How can we achieve sustainable construction?
The construction sector is a major consumer of natural resources, yet the climate crisis demands smarter, more sustainable construction solutions. To achieve United Nations Sustainable Development Goals we must embrace environmental engineering, by doing everything we can to minimise human impact from the built environment and protect the natural world.
There is growing industry consensus that the way we design, build, operate and dispose of our buildings and associated facilities need a major overhaul. Our aim must be to obviate waste, increase efficiency, reduce greenhouse gas emissions and promote construction methodologies that support both people and the environment.
In 2018 the UK generated 222.2 million tonnes of waste, with the construction industry responsible for around 30%.1 The good news is that 92.3% of non-hazardous waste generated in the construction industry is recovered, but this has remained static for the past 10 years with no meaningful improvement. To reduce the quantity of waste and minimise the need for recycling even further, we must move towards sustainable construction practices and a circular economy where buildings, components and materials are used more than once.
Why is the circular economy important?
Pollution has a negative effect on people, our water systems and the ecosystems around us. Waste leads to pollution, whether it be from littering, incineration or landfill. So if we want to live in a less polluted environment, we have to reduce the amount of waste we create.
It is generally accepted that we should be using less of the world’s natural resources. By generating waste we are throwing away resources that are often only lightly, or sometimes never, used. By moving to a regenerative model of reusing products multiple times, we facilitate waste reduction by using fewer natural resources. In addition, we support natural processes, use less water, increase biodiversity and replenish biological materials. This is one of the most powerful ways we can tackle climate change.
What is the circular economy in sustainable construction?
The principles of a circular economy involve planning ahead for the reuse of products, materials and resources to minimise waste. The key design principles are shown below:
Only once circular design principles are fully integrated can residual waste be identified and managed in a responsible manner to maximise its highest value.
This is entirely applicable to sustainable construction practices.
There are many benefits of adopting circular economy principles to create a more sustainable construction industry:
- Reduced waste from construction projects
- Reduced depletion of natural resources
- Increased lifespan of buildings
- Retaining the value of materials and building assets.
Design strategies for sustainable solutions in construction
- Define the metrics for the project from the outset so the whole team knows the goals.
- Prepare a material inventory with opportunities to reuse materials
- Prepare a Circular Economy Statement which describes the strategies that the project is going to adopt. This ensures everyone is working with the same processes in mind and any risks are known and managed from the outset.
Maximise reuse in the built environment
- The key sustainable construction principle for reducing the quantity of new materials used in the industry is to build less. This is most easily achieved by reusing existing building stock. Existing buildings have the potential to be refurbished by retaining existing building elements and improving them to suit future uses.
- If we have to build new buildings, we must consider how many of the materials can be from reused products, components or buildings. For example, where there are buildings being demolished on site or locally, materials can be sourced from these buildings, refurbished, and then used in the new building. Alternatively, a national circular economy should be developed to enable the sharing of good quality reused products.
- Many structural elements, such as steel beams or concrete prefabricated floor slabs, have a life expectancy which far outlasts a building’s lifespan. By knowing these products are going to waste through the demolition of existing buildings, designers can incorporate these components into their design from the outset, using fewer new natural resources and raw materials.
- Instead of breaking components into smaller pieces and recycling the individual materials, reusing a component in its primary form has a higher value for sustainable construction. It results in fewer modifications, and less manufacturing and construction. This uses fewer materials, less energy and minimises environmental impacts. The value of the item is retained with the potential to reuse it again in the future. This enables circular principles to continue in the future.
Design for optimisation
- Sustainable construction increases the lifespan of buildings through flexible and adaptable design
- When designing new or refurbished buildings we must plan for the unexpected. Buildings need to be able to adapt for future uses and by designing this in from the start we will use fewer materials in the future.
- The façade has a shorter life expectancy than the rest of a building due to the nature of the materials used, exposure to the elements and the impact of UV light. To prolong the life of the building, the façade should be replaceable without affecting the structure of the building.
- Each component of the façade should be replaceable individually, to allow panels to be swapped in or out to respond to changes in building use. For example, if an occupied space were to be replaced with a non-occupied space, the glazed component could be swapped for an opaque component, improving the energy efficiency of the façade. The replaced glazed component can be stored for use elsewhere on the building or on another similar local building.
- Internal wall positions should be moveable to enable internal spaces to be modified easily. Being able to create new spaces means the building will have a longer lifespan with fewer major changes.
- Having the ability to add or remove services to suit internal layout changes or adapt to a changing climate will allow the building to be used for longer. Services (heating, cooling, lifts, sprinklers, plumbing, etc) have one of the shortest life expectancies of all elements of the building, due to their moving parts. By building in easy maintenance strategies from the outset, services are likely to be better maintained and need fewer replacements over their life.
