LCA in Early Design Phases

What was the design process?

We designed the house using LCA in two steps:

First, we looked at criteria for low climate impact in the program and sketch phase. How can we optimize material use and lifespan? Which parameters have the biggest impact on lowering climate impact?

Next, we studied the impact of different materials, their quantities, and their lifespan. We used One Click LCA to compare constructions for the building foundation, frame, and envelope.

An important starting point for the study was to question the concept of building area as a neutral functional unit when analyzing climate impact – i.e., simply measuring a building’s performance in kg C2Oe/m2 building area. Disregarding the actual size of the building may even be contradictory to the purpose of minimizing climate impact. Basically, a 40 % smaller building reduces the climate impact by 40 % before we even start adjusting and fine-tuning construction and material selection. In addition to optimizing the numbers per m2, we therefore need to consider the impact of housing area itself.

In addition to designing a long-life, flexible, and adaptable house, our main challenge was to design a house which also uses a significantly smaller amount of building material. Our analysis led us to aim for a smaller house which would retain the qualities of usability, flexibility, adaptability, daylight, and space normally associated with larger houses. Despite its size, the house should be able to adapt to the changing needs of its inhabitants over time, without the need for rebuilding.

How did One Click LCA help you achieve your goals?

We also looked more closely at life expectancy, where we found One Click to be a highly useful tool, since lifespan is easy to adjust both for materials and for the building for itself. If you have a good idea of ​​the lifespan of building components, One Click is easy to work with. Our calculations show that using high quality materials, with a long service life, pays off even more than we expected, both for reducing climate impact and for the long-term economy of the building.

The strength of life cycle analysis is its high level of detail. However, in early design phases we often need to be able to try out different solutions without having to model construction methods and material in detail. To be useful as a tool in early design phases, LCA needs to be a fast tool that keeps pace with the sketching and the testing of a variety of ideas and solutions. If the tool is too time consuming, there is a risk that it will only be used for evaluation in the late stages.

To find a way forward, we tested a number of different paths. After having tried several different ways of finding a good balance between level of detail, speed and accuracy, we settled with a method where we transfer simple and approximate areas manually from our BIM-modelling tool, Revit, and use ready-made construction types in One Click LCA with smaller adaptions to evaluate different designs. In the future, as the range of nationally adapted construction models grows, this method will be even more useful.