PHOTOGRAPHY: Rachelle Grant
clearwater quays COMPREHENSIVE CASE STUDY
Completed in 2022, the Clearwater Quays Apartment in Christchurch, a five-level, luxury, residential apartment, is not just carbon neutral, it’s carbon negative, sequestering over a million kilograms of CO₂ by using mass-engineered timber in place of traditional materials.
A recently released case study (see below) provides important learnings for industry professionals considering mass-engineered timber in their next project.
With the built environment contributing nearly 40% of global GHG emissions, the awareness and demand for more sustainable materials is increasing. The MBIE-led Building for Climate Change programme framework proposes to set mandatory reporting and measurement requirements for whole-of-life carbon emissions, with a sinking cap on Embodied Carbon. This pending regulatory requirement, in addition to consumers and businesses increasingly demanding sustainability in the buildings they buy or lease, is driving industry change towards more sustainable building solutions. Businesses are demonstrating their sustainability credentials through their selection of construction materials focusing on lower embodied carbon levels.
The innovative use of engineered timber, a Design for Manufacture (DfMA) and Early Contractor Involvement (ECI) approach in this project also resulted in a 25% reduction in construction time.
“Calculations show that using wood in place of concrete to build this five-storey demonstration building is removing over a million kilograms of carbon dioxide from the environment,” says Barry Lynch, director of Logic Group, and Eoin McLoughlin, senior quantity surveyor for the Clearwater project.
Mr Lynch says carbon calculations for the Clearwater building show its timber construction saved 87,400kg of carbon dioxide (CO₂), compared with a CO₂ release of 952,600kg if it had been built of concrete, and 794,600kg if built of steel and concrete. The $3.37m price to design, develop and construct the apartment block would have been $3.89m for concrete construction or $3.59m for steel and concrete. The calculations include financial impacts of construction time.
The building has a total floor area of 2,130 m² with two open-plan apartments per level overlooking the lakefront of the prestigious Clearwater development in Christchurch.
The Clearwater case study is now available online for construction professionals (see below). The project has been deliberately designed to be open source, with all project information being made available to showcase the advantages of the new building materials and methods.
The ‘Mid-Rise Wood Construction Programme is part of the government’s Industry Transformation Plan to encourage high value domestic processing and manufacturing from New Zealand’s plantation forests and deliver a zero-carbon construction sector by designing to increase low carbon materials used in construction. Programme projections suggest if engineered timber is widely adopted, this construction method could save the country $330m annually by 2036.
The Programme is now focused on providing early-stage design support for commercial projects considering mass engineered timber.
PHOTOGRAPHY: Four Walls Photography Ltd
PHOTOGRAPHY: Rachelle Grant
SOURCE: CASE STUDY VIA LOGIC GROUP
Mass Timber vs Concrete/Steel | Cost Comparison
Construction = Structure/Foundation cost, including all material
Specific costs like fire, weather and acoustic
Mass Timber vs Concrete/Steel | CO2 Emissions
Structural Comparison Only
key learnings & insights
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Cost Comparison
While mass timber materials initially had a higher cost than concrete or steel, overall project costs were reduced by 6% due to shorter construction timelines and lower development costs.Time Savings
Mass-timber construction saved 2.5 months during the critical frame-installation phase compared to traditional methods, leading to significant financial and logistical benefits. -
Carbon Footprint
The project achieved a net-negative carbon output of 87,500 kg compared to 800,000–950,000 kg of carbon emissions from concrete and steel builds.Reduced Waste
Off-site prefabrication minimised material waste and optimised efficiency, with recycled and sorted waste management practices further reducing the environmental impact.Traffic Reduction
CLT floors required fewer truck deliveries, significantly decreasing site traffic. -
Acoustic Performance
Innovative design, such as floating floors and double-stud walls, exceeded Building Code requirements and balanced structural and acoustic needs.Collaboration
Close coordination between structural and acoustic engineers was essential to manage flanking noise transmission and optimise acoustic outcomes. -
Fire Safety
Solutions included intumescent coatings, sacrificial plywood layers, and fire-rated designs for intertenancy floors and columns, ensuring compliance with fire regulations.Moisture Control
A sealed façade system with a drained cavity and durable aluminium cladding ensured a weather-tight envelope, protecting the timber from external moisture. -
Team Integration
Engaging contractors, engineers, and designers early in the process led to more integrated solutions and streamlined workflows.Design Detailing
Mass-timber projects require more detailed and precise construction drawings upfront to reduce delays during the shop drawing phase. -
Digital Twin Models
3D BIM and cost modelling enabled accurate cost, carbon, and material analyses, facilitating data-driven decisions and optimal project planning. -
Demonstrating feasibility
This project serves as a reference for the cost, environmental, and practical benefits of mass-timber construction, encouraging broader industry adoption.Standardisation and supply chain
Increased market competition and improved prefabrication methods are making mass timber more accessible and competitive.