Scott Wilson, Europe Director of Sustainability at Black & White Engineering, demystifies an ever-evolving world of sustainability in construction.
Construction firms are working to develop their sustainability strategy as sustainability is becoming more important to both investors and consumers. They are tackling the scope of emissions and working to achieve net zero carbon. While the work is important, many are having difficulty with terminology and defining terms when discussing strategies.
Scott Wilson is Europe’s Head of Sustainability at Black & White Engineering. He shared his thoughts on sustainability with Construction Digital.
Wilson holds an MEng in Mechanical Engineering, is a BREEAM Assessor, is a Low Carbon consultant (LCC), and is a Level 5 Non-Domestic Low Carbon Energy Assessor.
He has a background in the building services industry and helps deliver low-carbon, sustainable buildings. He also considers the affordability and feasibility of various solutions. He has extensive experience in energy modeling, such as thermal comfort, compliance with building regulations, and daylight analysis. This gives him a thorough understanding of what works.
“Carbon neutrality is the easiest thing to achieve, especially if you’re rich.” Carbon neutrality is achieved by offsetting all carbon emissions to neutralize their impact. “The problem is that it doesn’t require any actual reduction in carbon and carbon offsets are available for as low as 10 USD per ton,” he says.
“The term net-zero expands the definition of greenhouse gases to include all those that are usually expressed in CO2 equivalent values. Net zero, it is generally understood, requires a reduction of carbon emissions before offsets.
“The differences are significant as there are clearly different outcomes.” By purchasing offsets, a company or building could claim to be carbon-neutral. In the short term, this often does not affect reducing emissions and climate change. Planting trees is one of the most popular schemes. This initiative is a good one. Trees absorb CO2 while they grow. They also create habitats for wildlife. They can help reduce the “heat island” effect that occurs when cities replace their natural land cover with dense concentrations of buildings that absorb and retain heat.
The problem is that this value isn’t realized until the tree has grown to full size. It can take up to 100 years for the tree to reach full maturity. By then, the damage will already be done.
Maximum offset carbon and time to maturity
Wilson believes that carbon offsetting has a role to play in solving the problem despite the problems.
It can be a great funding mechanism for projects to decarbonize that would otherwise not see the light. Carbon offsets are still a viable option but should only be used as a last resort after other options for carbon reduction have already been explored.
Fabric first, then anything else
The construction industry must prioritize immediate carbon emissions above annual emissions due to the delayed benefits of carbon offset products and the direct negative impacts that construction can cause.
The “fabric-first” approach is a standard industry practice for reducing energy consumption by focusing on a building envelope’s heat loss. This has led to strategies such as increasing insulation levels to those seen in passive house standards. This emphasis on insulation could be reconsidered with the current shift to a decarbonizing power grid.
Carbon emissions from building operations continue to decrease as energy production gets cleaner. The added insulation has a diminishing impact, which can sometimes lead to diminishing returns. The move from double-glazing to triple-glazing requires 50% more glass and thicker insulation. This results in a higher embodied carbon.
It may take many decades for these increases in embodied CO2 to be repaid through energy savings. In some cases, this may not even be possible in the lifetime of a building. It is important to take a nuanced approach, which does not only focus on U values but also takes into account the entire life cycle of the building. The construction industry, for example, can look at alternative materials such as aerogels that are made from wood fibers or construction waste, which offer insulation with a lower embodied CO2. These innovative solutions maintain high levels while reducing carbon footprint.
The traditional hierarchy of design is also in need of being re-evaluated. It consists of reducing the demand, improving energy efficiency, and incorporating renewable energies. Its lack of attention to the carbon footprint over the entire lifecycle of a building is what causes problems. Different buildings require different solutions. A building that is heated with high-efficiency heat pump systems may benefit from improved insulation, but a building that has a gas system may not. Such improvements will likely increase the embodied energy with little impact on the operation.
This variance highlights the importance of early life cycle carbon assessments in the design process. These assessments should guide major design decisions throughout construction, taking into account not only the operational phase of a building but also its construction and maintenance stages, as well as its end-of-life. The industry can align itself better with global sustainability goals by shifting its focus from operational carbon to an overall life cycle perspective.
The case for whole-life carbon assessments is evident. Assessing a building from its cradle until its grave is the only true way to determine the impact. Designing with cradle–to–cradle principles allows for the design to take into account the future and ensures the building materials are repurposed at the end of the building’s lifetime for future use as part of the circular economy.
To achieve this, the industry must rethink the design of buildings and the way they are designed by incorporating expertise earlier in the process. This requires a significant shift in which short-term energy-efficiency measures are balanced against long-term considerations about embodied CO2. It is a cultural shift to consider immediate carbon emissions more important. This requires collaboration, innovation, and the willingness to redefine conventional practices. The construction industry can only contribute to a future with low carbon emissions by adopting a holistic approach. This will also reduce the negative effects of greenwashing that may arise from focusing solely on the visible aspects.