Breaking timber in Denmark: How, why and what next

In an industry grappling with ways to reduce its carbon footprint, Scandinavia is a global leader in structural timber. One long-standing champion is C.F. Møller Architects, headquartered in Copenhagen and with studios in Aarhus, Aalborg, Oslo, Berlin, Stockholm and Malmö. As the practice celebrates its centenary, Rob Marsh, head of sustainability, explains how its enthusiasm for timber affects its operations and the specific challenges facing Denmark – with a few UK parallels along the way.

How did you get into sustainability in the first place?

I was always interested, even as a student at Oxford Brookes in the 1980s – it was all about energy-saving in those days. Afterwards, I worked for Aldington, Craig + Collinge in Haddenham, on schools and housing projects with a focus on materiality. Many of my colleagues ended up working for Norman Foster, but I felt I needed something different. By the end of the decade, the agenda was shifting to materials, environmental impacts and timber buildings – I started a PhD in sustainable housing design at the Martin Centre, Cambridge, in the mid-1990s, then wound up in Denmark, and I've been here for about 30 years.

And you've moved between practice and research?

After 15 years at the Danish Building Research Institute in Aalborg, looking at all aspects of sustainability – energy, daylighting, materials, lifecycle assessments – I decided to go back to practice, landing up as head of C.F. Møller's sustainability department in 2017. It was just about the time that everything we’d been working on in research for 10 to 20 years was becoming more and more relevant in architectural practice. My team now totals about 10 or 15 people, in a company of roughly 300. We work directly with our competition architects, developing projects and meeting clients face to face, but also get involved in the more detailed phase after comes after winning competitions.

How is Danish architecture tackling sustainability?

In 2023, new CO₂ requirements were introduced in Danish building regulations, which are being tightened next year, so there’s been a huge focus on these issues over the last five years. As part of that, C.F. Møller has been promoting timber buildings because, in contrast to Norway and Sweden, there actually isn't much timber in Denmark, so the concrete industry dominates. We've basically been taking the practice’s experiences in Sweden and Norway, and importing them back to Denmark. We're building the country’s largest timber building – a 33,000m² office for the Danish state in Odense, called WoodHub – which should finish next year. We’ve also got several large timber buildings in Germany – probably the biggest is the Ministry of the Environment, close to Potsdamer Platz, which is about 50,000m², and we’ll soon be completing the i8 office campus in Munich.

As a practice, how do you introduce sustainability into projects?

The process of getting sustainability into the early stages can be quite technical, and that's typically something architects find difficult to cope with, especially Danish architects, who traditionally have a strong focus on the artistic side of things. Our approach has generally been to use computational design with parametric tools with Rhino and Grasshopper, making tools for daylighting, microclimate, LCA [Life Cycle Assessment] and so on, which we use in competition entries. Then, when we win, we can go on to the project design, where we’ve developed Revit plugins for LCA, so we can continue into the BIM world.

Does using timber as a structural material change the initial criteria for parametric design?

Yes, it has effects on things like structural grids, going from, say 8-9m for a concrete school, to 6-7m, which creates quite a few challenges in relation to the size of elements, floor spans, and so on. As a result, there are some different elements in the equation – you can't do everything just like you used to. We've done some competitions on which we’ve basically run parallel timber and concrete projects to see how far we get.

And in terms of financial outlay, do timber and concrete usually end up roughly the same?

I think timber generally costs a bit more at present, but that's mainly because contractors don't have the experience to deal with it, so there's a larger risk premium in everything that puts the prices up. But if you're looking at prefabricated timber modular housing, that's often cheaper because it’s very standardised – you know what you're getting. And we are doing two projects in Stockholm at present where we're building a timber structure on top of concrete buildings from the 1940s and 1950s – that gives you additional storeys effectively and affordably as the timber weighs a lot less.

Do you feel confident that in, say, ten years, there'll be enough professional expertise around?

I’d say that a lot more people are getting comfortable using timber. If we look over the period from 2018 or 2019 to today, all the large Danish architects. contractors and engineers have done one or two large timber buildings, so everybody is starting to get some experiences to draw on.

