CIBSE AWARD WINNER | WARM This is the missing loop in construction, observes Godber. There is nothing quite like saying weve tried that and this is what happened. That kind of experience is invaluable in developing solutions that work, she adds. An example of the impact that postoccupancy studies can have on a design is in the practices move away from specifying combi-boilers. Historically, we specified combi-boilers because it was a cheap way of dealing with heating and domestic hot water demand, says Godber. But, through our post-occupancy studies, we found the efficiency of the boilers when they operate in hot water mode which is nearly all of the energy consumption in a Passivhaus was around 62%. This finding forced us look for alternative, more energy-efficient solutions, she says. 62% Average efficiency of combi-boilers revealed by post-occupancy studies Passivhaus roots Warms involvement with Passivhaus started soon after Godber and her father had joined forces. We started Warm in 2009 and that was when we got our first Passivhaus project, which was for 20 homes in Cornwall, Godber says. The thing that really chimed with us about Passivhaus was that it was based on a huge amount of research derived from the best low-energy building solutions from around the world. The Passivhaus standard and all the technical guidance around it are based on real data of how buildings actually perform, she says. Father and daughter were struck by how well Passivhaus had been thought through in terms of the tools and processes it had in place to support the design team in optimising a design. They were also impressed by the requirement for a scheme to be certified as part of a rigorous quality assurance regime. To certify a scheme, you have to have an independent specialist someone who understands building physics to check over everything in the design, which is quite unusual, says Godber. Passivhaus is a good way of ensuring quality and low energy for any buildings that are occupied by people, as opposed to empty warehouses, where there is a need to keep people comfortable, says Godber. She warns that if Passivhaus, or something similar, does not become mainstream construction practice, the UK will be truly screwed in terms of what is needed in building carbon savings. We need our buildings to be performing as designed, she says. If the UK adopts Passivhaus as a compliance standard, is there a danger that build costs will rise? At the moment, there is a significant over-cost because Passivhaus is unusual and, therefore, perceived as high risk because it is not something contractors are used to doing, says Godber. She says if it becomes mainstream, this over-cost should soon start to disappear. In Brussels, Passivhaus is what everyone builds. Here, it has Warm advised on all aspects relating to Passivhaus at the University of Leicesters Centre of Medicine including the integrity of insulation and ventilation commissioning Sally Godber and Peter Warm Warm carries out Passivhaus training sessions including a course for contractors and training on retrofitting www.peterwarm. co.uk/training/ 30 September 2019 www.cibsejournal.com CIBSE Sep19 pp28-30, 32 Warm.indd 30 23/08/2019 16:25