Footprint: Sustainable design cuts costs and carbon for investors and occupiers alike, says Derwent’s Benjamin Lesser
Every building leaves a carbon footprint on the planet as a result of its construction, operation, and the daily commute to and from that building by those occupying it.
The Derwent approach is to minimise the total carbon footprint over the lifetime of a building to avoid premature obsolescence and maximise value in the long term. Low-carbon, design-led regeneration ensures optimum value for both investors and occupiers.
This starts by choosing central London sites where public transport, cycling or walking can be used by a large number of people, minimising carbon emissions from commuters, an often overlooked but significant constituent of the carbon footprint equation. In urban locations, the commute can account for anywhere between 20 and 40 per cent of the total carbon emissions over the course of a building’s life, as documented in Energy Labelling: A Broader Perspective (2010), available on the UK-GBC website. High quality, easy to access cycle lockers and shower facilities encourage and support this objective.
Secondly, many (but not all) existing buildings can be adapted and brought back into useful life to create contemporary new workspaces that offer the attributes occupiers desire: generous floor-to-ceiling heights and high levels of natural daylight. This conserves the embodied energy held in the structure and reduces the transportation of demolition and construction waste, cutting both emissions and costs. Exposed structure and thermal mass help condition the space environmentally, working with either mixed-mode natural ventilation and cooling with opened windows and low-energy air displacement, or in-slab cooling via capillary pipes.
Using a single material for the structure and for conditioning the space and as a self-finished soffit for up-lighting the office space is doing ‘more with less’ – a philosophy at the core of sustainable thinking.
Designing with fewer materials reduces the need for additional surfaces and finishes such as metal suspended ceilings, which uses fewer natural resources, less energy in extraction, manufacture and ultimately costs less to deliver.
The BREEAM Excellent-rated Angel Building in London’s EC1, shortlisted for this year’s Stirling Prize, retained the building’s original frame and provided new cores, envelope and services, with a cost saving of approximately 20 per cent compared to a new-build scheme. The low-energy mixed-mode air displacement cooling system with exposed slabs achieves a 44 per cent reduction in CO2 emissions compared to a typical office building. Angel Building architects Allford Hall Monaghan Morris developed a Concrete Carbon Calculator with the University of Bath to understand the environmental benefits of retaining the structure. AHMM estimate that 33,000 tonnes of concrete were retained at the Angel Building (equating to 10,000m2 of landfill), with savings equivalent to the entire regulated energy usage of the new building for 13 years in operation.
A commitment to sustainability cannot stop when construction is complete. Derwent work with Arup, in partnership with occupiers, suppliers and staff to monitor energy, resource use and waste recycling across our portfolio. Part of our remit is to assist tenants in measuring and reducing operational energy use, which reduces their exposure to the Carbon Reduction Commitment. In 2010, these initiatives reduced carbon emissions by 19 per cent at one building and by seven per cent at two others. This programme is now being rolled out across all our buildings.
At the Tea Building in Shoreditch, east London, an industrial warehouse refurbished in 2003, a rolling refurbishment programme called Green Tea will take place while the building is occupied with 40 different tenants. Improvements include installation of a heat-exchange system (a thermal loop which enables different parts of the building to share heating and cooling), new double-glazed windows, more efficient lighting and roof insulation. Annual carbon emissions are predicted to be halved from 63kg/m2 to 31kg/m2 and the EPC rating improved from E to C.
Our proposed White Collar Factory scheme for City Road, currently in for planning, incorporates the high-value attributes of the refurbishment projects into a new-build scheme. Flexible office space with generous ceiling heights and good daylight is provided in a variety of building sizes grouped around a new public space. High-quality sustainable design, both in refurbishment and new build, makes financial sense and ensures long-term value.
Benjamin Lesser is development manager at Derwent London