Christchurch Civic Centre - New technology with new facilitiesFully automated Specialty Venetian Blinds in a double skin facade

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November 2012

Owners - Resourse Co-ordination Partnership Ltd (JV Company of Christchurch City Council and Ngai Tahu Property Ltd)

Client - Christchurch City Council, New Zealand

Architects - Michael Shore, Athfield Architects

Builders - Hawkins Construction.

Engineers - Powell Fenwick

Awards - New Zealand Green Building NZ Star 6 rating. - Dulux colour Award for interiors.

The Christchurch Civic Centre building refit

attained a New Zealand Green Building

Council 6 star rating surpassing the 5 star

rating brief requirements.

The Christchurch Civic Centre building is a significant structure both culturally and physically. The original 40 metre high concrete and stone aggregate building located at 53-59 Hereford Street West was previously the New Zealand Mail Centre constructed in the 1960’s.

The Christchurch City Council began leasing the building in August 2010, accommodating their staff of 1,116 into the NZ $113 million refit which included a five metre extension to the northern facade on Worcester Boulevard and 3 partial mezzanine floors. On completion, it has been reputed as being suitable to house the council for the next 100 years.

The building’s new public ammenties include a public cafe and an expansive walkway cateringfor outdoor activities.

“It’s great to have exceeded expectations by achieving a 6 Star rating within the approved budget.” Gill Cox - Chair of Civic Building Joint Venture.

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Property aspirations

A 50 percent stake holder in the Christchurch Civic Centre is South Island iwi Ngai Tahu, a substantial New Zealand business with a focus on five key areas: Property Investment, Property Management, Property Development, Rural, and management of the tribe’s Right of First Refusal to purchase Crown property assets. They jointly purchased the property in 2008 with JV Company of Christchurch City Council, the first private/public partnership of its kind in New Zealand. The joint venture

parties formed Resource Co-ordination Partnership Ltd and were instrumental in the key environmental sustainability and durability considerations of the retrofit project, including the use of local sustainable and low-VOC materials.

These, along with other factors, have contributed in making the Civic Centre one of the ‘greenest’ buildings in New Zealand.

A carved totem pole stands at the walkway entrance, in symbolic recognition of the project collaboration between Ngai Property and Christchurch City Council.Its inscribed base depicts the Maori name for the building “Te Hononga”, meaning “the joining”.

The double skin facade design requirement

Key personnel from the Christchurch Civic Council and the project team were unanimous in their decision for a double glazed skin for the Christchurch Civic Centre’s facade. Research results had shown that this facade design had many benefits architecturally, as well as environmentally, for the centre’s refit.

The architects could place work stations much closer to the 5.8 metre floor to floor high glazing as the thermal buffer zone was now accommodated in the space between the two skins, maximising the usable floor space. The clear glazing specification would save substantial costs and the double skin facade’s smooth outer skin would be easier for maintenance and cleaning, enabling the facade to last longer before the components needed replacement.

The energy efficiency from a cooling and heating perspective would also add to the comfort levels for staff situated close to the facade. The double skin facade component was envisaged as a considerable ‘green’ feature, as other green technology could be hidden in plant rooms away from the public eye.

Overall, these elements were deemed important benefits by the building’s new tenants, Christchurch Council, as their lease agreement could potentially endure over 70 years.

Architectural design completion

The architect’s design transformed the “brutalist” construction of the former building. The heavy concrete northern facade was replaced with a curtain of doubleglazing to maximise daylight and views. A 3 metrewide buffer zone adjacent to the glazing was included to allow for heat and solar glare repercussions.

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“The Christchurch

Civic centre will

deliver significant

tangible benefits

such as energy and

water savings, as

well as an improved

working environment

for increased staff

productivity and lower

absenteeism through

illness.”

Jane Henley -New Zealand Green Building Council (NZGBC), Chief Executive.

“Another benefit is

that it also provided a

smooth outer skin for

maintenance/cleaning

and would probably

enable the facade to

last longer before the

components needed

replacement.

The use of the

venetian blinds also

allowed us to use

clear glazing and still

achieve very good solar

control.”

Michael Shore -Athfield Architects.

Top images: Original building, artist’s impression and refit under

construction

Left: View of building forecourt with carved stone tribute.

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Despite the fact that this zone could be used formeeting areas, coffee and break out areas, the architect realised it was potentially a waste of usable floor space.

The widened walkway access, its seating, planting and ambient lighting created a pleasant social area, and the 2 level high cantilevered portal added a prestigious element.

