PROFILE: Thermal Performance


    Halfen outline the innovations available to mitigate cold bridging and improve thermal performance…

    With the ever increasing need to improve the thermal performance of our buildings, designers and specifiers are always looking for new methods and products to achieve these aims. Cold bridging at balcony and walkway connections is potentially a significant contributor to heat loss from a building. The latest generation of the Halfen HIT insulated structural connectors provide an effective solution to these cold bridging problems. However besides these very important thermal issues there are a number of other considerations that should be taken into account when selecting a thermal connection product.

    ETA & CE Marking

    Under the Construction Products Regulation (CPR), it is now mandatory for manufacturers to apply CE marking to any of their products covered by a harmonised European standard (hEN) or a European Technical Assessment (ETA). Halfen’s HIT thermal connections have undergone an extensive third party review and approval process together with a rigorous testing regime to enable the HIT-HP & HIT-SP products to gain its European Technical Approval (ETA-13/0546). This approval uniquely allows Halfen to CE mark the HIT thermal connections giving customers added confidence to specify and use the Halfen HIT system.

    Robust and easy to install

    With many thermal units, one of the key problems once they have arrived on site, is that they can be easily damaged during normal handling, transporting or installation of the product. Some units needed to be very carefully stored to ensure they did not degrade when exposed to the elements.

    The latest generation of Halfen HIT HP and SP thermal connections sought to address this reoccurring problem on site with a number of key innovations. The new units now come encased in a hardened plastic shell which both firmly holds the essential HIT components in place whist providing a robust and easy to handle unit. This in turn means that the HIT units are easy to place and install, something which is made even easier by the fact that the new generation of HIT HP and SP units have eliminated the protruding compression studs and shear bars.

    Fire protection

    The shell also contains the high quality fire protection material which enables every HIT HP and SP unit to attain F120 fire protection as standard. This is something which is often only offered as an optional extra at additional cost.

    The standard fully encased fire protection is a major improvement on previous products because of the way in which this is provided in traditional systems. The old method of fire protection normally involved the provision of cementitous fire board top and bottom of the insulation. The main problem with this form of protection is that it can be easily dislodged, cracked or crushed during normal site operations. To ensure that fire protection is maintained, all the damage needs to be repaired or the fireboard replaced. Whilst it is possible to provide replacement fire board it is difficult to glue this into place on site.

    It is important to remember that the cementitious fire board also needs to be provided at the sides of the thermal units to ensure complete protection of the structural components. This is something that is often missed and yet could cause major structural problems in the event of a fire.

    Finally the addition of cementitous fire board to the traditional insulation units will reduce the thermal performance particularly if these units are attempting to achieve a two hour fire rating. Again this is something that can be overlooked however it is not something you would need to worry about when using the HIT HP units as the fire protection is standard and fully included within the thermal performance figures of the unit.

    Passive House

    The unique innovations implemented in the new second generation of HIT products have resulted in some substantial improvements in the thermal performance of the system. The utilization of the CSB components has enabled Halfen to eliminate the thermally inefficient steel compression pads and shear bars penetrating through the insulation. This has resulted in Halfen achieving Passive House approval for its HIT products, including some of the standard 80mm thick HIT-HP units.

    Psi values

    When HIT products were first introduced it was often sufficient that the designer was doing something to counter act cold bridging. With the ever increasing thermal requirements from part L, designers are having to look much more closely at the thermal performance of products they select and use. Even today though, designers should be cautious when reviewing thermal values as some published figures are not appropriate for linear connections.

    With the Halfen HIT system, the quoted Psi values are both internationally recognized as the correct thermal values for linear thermal breaks and are approved by official third party organizations.

    To conclude, thermal performance is one of the key factors when selecting products for potential cold bridging connections therefore care needs to be taken when reviewing thermal values. There are also other issues such as fire protection, robustness and easy of installation that should also be considered and third party approvals such as ETA, CE marking and Passive House can give the customer, specifier and end user confidence in the product selected.

    Mark Smith CEng MICE

    Technical Director

    HALFEN Limited

    Tel: +44 (0)158 247 0327


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