When the Window Energy Ratings scheme was launched just 7 years ago, most predicted that it would take the PVC-U sector until 2011 to produce a practical and affordable A rated window.

Instead, REHAU was the first to achieve an A rating on a double glazed PVC-U window in 2006 – just two years after the scheme was launched, demonstrating both the inherent dynamism which exists within the industry and the commitment of the leading manufacturers like REHAU to meet the challenges of the energy efficiency agenda. 

Whilst A rated windows have rapidly become a mainstream solution, there is still no mandatory requirement for them in the Building Regulations – instead this requires only that a window needs to be rated C or above or to achieve a U-Value rating of 1.6.

REHAU encourages architects and specifiers to choose the U-Value route, largely because it provides more flexibility, particularly in satisfying the requirements of the Code for Sustainable Homes, and also because the market has moved way beyond the artificial ceiling of an A.

In recent months, for example, REHAU has launched both a standard triple glazed window which achieves a U-Value of just 0.8 and a Passivhaus certified composite window system with a U-Value closer to 0.7.

The REHAU THERMO 0.8 U-Value window is suitable for use in homes built up to Code for Sustainable Homes Level 6 and is expected to prove popular with specifiers since, using the formula required to demonstrate compliance, it presents specifiers with a simple and cost effective route to reducing overall U-Values.

The new window is based around REHAU’s standard S706 and REHAU Edge profiles combined with a triple glazed, Argon filled 44mm sealed unit.   A single leg bead from REHAU’s standard range which has been used for many years with panes up to 1200mm x 2100mm, neatly accommodates the glass.

REHAU THERMO is an open out, casement window which has been fully weather tested to 600Pa, has achieved security accreditation to BS7950 and is fully certified to the 0.8 U-value at the standard size of 1230 x 1480mm.

The most innovative part of the design is the new REHAU THERMO foam insert which is applied either during or post manufacture into the legs on the outer edge of the window to provide the additional thermal efficiency necessary to achieve the 0.8 U-Value target. 

For applications which require a Passivhaus certified window, REHAU has developed an innovative solution manufactured using the RAU-FIPRO® fully recyclable fibre composite material.  These kinds of fibre composites are already used extensively in aircraft construction and Formula 1 design, so the performance and durability of the material has been extensively proven in the toughest commercial environments.

It is the inherent strength of this material which enables the system to perform as if fully reinforced without any requirement for steel, thus eliminating the thermal bridges which can occur in conventionally reinforced PVC-U and through which energy can be lost.

REHAU GENEO® can achieve U-values from 1.1W/m2K when double glazed and Argon filled, which is appropriate for low energy homes, right down to 0.73W/m2K when triple glazed and Krypton filled, which meets passive solar house standards.  It also achieves the highest Class 5 levels of sound insulation and up to Class 2 break in protection without steel reinforcement.

REHAU GENEO® windows have recently been installed in only the third commercial office building in the UK to be fully Passivhaus certified – the new regional headquarters of Interserve Construction in Syston, Leicestershire.

Further details of all REHAU’s window systems are available via the website at www.rehau.co.uk