Achieving Net Zero on Your Next Site
With so much talk of sustainability, pushing your ESG credentials and how the UK government wants to achieve net zero by 2050, now is the time to take action and make sure you’re paving the way for the future. We all have our part to play, and with the built environment responsible for 38% of global emissions, and the construction industry responsible for 25% of the UK’s carbon footprint, it has never been more important to act. Thankfully, there are many organisations that have been created to provide a clear roadmap to help the industry do its part for net zero and we have helpfully outlined several ways in which you can help.
What exactly is net zero?
Also known as carbon neutral, in essence, it’s making sure that the emissions produced match those that are removed from the atmosphere, keeping the balance in check, so levels don’t rise. You’re effectively making as much energy as you are using. You may also have heard the term gross zero, which means stopping all emissions outright. While this would end our environmental issues caused by emissions, it’s not something that can realistically be done at the moment because of the way the world currently works. Across all sectors, emissions are - and will be - created, so we can only find ways of reducing and offsetting them, at least until better technology becomes available.
Who can we turn to for guidance?
Programmes like the World Green Building Council’s global Advancing Net Zero project and the Net Zero Carbon Buildings Framework from UK Green Building Council (UKGBC) give some structure and guidance to undergoing this overwhelming challenge. The aim is to bring a collective responsibility and language to inform and provide guidance to the sector. They highlight issues such as embodied carbon, share case studies about sustainable developments and provide insight into costings and timeframes.
What is embodied carbon?
This simply refers to the CO2 emissions associated with materials and construction processes throughout the whole lifecycle of a building. It’s one of the main factors involved in achieving net zero targets, as it encompasses CO2 generated during the manufacturing process of building materials, transportation to the site and the construction practices used. This is entirely distinct and separate from operational carbon, which is covered later. UKGBC’s definition goes further to include the wider development, by also accounting for roads, hard surfaces, utilities, heat networks and infrastructure.
Concrete and cement are the largest emitters of CO2, with cement production alone accounting for 7% of global CO2 emissions. They are both the largest contributors of embodied carbon. While the actual emissions of embodied carbon are unregulated, studies have been conducted to measure its reduction using alternative methods. UKGBC put together a document for low carbon developments by working with Grosvenor on their development, Trumpington South.
Different solutions put forward were to replace all hard surfaces with block paving, reduce the number of car parking spaces and increase soft landscaping in an effort to minimise hard landscaping space. According to their research on the development, hard landscaping made up 91% of the masterplan’s total embodied carbon, and the other 9% was taken up by utilities, which is a lot of embodied carbon to consider that isn’t an individual dwelling. Using asphalt to pave the road surface and parking areas would have resulted in concrete kerbs being used, resulting in more embodied carbon. Simply replacing asphalt with block paving reduces embodied carbon by 17% on the roads, but removing the kerbs and replacing with soft edging only had a 2% saving. By replacing parking areas with recycled plastic, UKGBC claims that a massive 60% reduction in carbon could be achieved. While this could be used on the main roads throughout the development, it isn’t recommended as a sustainable alternative to block paving due to heavy traffic and increased wear, and would therefore require replacement more frequently.
Offering fewer car parking spaces as a way to reduce private vehicle usage is considered reasonable because of an increase in car share use and the availability of active travel plans on new developments. By reducing parking spaces on the development, UKGBC notes that this extra space gives way for communal gardens, soft landscaping (including more trees) and bicycle storage, increasing biodiversity and reducing reliance on conventional means of travel. Alternatively, the space could be used for an additional five homes on the development, giving rise to the availability of more low energy homes.
The other way to reduce embodied carbon is to look at alternative forms of heating. UKGBC’s study of Trumpington South didn’t look at gas fired boilers, as these need to be phased out as soon as possible and any currently fitted ones will likely need extensive retrofitting to low carbon alternatives. Individual houses are most likely to feature air source heat pumps or a district heating system in order to lower these levels of embodied carbon. While both have their benefits, either option features a trade-off in emissions from the dwelling to the masterplan or vice versa, keeping embodied carbon an issue on the development regardless. Because on-site energy production requires space and infrastructure to be installed, this equates to around an acre of land, or 12 homes, while individual air source heat pumps carry their own carbon through setup and installation. According to the study, there is a less than 1% saving in embodied carbon on the development by using a development-wide district heating system compared to individual air source heat pumps. Based on this, it may be worth considering air source heat pumps on your next development so you can utilise the extra space from reduced car parking at the same time, whether for more trees, bicycle storage or more homes.
What is operational carbon?
Operational carbon comprises of CO2 emissions in relation to the heating, hot water, cooling, ventilation and lighting systems of an individual dwelling. To achieve a net zero target in terms of operational carbon, all of these need to be powered by renewable energy. In order to reach the 2050 target, 1 in 4 existing homes in the UK will need to have photovoltaic (PV) panels installed, but this statistic will likely increase before 2050 if new builds don’t feature PV panels as standard. While the national grid will not be fully decarbonised even in 15 years, it’s mainly up to buildings to make use of renewables to achieve net zero goals, which is why new builds are expected to feature renewable energy generation.
