Case study: Offsite manufacturing delivers multi-storey timber frame apartments
This case study showcases how a multi-storey timber frame apartment complex across three six-storey buildings containing 216 modules is being constructed with offsite manufacturing.
After seeing a market demand for suppliers who could deliver quality housing at pace and scale, Property Partners decided to investigate offsite-manufacturing. They started researching offsite manufacturing methods around the world, and ultimately decided that the Swedish model was the best approach for them to bring to the New Zealand market.
While the use of offsite manufacturing techniques is becoming increasingly popular around New Zealand for small-scale builds, Property Partners wanted to use timber volumetric modular construction, a form of offsite manufacturing in which buildings are put together by connecting a series of pre-built modules and stacking them vertically to build apartments. This offsite manufacturing method is common in Sweden and globally.
After seeing the benefits of volumetric modular construction methods in their own work, Property Partners decided to invest in a manufacturing plant in Wiri, Auckland and launch a subsidiary, Evergreen Modular, to focus entirely on volumetric modular construction. The investment into the manufacturing plant has allowed Evergreen Modular to deliver several large-scale offsite manufactured projects across New Zealand, including in Wellington, Hawkes Bay and Auckland.
This includes 108 apartments in Richardson Road, Owairaka, Auckland. The Richardson Road project consists of three six-storey apartment buildings containing 216 modules. Upon completion, the project will be constructed completely with timber volumetric modules, which is a first in New Zealand and a significant step forward for timber volumetric modular construction at this height.
In 2017, one of Property Partners’ key clients asked its suppliers to find new solutions that would increase the scale, pace and quality of housing supply to address New Zealand’s housing crisis. This happened around the same time as the publication of the Auckland Unitary Plan, which provided a long-term strategy for Auckland’s growth and allowed for significantly more intensification across the region. As a result, Property Partners started putting serious consideration into setting up an off-site manufacturing facility for volumetric modular apartment construction in New Zealand.
Volumetric modular construction is a type of offsite manufacturing in which buildings are put together by connecting a series of pre-built modules.
Property Partners(external link) - propertypartners.co.nz
Property Partners began researching offsite manufacturing methods and techniques used around the world, including China, the United States and Sweden, and did a study tour to learn from some of the world’s best prefabricated house manufacturers. Of all the offsite manufacturing markets, Sweden stood out as a world leader, and there were also lessons to be learned from Sweden’s own housing crises. In 2018, the team travelled to Sweden to learn more about offsite manufacturing. They built connections and relationships with key people from one of the world’s leading manufacturers of machinery and systems for offsite manufacturing, who they still collaborate with to this day.
Property Partners wanted to test whether the concepts and techniques they learned about in Sweden could work in New Zealand. In collaboration with design consultants and the offsite manufacturing processing team at Auckland Council, they produced a code-compliant design using volumetric modular construction techniques. The design was modelled on a three-storey walk-up apartment that used conventional construction methods.
Auckland Council – Modular components and buildings(external link) - aucklandcouncil.govt.nz
In 2020, Property Partners used a volumetric modular construction approach for one of the buildings on a Kāinga Ora project. Despite being the last building on the project site to start, it was the first to finish. The completed building sat there for nine months waiting for the rest of the project to catch up. Because the building was empty, the biggest challenge was keeping the external stair wells clear of nesting birds.
Kāinga Ora project(external link) - kaingaora.govt.nz
The success of this project gave Property Partners the confidence to invest in a volumetric modular manufacturing plant in Wiri, Auckland, and use this type of construction for multi-level apartments. Property Partners decided to launch a subsidiary, Evergreen Modular, that would manage its Wiri manufacturing plant and focus solely on delivering volumetric modular construction projects.
Evergreen Modular(external link) - evergreenmodular.co.nz
Note: Property Partners is a group of companies that work together to deliver a range of property development services for a variety of corporate and government clients. Evergreen Modular is one of four subsidiary companies within Property Partners, alongside Oxygen Architecture, Habitat Living and Build Partners.
Property Partners has been developing its volumetric modular construction approach over the course of several years. They made a prototype design model based on an existing three-storey walk-up apartment as it allowed them to do an ‘apples-to-apples’ comparison with conventional site-based methods. Due to the seismic conditions being different in New Zealand to those in Sweden, Property Partners’ architectural subsidiary, Oxygen Architects, went through a number of additional design and installation challenges. These issues were worked through with the architectural and build teams, who made the necessary adjustments.
