Investing in nearly zero-energy wooden buildings helps combat climate change. Wood is becoming the next go-to construction material to help reduce the construction industry’s carbon footprint and lifelong carbon emissions of building stock.
Wood is the answer
The EU and EU national policies have stepped up efforts to combat climate change by boosting wood construction. Wooden buildings can result in 50 % reduced greenhouse gas (GHG) emissions compared to conventional buildings with steel and concrete structures. One way to achieve this is with wooden nearly zero-energy buildings (NZEBs).
The EU-funded NERO project, co-ordinated by Kouvola Innovation Oy, collected and identified best practices and technical solutions that significantly reduce the costs of wooden NZEBs in four different seasons.
“The growing use of wooden products in buildings gives us a material that is light, durable, more local, circular as frame material and structure and acts as a long-term carbon sink,” explains project coordinator Tero Hasu.
The project team collected construction costs, implementation and operational energy data examples of carbon emissions from 17 demonstration buildings, 11 of which were already completed, and 6 demos being planned and mainly completed during the project. Life cycle assessments (LCAs) on the case and demonstration NZEBs were conducted to analyse the environmental impact of representative NZEBs in partner countries. Such information was used to compare technical solutions (e.g. structures and envelope systems) among the buildings to identify the areas of potential abatement of embodied emissions and energy.
A look at two of the case studies
In one case study in Växjö in Sweden, where wooden public buildings have been a top priority, NERO developed multi-family buildings one step further. Project findings showed that the national NZEBs could give 30-40 % lower delivered operational energy use than stipulated by the existing national building code.
The LCAs showed that wood-based buildings give significantly lower production stage primary energy use and lower carbon footprint than non-wood alternatives. Cost-optimal analysis showed thicknesses of insulation to achieve the NZEB energy level are considerably higher, than required to meet the minimum energy requirement by the code. Implementation of the NZEB solutions results in economic benefits, but not as much as the implementation of cost-optimal solutions.
In another case study in Trondheim in Norway, an analysis of the case and demonstration NERO buildings showed that replacing concrete for large use of cross-laminated timber for structural elements was deemed important with at least a 30 % reduction of GHGs. It is expected that a large uptake of such a construction technology in the Nordic market will reduce these costs.
“The trend for the near future is clear. At least here in the north, an increasing number of main structures for new buildings will be made of wood,” concludes Hasu.
In the long run, prefabrication and industrialisation of production coupled with a lean process at factories and existing supply-demand balance on the market through a wider market uptake will bring the biggest emissions reductions. Also, near future recommendations, guidance and legislation for emissions in construction allowed will yield the same results.
The benefit from reducing the amount of concrete was evident in the NERO project where LCA was defined. Today, however, having only a carrot without a stick, the benefits are difficult to quantify in terms of societal cost savings.
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