“Post-occupancy evaluations in themselves aren’t new but doing them systematically and comparing them with design stage predictions about operational building performance is,” says Judit Kimpian, Head of Sustainability at global architectural practice AHR. The firm has not only invested time, expertise and money into carrying out pioneering research in this field, but found the results so compelling that it has done everything in its powers to share and disseminate them.
It all started about seven years ago when Kimpian realised that the practice needed to understand its direct and indirect carbon footprint. “So apart from looking at things like our own fuel consumption, I started to look at what our projects were consuming,” she continues. What she found was huge confusion. “Nobody could tell me how much energy a building is predicted to use because the only calculation that you are asked to perform in this area is for compliance and that only concerns a building’s potential energy use.” What users may or may not do in the building was not taken into account she continues, nor were any procurement issues, how the building was commissioned or how effectively all the design parameters were implemented in practice and if anything had changed during the construction process. “We may think we are designing low-carbon buildings but they don’t necessarily end up being so when operational.”
Kimpian joined up with various architecture practices and other built environment professionals such as developers, contractors and engineers and embarked on a six-year research project into how low operational energy use could be achieved in new and refurbished buildings, and how the risks of unexpectedly high energy consumption could be minimised.
First she launched the CarbonBuzz project in 2007, a free online data-hosting and benchmarking service that collects building energy use data. Then AHR looked at the energy consumption of seven buildings it had designed (five of them schools) and compared those to compliance calculations adjusted to reflect actual operating conditions. “What we found was that there was a huge gap between what we expected to happen and what was really happening on the ground,” says Kimpian.
What they also found was that one of the most significant barriers to lowering energy use was the use, or rather misuse, of building management systems. “When we looked at the buildings we saw things going very, very wrong with commissioning and very wrong with handover,” explains Kimpian. “Currently a building management system (BMS) is only as smart as that person who is setting up and running it,” she explains. But thorough and seasonal commissioning is frequently compromised and the person or people operating the BMS often don’t have the background or training to manage the system’s complex computerised controls. The fact that the BMS was often located in the wrong part of the building didn’t help. “In one case we found the BMS computer in a basement room where nobody went.”
Ironically, problems with controls were more acute in cases where architects and engineers had attempted to design a low-carbon building with multiple energy streams. “The risks associated with complexity are enormous,” says Kimpian. In a building where the heating is supplied by gas boilers and ground source heat pumps or biomass boilers, and where there may also be solar hot water systems and a lot of different heating zones, it is hard to understand what’s driving what and the result is almost always excessive energy usage. The answer is not necessarily cutting out the building management system says Kimpian, but keeping things simple, well-commissioned and well-maintained. Interestingly, she adds, the research also found that when occupants were happy with the building’s architecture, and found a building had access to plenty of daylight and was easy to navigate and understand, they were a lot more forgiving about comfort issues.
Other important risk areas that impacted on achieving low energy use were the difficulty of extracting robust energy data from buildings, where elaborate metering systems are often installed but contractors rarely commission them properly and end users seldom read them. The handling of openings in the building fabric was another issue. Whether automated or manual, doors and windows often gave rise to issues around usability and energy consumption. This could be anything from an automated window with an actuator that had been value engineered and wasn’t working correctly to a door that people weren’t told how to use. “One school kept all their ground floor corridor doors – which were also fire escapes - open year-round because they didn’t know that they could be opened both from the inside and the outside ” says Kimpian. “Suddenly this building had a huge heating demand.”
Perhaps the biggest learning of all says Kimpian was that going after the energy data early on is key. Something that a scheme AHR won while carrying out these research projects aptly demonstrates. Keynsham Town Hall, a new HQ for Bath and North Somerset Council soon became “a game changer” she believes. The client wanted a major reduction in energy bills so the architects recommended that it should target real operational energy use and put it into the contractor’s requirements. “We said ‘if your business model depends on this then target a DEC ‘A’ Rating and do all the risk analysis upfront’,” says Kimpian. The team found that doing so created a better information flow from design to contractor teams and that value engineering was largely avoided.
It’s rare for an architectural practice to take the business of pre- and post-building performance so seriously but AHR believes it is vital. “If you think about the car industry, it spends a huge amount of its budget looking at feedback from testing and trials and using it to improve the next round of products,” says Kimpian. People argue that architecture is different because every building is unique. “That’s true,” agrees Kimpian, “but they are not that unique.” By understanding the operational energy use of a building, architects have a much easier time arguing for and implementing design features such as greater thermal mass, passive ventilation and more generous floor-to-ceiling heights.
The research has revealed a huge design opportunity for energy-literate architects as well as a great business opportunity for savvy clients. “Apart from lower energy and maintenance costs, investing in energy efficiency measures that also improve the long-term resilience of a building portfolio is a win-win for all,” says Kimpian. AHR now offers building performance evaluations to all its clients as a matter of course and is a champion of BSRIA’s Soft Landings Scheme.
Significantly, AHR has been keen to share its findings and solutions. The practice has published a number of peer-reviewed papers on the subject, sponsored doctorates and Kimpian sits on the boards of professional bodies such as the RIBA Sustainable Futures Group and the CIBSE Energy Performance Group. Next step is the setting up of a CPD on building performance in collaboration with RIBA and UCL says Kimpian. “By putting as much information back out into the public domain as possible, AHR hopes to ensure that any lessons learned actually permeate industry practice.”
Giovanna Dunmall is a freelance journalist based in London who writes about architecture, design and the arts for publications such as the South China Morning Post, Economist online, the National, the Guardian, DETAIL, Frame, Mark, Azure, Metropolis, Blueprint and Wallpaper.
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