New buildings will be expected to have low operational energy demands, making it easier to offset any emissions and generate the necessary power to cover most costs. While it will help ease pressure on the national grid, in most cases it won’t be possible to cover full operational costs using on-site renewables. We need to start doing our part to ease the burden on the national grid.
What is offsetting?
This involves buying permits generated by projects dedicated to removing emissions from our atmosphere in order to compensate for any emissions unable to be eliminated through the construction process. Offsetting is typically used in the final stage and must not be relied on for all emissions because the technology is expensive and improvements may not be available for a few decades.
In 2021, only two accredited offset schemes existed, according to the UK’s Environmental Agency, but many organisations exist today. They usually require payment to plant trees or invest in renewable energy systems after calculating your carbon footprint. Any offsetting scheme you choose should be regulated, verified and third party audited, and will give you certification. Not only this, but it’s important to publicly disclose the details of any offsetting, so buyers, developers and governments alike can see you making a difference.
How much is this going to cost?
With all the talk of actions that can be taken to get towards net zero, there will inevitably be a conversation about how much this will all cost. While some sources indicate costs of alternative sustainable means are more expensive, especially in the short term, UKGBC indicated in its report of Trumpington South that while alternative measures were put forward, costs only increased by 0.6% between their proposed basic and most sustainable scenarios, whilst achieving a 20.3% reduction in embodied carbon. Other sources, like the Committee on Climate Change, seem to indicate that construction net zero will cost 1¬-2% of the UK’s GDP to 2050, which equates to about £50-70 billion a year.
Naturally, as with all supply chains, investment and procurement of more sustainable materials will lead to an increase in their adoption and drive down their costs. The government also has a part to play in strengthening supply chains. By shifting its focus away from short term targets and focussing on whole life carbon performance, this will encourage the industry, and thus suppliers, to think creatively to deliver more innovative solutions. The main question to ask is not about what short term costs will be, but what the overarching cost will be if we fail to meet net zero targets by 2050. If more sustainable means aren’t integrated into new builds from the offset, extensive retrofitting will cost more in the long run, both in terms of installation and more embodied carbon, so the vicious cycle continues to harm net zero efforts caused by inaction.
How do we implement change?
How does this all boil down to simple steps that you can follow and implement? The best thing you can do is become familiar with the net zero brief and what is required of you to make sure you’re driving meaningful change. From there, it’s simply a case of minimising embodied and operational carbon, maximising the use of renewable energy and then offsetting any remaining emissions.
Think of alternative materials to use in order to reduce embodied carbon. A greater emphasis should be placed on materials that can be easily recycled or reused at the end of the building’s lifecycle. This step will most likely be the hardest to implement, but continual emphasis on it will drive industry change and lower costs. If you must use concrete, mix it on site and reuse materials where you can, as was done for the London 2012 Olympics. This will reduce transport costs as well as any more embodied carbon.
Make sure systems are installed that help the building run on low energy costs. While gas boilers may be the easiest and cheapest option for now, you’re doing yourselves (and the wider population) no favours by still fitting them. Gas fired boilers are the main heating source for 85% of homes in the UK, but none of them should be operational by 2050 in order to meet net zero targets. Instead, 80% of homes need to be using a heat pump system. With various reports indicating that the UK is likely to miss the 2050 net zero target, it’s more important to implement these changes now in order for us to have a chance.
It’s frequently reported now that homebuyers want to move into greener homes. Shakespeare Martineau surveyed 500 buyers and an overwhelming 77% said they are likely to consider a green home as their next property. Almost 40% said it was on the grounds of environmentalism, while almost 30% mentioned that it will save them money, and 35% citing a reduction of energy bills. By equipping new homes with sufficient energy saving smart home technology and renewable energy generation, you will attract buyers more quickly whilst helping reach net zero targets.
After reducing your carbon footprint throughout the whole building process and lifecycle of the building, the rest can be omitted through carbon offsetting. Where emissions are inevitable, offsetting removes these from the environment. It’s equally important not to rely on offsetting in order to continue a “business as usual” approach. Offsetting is a last resort for inevitable emissions, not any and all emissions.
What can we conclude?
Net zero is a monumental challenge, and with retrofitting becoming a bigger issue in the future, it’s important to tackle it today. A “business as usual” approach is very much frowned upon and will get us nowhere, shifting the blame to someone else to worry about or delaying action. By taking issues into our own hands, as an industry, we can enforce government change and industry attitudes in order for construction to achieve net zero by 2050. You can inspire others to take similar action, which will remove any barriers to implementation through increased adoption. Sign up to the Net Zero Carbon Buildings Commitment and #EndGasNow pledge today to start implementing changes for tomorrow.
Bibliography
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