If you have ever taken a stroll in a Danish suburb, you will have seen the vast amounts of brick buildings, and in the city centre both brick and concrete structures are prevalent. Wooden buildings are largely non-existent, except for summerhouse areas. When wood has so many appealing properties as a construction material, why is it so under-represented in the Danish building mass?
Maybe the answer can be found in the past. Let’s start with a quick history lesson. In the early days of Denmark wood was widely used in buildings, and as fuel for heating and cooking. But something happened during the 1600s and 1700s that made people reconsider their building practises. The forests in Denmark were being depleted, and measures were made by the crown to reduce the wood dependency of the commoner, after all the wood was necessary to maintain the huge royal fleet to kick Swedish ass (with varying levels of success). There was also the issue that most wood buildings at the time eventually burn down in city fires. Armed with tax exemptions for stone building citizens, the king succeeded in massively reducing the use of wood as a construction material.
So what alternative did people have for making their houses? For those of you that don’t know Denmark, I’ll tell you that the soil in this country consists mainly of clay and sand, and the underground is rich in calcium. The new building materials are a result of “we use what we have”. Bricks and mortar are basically made from sand, clay and calcium, and concrete is made from sand, gravel and cement, which consists largely of calcium. So this is a quite obvious development for the Danish building tradition to take, at least at the time.
And so times goes on, and today people are still building buildings of brick and mortar, and concrete. However, the underlying situation has changed somewhat. We are no longer in war with Sweden, there is no wood consuming fleet to be maintained, and we have this new annoying problem called “climate change” that is causing us to spend tons of money and human resources on reducing our energy consumption, because energy = greenhouse gasses. We still have a country with the materials for concrete and brick buildings, but the production of these materials requires huge amounts of energy. This is because bricks are made by burning clay at around 1000°C, while cement production requires temperatures of 1500°C.
So this is where wood can be used with really great benefits. Trees grow by capturing CO2 from the atmosphere, and while using the wood you effectively store CO2 in your buildings. But for some reason many Danes hold misconceptions about the usability of wood as a construction material. I encountered this when I first got to Denmark to start my studies as a civil engineer. I grew up in Oslo, in a wooden house, and was thus very convinced about the usefulness of wood as a building material. When I talked to my Danish classmates, they claimed that wood buildings required tons of maintenance, that they would rot easily, the houses had a really bad indoor climate and also that they were inferior to concrete buildings when it comes to keeping the house warm.
I was somewhat perplexed by this new information, as I had not encountered or heard of any of those problems. This is also why I name them “misconceptions”, they are simply not true. If we consider the maintenance first, I agree that there might be a bit more required for wooden buildings, but not overwhelmingly so. A wooden building has to be painted every 12-16 years, and maybe washed every once in a while. If using treated wood, the lifetime is around 20-25 years before it needs to be replaced.
Rotting wood is only a problem if the construction is not done properly and water is led into the construction. The problem with fungi in wooden buildings are more often connected to the lack of ventilation inside, in the same way as in brick and concrete buildings.
When it comes to energy, there are pros and cons about wood and concrete/bricks. A wooden construction takes up less space, so there is room for more insulation. Thereby you have a building that loses less heat while allowing more daylight to enter. One argument about heavy buildings, such as concrete and brick buildings, is that the temperatures are maintained at a more stable level (because of thermal mass) compared to wooden buildings. This is true, but there are also disadvantages to this. For instance, a heavy building needs much longer to heat up, so the effect turning off the heat when the building is not in use, for instance in the night, has limited effects.
In the last years many interesting projects for big buildings using wood as a construction material have been made, for instance a 14-storey wooden apartment building in Bergen, Norway. I think people tend to underestimate the possibilities of wood as a construction material. It can even be used instead of steel structures (which, by the way, is a very emission-heavy material) in buildings that require large spans, as exemplified in the ice skating arena of 25 000 m2 in Hamar, Vikingskipet. This building uses wood as the only structural material in the roof, which is also the case in the indoor biking arena Ballerup Superarena in Denmark.
As much as its sustainable quality impresses me, my love for wood as a material is mostly because of its aesthetic value. It has this absolutely luxurious feeling to it. Wooden buildings feel warm and appealing. I’m not saying that all building should be from wood, but there is a great potential for making the building mass in Denmark more diverse, and I would personally love to see more wooden buildings in Denmark in the future.