In the face of concerns around climate change, the UK government has made much of its green credentials.
Three years ago, it strengthened the 2008 Climate Change Act by setting an ambitious – some fear near-impossible – target of achieving net-zero carbon emissions by 2050.
Add to this the growing number of local authorities that are setting their own emissions goals, and it’s easy to see why the pressure is mounting on the construction industry to work much harder at delivering a green built environment.
According to the UK Green Building Council, the UK’s built environment is currently responsible for 40% of carbon emissions across the country.
This is not something the industry, or indeed society as a whole, can ignore.
What everyone wants to see are buildings that have as little impact on the world as possible, from the materials, construction processes and amount of operational energy used; maintenance, refurbishment and any work involving a change of use; and their end-of-life disposal.
The aim is to create buildings that are – or are as near to – net zero as possible.
What is a net-zero building?
So what exactly is a net-zero building?
According to the World Green Building Council (WGBC), a net-zero carbon building is one that is ‘highly energy-efficient [and] that is fully powered from on-site and/or off-site renewable energy sources and offsets’.
The WGBC has created a framework commitment, which in its words ‘challenges business, organisations, cities, states and regions to reach net-zero carbon in operation for all assets under their direct control by 2030, and to advocate for all buildings to be net-zero carbon in operation by 2050’.
It aims to maximise the chances of limiting global warming to below two degrees centigrade and reduce operating emissions from buildings.
For an industry that historically has struggled to address the issues around carbon emissions, together with energy and operational efficiency, this is a big ask.
The challenges are considerable, and they must be acknowledged and tackled. While no building can be completely emission-free – there will always be some carbon emitted from manufacturing the materials and products used in construction – the key is to get that down to a bare minimum.
Once a building is in operation, one should seek to minimise as much as possible its energy use, preferably from an increasingly decarbonised grid. There is clearly much to play for.
To further the debate about how to deliver a net-zero built environment, Bluebeam, together with Building magazine, hosted a virtual roundtable to discuss the subject. Click here to read the full story.
Facing up to the challenges
James Chambers, regional director UKI at software provider Bluebeam, suggested after having expended so much energy and activity on delivering a building it was a bit of a contradiction to then call it net zero.
‘Some serious consideration should be given to the construction approach and methodologies in putting up the building to start off with, along with asking the question, “What’s your goal here?”‘
But he was confident the UK sector could respond to the challenge. ‘A lot of this is strangely reminiscent to what Britain went through over a decade ago with BIM being mandated. At first, the industry was a bit reluctant to jump onto it. But subsequently, it grasped it, and that has fed into supply chains and third parties, vendors, the technology and solution providers.
It’s hugely encouraging that this has happened before, and now that there’s a defined target of 2050, people are going to be a lot more proactive about this.’
The supply chain was an important element, said Craig Robertson, head of sustainability at Allford Hall Monaghan Morris architects. It was vital to model accurately – and at an early stage in the design process – what would be going into a building, he said, to be able to determine where the carbon was contained.
‘We need to get data from our supply chain, and we need to be able to interrogate our contractors and their supply chains to ensure that we get the things that we think we’re going to get, or that we’ve accounted for. Because if that’s going to change through the procurement process, we need to be able to account for that and give us a running carbon total so we can adapt the design as we go.’
The green agenda doesn’t end once a building has been completed; one then has to consider the operational side. Gathering data around what went on in a building once occupied is essential to monitor its energy usage and thereby assess its carbon emissions.
The right specification of metres and sensors is crucial, according to Kathryn Donald, digital design leader at engineering consultant Max Fordham. Buildings that are flexible, that respond to the needs of their occupants, will produce a lot of interesting data, she said.
‘The building can adapt to all of that data, but you need to be able to collect it’, Donald said. ‘Having systems in place that can talk to each other is very useful. You need to be forward-thinking so that your technology – software, hardware, digital platforms – does what you want it to do.’
But Debbie Hobbs, head of sustainable business at developer ISG, warned that for that data to mean anything the equipment had to be maintained properly. ‘Having done thousands of energy audits, I can’t tell you the number of buildings I’ve been to where the outside air temperatures aren’t calibrated. Controls won’t work if you don’t maintain them properly.’
Another factor helping the drive toward net-zero buildings comes from the client side. Roger Macklin, technical director at engineer Hoare Lea, highlighted the experience of Australia, where there is an eco-rating system for buildings under the National Australian Built Environment Rating System.
‘The reason it was so successful’, Macklin said, ‘was because essentially the biggest user of office space over there, which happens to be the Australian Government, basically said, “We’re not going to touch a building which has a rating of fewer than five stars.”‘
Developers recognised they’d lose a lot of revenue if they didn’t respond to this system, Macklin said. ‘If major landlords [in the UK] said we’re not going to take on any building which has [a poor] embodied carbon rating, then that drives the market really significantly. There would simply be no market for a building which didn’t have a rating of a certain value.’
A carbon passport?
Macklin also suggested buildings might be mandated to hold some sort of carbon passport or certificate, whereby a building would be forced to report the energy it consumed throughout its life, and therefore the carbon it consumes.
What could well be the catalyst for net-zero buildings is demand from staff – particularly younger, more environmentally-savvy employees – who will only want to work in buildings that can prove their energy-efficient credentials.
‘Achieving an operational net-zero situation is very important for many businesses’, said Alex Edmonds, associate director at engineering consultant Robert Bird Group.
‘A lot of activity is being driven by this attitude which tends to come from younger generations who are coming through the business. They want to see more of those kinds of environmentally friendly features and sustainable features in buildings.’
The final word went to Andrew Pratt, a director at engineering consultant WSP. ‘When I first joined this industry 20 years ago, the technology was minimal. We had drawing boards, fax machines, paper copies and envelopes and franking machines. Now we can work in a 3D environment online. I can go onto a website, pick up my BIM 360 model, and it all works fine. I’m hoping that every technology we add is an extra weapon that can be used to combat the carbon issues that we have today.’