By the end of 2020, the UK parliament, 300 local councils and more than 1000 architecture practices formally acknowledged that climate change had become an emergency. This sentiment must translate into action - and the next decade is of critical importance. In 2018, the Intergovernmental Panel on Climate Change predicted that to keep warming within a 1.5 °C limit, global emissions need to be reduced by 45% by 2030 and reach net zero by 2050. Architecture and construction play a major role in achieving these targets; in the UK, almost 50% of annual carbon emissions can be attributed to buildings.
In 2019, Walters & Cohen became signatories of Architects Declare, committing to reduce waste, promote biodiversity and push our projects beyond the target of net zero carbon in use. This is an ambitious goal, but we draw confidence from our long track record of sustainable buildings. We were delighted that our efforts were recognised with the 2016 RIBA London Sustainability Award for Regent High School – quite a feat considering it was 70% refurbishment – and we continue to research and promote environmentally efficient materials, techniques and technologies.
The values that inform our projects are also applied to our own office. From 2020, we have committed to producing an annual sustainability report that helps us understand our own environmental footprint and how we can take steps to reduce it.
The 2021 report can be downloaded here.
It is at the earliest stages of a project that we can make the most impact: reducing the area of a building brief or finding a way to re-use more of an existing structure make a bigger difference than a later stage decision such as specifying a slightly more environmentally friendly flooring material. A good sustainability strategy starts with getting these big moves right. Carrying out masterplans and space audits is a great asset when it comes to these early decisions, acknowledging what our clients are starting with and making a plan for where they want to go, ensuring sustainability goes arm in arm with their vision for the future.
Thinking about sustainability continues after the big moves have been made: the environmental impact of a design is considered at every stage, from masterplan to construction, so that sustainability is not a ‘bolt-on’ but fundamentally embedded into a building’s design. This means we rarely find ourselves making a decision based purely on carbon footprint, yet we find that improving a building’s environmental efficiency also improves the design in other ways. Below are some examples of this principle in action.
Construction is hugely carbon intensive: just one square metre of new build results in similar emissions from driving 3000 miles by car. Making the most of existing buildings creatively can avoid a huge proportion of these emissions, not to mention preserving and celebrating our architectural heritage.
Our experience includes revitalising a dilapidated boathouse into a boat-building academy, restaurant and exhibition space at Portsmouth Historic Dockyard; turning an old factory with saw-tooth roof into an engineering college; and at Regent High School, the new building wraps around the original school building, improving its thermal performance and giving it pride of place in the heart of the school.
Our design ethos favours clean, simple volumes, avoiding extraneous details or extravagant forms that require a disproportionate amount of material to construct. By using compact forms we also reduce the amount of heat loss area per square metre of useable floor area, which can dramatically reduce a building’s energy consumption. We believe that not overcomplicating a design also makes it more beautiful.
Natural materials require much less processing to produce, which generally equates to a smaller environmental footprint. Timber products can even act as a carbon store, locking the CO2 absorbed by the tree (while it grows) into the building fabric until the end of the building’s life. The photo shows the cross-laminated structure of King’s International College, designed by W&C for The King’s School in Canterbury: this stores 585 tonnes of carbon dioxide, which is equivalent to driving approx. 1.6 million miles. Natural materials are also healthier for a building’s occupants, as they emit fewer volatile organic compounds, and the subtle variations in these materials make them attractive as finishes.
We aim to make the fabric of our buildings more efficient not simply by adding extra layers of insulation, but by finding the right balance of glazing and solid wall (i.e. the glazing ratio). Even the highest-performing triple glazing provides a fraction of the insulation that a solid wall does. By using no more glazing than is required to fill our interior spaces with daylight, we can design high-performing buildings with a modest budget. Vajrasana Buddhist Retreat Centre, pictured here, achieved a low average whole-envelope U-value of 0.23 (0.4 to 0.5 is more typical for a modern building). A good glazing ratio also increases wellbeing through better exposure to natural light and reduced risk of overheating.
We always aim to keep construction waste to a minimum by considering the standard dimensions of construction materials, minimising the need for offcuts. For example, here is an exposed concrete shaft for a new science building at the King’s School in Canterbury. We were able to adapt our formwork design to allow the same boards to be used on every floor, saving a considerable amount of material. Minimising waste also makes for a happier contractor! Quality assurance is an important issue at the construction stage. If airtight membranes and insulation are not installed well, they will not perform as well as they are designed to.