Property Partners used the learnings from the design model and applied them to another project. The apartment building they manufactured offsite had the same architectural design as the conventionally built apartment buildings they were also working on as part of the project. They leased an empty warehouse to manufacture the volumetric modules. Although the process was very manual (since they did not yet have any manufacturing machinery), Property Partners used similar techniques to the ones they had learnt about in Sweden. Once completed, the modules were loaded onto trucks and taken out to site. The modules were then craned into place, which only took one and a half days. Property Partners then completed the ancillary work, such as landscaping, access stairs and services.
Evergreen Modular animation(external link) - linkedin.com
After seeing the benefits of volumetric modular construction first-hand, Evergreen Modular invested in an offsite manufacturing plant. Setting up their Wiri manufacturing plant was challenging as the industrial lease market was tight, the company still needed to do due diligence and there was a lot of work to complete to get the site operational. The production line had to be designed from scratch and equipment had to be imported from Europe to ensure the production line was set up properly. The inventory system, quality assurance system and inspection testing systems also had to be set up. Evergreen Modular then had to find and train 60 staff in the midst of the Covid-19 pandemic, all while setting up and developing its offsite manufacturing processes and systems. It took a lot of effort to get everything up and running, consulting with their Swedish partners for tips and tricks along the way.
Since launching its Wiri manufacturing plant, Evergreen Modular has focused on a few key things to increase efficiency and create cost reductions that can be passed onto clients:
- Building capacity: Evergreen Modular is currently working at increasing capacity without overinvesting in the factory. They have taken things slowly, focusing on getting the basics right, such as implementing and refining their processes, products, software and systems, as well as training and developing their staff. Once they are confident that they have built a strong foundation and are in a position to scale up, the company is planning to bring in more automation and invest in a large-scale purpose-designed facility.
- Improving products and processes: Refining the product and how that product flows through their production line, and connects to the building site, is crucial. Evergreen Modular has worked to improve their design for manufacture and assembly (DfMA) processes and how they standardise various structural components.
- Implementing software and systems: Evergreen Modular has focused on implementing the right software and systems that will enable them to scale up when the time is right. For example, the manufacturing software has the capability to produce a simple A3 printed shop drawing, which the floor team can use to make walls, floors and ceiling elements. The same datafile can direct a chain of automated robot cells simultaneously working together that can produce the same elements whilst maintaining precision tolerances. Future-proofing their software now will give Evergreen Modular the ability to scale up quickly when they are ready to do so.
- Research and Development (R&D): Through their R&D department, Evergreen Modular continually makes small improvements over time. The R&D working group includes team members from Evergreen Modular, Property Partners, Oxygen Architecture and Build Partners (another Property Partners subsidiary), as well as a specialist team of consultants and engineers. The group meets monthly to review lessons learnt and come up with better ways to design, manufacture and deliver modular construction. There are project reviews at various stages throughout each project to capture learnings, and those learnings are subsequently used in other projects. Evergreen Modular have regular meetings with their Swedish mentors and continue to bounce ideas off them to keep learning and improving.
The Wiri manufacturing plant has enabled Evergreen Modular to deliver several large-scale projects, including 108 apartments in Richardson Road, Owairaka, Auckland. Evergreen Modular is using cutting-edge offsite manufacturing fabrication that was modelled in a fully detailed building information modelling (BIM) environment, as well as a DfMA methodology. The Richardson Road project consists of three six-storey apartment buildings which will be constructed primarily using timber volumetric modules. The project is the tallest timber-framed building in New Zealand to have used offsite manufactured timber volumetric modules. The project also included a number of unique aspects, such as a seven-storey high scaffolding with a slidable roof for all weather construction.
Richardson Road(external link) - propertypartners.co.nz
Outcomes and benefits
Less on-site construction time and reduced overall construction costs
Using timber volumetric modular construction techniques, Property Partners and Evergreen Modular have been able to reduce the overall time on site by 40 percent compared to a traditional build. This has inevitably resulted in overall construction cost reductions for their clients. The time savings of offsite manufacturing are significant, but so are the cost savings.
Better community interactions
Less construction time on site has resulted in less impacts on the surrounding local communities that Evergreen Modular builds in. Since a large part of the works are completed in the factory, the project does not take over the street with noise, dust and tradies’ cars lining the roads for months on end.
Improved quality control
By building in a controlled environment, Evergreen Modular can be very confident about the quality of their products. The manufacturing process is repetitive, and Evergreen Modular has an experienced team who have gotten very good at what they do which has resulted in a limited margin of error. Evergreen Modular has developed standard operating processes and procedures for all parts of the factory and the production line is constantly being optimized for quality and efficiency. The controlled indoor environment means that materials are protected from the outdoors, which ensures that the quality of materials is retained.
