Tinline

Entrant: 
Irving Smith Architects Ltd

Category: 
07. Sustainable Development Award

Photographed by: 
Patrick Reynolds

Key team members: 
Architecture - Irving Smith Architects Ltd
Contractor - Coman Construction Ltd
Structural Engineer - Structex
Services Engineer - Jacksons
Fire Engineer - BCD
Project Management - Aesculus. QS - BBD

This building considers how we might increase the utilisation of timber in our construction industry by making more structural timber buildings on smaller, central sites.

51-55 Bridge Street is  a development aimed at commercial and office tenancies. The building comprises 1920 square metres across two full levels and a partial upper floor. Site occupies three former narrow commercial lots, spanning from Bridge Street to the public carpark behind. 
Completed, the building supports commercial tenants across two levels at its north and south edge and the developers’ relocated offices to the upper ‘penthouse.’ The internal  street enhances connectivity of this new build to Central Nelson. 

At each street elevation, a shaped screen formed from perforated metal sheet, folded to form a self-supporting triangular pattern, provides privacy at the southern elevation, and important shaded ventilation to the north.

The building employs a Hybrid engineered timber structural system. This represents a upscaled development of ISA’s recent office building (Wall-E).

This Hybrid Concrete Timber design uses concrete foundation, slab, and perimeter walls to meet geotechnical, fire resistance and weather tightness requirements at the buildings edge. Structural Posts, Beams, Floors and Stairs use a combination of Laminated Veneer Lumber (LVL) and Cross Laminated Timber (CLT). 

Timber Structures have been left exposed and expressed throughout the development. Subsequent building fitouts (by others at the lower floors) have embraced this building aesthetic,  retaining exposed and expressed structure to private and public space.

A single, flitched Timber / Steel Cross Brace at either end combines with a central concrete lift and services tower to brace the building laterally. With less concrete and steel, 1920m_² of commercial floor area has a reduced carbon footprint compared to a typical steel and concrete model in the order of 480,000kgCO₂-eq or 250kgCO₂eq/m_². 

Conceived as five standalone tenancies, interconnected by a shared internal street with elevator and stair access, the building could be reconfigured to sustain more tenancies including retail, hospitality, commercial office, or inner-city accommodation. The independent horizontal and vertical circulation, with considered early warning fire systems enables this long-term flexibility of use.

The Development, designed to be 100%v electric and to achieve a 4.5-star NABERS rating, incorporates a series of sustainable features. These are distributed to the five tenancy units by a shared central services core:

• Low Energy Lighting
• Lighting Control systems
• Low use water fittings throughout
• Power and Water metering systems
• HVAC systems incorporating significant Heat Recovery systems.
• HVAC systems that use water to minimise refrigerant use.
• Passive sustainable approaches are included throughout:
  • Incorporating Natural ventilation and daylighting to office spaces.
  • Ensuring shade to reduce heat loads on the Northern elevation, using overhangs, deep canopies, and perforated metal screen.
  • Building insulation, greater than NZBC requirement, reduces heating and energy requirements across the building lifespan.
  • Provision for future installation of Solar Panels to the Northern roof.

Development occurs adjacent Nelson’s inundation zone. Floor levels and building edges are manipulated to manage the impact of this risk.