Thermoblock offers the right formula for autosport test facility

The construction of an advanced new testing facility for motor sport engines in Wales features the use of Marmox Thermoblocks at ground floor level, specified in order to help comply with the latest edition of Part L to the Building Regulations.

The Sports Engine Testing Facility at the University of South Wales Pontrypridd is being built by Willmott Dixon Construction Limited working as main contractor. While the 1,000 square metre, two-storey structure utilises a steel frame, the exterior walls are being raised in cavity blockwork with the Marmox Thermoblocks in two different thicknesses subtending both the inner and outer leaf.

Developed specifically to deal with the issue of thermal bridging, but able to carry full structural loadings, the specialist units have been supplied through the local Jewson Builders Merchant for installation by the groundworks sub-contractor. 200 of the Thermoblock 140 mm size variant were laid as the perimeter to the ground-bearing reinforced concrete slab; virtually eliminating heat loss at this critical wall/floor junction. Then a similar number of 100 mm wide Thermoblocks form the bottom course to the outer leaf. Each block features a layer of alkali-resistant fibreglass moulded into the top and bottom surfaces in order to provide a strong bond with standard sand and cement mortar.

The stepped end joints to the blocks though are formed using Marmox Acrylic Sealant to help create an additional horizontal moisture barrier. The individual blocks are formed of XPS which has a lambda value of 0.033 W/mK, containing a series of load-bearing concrete columns to transmit and distribute the weight of the masonry above.

A spokesperson for the project design team commented:

“Countering linear thermal bridging at the perimeter of the floor construction is a crucial aspect of compliance with the latest version of the Building Regulations for non-domestic as well as residential properties, and the Marmox Thermoblock offers an ideal answer to the challenge. They achieve the required psi value while being both robust and simple to install.”

Individual Thermoblocks are 65 mm deep – equivalent to a course of bricks – and with the 15 mm overlap at either end give an installed length of 600 mm; being available in options of 100 and 140 mm. As well as masonry walls, they can be employed in timber frame construction and at other positions such as beneath window openings or at first floor level, the roof-wall junction and under party walls.

The XPS with its ultra-low thermal transmittance increases the path for heat loss, to outperform what are termed Enhanced Construction Details. While these cut heat loss by between 35 and 55 per cent, utilising Thermoblocks can reduce CO2 emissions still further to between 60 and 90 per cent, offering an important contribution to the points required in SAP calculations. Crucially, being able to employ a defined, very low thermal transmittance – derived by thermal modelling or measurement – achieves a far more advantageous result than adopting the ‘default’ figure offered in SAP.

Using standard ACDs will add a heat loss of 0.08 Watts to the U-values for a property, while Enhanced Construction Details can cut this to 0.04 Watts; but incorporating Thermoblock can bring this right down to 0.01 Watts or less. The same principle applies to the European PassivHaus standard or the recently launched Fabric Energy Efficiency Standard (FEES) which the Government is now promoting as the route to achieving Zero Carbon construction.