It sounds as if there are some parallels with the British situation, importing knowledge and timber from elsewhere – generally Scandinavia.

Well, all the timber is coming from Scandinavia or central Europe. But we're also running out of gravel for concrete anyway – the latest we've heard is there are plans to start knocking down mountains in Norway and then sail it to Denmark. So it’s OK to import the timber from Austria or Sweden.

When you started, did you realise that timber would become so key in sustainable construction? Has it drawn the focus away from other areas?

As soon as you get into the LCA business, it’s pretty obvious the timber is much better than concrete – and I think that was clear 20 or 30 years ago, it doesn't take much calculation. When we do an LCA now, we generally use a step model, looking at things that have the biggest impact first. And the first step is to go from concrete to timber. Then there's looking at structural optimisation, then some things about using EPDs (environmental product declarations) on materials. There are also certain strategies around circularity. But we start with issues that have larger impacts.

Has government regulation been helpful?

In the new Danish regulations, the LCA is 12kg of CO₂/m² per year, over 50 years, and lot of clients – public and private – want to do better than that, so it's been a huge boost. You can see throughout the industry, there are architects specialising in these areas, and engineers specialising in calculating timber constructions. Suppliers of building materials have all got EPDs on their products, which wasn't the case five years ago. And contractors are getting a lot better at collecting documentation and running building sites to minimise waste and energy. Throughout the industry, everybody's having to respond in some way or other.

Are the regulations across Scandinavia and Germany aligned?

The regulations in the Nordic countries are quite, though not totally, similar. In Germany, all building regulations are done at state level – Baden-Württemberg, Bavaria and so on – not at federal level, so there are 16 different sets, which can cause problems as projects in Munich are covered by very different rules to those in Berlin.

A lot of the clients you've mentioned are public – do they tend to be early adopters?

I would say that in in Denmark most are public sector, but on our German projects we've got quite a few in the private sector. Sweden is 50/50. In Norway, it's mostly public – it’s quite a mix.

Where does housing fit in, compared to other typologies?

Most multi-storey housing is speculative, so there's quite a high risk in doing a timber building, which developers are rarely willing to take. And the market in Scandinavia and Germany is quiet at the moment anyway, so if there is housing, it’s just going to be normal. Office buildings tend to be easier, whether public or private – the client already wants a building, and they're willing to take the risk and pay for it. It's the same with schools. We have quite a few schools and sixth-form colleges keen to do something different and interesting – they're typically public or half-public clients and are willing to take the risk because timber is something they actively want. Timber’s association with wellbeing – in contrast to concrete – is high up their agendas too. Then there's the relationship to learning itself, using the building as a teaching tool about sustainability and the environment, which also carries weight. So we have quite a few schools on our books – we’re currently working on the OSW School in Kassel and the New Harstad High School in northern Norway.

There is currently quite a bit of attention around recycled timber as a step towards net positive – that feels a bit difficult to imagine in the context of high rises.

Yes, I'm pretty sceptical about reusing structural components; certainly from the Scandinavian point of view it’s difficult to find a contractor or client willing to take the risk – there's a lot of it in the process, and they're not willing to expend money because of the legal responsibilities. In contrast, there’s a growing market for recycled components like internal and external cladding.

And what about making buildings deconstructible?

I think design for disassembly is a way off. We tend to say, if you do a timber building, all the joints are mechanical, so it can be easily dismantled in the future, but it's obviously best to make a building that lasts 150 years rather than 50 years.

C.F. Møller closed its London studio in 2022 after 20 years. Can you imagine re-entering the UK market?

The fact that we left, I think, speaks for itself. We’ve just completed our final UK project – the Springfield University Hospital in southern London. It’s difficult for UK practices to work in the EU too. How do you deal with regulations and qualifications when you can't transfer them from the EU to the UK and back again? That's what one of the things Keir Starmer certainly needs to look at – whether we can get professional qualifications aligned again.