Tweet                                                

PrefabNZ and the leaner, greener construction market

Pamela Bell
Pamela Bell

Social housing and the retirement sector offer an enormous opportunity for New Zealand’s growing prefabricated construction sector to demonstrate its ability to deliver affordable, sustainable dwellings, according to PrefabNZ’s chief executive Pamela Bell.

The organisation’s Pipeline Report for Social and Retirement Housing, released this month, states that 75,000 social and retirement housing units will be needed by 2030. The current delivery rate of business as usual construction is up to 3000 units a year, which means a shortage of about 30,000 dwellings by 2030.

PrefabNZ said there was an opportunity for the prebuilt sector to supply fit-for-purpose, on-time and on-budget solutions, including what the report called “pre-built bite-sized innovations that can be readily absorbed into business as usual”.

Ms Bell said PrefabNZ has the support of the government for growing the sector. This includes the Ministry for Business Innovation and Employment supporting various initiatives including productivity partnership awareness and the development of educational and research materials.

BRANZ also supports the organisation’s research and advocacy activities. The pipeline report is the fourth stage of a Levers for Prefab Action Plan that has been funded by the BRANZ Research Levy.

Memorandums of Understanding are in the process of being finalised with a number of key organisations, including Community Housing Aotearoa, the Retirement Villages Association and Wellington City Council. The organisation also sits on the Construction Industry Council and has signed MOUs with the NZ Institute of Architects, Modular Building Institute (US) and Australia’s PreFabAUS.

It also collaborates with the NZ Green Building Council. A joint expo of residential innovations, HIVE Home Innovation Village at Canterbury, showcased both green building ideas and also prefabrication. The next HIVE is planned for Wellington soon.

The organisation is also working with the NZGBC on the development of Green Star-rated modular prefabricated education buildings.

“There has been more talk about prefab lately in NZ,” Ms Bell said.

This is not so much in the commercial property sector, where she said construction was already “relatively efficient”, and has been utilising prefabricated elements such as wall panels for some time, but in the residential space.

“The NZ building industry is dominated by firms with five employees or less – they constitute 95 per cent of companies,” Ms Bell said.

For these small firms, prefabrication of building elements, modular pods and whole dwellings is an opportunity to reduce costs and increase the speed of building.

PrefabNZ has also pointed out it can address quality issues. BRANZ research has shown that around 91 per cent of dwellings in NZ have construction defects on completion.

Engineered timbers

There is a growing interest in using engineered timbers for prefab, Ms Bell said. These include laminated veneer lumber for beams, and compact laminated timber for walls and flooring systems.

“It is very much at the early stages,” she said. “But it is growing.”

Another industry source said that recent projects using CLT elements have demonstrated that the factory setting can ensure the quality of building sealing, generating major sustainability gains.

The Fifth Estate has been told by many people in the property sector that poorly sealed buildings are one of the major defect issues in NZ’s residential sector, and that it is an issue which dramatically comprises energy efficiency, thermal comfort and occupant wellbeing.

The materials themselves are also carbon sinks, and are being fabricated using local wood, giving multiple wins.

Vanessa McGrath, NZGBC’s manager of rating tools, said she thinks timber will be a growth area for green prefabricated building.

The organisation is currently working on the methodology for rating prefabricated portable classrooms. These are to be designed and built for the NZ Ministry of Education, which has a policy of Green Star ratings being achieved for new school buildings, Ms McGrath said.

The tool will rate the prefabricated elements on the basis of design, and before they leave the factory for points around materials. Once the classrooms are on-site, the tool will rate those elements that apply when a building is in-situ.

One of the big shifts the school buildings will help with, she said, was changing market perceptions around the design and aesthetics of prefabricated buildings.

The classrooms are a modular unit that creates a quality open-learning environment, she said. They are stackable, and in design terms bear no resemblance to the “cheap and nasty” portable classrooms of the past.

Ms McGrath said the level of quality that can be achieved in the factory setting is a sustainability gain for any project, including residential developments.

“It comes down to being able to ensure the quality and how things are sealed.”

Ms McGrath said that there was a need for “re-education” of the property market, so there was more understanding of the quality of design and construction that can be achieved. The school buildings, she said, would be a good demonstration of this new generation of building.

Tailoring

In terms of housing, she said there was a big opportunity for modular elements that can be tailored to people’s needs and changed over time through adding or removing elements.

There is an added sustainability benefit to this, she said, in terms of reducing wasted embodied energy in materials for rooms people rarely or no longer used but may even be wasting energy heating or cooling regardless.

It also means housing can change through time as the occupants’ lives change.

She said the NZ property industry would move in the direction the UK has, where for the past few years there has been a greater demand for prefabricated buildings.

In terms of the average developer, she said a HomeStar or Green Star-rated prefabricated solution would mean they have the security of knowing that when the project is erected on-site, the quality and value is there.

“It’s de-risking the proposition [for them],” she said. “They know those Green Star points have been secured.”

More Articles on this Topic