All windows are fixed lights and span floor to ceiling height with large double glazed units – the largest of which are 1m wide by 2.2m high. This maintains unbroken sightlines externally so retains John Madin’s original aesthetic vision. Although unnecessary from a structural integrity or safety perspective, internally each window features a mid-rail fixed to the surrounding wall to provide building users with a visible barrier.
The specification of the new windows represents a significant upgrade on the existing. Every window is fabricated using the Technal FXi65 thermally-broken aluminium profile system which offers slim sight lines and lasting long term performance. These are powder coated to match the grey colour of the existing.
The profile’s design incorporates a highly efficient 19mm flush polyamide thermal break to minimise thermal transmittance. This works in conjunction with 28mm, 1.1 W/m2K argon-filled double glazed units to achieve a low overall whole window U-value of well below the required 1.8 W/m2K. The glazed unit features low-emissivity (low e) and body tinted glass manufactured by the float process.
Tinted glass meets the brief for Glassolutions extremely well at Fifty4 Hagley Road thanks to its coloured appearance and solar control properties. It is specially designed and manufactured for exterior applications of this type with exact colour tint match for the replacement windows to replicate the originals.
Thermal performance is complemented with proven weather-tightness. The project demanded superior resistance to the weather including extreme wind loadings due to the high rise nature of the towers. Technal’s window system meets the brief, achieving the highest classification for air permeability in tests up to 600 Pa, full water-tightness up to 1200 Pa, as well as a rating up to the equivalent pressure of 2000 Pa for wind resistance.
Glassolutions typically had a team of between six and 18 installers working on this project on a daily basis. The project perfectly illustrates how the thermal performance of a notable commercial building can be transformed without any change in the external appearance – something which is vital for iconic and listed buildings.
Important too is the fact that Glassolutions completed the work without significant disruption to the day-to-day operation of tenants. And in the longer term, Mercia Real Estate will benefit by this refurbishment work adding value to the building and delivering a financial return on investment.