builder in london refurbishing a house with red bricks, bricklaying and mortar joints

In our time of climate emergency, striving for environmental best practice is essential. What role can sustainable engineering play in ensuring greener construction methods?

With the impacts of climate change escalating rapidly, we should reflect on the contribution made by our built environment. We must assess both ’embodied energy’ and ‘energy in use’ in our buildings. Embodied energy is the energy used in the manufacture and processing of materials, delivery and assembly on site. Energy in use is the energy used from completion onward in terms of heating, cooling and power.

Structural engineering design can significantly affect the embodied energy in the building, so it is key that a structural engineer’s approach is considered very carefully as we move toward achieving net zero.

Although a structural engineer’s primary role is to design structures that are robust, they also have a responsibility to minimise embodied carbon by using appropriate materials, and by avoiding over-engineering structures.


Discover Architecture for London’s architect designed sustainable buildings. If you would like to discuss your project please contact us.


How to approach sustainable engineering

Architecture for London offers a complete architectural, engineering and construction service, to meet our sustainability objectives.

1. Design and planning

The early design and planning stages allow a structural engineer to assess sustainable options through consideration of material use, design methodology and construction techniques. This prioritises the reduction of embodied carbon from the project outset.

2. Production of building materials

The processes associated with material production will have a large impact on the embodied carbon of a project. Through careful consideration and evaluation of material specifications and certification, a building’s embodied carbon may be better understood and the impact of its materials reduced.

3. Reuse, refurbish & retrofit

Minimising the need for new building materials through the adaptive reuse of existing materials, fittings, and furnishings can be one of the most effective strategies for reducing the environmental impact of any building project. With over 50,000 buildings being demolished each year across the UK, tons of potentially reusable material are sent to landfills annually.

The government is yet to enact any formalised retrofitting policy in the UK. Our team, however, are developing new methods of procurement, design, and construction that prioritise principles of material and spatial reuse. Our project, Low Energy House, serves as an exemplar for the sustainable refurbishment of a typical terraced home in London.

 

Sustainable engineering modern house extension london with courtyard tree and water feature
Primrose Hill House, a house extension in North London

Structural engineering for a sustainable home

Homeowners can take the following steps to reduce embodied carbon in residential building works:

Select a sustainable engineer

Research structural engineers in your area and review their recently completed projects to assess if their experience aligns with your project. Key considerations might be energy-efficient material use and innovative construction techniques. Your architect may be able to guide you in this selection process.

Engage a structural engineer early

Appoint your structural engineer shortly after the initial design stages. This will allow for collaboration between you, your architect and your structural engineer. As a result of early collaboration, sustainable engineering and eco-friendly design solutions are more likely to be considered from the outset.

Structural materials

Where possible, opt for sustainable alternatives to traditional materials. It’s important to remember that around 50% of a building’s embodied energy may be in its structure. Therefore you should aim to minimise the amount of high-embodied energy materials used in any proposed new structure.

Reduce the structure

In a refurbishment project, the act of removing all internal walls to create an open-plan space, will result in a requirement for additional structure. Sustainable engineering should balance the desire for a particular layout with the embodied energy of the structure. A simple solution is often to retain some internal nib walls to provide lateral stability. This means that large steel box frames are not required, and a single timber or steel beam can be used instead.

 

primrose hill house construction photo with scaffold and site workers
Construction of Primrose Hill House, a house extension in North London

Sustainable material choices

Structural elements in buildings are typically quite carbon-intensive. Choosing the right materials, in the correct configuration can have a considerable impact.

Steel

The use of steel should be minimised due to its energy intensive manufacturing process. Timber or stone should be substituted for steel where possible. Where its use is unavoidable, using reclaimed steel components should be considered. Levels of embodied carbon in reused steel are 30 times lower than in newly produced beams and columns. Smaller-scale projects may be prime candidates to utilise reclaimed steel.

Concrete

Concrete is one of the most popular building materials due to its durability and versatility. It is often used for foundations, exterior surfaces, floor construction and superstructures. In recent years concrete has come under close scrutiny for its high embodied energy.

The embodied energy in concrete can be reduced by incorporating cement substitutes in concrete and recycled aggregates in production, as permitted by the British Standard BS8500. There are a number of cement substitutes currently available, including fly ash, silica fume, limestone fines and ground granulated blast slag (GGBS), a by-product from steel manufacturing.

Depending on the concrete mix required and finding a suitable concrete producer, recycled aggregates can make up to 20% of the concrete volume, resulting in a reduction of landfill waste and the mining of natural resources. Ultimately however these alternatives do not make concrete as sustainable as timber and stone and its use should therefore be minimised.

Architecture for London advocates for alternative materials to concrete wherever possible.

Bricks

The brick production industry is also working to reduce carbon emissions in production through the modernisation of production facilities and promoting greener ways to incorporate bricks into construction processes. Stone masonry contains lower levels of embodied carbon and is quickly becoming a viable alternative to traditional clay-fired bricks in Britain.

Structural timber

The use of structural timber presents a notably lower level of embodied carbon compared to steel, concrete, or masonry, with certain applications demonstrating carbon-neutrality or even carbon negativity. While timber structures may appear advantageous from a sustainability perspective, it is crucial to engage in discussions with your engineer and architect regarding the specification, procurement and installation of timber elements. This proactive approach ensures that the material’s potential for minimal embodied carbon is fully realised.

Along with traditional solid timbers there are a number of engineered timber products commonly used in construction today. Engineered timber can offer a range of benefits as a structural material; such as increased span length, increased load carrying and can avoid expansion and shrinkage seen in traditional timbers. Common engineered timber products include Cross-Laminated Timber (CLT), Glued laminated timber (GLULAM) and Dowel-Laminated Timber (DLT).

Stone

In recent years, an increasing number of projects in Britain have adopted locally-sourced stone as a structural material. With a history of use in construction spanning thousands of years, stone offers a carbon footprint ranging from 5% to 40% of that associated with concrete and steel, depending on the energy invested in finishes and transportation. Collaborating with a specialist subcontractor, in tandem with your engineer and architect, is instrumental in fully optimising the procurement, transport, and construction processes for the incorporation of stone elements. Materials should be sourced locally as much as possible to keep carbon emissions as low as possible.

Certification for sustainable buildings

There are a number of sustainability bodies widely recognised across the UK which aim to assist in the design and certification of sustainable buildings.

LEED

LEED is a green building certification program used worldwide. It includes a set of rating systems for the design, construction, operation, and maintenance of green buildings, homes, and neighbourhoods. LEEDs program goal is to assist building owners and operators in promoting environmental responsibility and efficient resource use.

BREEAM

BREEAM is the world’s longest established method of assessing, rating, and certifying the sustainability of buildings. BREEAM is an assessment undertaken by independent licensed assessors. They consider various environmental factors like energy and water use, transportation, materials, waste, and management processes.

Passivhaus building standards

Passivhaus certification proves the highest levels of energy efficiency in buildings, ultimately decreasing their environmental impact. Passivhaus’s performance criteria can create ultra-low energy homes that require minimal energy for space heating.

Architecture for London are leading Passivhaus architects and builders in London.