It’s widely recognised that the construction industry contributes significantly to our global carbon footprint. Structural engineers possess a unique skillset to influence this, with innovative approaches shaping design strategies and driving essential advancements toward long-term sustainability and progress.
In this article, we unpack practical, high-impact strategies that can make a significant difference in creating sustainable, low-carbon structures.
Author: Daniel Gray - Structural Engineer, Associate
Located in our Wellington office, Daniel is an adept structural engineer, with expertise encompassing the design, development, and management of complex construction projects.
References: Structural Engineering Society New Zealand’s top tips for low carbon design.
Design with the End in Mind: Planning for Disassembly and Reuse
A core principle of sustainable design is creating buildings that can be easily adapted, disassembled, or repurposed at the end of their life in order to reduce waste and conserve resources. Design for disassembly emphasises bolted rather than welded connections, facilitating the removal and reuse of steel and other structural components. Detailed material records or “material passports” offers future designers essential information about each component, making reuse more feasible and helping the building serve as a future resource.
Steel, for example, is a key candidate for effective reuse. With the right detailing and documentation, structural elements like beams, columns, and bracing can often be removed and reused in other projects. This method not only extends the material’s life but also minimises the need for new production, contributing to a circular construction economy.
Optimise Concrete Use with Prestressed Solutions
Concrete is an indispensable material in construction, but its production is a major contributor to carbon emissions. By employing prestressed concrete techniques, designers can optimise structural efficiency, providing a durable low-carbon solution. The benefits include:
Material Efficiency: By using prestressed concrete, projects can achieve the necessary strength and stiffness with a reduced volume of concrete, cutting both material costs and emissions.
Enhanced Durability: Prestressed concrete components are less prone to cracking, which extends the life of the structure and minimises the need for repairs or replacements over time.
Prestressed flooring panels designed by Maynard Marks for the City Rail Link’s Te Waihorotiu Station, offering strength and durability whilst reducing material consumption for this pivotal project.
Low-Carbon Concrete and Thoughtful Mix Specifications
Concrete mixes can vary widely in their carbon impact. A practical way to reduce emissions from concrete is to specify low-carbon alternatives that incorporate supplementary cementitious materials (SCMs), such as fly ash or slag, to replace a portion of the cement. This substitution reduces the energy-intensive production of traditional cement. Specifying a lower strength mix for non-critical components or using compacted fill instead of concrete in certain applications can further minimise the embodied carbon without compromising structural integrity.
Practical Mix Selection Tips:
Tailor Mix to Function: Not every concrete element needs high strength. Using a 25 MPa mix instead of 30 MPa for foundations, for example, could reduce emissions by up to 8%.
Consider SCMs: Using SCMs allows suppliers flexibility in achieving strength requirements while significantly lowering the carbon impact.
Reconsider Structural Grid Layouts to Optimise Material Use
Long spans and open spaces have long been prized for their architectural appeal, but they come with a carbon cost. Longer spans require larger beams, increasing the volume of steel and concrete used. Engineers can make a substantial impact on embodied carbon by exploring smaller grid systems or adding intermediate supports. By shifting to a more material-efficient grid, we can reduce both cost and emissions while still achieving functional and flexible interior layouts.
Early involvement with the architectural team is essential to align structural layouts with sustainability goals. Architects and engineers can work together to evaluate whether the design requires extensive open spaces or if smaller spans would be equally effective and more sustainable.
Structural grids designed by Maynard Marks
An Integrated Approach
By rethinking traditional construction practices and prioritising design decisions that lower embodied carbon, engineers and architects can make a profound impact on a building's environmental footprint. Through a combination of technical innovation and collaborative planning, we can effectively future-proof our built environment.
If you have any questions about sustainability in structural engineering or require assistance with your project's structural design, feel free to reach out to our team below.
Daniel Kennett | Auckland & Christchurch | daniel.kennett@maynardmarks.co.nz
Daniel Gray | Wellington | daniel.gray@maynardmarks.co.nz
