Wooden Buildings Strive for Low Energy in the North
How energy efficient can wooden buildings be, when facing a really trying climate? Construction of wooden buildings is not exactly a new thing in the Nordics, but Climate Change requires us to take a long, hard look at the carbon footprint of all real estate.
In order to promote the cause of energy efficient wooden buildings in the North, four countries – Finland, Sweden, Norway and Estonia – came together. NERO project develops and demonstrates technical solutions, which significantly reduce the overall costs of new nearly Zero-Energy Wooden Buildings (nZEB) and districts (in comparison to the current situation).
The first step of NERO project has been to collect data from 11 wooden buildings, both public and indirectly public-owned. These buildings are all relatively new, having been constructed in 2013 – 2017. Each building was frequently visited by NERO research teams eager to assess the possible differences between predicted and actual energy and indoor environmental performance. Another big theme was to analyse the differences in building structures and technical systems.
Push for Greener Buildings
The drive for more energy-efficient public/semi-public buildings is increasing, as the European energy policy keeps pushing the Member States to transform their building stock into nZEBs. By the end of 2018, all new buildings owned by public authorities should comply with the obligation lined out in the Energy Performance of Buildings Directive (EPBD).
Finland serves as the coordinator of NERO and has the most buildings (5) participating in the study. Two of these buildings are daycare centres located in Kouvola. Both centres are quite new, Lehvätie daycare centre having been completed in 2015 and Marja-aho daycare centre in 2016. Both daycare centres were raised by local builders specialised in wood construction.
The NERO teams performed their measurements in 2018, first visiting the centres in February and then again at the end of May. This way the research team could get a handle on the building performance in winter and (almost) summer.
Theory vs. Practice
The NERO team conducted several measurements – e.g. outside/inside temperatures and air carbon dioxide content – and interviewed the personnel: what things are working well with regards to the building itself? What’s out there that needs to be improved in some way?
One interesting finding was the striking contrast between the – very theoretical – Energy Performance Certificate (EPC) and the actual energy performance “in the field.”
The Lehvätie daycare centre, for one, operates in three shifts, meaning a greater burden on the building systems. Then looking at Marjo-aho daycare centre, it features, for example, a kitchen which is used to cook the kids’ meals daily – again something which impacts the energy consumption profile of the building.
However, these things were not taken into account in the composing of the Energy Performance Certificate. There were also several other factors which were excluded from the certificate, but which do make a difference in the actual energy consumption.
While the discrepancy between EPC and reality raised some eyebrows, the other findings in the two Kouvola targets were quite positive. Measurements confirmed that the buildings are in fine working condition. The interviews sent out a positive signal, as well: the interviewed daycare personnel stated that thermal comfort, indoor air quality, acoustics, odour and illuminance were all on acceptable levels in both centres.
Presently, NERO is advancing to Phase II with new targets. Among them is the new Lehtomäki daycare centre in Kouvola which opened its doors in 2018. Once the “new crop” of wooden buildings has been measured and analysed, it is time for the NERO final report in mid-2020.