Building design to minimise carbon emissions

March 2020: A novel technique to assemble wooden buildings uses preconfigured sub-units of cross-laminated timber to build 8-12 story high buildings. The technique only emits half the emissions compared to conventional steel and/or reinforced concrete constructions and allows for buildings to absorb carbon post construction.

Information

A new five-story building in Boston will be entirely made out of wood and assembled on site from factory-built sub-units. The wooden net-zero-energy building will be made from cross-laminated timber to reduce GHG emissions in comparison to standard building materials. The technique is competitive with steel and concrete buildings between 8-12 stories. Each sub-unit has a modular design and – similarly to LEGO blocks – preconfigured modules can be assembled in different ways to create a variety of structures of different sizes and for different uses. This novel construction technique may allow for wooden buildings to reduce GHG emissions during construction and increase use of high-rise wooden buildings in urban areas. In addition, wooden structures are naturally well insulated which – alongside glazing and cladding - could reduce residential need for heating and cooling.

Implications and opportunities

The use of preconfigured modules for wooden buildings may allow for these buildings to be scaled in urban areas. In comparison to standard houses and construction sites, the total carbon emissions would be less than half compared to buildings made from conventional steel and/or concrete. The design could be relevant for urban developers exploring designs for future ‘post-carbon’ cities and governments seeking to decarbonise the building sector. In addition, a shift towards wooden buildings would mean that buildings themselves could absorb carbon post construction. Further, it could increase markets for large-scale sustainable forestry and offer new housing opportunities for growing populations.

Limitations

The authors acknowledge that current forestry capacities would be insufficient to supply large-scale construction material for wooden buildings. Such upscaling would require careful upscaling of sustainable forest management capacities and require strict governance. The benefits rely on the timber used being replaced by sufficient numbers of trees to replace the original and to offset emissions from the processing and transport.

Sources

Chandler, D.L., (2020). New approach to sustainable building takes shape in Boston. Retrieved from http://news.mit.edu/2020/mass-timber-sustainable-building-boston-0305

Churkina, G., et. al. (2020). Buildings as a global carbon sink. Nature Sustainability. doi:10.1038/s41893-019-0462-4