Design for disassembly (to be balanced with safe deconstruction)
- To facilitate truly sustainable construction, at the end of the building’s life it is important to be able to disassemble it in a safe manner. The design should accommodate reversible connections, ie things that can be undone and dismantled. This is particularly important in the superstructure, where traditionally the easiest method of deconstructing is to crush the building.
- The use of bolted connections on steelwork joints is safer as hot trades such as welding are omitted. The connections are also quick and easy for less well skilled labour.
- The joints can be unbolted at the end of the building’s life, potentially with the use of temporary propping. It is important that the method statement is considered at design stage so that the assembly and disassembly method are developed concurrently (planning ahead for reuse).
- The disassembly should encourage components to be removed in their entirety. A high-quality component has more value than its individual parts. Not only can it be reused in its component form but it can be disassembled further in a local offsite facility, reducing on-site pollution. This provides additional opportunities for reusing materials.
Use technology for green buildings
- Using digital design tools as part of a sustainable construction strategy enables exact material quantities to be determined, down to the number of screws and bolts required for a building. This allows materials to be ordered with minimal wastage.
- Material passports can be assigned to every material within the building, listing out its environmental and technical performance. This means materials can be selected on their environmental merits. At the end of the building’s life, materials can be correctly reused and disposed of due to the knowledge of the material.
- 3D printing building components enables exact shapes to be manufactured, improving accuracy and reducing waste for more sustainable construction.
- Virtual reality can be used to create replicas of buildings and spaces so the client and building users can experience a building before construction. This means modifications can be made to the design to improve it, reducing the likelihood of post-completion changes and the associated material usage.
Product as a service
- Product hire allows products to be used multiple times during their life across a number of different buildings and applications. This means the product is used more times over its life, making it more worthwhile to manufacture and reducing the number needed, which equates to a more sustainable construction practice.
- Take-back schemes, where manufacturers and suppliers will take back products and materials at the end of their life, enable waste to be minimised and known materials to be recycled within the production process. This reduces raw material requirements for new products.
Minimise impact and waste for sustainable construction
- Use low impact materials by considering the environmental impact at specification stage, alongside cost and technical considerations. This also includes the manufacturing location of materials and the transportation distance to site.
- The recycled content of materials should be maximised without significantly impacting the technical characteristics of the material.
- Designing out waste can be achieved with clever and simple use of materials, eg. altering the centre point of ceiling tiles to limit offcuts to a single side of the room, rather than both sides.
- Designing with/for components promotes offsite assembly of repeated modules. Any leftovers from building the components can be used on subsequent projects, recycled onsite or restocked, minimising wastage.
How can we minimise risk in the building sector?
Minimising risk in the construction industry is important in encouraging developers and designers to take account of circular economy principles. Early decision making will give developers and funders confidence in design and construction choices and will have the largest impact as a result.
The following are suggestions of how risk can be minimised whilst maximising impact and implementing sustainable construction:
- Ask yourself whether you really need to build a new building or whether repurposing an existing building could achieve the same end goal.
- Undertake a pre-demolition audit to understand the potential for reuse on the existing site. Use this information to develop sustainable construction design solutions.
- Understand the potential reuse of buildings or building components locally, including the need to transport and store materials.
- Balance cut and fill to reduce off-site waste and new material brought to construction sites.
- Use lean design principles to reduce the amount of material overall. This will also reduce the embodied carbon.
- Consider design for deconstruction at the start of the design process rather than try to retrofit it into the design part way through.
- Be clear on the potential flexibility that is needed by the proposed occupants and consider what future flexibility could be included with minimal additional materials, allowing the building to be adaptable and future-fit.
- Embrace digital design to have more understanding and control over the design decisions and material quantities.
- Use recycled materials wherever possible and adapt project aspirations to suit.
- Develop clear and concise operation and maintenance (O&M) information to enable the future building to be well maintained and have the potential to be reused or recycled as valuable components in the future.
- Consider each layer of a building, with a different strategy for each which responds to the life expectancy of each layer.
Conclusion: driving greater sustainability
Sustainable construction methods and designing for the circular economy are both possible, and essential. Bryden Wood’s long-term commitment to design for manufacture and assembly (DfMA) shows how it is entirely possible to design varied and beautiful buildings using standardised, component-based designs that naturally promote reductions in materials, optimisation of components, reductions in embodied and operational carbon, and plan for end of life reuse.
While the building sector is already becoming familiar with certain sustainable design principles, like reducing energy consumption and striving to improve a building’s energy efficiency, these less common, lean design methodologies should also be adopted as key sustainability principles that will help us combat climate change, cut carbon emissions and reach our net zero targets. By considering the entire life cycle of a building, and adopting circular construction methodologies, firms can begin to reflect some of the values found in contemporary, circular business models, helping to create a more sustainable built environment and future.
To learn more about our Design to Value approach to design and construction, sign up for our monthly newsletter here: http://bit.ly/BWNewsUpdates