Carbon reduction and environmental sustainability
Possibly the most impactful and long-lasting benefit of timber volumetric modular construction is its low carbon output. Evergreen Modular completed a lifecycle embodied carbon assessment for the Richardson Road project and the results were eye opening1. The volumetric modules used New Zealand-sourced sustainable timber, which resulted in 103 percent less embodied carbon than an equivalent concrete apartment building. This type of timber-based volumetric modular construction also achieves a reduction of 49 percent in carbon over a 90-year lifecycle2 when compared to an equivalent concrete apartment building.
Overall, offsite manufacturing is more environmentally sustainable as the process requires only the amount of building materials that are actually needed. This means products aren’t wasted unnecessarily. Evergreen Modular uses a New Zealand-sourced and carbon-positive timber in their construction. When compared to cross-laminated timber or other mass timber structures, an engineered timber frame means that they can achieve the same square meterage using a fraction of the raw materials, making every tree they use go further. This approach reduces the weight of the overall building, which means lighter foundations. This has the added benefit of being able to build on a variety of ground conditions.
Better health and safety
Evergreen Modular has found that offsite manufacturing has better health and safety outcomes for their staff. Since they work in a controlled factory environment, the workplace is very structured. There are not the usual risks you would find in a typical outdoor construction site. Everybody works at ground level on stations that they know, which also creates manufacturing efficiency gains.
Evergreen Modular also found other wellbeing benefits of offsite manufacturing. The offsite manufacturing approach requires a strong team environment where all workers are helping and learning from each other. To be able to work in an offsite manufacturing environment, the team at Evergreen Modular makes sure that all their employees are properly trained and well-supported. They have built a tight knit team who are used to working with one another.
People often assume that timber volumetric modular construction will all look the same, but this is not the case. The high-quality chassis that Evergreen Modular creates can be used across a large number of applications, whether it’s apartments, retirement villages, hotels, or student accommodation. By working closely with their architectural team, Evergreen Modular is able to customise the exterior and interiors of a project as much as specified. The internal fittings can be as cost-efficient or high-spec as desired by the client.
1. The lifecycle embodied carbon assessment was an independent study conducted by the Kāinga Ora Carbon Neutral Housing team to current New Zealand best practice for whole building lifecycle embodied carbon assessments. The study was conducted in partnership with the Evergreen Modular who supplied the building material quantities from their offsite manufacturing fabrication process, and the project design and documentation.
2. Carbon LCA calculated using LCAQuick v3.4
Learning is an ongoing journey
Evergreen Modular treats its current manufacturing facility as a learning factory, a place for them to test, improve and refine their processes, products, software and systems. While this is most obvious through their R&D programme, learnings are captured through all aspects of their work. They use their learnings to improve what they are doing in their other projects, both current and future, and have enabled the business to scale up quickly as required. Lessons from their design model helped inform their first offsite manufactured project, and the subsequent lessons from that helped inform their more recent projects, such as Richardson Road.
Valuing your mentor’s advice
Building connections and relationships in Sweden played a huge part in developing the Evergreen Modular offsite manufacturing approach. Those relationships are still going strong, and the New Zealand team frequently touches base with their Swedish mentors to test ideas. When the Accord asked Evergreen Modular what they would have done differently next time, they said they could have followed the advice of their Swedish contacts more closely. New Zealand firms sometimes tend to think that things are a bit different down here, and Evergreen Modular couldn’t help but put its own spin on things using the Kiwi ‘No. 8 wire’ mentality. Taking learnings from the Swedish and adding in the New Zealand context has been an ongoing R&D process. While it has taken a while to work through the best methods, testing and trialing different approaches has taught them great lessons and has allowed Evergreen Modular to make better decisions going forward.
Building differently requires a different mindset
Going down the timber volumetric modular construction route has inevitably attracted people who are open to change and want to see innovation in the construction industry. Making buildings in a factory requires a DfMA mindset, and traditional building work only happens on site once the modules have been set in place. Those switching over from traditional building methods and techniques into offsite manufacturing are likely going to need to break some old habits and change how they think about the overall building and construction process.
Taking your time
Evergreen Modular has been careful about building capacity over time. They noticed that other companies often put too much focus on the automation and technology but not enough time and effort on the processes and systems. They have made a conscious decision to take things a bit more slowly, building and refining their products, processes, software and systems while focusing on training and growing their people. Their slow and steady approach is evident in how they started their offsite manufacturing journey, by creating a design model and then an initial project before investing in a manufacturing plant. At this point in time, Evergreen Modular is planning and preparing for the next step to scale up.
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