Durisol UK helps Interserve’s new office meet PassivHaus standards

A group of architects from Pick Everard recently visited Interserve’s new East Midlands regional office at Watermead Business Park in Leicestershire. The building, heralded as the ‘first carbon neutral Passivhaus commercial office in England’, gave many their first introduction to Passivhaus standards.

The 6000ft2 office space was designed by CPMG Architects for Raynsway Properties to a brief which called for a building that would actively promote sustainability.

Interserve have predicted energy costs of the new building to be £2821.69 per year with annual CO2 emissions of 17.73 tonnes. Their previous office used to cost them £23,336.10 in energy bills per year and emitted 111.67 tonnes of CO2. From these figures, it is easy to see the benefits of the move to this low energy office space. This Passivhaus office is predicted to save £20,000 per year in comparison to their old premises. The building is constructed from Durisol blocks, which are made from a mix of wood fibre and cement. The walls are built without the need for mortar; the blocks interlock with concrete and reinforcing bars for stability. This was combined with Celotex insulation to the walls. The building is clad in FSC-certified Thermowood cladding.

Waste was carefully thought about throughout the construction process. All cut offs from the Durisol blocks were sent back to the manusfacturer after each delivery, to then be broken down and recycled.

Building facts:

• Wall u-values: 0.12W/m2K

• Roof u-values: 0.13W/m2K

• Floor u-values: 0.13W/m2K

• Window u-values: 0.7W/m2K

• Air tightness: 0.885m3/hr/m2 @ 50pa

• 135m2 of roof mounted PV

• 40% south facing glazing

• Triple glazed windows with Levolux external blinds to the south facade

• Began on site: September 2010

• Completed: September 2011