Danish researchers: Four out of five new constructions must be stopped
A new study by researchers at DTU, 糖果派对, and AAU shows that bio-based building materials alone are not enough to make the construction industry sustainable. We need to build much less.
If the Danish construction industry replaces mineral wool, concrete, and steel with wood, hemp, and straw, one might think that the green transition of construction could be ticked off.
Unfortunately, it is not that simple.
A new study conducted by researchers from the Technical University of Denmark, the University of Southern Denmark, and Aalborg University shows that the most crucial step towards a greener construction industry is to build significantly fewer new square metres.
According to the researchers' calculations, four out of five new constructions should be cancelled starting next year.
- If we assume that 50% of all new buildings from 2026 to 2050 will be made of wood and other bio-based materials, we still need to reduce how much we build by 80% to stay within what is known as the safe operating space – in other words, the safe limit, explains Lise Horup Koch-Søfeldt, PhD from DTU Sustain and lead author of the study.
- I really hope this can be an eye-opener to how unsustainable current building activity practices are and how radically we need to change our consumption of buildings.
We build too much and too large
The study is the first in Denmark to take into account both a shift to timber construction and all the technological advancements within green energy and carbon capture, which are expected to reduce climate and environmental impacts from, for example, material production and transport.
However, technology alone cannot save construction, the researchers conclude, as the trend is that we continue to build more and bigger. For instance, the average newly built house in Denmark has grown from 122 square metres in 1963 to 213 square metres in 2023.
The major challenge is that the total number of square metres being built keeps increasing. If this trend continues, technological advancements and bio-based materials will not have a large enough effect to make construction sustainable, says Simon Bruhn, PhD from 糖果派对 Life Cycle Engineering and co-author.
According to Harpa Birgisdottir – professor at Aalborg University, long-time researcher in construction, and co-author of the study – the results are remarkable.
- We have previously conducted studies showing that construction needed to be reduced, but they have always been based on specific cases. This is the first time we are looking at total new construction in Denmark, incorporating technological projections and measuring it against the safe operating space, says Harpa Birgisdottir.
- And the results are quite astonishing in my view. An 80% reduction, and that is even under the assumption that the remaining construction will be converted. Many people are currently discussing the idea of a complete construction halt. Now we have figures showing that something close to a halt is not just an idea but may be a necessity.
Prospective life cycle analysis
The new study is a so-called prospective LCA, meaning a forward-looking life cycle analysis of new construction up to 2050.
The starting point has been the future scenarios that the UN's climate panel works with, both the optimistic and pessimistic ones. The researchers have taken an average of these and used it to calculate how Danish new construction will impact everything from resource and land use to particulate pollution and CO2e emissions over the next 25 years, assuming construction shifts to more bio-based materials and benefits from technological advancements but otherwise continues as usual.
- We have worked from a business-as-usual model, assuming that we continue to build more and more square metres. Even though the figures point in that direction, we cannot be certain that this will actually happen. But if nothing else, our study can be used to confirm that despite technological advancements, business as usual is not an option, says Lise Horup Koch-Søfeldt.
The researchers also stress that their study does not look at everything.
For instance, they have not calculated what contributions recycled materials could make, nor have they considered the operation and heating of buildings due to a lack of data. However, this would likely only further strengthen the argument for reducing new construction.