Harmonisation of product standards for buildings products enables buildings to satisfy the European Construction Products Directive CPD (1). This established six 'essential requirements' each with its own interpretative documents (2):
No. 1 Mechanical resistance and stability lNo. 2 Safety in case of fire lNo. 3 Hygiene, health and the environment lNo. 4 Safety in use lNo. 5 Protection against noise lNo. 6 Energy economy and heat retention Interpretative document No. 1 (for metal-faced sandwich panels), No. 2 and No.
6 are of greatest importance for thermalinsulation products. The interpretative documents form the basis for the 'mandates' requirements needed to draft harmonised standards. The European Commission awards these mandates to bodies such as the European Committee for Standardisation (CEN) or the European Organisation for Technical Approvals (EOTA) which then draft the standards.
European standardisation of thermal insulation products CEN/TC 88 'Thermal insulating materials and products' was created in 1988 and individual product working groups (WG) were established. All products used today for insulation in buildings are included in the scope of CEN/TC 88. Rigid polyurethane foams (PUR and PIR types) are dealt with in:
WG 6 'Thermal insulation products for buildings - Factory made rigid polyurethane foam products'.
Together with the other factory-made insulation product standards, EN 13165 for factory-made rigid polyurethane foams was finished and approved in 2001.
WG 10 'Thermal insulation factory made products for building equipment and industrial installations' - with PUR/PIR task group for products made from PUR/PIR slabstock foam lDraft standard 'prEN 14308 for the PUR/PIR products' has been presented now for a six-month CEN enquiry. The final formal vote may be taken at the start of 2003.
WG 15 in situ formed products as thermal insulation for buildings and for industrial installations with PUR task group for in situ rigid polyurethane (sprayed foam for roofs/walls/etc, dispensed foam for cavity walls, dispensed and sprayed foam for industrial installation).
For the PUR in situ products, a package of draft standards has been prepared now for the CEN enquiry (prEN 14315/14318/ 14319/14320). A final formal vote is expected for 2003.
CEN/TC 88 deals with all properties of building products relevant to their use as thermal insulating products. But the load-bearing capacity of products, such as metal-faced sandwich panels with insulation core for curtain walls and roofs, is not included.
EN 13165 for factory made rigid polyurethane foam products Standard EN 13165 for factory-made rigid polyurethane foams (WG6) was agreed in 2001. It covers:
Thermal conductivity (thermal resistance) lLength, width, thickness, squareness, flatness of boards and associated tolerances Dimensional stability lBehaviour under compressive stress and compressive creep
Tensile strength perpendicular to faces (adhesion of faces)
Flatness after one-sided wetting
Water absorption and water vapour transmission
Sound absorption (only if relevant)
Release of dangerous substances (not yet harmonised and still national requirements relevant) Thermal conductivity The most important property of a thermal insulating product is its thermal conductivity. The manufacturer has to specify a long-term 'time averaged' value for its product which can realistically be expected over a reasonable economic life. An economic life of 25-50 years is assumed for thermal insulating products.
Fire classification (reaction to fire) As fire behaviour is generally considered to be very important, the CE mark can only be used if harmonised CEN standards also exist for testing and classification of the fire behaviour. This is dealt with in another paper.
Evaluation of conformity and marking and labelling The standard requires the manufacturer's proof of the declared properties of the rigid polyurethane foam product, obtained by internal monitoring (factory production control in accordance with annex B of the standard). The manufacturer is fully responsible for the correct declaration.
Different systems (levels) of attestation of conformity and different involvement of the approved body have been defined by the EU Commission:
System 1: Factory production control by the manufacturer plus initial type testing with following continuous surveillance by the approved body.
System 3: Factory production control by the manufacturer plus initial type testing by the approved body.
System 4: Factory production control by the manufacturer only.
System 4 is sufficient for most of the properties. System 3 is only required for:
Reaction to fire class lThermal resistance lCompressive strength lWater permeability lRelease of dangerous substances For the reaction to fire classification, the manufacturer may elect to use the higher level of System 1 if the classification result is influenced by various production factors.
If the manufacturer has monitored his product according to the testing methods specified in the CEN standard, and has labelled the product according to the terms of the standard, they can provide this product with the European CE mark.
At present, there are still conflicting opinions on the attestation of conformity system in the different European countries, as the existing low involvement of an approved external body is felt in some countries not to be sufficient.
In an attempt to improve this situation, there is a European 'Key Mark' Scheme for a certification procedure that manufacturers can undergo voluntarily and that includes continuous external monitoring by an approved body for all declared properties.
Existing national quality-control groups may also offer a voluntary monitoring system with their specific quality mark.
In the UK, products need not be CE marked if a manufacturer does not intend to export them to a EU member state, where CE marking is mandatory.
CEN standard for metal-faced sandwich panels Metal-faced sandwich panels with thermal insulating cores are used as self-supporting elements for curtain walls and roofs in industrial buildings. They are statically stressed by their own weight, wind, snow and changes in temperature. The following evidence should be provided:
Determination of the permitted span of the sandwich panel (by testing or calculation).
Determination of the fastening according to type and number of fasteners (screws).
In 1996, the industry started to draw up a harmonised European standard for metal-faced sandwich panels; besides the commonly used cores of rigid polyurethane or polyisocyanurate foams, this standard will also cover cores of polystyrene, phenolic foam or mineral wool.
Standardisation work is being carried out by a subcommittee (SC 11) within the existing CEN/TC 128 'Overlapping roofing products and products for external wall cladding'.
Conclusion The CEN time schedule allows countries to adapt their national standards and regulations within 2002. Theoretically CE marking of insulation products was possible from March 2002 onwards.
EU member states must allow for CE marking at the latest by March 2003. Conflicting national standards must be withdrawn, but a longer transition period of old and new standards in parallel may occur. It may also be within the hands of industry how quickly the change to CE marking will happen.
But in some countries CE marking may still not be required for those insulation products that are not exported to another EU member state.
More time is needed to complete the work on harmonisation of insulation products for industrial installation, in situ formed insulation products and metal-faced sandwich panels. CE marking according to these standards may be in place in 2004/2005.
Dr Robert Walter works for Bayer