Nicholas Hare Architects unveils its new green design for Christies Care’s office

The newly-completed office building for Christies Care on a rural site in Suffolk is perhaps Nicholas Hare’s greenest building yet. The design followed Passivhaus principles and achieved an EPC ‘A’ rating. It is largely built of wood; the external cladding is of specially treated, unpainted timber boards and the superstructure is of cross-laminated timber. Furthermore, it was erected in three weeks.

Gallery

Fact file

Date of occupation:

November 2016

Internal area:

484m2

Contract value:

£1.1m (traditional contract)

Contractor:

SEH French

Structural engineer:

Integral Engineering Design

Environmental/M&E engineer:

CouchPerryWilkes

Quantity surveyor/cost consultant:

Bremner Partnership

Photographer:

Alan Williams Photography

C

hristies Care arranges home care for all sorts of people. Nicholas Hare’s brief was for a new office building to house about 60 people next to its existing buildings on the edge of Saxmundham. The decision was taken to focus on two aspects of greenness; in the selection of materials and energy economy, targeting an EPC ‘A’ rating and following Passivhaus principles without the rigour and expense of certification.

Design approach

The building is a simple two-storey box with a pitched roof. The long axis runs north-south, so that the windows along its side walls face east and west. The deeper and more open offices are on the west side, so the windows are larger there than on the east. All of them will need blinds to cope with sunlight.

The wet parts are at the north end, and on the south there is a generous glazed screen to the cafe, with a deep canopy to protect it from summer sun. Above it at high level in the gable is a circular window. This will allow sunshine to track across the open office on the first floor, and is actuator-operated to help purge hot air in summer.

Construction

The entire superstructure of the building is of cross-laminated timber (CLT) and was erected in three weeks. The CLT is generally visible internally and the most basic industrial quality was chosen. The surface was given a dilute white spray to reduce the effect of darkening.

The external wall cladding is of vertical Accoya tongue and groove strips. The client opted for it to be unpainted, understanding that it will go grey and stain unevenly. Whilst the roof cladding is of pre-patinated zinc. The external areas are largely grassed and planting will be carried out by the client in the spring and autumn.

Social sustainability

Christies Care is a major employer in the market town of Saxmundham. Its previous main office was in an unsatisfactory old Post Office building. The new building provides the opportunity for continuing and growing employment in the town. The entire superstructure of the building, including the external walls, is of timber – CLT combined with glulam columns and beams. This calculated to sequester 180 tonnes of carbon, which in terms of embodied energy, much more than offsets the transport from Austria. The external wall cladding is also of acetylated timber (Accoya), which uses a timber which would otherwise be unusable for construction. Floor finishes were chosen for their sustainability, being generally Desso ‘Airmaster’ carpet or lino.

Energy performance

The building has achieved an EPC ‘A’ rating and the design generally followed Passivhaus principles but without certification. This meant that a standby l.p.h.w heating system could be installed, partly for psychological reasons and partly to deal with cold mornings. The building achieved an air leakage rate of 1m3/hr/m2 at its first testing – testimony to the form of construction and a careful contractor. The main ventilation is through a centralised mechanical system, using a Passivhaus-approved heat recovery AHU. On the upper floor, displacement ventilation is delivered through floor grilles. The windows generally are opening to give improved ventilation in temperate conditions. All of the light fittings use LEDs.

Hugh Gathorne-Hardy, Chairman at Christies Care, Saxmundham, commented: “We’ve been in our new offices for over three months now and the pleasure of admiring it and walking inside every morning to work is as strong as our first day just before Christmas. Our team are happier and more productive than they were in our old, cramped offices. Our receptionist has said what a pleasure it is to show people to it, because they turn a corner and see this beautiful building.

“The construction and planning too were remarkably easy. Nick and Beatriz were always on the ball, their expertise in not only designing a great building but making a great team of builders, M&E, engineers and so on, made the whole process a pleasure. Started on time and finished on time, we couldn’t ask for anything more.”

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