St Albans Community Centre is the first to achieve net-zero

This story explores the planning, design aesthetics, and challenges of designing a community centre at St Albans, Christchurch, New Zealand.

Project site and context

St Albans is a diverse, predominantly working-class suburb comprising various socio-economic and cultural groups. It is porous, walkable, and well-resourced, which is reflected in the existence of many strong local community organisations. The site for the community centre was an aggregation of four smaller properties spanning two streets. One major challenge was to define the primary pedestrian entry to the site from Colombo Street while providing vehicle entry from the rear.

Planning and design

The building’s form projects a civic image to the street frontages, while not being overborne. The site planning carefully considered assembly areas at the entries, a generous mid-block pedestrian connection, and swales for water treatment, while providing some space to adjoining neighbours. The form of the building was developed by exploring the interface of the street and the forecourt areas. The entrance was defined, and the shelter was formed by sculpting out the wall volume at the front and rear. At this point, the triangulation of the façade simplified the geometric moves, with the surface definition of the timber slats helping to define the differing plane orientations and amplifying the perception of depth.

Material selection and construction

Due to the underlying poor geotechnical soil conditions, the building was required to be lightweight. The flood zoning required a minimum floor level of approximately 650 mm above the ground level. The response to these requirements was to find the building on timber piles, with bearers up to 2.5 m centres supporting the floor. Using a cross-laminated timber floor, deflections for the 5-kPa crowd loading were minimised, and the secondary structure was eliminated.

The primary wall structure is cross-laminated Spruce timber. Spruce glulam beams, in conjunction with CLT shear walls, support a CLT ceiling, with purlins overgenerating a void for insulation and services. The CLT is exposed internally to maximise the permeability of vapour flow and create a durable, beautiful finish. The external cladding comprises Pinus Radiata weatherboards with a low-toxicity preservative and surface treatment. The roof cladding is long-run prefinished steel. Timber slats are incorporated as solar shading and security devices.

Sustainability Statement

The community centre is the first building commissioned by the Christchurch City Council to achieve a net-zero cradle-to-grave embodied energy as measured by the BRANZ LCA Tool. Construction was predominantly prefabricated, minimising time on site, safely working at height, and avoiding wastage of materials. Using CLT as the exposed internal surface finish, additional lining materials were not required except in bathrooms and kitchen splashbacks. Heat pumps provide efficient heating and cooling, with heat exchangers on the main hall plant recovering energy from spilt air. A BMS system connected to the council’s facilities team runs the building. Lighting is low-energy LED throughout, with timers and automated daylight sensors. Open windows provide natural ventilation as an alternative to mechanical ventilation in smaller spaces. Natural daylight levels generally allow spaces to be used without artificial lighting during daylight hours.

For more details, visit: https://www.pc-architects.co.nz/lab-works-architecture

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