Gymnasium Carbon Footprint Model

This section provides information on the gynasium building used in the NZ Wood carbon footprint model.

Many modern buildings tend to make extensive use of timber, steel, and concrete materials in construction, all of which can be energy-intensive to produce, via processes that have the potential to cause adverse environmental impacts and give rise to CO₂ emissions.

However, recent developments in wood technology and engineered timber products, seismic and acoustic design, fabrication and construction techniques have enabled timber to be utilised much more extensively for instance in the basic structure of medium-rise, multi-storey buildings, such as a typical ‘down-town’ office block.

While there is a tendency for buildings to be labelled according to the main material used for their sub-structure and super-structure, the vast majority of buildings use a large number of different materials, from a variety of sources, both national and international. From a materials perspective, a building becomes a very complex system and it is often not immediately clear which materials or combinations of materials provide the best environmental performance.

Studies have indicated that when considering the environmental impacts of building materials, the structural components used in a building are of significant importance. 

The building designs covered by the NZWood carbon footprint model emphasis alternative structural design options where the predominant structural material is either timber, steel or concrete.

Description of building design

The Gymnasium (a 680 m² secondary school gym) is typical of the types of buildings being funded by the NZ Government.  The built design –as detailed below – were modified and re-designed to provide the alternative designs.

Cost and environmental impact analysis (June 2006) by Ian Page

See BRANZ report E408 Timber in Government buildings - PDF

Summary of as-built design

A steel portal frame with steel purlins, steel girts, infill timber framing and sheet steel cladding.  All designs have a sprung timber floor on a concrete slab, plus a sheet steel roof.  The walls are finished with particle board and Woodtex linings Apart from the gym space and the seating area, there are no ancillary spaces included.

Summary of redesigned buildings

Alterations to the as-built design only have been detailed.

• Steel design – largely as above.

• Timber design – LVL for the main portal frames, end columns and the roof and wall bracing.  The roof purlins, wall framing and wall girts are sawn timber. 

• Concrete design – 150mm tilt slab wall design (with horizontal battens and vertical studs) extending up to the eaves, laterally supported at the top by a one-leg portal steel roof frame.

View Gymnasium building comparison data - Excel document