A large, interdisciplinary project in Denmark has demonstrated how to renovate in a climate-friendly way. Rather than demolishing and starting over, the objective of the research was to emphasise that renovation is better for the climate. The project fills the gap in databases, calculation methods and climate requirements for renovation efforts.

While many local and national governments as well as companies around the world are starting to accept that renovation is better for the climate than demolition and new construction, there are not a lot of tools to support projects. On the other hand, shared databases, calculation methods, and climate requirements for new building projects with a focus on climate-friendly construction already exist. A large, interdisciplinary project from Denmark, sponsored by philanthropic association Realdania, aims at increasing knowledge, developing shared methods, and generating shared data for the construction industry. This will enable the sector to perform more comparable assessments of the climate impacts of different renovation scenarios from a lifecycle perspective.

Renovations offer best value for money

The result of the research project is a report called “Renovering er bedst for klimaet” (Renovation is best for the climate) and a technical background report focusing on climate data for renovation. Both reports are freely accessible and are targeted at both the construction industry and politicians in order to help with making decisions about conservation and renovation on a more informed basis.

“Until now, we have had little knowledge about how to renovate in the most climate-friendly way, but in this project, calculations of the climate impact have been made for various renovation scenarios covering a number of different building types. The clear conclusion is that renovation is better for the climate and that in a lifecycle perspective even minor renovations are better than demolishing and building anew,” says Thomas Waras Brogren, Project Manager at Realdania.

“The project group has also calculated the financial aspects of a number of renovation scenarios, and these results show that in the long run renovation is often a more favourable overall economic solution than building anew. Therefore, we can say that renovations will often give the best value for money in terms of climate impact,” he adds.

Biogenic building materials

Calculations in the report are based on the Danish 2025 emission factors that the country is using for lifecycle assessment calculations. They differ significantly from the 2023 factors that are currently being used because the Danes expect that their energy sources will have lower CO2 emissions in the future than they do today.

“With the new Danish emission factors, there will inevitably be a greater focus on not only reducing operational energy costs, but also on reducing the climate impact of building materials and the construction process itself. Because we want to reduce climate impact now, rather than years from now, the timing of emissions may well be one of the factors that will receive more focus in the future. It may also become increasingly relevant to use more biogenic building materials. All of this will affect the way we conserve and renovate buildings in the future,” concludes Thomas Waras Brogren.

In-demand knowledge

For other countries to use the calculations and tools presented in the reports, it will be necessary to adapt some numbers. After all, Denmark is one of the countries that is doing well on its path to net zero and its emissions are already reasonably low. However, the main idea that preserving and renovating buildings has a lower climate impact than demolishing and constructing new ones applies in all countries.

According to the authors, the reports are aimed at EU countries, specifically Finland, Norway, Sweden, France, the Netherlands, and the UK. They provide examples from these countries and show how it is possible to work with climate requirements and renovation.

In addition, both reports offer suggestions for architectural considerations in climate-conscious renovation works. For example, biogenic materials like wood and cork will likely become more popular. Another approach is to work with cautious renovation, in which only the most necessary parts are replaced.

Knowledge on topics that impact future climate-focused renovations will be more and more in demand. In the reports, readers will learn how to consider factors such as performance inadequacies for buildings already in operation; different models for calculating CO2 shadow costs of construction projects; how residual lifespans can be determined; and dynamic lifecycle assessment, in which earlier emissions carry greater weight compared to later emissions.

Net zero by 2045

A wide range of specialists from architectural and consultancy firms like Arkitema, Cowi, BUILD and the Danish Council for Building Sustainably have collaborated in producing the reports, contributing practical knowledge and examples. In addition, an advisory group of sixty people from the Danish construction industry has followed the project, contributing input on various options, and new perspectives on climate-friendly renovation.

Already, Denmark is making great progress towards net zero. The government recently announced that it will reach net zero by 2045 instead of 2050, as well as reducing CO2 emissions by 110 percent. This would mean reaching a negative level in 2050 compared to 1990 levels.

Learn more about the innovative, dynamic capital Copenhagen in topos 119, an issue about the city’s urban development with a focus on a female view of architecture.