RAVE promotes low-carbon construction in Kajaani

The site of the former bus station in central Kajaani will soon be home to the Sammonkaari apartment block. This multi-generational residential area is designed to be close to shops and services, and its modern and environmentally-friendly solutions were chosen to suit the varying ages of its users. The area’s first block will be constructed in three phases, starting with student apartments and a grocery store at street level. This first phase has been completed.

Text and photos: Jenni Kuronen

Read the article in Finnish: RAVE-hanke edistää vähähiilistä rakentamista Kajaanissa

The RAVE project did its part to facilitate low-carbon construction design in Sammonkaari. To make the design work easier, the project produced up-to-date information on low-carbon construction, and commissioned a low-carbon assessment and energy plan for the block from industry experts. A handy energy manual was written in the process.

Energy plan

The project’s energy plan was prepared by Sweco. The company compared various energy systems and their combinations, exploring the potential of renewable and recyclable energy and the impacts of different structural solutions on energy efficiency. For Sammonkaari, the renewable energy options compared were solar electricity production, waste heat recycling and geothermal heat. The results were collected into a handy energy manual that helped designers choose the right energy solutions for the area’s buildings. The project proposed a smart technology solution that would utilise energy recycling and free energy alongside district heating and grid electricity. Finally, the results were leveraged to improve the design of structures and energy solutions and the selection of HVAC systems.

Low carbon assessment

The low-carbon assessment was carried out by Granlund in accordance with the Ministry of the Environment’s low-carbon assessment method for buildings (2019). Low-carbon assessments are a form of preliminary planning that will be included in construction planning processes in future. For Sammonkaari, Granlund calculated both the carbon footprint and handprint. The results were compared to a corresponding precast concrete building that met the minimum E-factor requirements of current building regulations.

The carbon footprint assessment covered the building’s entire lifecycle from material procurement, manufacture, and transport to building construction, use, maintenance and eventual demolition and recycling. Climate benefits that would not have materialised without the construction project were factored into the calculations.

The resulting carbon footprint and handprint for the wooden building’s entire lifecycle showed that it serves as a significant carbon store and simultaneously reduces the carbon footprint of the project’s materials. In short, the wooden apartment building in Sammonkaari is indeed low-carbon.

A building’s carbon footprint is most significantly impacted by the energy types used as well as the material choices and how much each material is used. For the first building in the Sammonkaari block, the project also investigated alternative solutions, which succeeded in reducing the lifecycle carbon footprint somewhat from the original calculations.

The chosen materials and products and their origins affected the calculation’s final results. For example, the use of low-carbon concrete products reduced the carbon footprint of the building’s complete life cycle. Thanks to the designer’s product comparisons and the emission reduction measures, the initial numbers were scaled down by roughly 3.00 kg CO₂ₑ/m₂/a, achieving a total reduction of roughly 500 t CO₂ₑ.

Figure 1: Summary of the Building 1 carbon footprint and handprint compared to a corresponding concrete frame. Figure adapted from Granlund’s report.
Figure 2: The impact of design solutions on the building’s carbon footprint. Figure adapted from Granlund’s report.

MANAGED BY KAJAANI UNIVERSITY OF APPLIED SCIENCES, RAVE seeks low-carbon energy solutions for construction. The project kicked off in August 2020 and is backed by the Northern Ostrobothnia ELY Centre with funds from the European Regional Development Fund (ERDF). RAVE hopes to pave the way for a low-carbon and resource-efficient society by furthering renewable and innovative forms of energy production and storage in construction. The project will continue until the end of September 2023. For more information about RAVE and the reports produced by the project, visit the project website at www.kamk.fi/RAVE.

Miia Rönkkö
Jenni Kuronen
projekti-insinööri vähähiilinen rakentaminen
Jani Moilanen
Silja Keränen