Four Oaks, Nailsea, Somerset

Built to Passivhaus principles, Four Oaks is a stylish, ultra-low energy three bedroom family home which achieves impressive thermal efficiency and air tightness. Large VELFAC window walls are vital to Four Oaks’ performance and are combined with moving external screens to ensure every room is comfortable to live in all year round.


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When designing Four Oaks, architect Michael Williams, of MJW Architects, worked to a rigorous, low energy brief without compromising architectural vision – one reason why he chose VELFAC: ‘The system delivers excellent thermal performance with a slim frame design,’ he says. ‘Many Passivhaus-certified window systems are ‘chunky’ in appearance whereas VELFAC windows maintain sleek and minimal sightlines even when units are triple-glazed. The system is also very cost-effective and comes with a warranty that other suppliers cannot match,’ he adds.

Full height sliding VELFAC windows are a major feature of the front facade, with additional glazing on the side elevations, including a VELFAC front door. Michael worked closely with VELFAC, and with the VELFAC Approved Installer, to ensure the glazing supported Passivhaus principles: ‘Triple-glazed VELFAC units already deliver U-values of 0.88 W/m2k which we further enhanced by improving insulation in the timber frame walls and around the internal frames,’ he comments. ‘To maintain airtight construction, outer and inner membranes were also overlapped and secured to the window units with VELFAC-recommended tape.’

Given the expanse of glazing, solar gain control was also important. ‘The Passivhaus solution to excessive solar gain is to restrict window area, but by installing VELFAC glazing together with external sliding shutters, we could increase glazing by 25 per cent without increasing solar gain. The internal VELFAC timber frame is finished in a clear lacquer so windows and shutters blend seamlessly, while external aluminium framing, finished in grey, enhances the sleek, minimalist design.’

Four Oaks was completed in 2017 and has been featured on the Passivhaus Trust website. It was also shortlisted in the ‘Best Individual Home’ category at the 2017 LABC Regional Building Excellence Design Awards, and in the ‘Best Eco Home’ category in the Build It awards 2018.


Sector: New build, Passivhaus-inspired home

Architect: MJW Architects

Specified for:

  • Slim, minimalist frame - even for triple glazed units
  • Excellent thermal performance and solar protection
  • Contemporary design
  • Competitive pricing and warranty
  • VELFAC technical support and Approved Installer network