As climate change becomes an increasingly tangible concern, reducing carbon emissions (or achieving net zero emissions) is quickly becoming a priority. In this series piece we unpack the realities of carbon offsetting - the good, the bad, and the ugly - to show how it can (and can’t) be part of an impactful sustainability strategy for your company.
Today we will put the construction industry under the spotlight, examining its environmental impact, and how we can pivot towards sustainability without being dependent on offsetting.
Carbon offsetting, at its worst (read part 04), is a smoke screen behind which all manner of entrenched environmental malpractices continue. The way we see it, a greener future involves all of us - every country, industry, company, and individual - taking responsibility for our carbon impact and focusing on direct emissions reductions.
The construction industry is a huge generator of carbon emissions. Cement production alone results in an enormous 2.8 billion tonnes of annual CO2 emissions; the USA’s annual emissions hover around 5bn tonnes, while China’s are around 10bn tonnes. In addition, there is the embodied carbon of other materials to consider (e.g. steel, bricks and glass), as well as the energy demands of powering construction sites (including generators and machinery), and the upstream energy demands of powering buildings. Taken together, the carbon impact of our industry cannot be ignored: “...building and construction are responsible for 39% of all carbon emissions in the world, with operational emissions (from energy used to heat, cool and light buildings) accounting for 28%. The remaining 11% comes from embodied carbon emissions… associated with materials and construction processes” (World Green Building Council)
While these figures are sobering, the construction industry has access to mitigation measures which, if widely adopted, can significantly reduce its carbon impact. All of these measures involve lowering outright emissions, rather than reducing net emissions through offsetting. Let’s take a look at what they are.
The primary drivers for reducing construction-related emissions:
We can reduce emissions by lowering the embodied carbon of structures and infrastructure, by designing and building with lower-CO2 materials. The emergence of “green” concrete is promising. Examples include Cemfree (which promises an 80% reduction in embodied carbon), or Wagners EFC (Earth Friendly Concrete), which uses chemical activation of industrial waste by-products to make low-carbon concrete which performs just as well, if not better, than traditional concrete.
Reducing embodied carbon also means doing more with less: we must move away from excessive over-design, and instead focus on utilising lightweight construction methods and fewer materials.
Heating, cooling and lighting account for the lion’s share of a structure’s carbon impact, over the course of its lifespan. Lowering such operational energy demands can be achieved through better thermal insulation and use of thermal mass, as well as design which reduces lighting requirements (e.g. taking advantage of open spaces, natural lighting and reflective materials).
Construction needs to undergo a mindset shift, towards designing with durability in mind. Each new structure comes with a carbon impact, so the less often we need to replace structures, the better. In addition, we must design with re-use and recycling in mind, by incorporating materials and components which are unlikely to up as landfill when a structure reaches the end of its lifespan.
It is imperative that the above measures are approached with care, as the interactions between them can be surprising. For example, concrete has relatively high embodied carbon and should theoretically be used as sparingly as possible. However, there is a trade-off: concrete also provides a lot of thermal mass, which is useful for reducing heating and cooling costs. In this instance, minimising the embodied carbon may actually increase the energy requirement for the building over its lifespan. Thus, designing with sustainability in mind is a balancing act.
Truly sustainable solutions must incorporate the whole-life environmental impacts of a structure, using a recognised environmental certification scheme (such as BREEAM in the UK, or LEED in other parts of the world), to allow designers to make choices which result in the most effective outcome overall.
Beyond these measures, it’s important to consider the environmental impacts of construction, beyond greenhouse gas emissions. For example, extraction of primary materials (sand, gravel, etc.) has a significant impact, as does water usage, water contamination, and demolition waste.
All in all, the issues our industry faces are major, but they are not insurmountable - provided that we take action now.
Where does Converge fit into this picture? Stay tuned for the next - and final - part of our carbon offsetting series.
About the author:
Helena Maratheftis writes regular content for Converge. She is a creative with an academic background in biology (BA) and the environmental sciences (MSc). Her special interest lies in science communication.
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