New six-storey commercial building designed for pivotal gateway site

The right location may not be everything but it's an excellent head start for a forward-looking office building particularly when it comes in the form of a prominent Christchurch inner-city site defined by the banks of the Avon River and looking to the iconic Bridge of Remembrance beyond.

Essentially, the PwC Centre, by architectural practice Warren and Mahoney, enjoys a pivotal gateway position between the Christchurch inner-city and the Botanical Gardens, and is also in close proximity to the Entertainment + Hospitality and Retail Precincts to the east.

And the six-level building's architecture is respectful of the high quality location, even in its cladding.

Warren and Mahoney's project principal Jonathan Coote says the form of the building is both about standing out and fitting in.

"The stepping of the facade along the street frontage creates a series of distinctive planes that are in keeping with the grain of an inner city block.

"The angled planes also help to reduce the visual impact of an extended flat facade, without losing the drama offered by a building with a long frontage."

One requirement of the developer was to avoid brise soleils or other shade options that would interrupt the graceful lines of the building.

"Our answer was to introduce fritted glass panels on the long street-side facade, interspersed with GRC matt panels the correct proportion of the two successfully reducing the heat load from the northern sun."

The southern side of the centre is partly finished in this cladding, but not to the rear, where future adjacent construction will obscure it anyway.

One talented staff member at Warren and Mahoney wrote some code based on an algorithm of birds swirling in flight, and this was applied to the frit pattern in the glass. There's even a tui shape hidden in some of the fritted glass panels so a visitor to the PwC centre with a child in tow has a ready distraction for them.

Apart from attractive patterning, the fritted glass has the practical function of mitigating solar gain without significantly interrupting workers' views.

The building is designed to present a defined base, middle and top respectively the ground floor set-back, the four central floors, and the top floor office space, occupied by law firm Chapman Tripp.

The centre's crisp aesthetics are given a human, warm feel through wooden batten soffits on the underside of the ground floor overhang, on the building's formal entrance canopy and on the ceiling of the open terrace on the second-to-top floor spaces taken by the naming tenant PwC.

Elements of the building form are a response to the environment, too. Being in proximity to The Avon, a height of nearly a metre was calculated as the likely rise of water in a one-in-one-hundred-years flood. For this reason, the entire building is raised above ground level by one metre.

Other examples include the fact that the tapered east end of the building presents a respectfully modest face to the river and Bridge of Remembrance. Plus the set back top floor delivers the 45% recession plane required by the city plan so the street to the north is not overshadowed.

And the building's raised base was given a head start thanks to Warren and Mahoney's response to Christchurch's most obvious environmental factor.

"This building isn't on piles, the entire structure is on a seismic-resistant giant raft of concrete, heavily impregnated with reinforcing steel. Partly underground, this also forms part of the one metre base seen above ground," says Coote. "The base was an ideal grounding for the building's speedily installed buckling-restrained brace system, too, which also allowed for largely uninterrupted floor plates."

With the main service and lift core spread thinly along the less sunny, south side of the building, the upper floors are fully open-plan and designed for a variety of tenancy configurations, big or small. The lower floors have an access corridor running the length of the building and are suitable for multiple tenancies.

The ground floor lobby is activated by a cafe and is the main public space in the PwC Centre, while retail will activate the building's exterior at street level.

And the modern office block is as green in terms of sustainability as its fritted glass is shady. Built to 130% of the New Zealand Building Standards it includes the latest in structural technology and mechanical and electrical elements designed to NABERSNZ 4.5 standard. There's even a discreet entrance and serviced showers for lycra-wearing cyclists, encouraging pedal power over petrol power.

On the top floor, Chapman Tripp's internal premises are 1178m², along with balconies totalling 190m². The lower floors weigh in at 1754m². Given the long footprint, the law firm asked the fit-out architects, also Warren and Mahoney, to set up a saw-tooth screen, much like an art gallery wall, opposite the elevators which are halfway down the space. This directs visitors to reception while the lawyers workspaces are behind this wall. A herringbone floor adds to the refined ambience here.

Story by: Charles Moxham

Photography by: Jamie Cobel