Thirty years isn’t long in the UK building world when we consider that buildings can last centuries. So, with the government’s legal commitment to decarbonise the economy by 2050, time is ticking to achieve net zero in the built environment.
Savvy developers have an opportunity to differentiate themselves by tackling the net zero challenge now. The UK Green Building Council has published its definition of net-zero buildings – its advice is straightforward, but what practical steps can be taken to make a multi-unit development net zero?
First, make it energy efficient
Driving down the total energy consumption of a development makes sense, because while we expect renewable energy supply to grow significantly, it may not be enough to meet future demand.
Set challenging energy intensity targets in the initial design brief and ensure that planning, design and contracting teams deliver them. The Design for Performance initiative from the Better Buildings Partnership could help as it provides a robust framework for driving improved energy performance. It is based on a similar initiative in Australia, which has seen the energy consumption of new commercial buildings fall by 50%.
Choose technology that can be supplied by renewable energy
In a zero-carbon economy there cannot be a significant role for natural gas in heating our buildings. Choose technologies that can be supplied by renewable energy, such as air source and ground source heat pumps. While they cost more to purchase and install than gas boilers, they usually cost much less to run and can offer significant cost savings.
Previous WSP research based on energy modelling and auditing of 600 buildings in Europe, Asia, Canada and the USA showed that using heat pumps, rather than gas boilers and traditional air conditioning chillers, can cut commercial building ventilation costs by a quarter, as well as improving air quality.
Generate as much energy on-site as possible
Maximising the amount of energy generated on-site through heat pumps and solar panels will help to future-proof a development. Most developments won’t achieve total self-sufficiency, but it will reduce the reliance on the grid. In future, it may even be feasible to generate renewable power off-site and supply it directly to a development using power purchase agreements.
Look at your energy network as a whole
As technology improves, we are likely to see mini distribution grids on multi-use developments with shops, offices, housing, etc. These will include battery storage, which allows peaks in demand throughout the day to be evened out across the site. This may facilitate a reduction in the size and cost of the main grid connection and brings opportunities to generate revenue by selling excess power back to the grid or even transferring excess power between buildings when it’s needed.
Rethinking retrofit – moving existing developments towards net zero
As discussed in WSP’s recent Rethink Retrofit report, it’s not just new developments we need to think about. A reported 80% of the buildings we’ll need in 30 years’ time have already been built, so new ways of reshaping our existing developments must be found.
The report suggests that the most practical and cost-effective method to make existing buildings net zero is retrofitting – adding new carbon-saving technology or features to existing systems. This can support a decrease in carbon emissions, make a building more energy efficient and improve occupants’ wellbeing and experience.
A total of 85% of those surveyed said that a lack of legislation around retrofit investment in their region is impacting decarbonisation of building stock, yet there is a keenness to see this realised. When asked about the average energy efficiency improvement they would expect to achieve by retrofitting a building over the next five years, two-thirds (65%) of respondents said it would be either a “good” or “very high” improvement.
A phased approach will be needed, especially for developments which are occupied. For example, measuring the current energy consumption may identify efficiency measures that can be installed quickly, with minimum disruption, and pay for themselves through energy savings – such as converting lighting to LED. More significant and disruptive changes, such as replacing a gas boiler with heat pumps or improving the building fabric, may need to wait until a major refurbishment or retrofit is planned to manage the costs. Net zero goals can then be built into the retrofit project, with savings to be made over a longer period.
Challenges exist
While the technology largely exists to make new buildings and developments zero carbon today, there are challenges in implementing it. Some technologies are still relatively immature, meaning that many developers have limited experience, and therefore confidence, in implementing them successfully. Also, initial capital costs can be higher than the existing technology it would replace, even though the lifetime operation costs may be significantly less.
However, the biggest overall challenge is the development process itself. We’ll need to think differently about what we prioritise when we design, construct and operate buildings. The normal pattern of working relationships between architects, engineers, contractors, etc will need to change as we put net zero matters front and centre.
What can we do today to make a difference?
Net zero must be factored into design and development briefs so that carbon can be considered from the outset. While current building regulations don’t yet come close to achieving net zero buildings, by setting energy targets and ensuring that they are achieved through planning, design and construction, most new developments could roughly halve their expected carbon impact.
Achieving net zero by 2050 is more than just a headline – it’s a very real target that the UK must hit to ensure continued prosperity and success. We in the built environment sector can make a considerable difference, and it’s vital that we do this, together.
Simon Clouston is technical director, sustainability and energy, at WSP
