HOUSING IN WOOD – A CO2 NEGATIVE BUILDING
The construction sector is one of the most important elements of the economy when it comes to managing society’s resources. It is responsible for 40% of society’s total energy consumption, 35% of its raw materials and produces 30% of all waste. If our aim is to have a carbon neutral society within the near future, the construction industry will need to be a very important participant in our attempt to achieve this goal.
Over a period of 50 years, building materials alone have contributed up to half of the total CO2 emissions and so there is an enormous potential to bring down this figure by making changes to our material use in the construction sector.
As architects we believe that it is vital that we are always looking to bring new techniques and technologies to how we can construct climate friendly housing to achieve the CO2 neutral society of the future. Therefore, we have designed an experimental residential building based on a typical building block – a type of housing which is currently being built in large quantities across all Danish cities.
This experiment takes its starting point by replacing the traditional heavy construction elements of concrete and brick and replaces them with timber elements, forming the structure of 10000 m2 of residential housing.
The result of this experimental approach, replacing concrete and brick with Cross Laminated Timber (CLT) elements, results in a reduction of CO2 emissions of 2762 tonnes relative to a traditional building method, corresponding to the equivalent carbon emissions from the power consumption of 100 households over a 22-year period. The building has an overall negative carbon footprint, absorbing over 1600 tonnes of CO2 in its materials.
Why build with wooden elements?
Timber is one of the few truly renewable building materials that we have and is therefore evidently an important solution in accommodating the challenges of energy consumption and waste management. Cross Laminated Timber is sustainable, easy to manufacture and to transport. Timber is renewable and CO2 neutral. All of these positive aspects make wood the obvious choice as a material to construct the enormous quantity of residential buildings that Denmark requires.
Over the next decade the entire building industry is facing a revolution due to increasing capabilities of robotic technology and digital 3D production. This will further expand the range of new possibilities for timber construction as the building material for the future’s mass produced residential buildings.
The benefits of constructing in wood are seemly endless, and include:
- A fast construction time. Unlike when building with concrete and brick, there is no need to allow the construction elements to dry before beginning the next level of the building. There is also no need to dry out the final shell of the building before beginning on the internal fittings. They entire construction process can be drastically streamlined and made more efficient.
- There is a reduction in the need for construction material transport: a truck can deliver up to 10 CLT elements in one load, as opposed to typically only two concrete elements.
- A cleaner and more efficient construction site – fixtures and fittings can be embedded without the need for noisy and dust producing concrete drilling. Direct assembly of components can take place quickly with screw fixtures.
- Greater precision: offsite manufacture of CLT components can ensure that tolerances are in millimetres, and can work well with accurate steel details, such as elevator fittings.
- Simple construction techniques and tools – In principle the structure is constructed from CLT elements, angle brackets and screws.
- CLT elements are very sustainable as a renewable resource. It can be easily disassembled and recycled, or it can be incinerated and used to produce CO2 neutral energy
- Timber creates a positive indoor climate
- Allows for a greater flexibility in space adaptability, apartments can be joined together, or extended easily