Double skin ‘green’ features

The facade is ventilated in two main ways. The principal being a natural stack effect. Motorised dampers are positioned across the top and bottom of the double skin facade and are closed and opened by the building management system to maintain required temperatures in the facade. Secondly, fixed openings in the double skin facade on each floor allow a portion of fresh air from the air conditioning systems to be introduced into the double skin, providing a form of heat recovery in the facade during winter.

The solar control story

Initial shading ideas for the double skin facade included external louvers or fins, together with internal roller blinds. Further options were required. The international company, New Zealand Window Shades, were then commissioned to provide a

solution for solar heat gain and glare issues while maintaining as much internal space, natural light and external views as possible. New Zealand Window Shades in turn partnered with Turner Bros., an Australian project management company with double skin facade solar control expertise. Turner Bros. recommended the Horiso Specialty Venetian Blind with the 100 mm slats to be installed inside the cavity with two sets of blinds over the floor to floor height.

The Specialty Venetian Blinds help maintain a constant, comfortable internal temperature and provide ample natural light without the excessive use of a high volume air conditioning system and artifical lighting. The deeper slat size while tilted allow for more light to infiltrate building areas and enhance the external views .

Specialty Venetian Blind control

The chosen automated control solution integrates the Horiso Solarai Control System with the building management system on each floor to operate the blinds. The application advantage in this case provides information on the raised floor air conditioning status. When the air conditioning

Top left: Engineering drawing for the double skin facade.

Left: The double skin facade nearing completion.

Above top: Specialty Venetians Blinds internal view.

Above: The building nearing completion showing the dual installation of blinds on the lower level.

system is in ‘free cooling’ mode, it utilises 100% fresh air from outside to provide the building with free cooling. The upper floor blinds tilt automatically at an angle for sufficient solar gain to maintain the ambient temperature. One Horiso Solarai controller operates every two blinds, taking into account the sun position and current brightness level computed from externally mounted sensors.

The sophisticated functionality of the Solarai programming takes into account the shading provided from the adjacent building to the north. The sections of blinds affected, will tilt at the prescribed angle, infiltrating natural light into the building and enhancing external views.

Gentle on the eyes interiors

The Christchurch Civic Centre’s interiors were also designed by Athfield Architects with colourways based on a neutral palette, off white, grey and black. These colours are integrated with natural timber finishes and complemented the seasonally influenced colour scheme for the soft furnishings, joinery and carpet on each level.

Key building facts

• Centrally located city building.

• Existing 5 storey 1974 constructed building with the 2 additional floors.

• Building is the second of its kind in New Zealand

to receive a NZ 6 star Green Star rating.

• Accommodates over 1,000 staff.

• 5 metre long entrance walkway.

• Public cafe.

• Automatic daylight dimming.

• Double skin floor to floor glazed facade.

• $3.3 million electricity generation installation.

• Occupany controls and sensors on escalators, activate

only when people approach.

• Rainwater harvesting providing 1 million litres of water annually. Used for toilets, landscape irrigation and water feature.

• Some materials used in rebuilding have 60% reduction in PVC, contributing to a healthier working environment.

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Christchurch Civic Centre Environmentally Sustainable Design achievements

• Reuse rather than demolition of the existing building has resulted in energy savings of 6,440 tonnes of CO2 emissions.

• Tri-generation generates electricity for heating, cooling and lighting using biogas piped across the city from landfill with savings of $1.3 million per annum.

• Biogas is methane gas that has 22 times more impact than carbon dioxide and it’s removal from the landfill has provided a re-vegetation program opportunity.

• Double skin facade integrated with fully automated sun-shading control system has reduced air conditioning energy consumption by up to 50 per cent.

• Two 185,000 litre water tanks collect water for flushing toilets and irrigating planters.

• Roof solar panels provide 85% of building’s hot water, contributing to a $1 million per annum energy cost saving.

• Building lifts generate power on reverse cycle operation.

The content of this case study was derived from sources which Horiso believes to be true at time of publication.

Above: Neutral natural tones used in the interiors.

www.horiso.com.au

Christchurch earthquakes

The tremors from several Christchurch earthquakes, particularly the latest on December 23 2011, caused no major structural damage. A thorough engineer’s report was commissioned.

Staff were able to work closer to the double skin facade, and with adequate natural light throughout the day, work continued at a comfortable level. Minor repairs were carried out on plasterboard, light fittings and concrete on some external public areas.

Images and content references:

Hawkins Constructions

Christchurch City Council website

fm magazine - HPR.

“The building will

provide the council

with a front door that

will show the residents

and visitor alike

what it means to be

truly sustainable and

visionary .”

Mark Soloman -Nagi Tahu Property Ltd, Chairman.