Aluminium Sliding Sash Window

In July 2010 the Alumatherm Sash Window was weather tested at the BBA labratory in Watford, Hertfordshire. A report was generated No 46675. The test was to BS 6375-1:2009 comprising of BS EN 1026 : 2000 Air permeability, BS EN 1027 : 2000 Watertightness and BS EN 1211 : 2000 Resistence to wind. From this data a class is given which indicates where the product is suitable for installation in the UK.

The window is calibrated for rig air leakage and then a sample settling in procedure. During the test the window is subjected to water soaking, water spray various air pressures and finally a gust test. All the gust tests are negative and positive. This means the window is sucked outwards and blown inwards. Results achieved were:

Air permeability, Class 3, 600 Pa, UK exposure category 2000
Water tightness, Class 6A, 250 Pa after 4 minutes. A repeat test later provided a 300 pa water tightness result.
Resistence to wind load, Class A5, 2000 Pa. The allowable deformation of the window profile is 7.2mm. Alumatherm's slim design achived 1.1mm with positive air pressure and 2.5mm with negative. This result is a fantastic deisgn accolade.
A final safety test was carried out with a safety screen placed in front of the window. Air pressure + and - were applied up to 3600 Pa equivalent to over 150 mph gusts
The written report stated 'No visible damage, beads stayed in place.'

Alumatherm was put together like a puzzle. Each section was the result of compromises between asthetics, strength, size, manufacture, cost and thermal performance. We have pushed materials to the limit joining thermal resin, Aluminium, glass and Upvc to produce a window that achieves only 1.7W/m2.K. By reducing the air leakage figure even slightly will push the product in to band B. This is to be re tested later this year.

The result for the thermal performance was carried out by Mr Phil Davies from Azon UK Ltd accredited simulators.

Even when the window has a deep bottom rail means slightly more Aluminium content and slightly less glass the window can still achieve a C rating. Alumatherm still has a C rating when one pane of 4mm Diamant glass is replaced with 6mm Diamant.

Diamant is a low iron glass which makes it clearer which allows more light in. The inner pane is Planitherm total + which reflects the heat back in to the room. Argon gas insulates the cavity of the unit reducing cold transfer. Warm edge, glass fibre spacer bars reduce cold transmittances through the edge of the unit.