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Cost reduction of new Nearly Zero-Energy Wooden buildings in the Northern Climatic Conditions

Periodic Reporting for period 2 - NERO (Cost reduction of new Nearly Zero-Energy Wooden buildings in the Northern Climatic Conditions)

Reporting period: 2019-03-01 to 2021-02-28

NERO project worked with cost reduction of wooden nearly zero energy buildings in a cold climate with four different kind of seasons. In such a severe and on the other hand changeable climate, heating and air conditioning are clearly dominating and the construction and running costs of heavily insulated nearly zero energy buildings are evident challenge. The project aimed to collected data from eleven existing case buildings representing educational and residential multifamily buildings and conducted more detailed construction cost breakdown and life cycle costs analyses for six demonstration buildings including also NZEB districts.
Life Cycle Assessments (LCA) on the case and new demonstration nZEB buildings of NERO were carried on to analyse the environmental impact of representative buildings in NERO partners’ countries. Such information was used to compare technical solutions (e.g. structures and building envelope systems) among the buildings to identify the areas of potential abatement of embodied emissions and energy.
It was also highly important to study new highly performing buildings with advanced technical solutions in order to be sure that such buildings can provide healthy and comfortable indoor climate together with superior energy performance at reasonable construction cost
In Finland, the case and demonstrations buildings consisted of wooden prefabricated modular based of day care centers and schools. In Sweden in Växjö the wooden public buildings has had top priority for many years. The NERO focused in Växjö has been to develop multi-family buildings even further. In Norway, the analyses of the case and demonstration NERO buildings showed the large use of cross-laminated timber for structural elements in replacement of concrete ones determined an important reduction of Greenhouse Gas emissions. The Estonian demonstration building addressed possibilities of reducing energy use and construction cost, summarizing provided evidence the wooden nZEB buildings are technically possible at affordable construction costs by using novel design processes and procurement models that enable scalable and modular production.
NERO collected construction cost and operational energy data from all case buildings. Metered energy data was studied against monitored indoor climate – the ventilation and thermal comfort questionnaire in order to be sure that energy performance targets of NZEB buildings have been achieved without compromising indoor climate and occupant comfort.
NERO studies focused on new demonstration buildings at greater detailed level. Our project studied the implementation of national nZEB technical solutions, design and procurement process data and experiences collected in these wooden projects.
The project-wide results showed that in many buildings both indoor climate and energy targets were not met in practice, and only in minority of buildings these targets were achieved simultaneously. There always has to somehow compromise between more efficient energy performance of the building and indoor climate comfort.
Since the numerical factors and values stated for the nZEB energy performance of buildings in the legislation of the Nordic countries refer to radically different things, it did not make sense to compare the energy use between the countries very deep. The realized energy consumptions vary a lot depending on the country. It was studied in some buildings in Finland and in Estonia today share of life cycled LCC energy costs rose from calculated. On the contrary, in main of buildings in Växjö and in Trondheim the local delivered energy was lower than stipulated by the national code. This all cannot be explained by properties of structures or quality of construction works, it shows something about theoretical and weak simulation protocols, gathered, and referred in NERO reports.
Calculations done the total costs, construction and operational costs are in general higher than in reference data, depending on life cycle length set. Additional energy investments may in some projects, depending on national or regional target setting. not be economically feasible.
LCA, analyses of five of projects focused on comparing the results of studied buildings that were the most similar. A conclusion, the analysis of the GHG’ emissions of the buildings presented showed whenever engineered massive wood elements being used to replace concrete in the building frame parts, the building's total emissions decrease by a considerable amount.
Totally NERO project organized during the project its own NERO seminars, own NERO workshops plus some of integrated stakeholder seminars and workshops. In all, totally there were 2 000 participants in NERO own gatherings, and in all 21 000 persons participating to events where the project introduced itself.
NERO data collection in new NZEBs revealed many unexpected risks and performance gaps both in use of energy and indoor climate. Collected evidence on problems and from well-functioning solutions and way of doing helped to identify critical aspects and steps to take both in design, construction, operation and maintenance, and generally to avoid drawbacks in highly performing buildings in future. NERO demonstration projects analyses did show good practices enabling to achieve reasonable construction and to reduce life cycle costs as well as good samples of emissions of NZEB buildings.

Identification of cost effective technical solutions for renewable energy on-site integration proved to be a bit problematic, the system design by the contractees is today still in infancy. The building-integrated solar power is today lacking the real significance.
Estonian study showed that without parallel design and cost estimation the target price cannot be achieved. Priority was given to energy performance measures reducing the energy need. In Norway, it showed that the use of massive industrialized wood has a large potential for reducing the buildings' embodied emissions, an aspect important for driving towards a Zero Emission building transition. It is expected that a large up-take of such a construction technology in the Nordic market as a whole will reduce the above-mentioned costs. Experience from Sweden showed, regarding the positive aspects of using wooden structures, it was emphasized the additional benefits are achieved in addition to the reduced carbon footprint.
We saw non-environmental reasons for using more wood. Industrial production gives fast production and construction processes, increases resource efficiency, efficient logistics and creates new jobs in rural areas, to the whole forestry and timber sector, new products and renewable energy. The wooden planar structural systems are not yet ready and largely available for a comprehensive market uptake, compared to dominant concrete systems. However, rapidly developing industrialization of wooden framed prefabricated light element systems evidently will bring life-cycled solutions in the branch, and to the whole industry.
Wood as building material develop companies, and creates conditions for new products and business, more actors and companies establishing on the local market. It also gives top research and drives innovation and cutting-edge technology. The cost reductions for wooden buildings will become more true directly after above mentioned implication are starting to bite, indirectly after the emissions and compensations are saddled with the full sum.
NERO logo slogan
NERO logo
NERO demonstration building ZEB Lab Trondheim, photo by SINTEF
NERO demonstration district Housing Fair Kouvola, photo by TUT video
NERO demonstration project Arken Växjö, photo by Växjöbostäder
NERO demonstration project Maardu Muuga, photo by AS Matek