Wood and the bioclimatic house:
Ancient principles for building houses can be used for achieving healthy bioclimatic homes.
New energy codes for buildings are knocking on our door. With TEK15 in Norway we are forced to build in a tradition that is already outdated, to be able to comply with the demands of more air tight and more energy efficient buildings. This means that the buildings will become more mechanized and it will increase the total emissions.
A house built by todays standards contains many different toxic and environmentally hostile substances, and when demolished the house must be treated as special waste. Waste from the building industry is one of Norways largest pollution problems.
You can find nine different material layers in a single wall. These materials all have different and often undocumented life spans, from 15 to 50 years, and all the layers depend on the others capacity to work.
The material-cocktail leads to an accumulation of degassing indoors because buildings by todays standard have almost no air leakage. Indoor climate must therefore be controlled so that excess humidity and pollution from building materials and other products are ventilated out, and 80 percent of the heat must be recovered in this process. Consequently we have created a need of a mechanical balanced ventilation system.
Moreover this is to be combined with a wish to build as cheap and as fast as possible.
In practice this does not work and much indicates that we are building constructions which will be expensive to maintain in the years to come.
We want energy-economization, but the complexity which follows shortens the life span. In other words not very energy-economic during the course of the life cycle.
This can be done easier, healthier and more solidly.
Wood is the only building block we have which binds more CO2 than what is used in production and trees can do more than binding carbon.
In our old stave churches we see that expertly detailed wooden constructions can last for hundreds of years, however they are not especially energy-economic. We have better solutions.
Engineered timber is wooden products mounted together in different combinations to achieve different properties like strength, rigidity, fire- and water resistance. Examples are glulam and cross laminated timber (CLT).
With these two products we get an excellent building system.
We have the load-bearing construction; the solid skeleton of engineered timber to the interior; the insulating wood fiber insulation; the woolen sweater, to the outside, and a naturally impregnated skin of for instance ore-pine as a protective shell-jacket.
Today we have the tools to make precise calculations about how a wooden wall will behave both through a day cycle and over time. We can build houses with walls which are dynamic and vapor diffusion open, without layers of plastic or synthetic materials.
Walls which "breathe" and that transport off excess humidity equalizes the indoor humidity and prevents mold and rot. In addition wood can be used as a passive heating and cooling battery through the storing of temperature. Storing of temperature, humidity and air pollution on the porous surface of the wood is used to stabilize indoor climate and enables passive climatization with natural ventilation.
If you build with wood all the way through you do not need spackle, caulking and other materials with potentially harmful chemicals which pollute the indoor climate. Then the need to ventilate is reduced which further lessens the energy need.
Constructions in solid wood binds CO2 in the building body and uses the inbuilt principles of nature to achieve both the thermal comfort and indoors climate which we want. We get a healthier indoor climate in a more robust and energy-economic construction, without having to adopt complicated and space consuming technical installations.
Buildings are a part of a life cycle, from cradle to grave. From the tree which grows in the forest to the house which is being demolished to give room for a new. The authorities and the building industry must contribute to the low-emission society with healthier and more solid buildings, in stead of like today, to contribute to the problem.