A building constructed to Passivhaus building standards is designed to maintain a comfortable internal environment for users by using minimal energy for heating and cooling. The standard is becoming increasingly more important within the commercial building environment.
Here John Lawrence, design manager for Kier Regional Building Central, explains how we used the Passivhaus Plus standard to create a zero carbon, eco office building for Cherwell District Council.
Passivhaus Plus combines a typical Passivhaus approach that aims to minimise energy requirements with the added requirements that show the building as a ‘plus’ site, being on-site renewable energy generation. This means that the building produces more energy than its occupants consume, both for heating and power, and combines a ‘fabric first’ approach, with full external shading to moderate solar gains and is connected to a Combined Heat and Power (CHP) installation.
The zero-carbon building offsets all carbon emissions produced through photovoltaic panels, ultra-low air tightness and mechanical ventilation with heat recovery. Other design features included an in-situ concrete frame with exposed concrete soffits and columns, timber ceilings with noise dampening acoustic baffles, solid timber flooring and an innovative acoustic green wall made from 17% nettle fibre mixed with wool.
A critical factor in achieving the eco standards for the building was obtaining the exceptional air-tightness seal of .59. This was achieved by the careful coordination of interface details and materials, rigorous quality controls, together with regular testing and inspections. Externally, the walls were super insulated, with recycled, shredded newspaper blown into the cavity walls.
The £4 million three-storey building was completed in 2018. A Passivhaus Plus standard was achieved along with a rating of BREEAM Outstanding, which exceeded the client’s requirement for an Excellent rating.
The learnings realised from delivering our first Passivhaus Plus project have been shared across the business and have been incorporated into further projects being undertaken across the country including the design and construction of Graven Hill Primary School, also in Bicester together with St Sidwells leisure centre Exeter, which when complete, will be the first Passivhaus leisure centre in the UK.”