An unusual office building clad in larch, designed to give the feeling of being among trees, with an enclosed woodland glade at its heart.

The Woodland Trust’s new offices are on a greenfield site and we were keen to create a ‘woodland experience’ from the moment people arrive. Staff and visitors are welcomed through a central garden space planted with birch trees, which encourages a range of interactions by providing both an informal meeting area and a place for eating lunch outdoors.

The building ascends in a spiral and thus makes a dynamic transition from landscape to building.  External timber cladding and decorative wood panelling internally express the core mission of the Trust and reflect the surrounding landscape. Internal spaces are grouped around a top-lit atrium, which is both reception area and staff breakout space, large enough to allow the 200 staff to come together for special occasions.

The client was keen for the building to be as energy efficient as possible, sitting lightly in its surrounding landscape. Three storey vertical windows on the north and south elevations provide natural light and ventilation, and the timber structure has been modified in a highly innovative way to increase thermal mass.

A series of ‘concrete radiators’ – concrete boxes fixed to the timber panelling inside - provide the necessary extra mass for passive heating and cooling.  We calculate that the CLT structure and timber cladding saved nearly 650 tCO2e in comparison to a concrete frame, making the building carbon negative and offsetting five years of operational carbon. The building achieved a BREEAM ‘Excellent’ rating.

CIBSE Case Study: Trees of Knowledge, CIBSE Journal 2014