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No.3 Rayns Way Passivhaus office


No. 3 Rayns Way Passivhaus office

Interserve recognises the importance of sustainability in all of its clients' projects. So when it came to constructing its own new regional office building at Leicester, the company was well placed to select building materials and methods that would optimise the build's eco-credentials and position it at the cutting edge of commercial property design. The result is a £1.8 million project, which is the first certified Passivhaus Carbon Negative commercial office to be built in the UK.

The design principles of Passivhaus have already been broadly accepted and highly acclaimed in the UK house building industry, where they are helping developers to achieve superior energy efficiency ratings as part of the Code for Sustainable Homes. However, building to Passivhaus standards in the commercial sector is in its infancy, with Interserve at the forefront of implementing this construction method for a variety of public and private sector projects around the UK.

Located at Watermead Business Park near Leicester, the new building has been constructed by Interserve in partnership with park developer Raynsway Properties. The two-storey 6,000 square feet office houses approximately 60 staff in a modern, fresh, working environment, running at a mere 10 per cent of the energy usage of such a building constructed conventionally. Super insulation, triple glazing and high levels of air tightness (0.44 air changes per hour) have all reduced the requirements for space heating and cooling, thereby providing high-level comfort with very low energy consumption and a class leading EPC of A+ -2.

A superior air-tight construction avoids heat loss through the external envelope. Reinforced concrete walls have been built using Durisol 80 per cent recycled wood blocks, which were delivered to site already insulated thermally and acoustically, with in- built fire protection.

With triple glazing and insulated foundations, the building is able to hold warmth during the winter and stay cool in summer, whilst the south-facing windows make the most of solar heat during the winter. The ventilation air passes into the building from an earth tube system, making the most of ground warmth in the winter and cooler ground temperatures in the summer. Efficient lighting has been installed to optimise daylight use by using automatic dimming controls.

With the Leicester site demonstrating perfectly Interserve's capabilities in building to Passivhaus standards, the company has now undertaken a number of other Passivhaus projects around the country, including a circa £10 million primary school new build in Leeds, which is set to be one of the most energy efficient schools in the world.

Project vitals




Raynsway Properties Limited




6 December 2010 to 1 September 2011


We work with high profile government and private sector clients, delivering everything from minor property services roll-outs to large complex construction projects.

Construction of the new Interserve East Midlands regional office to Passivhaus standards.