The goal is to respect planetary boundaries

With the construction of several beacon projects and with an award-winning CO₂ roadmap, we help set the course for how the construction industry can live up to the climate goals in the Paris Agreement.

Building Green is Denmark’s leading event for green solutions in the construction industry and hosts the prize-giving for the Sustainable Element award. On 3 November 2022, Artelia was on stage in the event arena Forum with the architectural offices EFFEKT and CEBRA to receive the cooperation award for Reduction Roadmap, a brand new tool that maps how the climate goals in the Paris Agreement can be translated into specific annual CO₂ goals for new Danish housing constructions. The tool, which is supported by the foundation VILLUM FONDEN and the association Realdania, is based on the latest knowledge on climate change and indicates that we must reduce emission by 96% within 7 to 14 years in order to reach Earth’s safe operating space.

This means specifically that emission from buildings must be reduced from a current average of 9.6 kg CO₂eq/m2 per year to an average of 0.4 kg CO₂eq/m2 per year. In this connection, the tool shows the speed with which the necessary reduction must take place year by year in order to reduce the construction industry’s contribution to climate changes.

This is of course a challenge that no industry player can take on alone, but something that requires joint actions.

Future habitats

The transformation from ambition to action is often difficult. Artelia is involved in several projects which give physical form to the idea of reducing climate footprint of buildings significantly.

One of them is the housing concept Living Places developed in cooperation with VELUX, EFFEKT and the contractor Enemærke & Petersen. The first prototype, Boligværkstedet, is being established in Jernbanebyen in Copenhagen in connection with the city's role as World Capital of Architecture in 2023. The whole idea with the concept is to show the road to a new generation of housing that takes both the planet and people’s health and well-being into consideration. Boligværkstedet has a record low CO₂ footprint which has already received much attention. Living Places was even presented at COP27.

From 4 to 1 planet

We work towards the same goal with the project Housing from 4 to 1 planet, where Realdania and VILLUM FONDEN have allocated DKK 60 million to a joint effort to promote residential projects with a climate footprint 75% below average. In this project, Artelia is facilitator for knowledge sharing and client consultant on the demonstrational projects that leading players on the market are asked to build. Part of the partnership’s funds will be invested in the innovation process in the individual projects, e.g. time used for creating ideas, for tests and documentation of different methods and materials, or for building damage insurance related to untested solutions.

The purpose is to create an ecosystem of knowledge where we provide our own expertise to the construction work while reaping new experiences that can be shared across the projects and create inspiration to the entire industry. We have taken part in several demonstrational projects previously and have experienced how new knowledge has been created –knowledge that other projects have benefited from.

Steffen Maagaard Market Director Energy Design, Sustainability & Indoor Climate Aarhus

Bringing bio-based materials into play

Bio-based floor structures of the future is the name of a project that illustrates how we go the extra mile to find even greener solutions that should be expanded across the industry. Realdania initiated the project that is based on the association’s test construction Mini CO₂ Houses Timber, where Artelia is engineer. In this project, it was obvious that floor structures were worth examining further with special focus on acoustics.

Floor structures are easily responsible for extensive CO₂ impact in constructions. They comprise a significant part of the building stock and are rarely made with bio-based materials with a low CO₂ footprint. This is due both to fire safety and not least to acoustics. To ensure efficient noise protection towards upstairs and downstairs neighbours, concrete is preferred in order to create weight, and mineral wool is used for suspension.

When focusing only on tower blocks in general, the floor structures often comprise approx. 15-20% of the total CO₂ footprint. The goal in the project is to examine the extent to which it is possible to minimise the climate footprint in floor structures if they also have to comply with the requirements in the building regulations regarding acoustics. In addition, constructability, economy and fire safety are also examined in the project.

Promising results

For this purpose, Artelia, JaJa Architects and the contractor CG Jensen have designed 23 floor structures that are primarily bio-based : 14 joist floor solutions and 9 CLT solutions. During autumn 2022, the many variants were tested at the acoustics laboratory of the Technical University of Denmark. Artelia conducted acoustics measurements of the two sound parameters listed in the building regulations’ requirements regarding floor structures : airborne sound insulation, which covers airborne sound such as speech, and impact sound pressure level, which covers structure-borne noise such as footsteps, chair legs, etc.

The results were very promising : for most of the CLT and the joist floor solutions, it is possible to comply with the sound requirements in building regulations 2018 and at the same time reduce the CO₂ footprint by 50-70% compared to a typical box girder solution in concrete.

As an acoustician, I am immensely satisfied with the result. I would dare to call it groundbreaking that we have tested materials and structures that are not normally part of the toolbox when we are creating satisfactory sound isolation. Therefore, these tests might very well open up for a greener approach to acoustics.

Jan Christensen Head of Department Acoustics Copenhagen

As Jan emphasises, the project sheds light on a number of completely new combination solutions with both untraditional components and constellations. For instance, materials such as sand and paper wool are used to obtain the acoustic qualities.

Specific EPDs give the greenest solutions

Another significant discovery in the project is the importance of using productspecific EPDs (Environmental Product Declarations) rather than generic and industry-specific environmental data. This is necessary when determining the actual CO₂ footprint for bio-based floors. This is because the generic data used for biobased materials are both very limited and at the same time show a higher average CO₂ footprint to be on the safe side. Product-specific EPDs, on the other hand, can show the road to products with an actual documented low footprint.

Our own comparison shows that the use of product-specific EPDs for bio-based materials showed a CO₂ footprint 25-70% lower than with the use of generic data. That is quite a difference when looking for the most sustainable solution, and the risk of deselecting the greenest alternative on that basis is high, says Steffen.

As Steffen points out, the difference is only 15% compared to box girders with EPS concrete. This illustrates that the generic data for concrete show a somewhat more accurate picture of the average and probably use better data as the material is more widespread.

But bio-based materials should definitely not be deprioritised just because generic data give an artificially high CO₂ level which can easily sway the decision in the wrong direction. On the contrary, they are crucial if we really want to do something about construction climate footprint. It is therefore important to use the product-specific EPDs, concludes Steffen.