Four Steps To Designing Out Carbon From New Buildings
The climate emergency makes lower carbon construction a priority. Carbon reduction is broader than how much energy a building uses during the operational phase and the sources of that energy. The whole life-cycle is involved, which means that carbon reduction starts with design.
Designing out carbon can be thought of in terms of four steps: defining the goals; choosing the right materials; choosing the right methods; evaluation and continuous improvement.
Defining Goals
Focusing more or less exclusively on operational carbon simplifies the problem, but also misses the point. One of the critical questions when planning the built environment of the future is whether renovating existing buildings is a lower carbon solution than creating new energy-efficient buildings from scratch.
Embodied carbon is the key factor. Many construction materials and processes have high levels of embodied carbon, which is why many cities have decided to prioritise retrofitting existing buildings over creating new ones.
Adopting the whole-life approach to carbon calculations involves understanding the implications of design choices, repair and maintenance needs and what happens at the end of the building’s life.
Choose the Right Materials
The industry is working hard to reduce the embodied carbon levels in concrete and steel. At present, extracting and processing the raw materials needed generates a significant proportion of the world’s carbon emissions.
If concrete was a country it would be the third highest emitter of carbon emissions in the world. Practical carbon reduction measures that can be deployed now include smarter designs that reduce the amount of concrete and steel and increase the structural timber content. Timber stores atmospheric carbon that is absorbed as trees grow, giving the material a net negative level of embodied carbon.
Choose the Right Methods
One major obstacle to carbon reduction has been the performance gap between design specifications and real world energy efficiency. Typical reasons behind the performance gap include inconsistencies in the certified insulation performance of different materials and quality control issues in the traditional construction process. These can lead to high levels of air permeability and thermal bridging losses.
BIM and MMC working together will deliver buildings with a continuous thermal envelope engineered into the fabric. These buildings will need less maintenance effort, which helps to further reduce carbon emissions during the operational phase.
Measure and Improve
By comparing real world performance to the model and capturing the lessons from every project it will be possible to design more carbon out of each new building in more cost-effective ways. A learning culture of open information sharing will go a long way towards accelerating progress in carbon reduction.
For more information about Osborne’s approach to lower carbon construction contact Richard King ([email protected]).
