LEED vs BREEAM: What's best?
The Leadership in Energy & Environmental Design (LEED) green building rating system is starting to gain ground in the UK, but can it challenge the dominance of BREEAM, the UK's design and assessment method for sustainable buildings? Dave Cheshire reports
There has been a marked increase in the number of LEED enquiries, particularly from multinational companies looking for consistency across global portfolios.
BREEAM, originally launched in the UK by BRE, is celebrating its 21st birthday while LEED is still only 13 years old. This maturity has given BREEAM time to become thoroughly ingrained in the system, appearing in design briefs and planning policies across the UK. There are more than 110,000 certified buildings, most of them in the UK. LEED is the young upstart with around 9,000 certified buildings with only 100 registered in the UK.
LEED, developed by the US Green Building Council (USGBC), took the structure and topics from BREEAM and adapted them to the US market. It introduced some good ideas. Building owners only get an award when the building is completed and can get additional credits for including innovative ideas that are not acknowledged under the scheme. BREEAM took ten years to take notice of these ideas. Up until 2008, owners could get a BREEAM certificate at design stage without having to follow through into construction.
One of LEED's greatest strengths globally is that it has been adapted to suit the US market. But this strength is also a weakness in challenging BREEAM's position in the UK. The strength of LEED is that it has had to be heavily marketed to succeed. This is because planning policy on sustainability is weaker in the States compared with the UK and there are fewer legislative mechanisms to encourage environmental assessment methods. This has forced USGBC to invest effort into marketing the scheme. This strategy includes demonstrating the benefits of green buildings to occupiers. Energy credits are based on cost in LEED, whereas BREEAM uses carbon emissions.
BREEAM has grown organically. Developers have adopted it in briefs as an accepted standard and planners have included BREEAM targets in their local plans. USGBC invites keynote speakers to its annual conference to raise its profile. This high-profile marketing has helped LEED push into other countries, notably the Middle East, China and India. Dominance in these markets is why multinationals want their UK buildings to be LEED-certified to secure consistency across their global portfolios.
The fundamental weakness of LEED in the UK is that its standards are tailored to the US market. This includes using 'footcandles' instead of lux measurements. But users have to use the American ASHRAE energy model to be awarded credits. This is because there are no federal building energy code regulations to reference, only state energy codes.
"California has Title 24, which is the equivalent of energy code building regulations, but most states don't have them and use an adaptive version of ASHRAE," says Vivien Fairlamb, an AECOM LEED accredited professional. "So, to assess a building in the UK you have to commission an ASHRAE energy model. This drives up the cost. It is also duplication of effort as Building Regulations requires an energy model to be built to demonstrate compliance."
BREEAM's key advantage in the UK is that it uses and builds on legislation and standards to award credits. The 2011 BREEAM Update uses the outputs from the building regulations energy calculation to award up to 15 credits. There are also credits for complying with standard commissioning codes and meeting targets that relate to Site Waste Management Plans, a regulatory requirement in the UK. The 2011 update also references UK initiatives such as Soft Landings, which is a framework that encourages project teams to stay engaged after handover to fine tune and optimise the building to run efficiently for the occupants.
UK-based teams are often familiar with these standards and conversant with the compliance requirements for the credits. In some cases, designers quote back the standards in meetings. This makes it cheaper and simpler to apply than LEED, as teams have had far less experience with the US standard.
"In the US most people in the design team are LEED-accredited professionals. Designers can take an online exam to become accredited," adds Fairlamb. "This is another weapon in LEED's assault of the global market. BREEAM introduced the concept of accredited professionals in 2008 and it's only now starting to catch on. More LEED-accredited professionals in the UK will mean more designers familiar with the requirements which should drive down costs."
So, how do the two schemes compare? A few buildings have achieved dual certification, but there does not seem to be much correlation between the two schemes. A project in the UK is targeting a LEED 'Platinum' and a BREEAM 'Excellent' rating. BREEAM 'Outstanding' was considered too much of a stretch as it required an Energy Performance Certificate 'A' rating. "It's very difficult to compare the two schemes as it depends on the site you're building on and the experience of the project team in the two assessment methods," says Fairlamb.
There are some notable differences. In general, LEED is slightly simpler, but this can also be considered a weakness if owners are pushing to improve environmental performance. As an example, for materials, LEED looks at the percentage of recycled content and local sourcing, whereas BREEAM gets more involved and tries to consider the wider environmental impacts of building elements by scoring against the Green Guide to Specification and a 'responsible-sourcing' index. This makes it more difficult to demonstrate compliance with BREEAM as there is often a huge paper chase involved.
BREEAM is arguably stricter as it sets more absolute targets. LEED sets relative percentage reduction targets. BREEAM water credits are based on cubic metres per person per year; LEED sets a percentage water use reduction target. A 40% reduction in water use achieves maximum credits under LEED, but only achieves one or two credits under BREEAM.
"Setting stringent targets does not always work. If you set targets too high, you can discourage people from going for the credit at all. Setting relative targets can mean that you don't encourage enough improvement in performance," says Allie O'Donovan, one of AECOM's most experienced BREEAM assessors.
Both schemes need to improve their understanding of whether a high rating actually translates into an improvement in the building's operational performance. They both simply rate the 'asset' and do not consider how the building will operate in reality.
BREEAM 2011 has started to address this issue by putting more emphasis on commissioning, handover and the first year of occupation. It includes credits for 'seasonal commissioning', collecting and analysing energy performance data for the first year; and providing extended aftercare. And all 'Excellent'- and 'Outstanding'-rated buildings have to now carry out a BREEAM In-Use assessment within three years of completion.
LEED is ahead of the game here. The questions about their claims led them to mandate all building owners to provide five years' worth of utility data to USGBC. If owners do not submit the data, then they have to sign a waiver allowing USGBC to obtain the data from the utility company.
BREEAM is currently dominant in the UK simply because it is better adapted to UK legislation and standards and, consequently, is cheaper to apply. LEED is gaining ground, particularly with fit-out only assessments and is preferred by multinationals as it is more globally-recognised.
If LEED is adapted to the UK market, then it will open up the field. BREEAM has already been learning lessons from LEED with the increasing competition and further competition should only help to improve both schemes.
Dave Cheshire is AECOM’s regional director for sustainability