirement to carry out the instruction,
a "must do" situation. The word "shall" may also be
used in this context.
'lnformative' means for information only. However, it is advisable to
conform to these requirements, as the whole standard represents a legal
requirement.
Scope
Part 1 of this standard deals with a number of key issues for all professions
dealing with insulating glass units in building.
For any sealed unit system of components and for any method of construction,
the energy savings for a given unit configuration will be relatively consistent.
Similarly, the personal environmental factors, such as noise reduction
and vision through the glass, will be maintained in the long-term, and
will also remain consistent from product to product.
Safety may be assured, as mechanical resistance will remain consistent.
The application of electrical current to the glass is limited to a safe
level.
Other important requirements, including product marking, are detailed
in this section.
The major application of insulating glass units referred to in this standard
are those fixed in windows, doors, curtain walling, roofs and partitions
where the unit edges are protected from direct ultraviolet radiation.
Sealed units with edge seals which are exposed to direct ultraviolet radiation,
and units destined for artistic applications, are not covered by this
standard. Additional standards apply to sealed units that have exposed
edges.
This part includes the requirements for the materials, the rules for the
description of the sealed unit construction, and the physical performance
of the system, including optical and visual properties.
Dimensional tolerances and recommendations for glazing and installation
are included in an informative annex.
Normative references
This European Standard incorporates a broad spectrum of requirements and
provisions from other standards and publications. Details of the normative
requirements from other standards and documents are shown elsewhere in
this guide. The normative reference generally indicates a ''must do"
legal requirement to carry out the specified element of the standard.
Definitions
Definitions
are included for the various elements of the sealed unit components, construction,
physical properties and quality control limits.
lnsulating Glass Unit System
A variety of raw materials, products and construction methods may be used.
It is permissible to substitute some materials. Possible substitutions
are detailed in Annex C Table CI and C2, and in EN 1279-4.
The manufacturer shall describe his system for conformity control, for
production control or quality assurance systems. Refer also to EN 1279-6.
The presentation of a detailed system description is discretionary.
Rules for system description, including action limits, are absolute limits.
Materials and methods of construction may be varied. A variety of glass
panes may be used. Cavity filling maY be air andlor gases. Cavity inserts
shall be non-volatile - see fogging test in ENl279-6. A variety of shapes
is possible. Cuwed insulating glass units are permissible, depending on
bending radius
Requirements
Conformity with the definition of insulating glass units.
All the insulating glass units supplied shall conform to the system description,
as tested and approved to the standard. ln this way the performance and
longevity of the products is assured. and the sealed units will be fit
for the purpose intended.
However,
it is permissible to have some substitution and changes, provided that
these are
carried out to the guidelines laid down in Annex C Table CI and C2, and
as in Part 4 of the
standard.
Non-European specification glass should demonstrate chemical and mechanical
stability similar
to EN 572 ond EN 1748 - I and 2.
Table I - Seal performance, applicable to all units
All the insulating glass units shall conform to the essential reguirements
of resistance to moisture penetration and glass-to-sealant adhesion, when
tested to the required conditions on prescribed equipment.
The requirements, test and equipment are detailed within this standard.
Table
2 - Seal performance, supplementary validation methods and requirements
for gas filled and coated glass units
Additional tests are required for inert gas filled units and when coated
glasses are used. Gas concentration and gas loss is measured.
In the case of coated glasses, sealant adhesion to the coatings and interlayers
of the coatings is
measured.
Performances
to the characteristics
The required performance to Table 3 characteristics shall be determined
by Annex B methods. The purchaser may also agree requirements with the
supplier, which are additional to this standard. Other than fire resistance,
edge design changes to table CI and C2 will not generally alter the glass
sealed unit performance.
Any changes which may affect performance shall be checked. Annex A EN1279-6
Durability is ensured by compliance with this standard, and by installation
to relevant European requirements or manufacturer's specifications.
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