Guiding Early Building Design with Streamlined Life Cycle Assessment

Importance Life Cycle Assessment (LCA) is a method that building practitioners can use to analyze the environmental performance of a proposed building design. However, surveys of building practitioners have shown that LCA... [ view full abstract ]

Importance

Life Cycle Assessment (LCA) is a method that building practitioners can use to analyze the environmental performance of a proposed building design. However, surveys of building practitioners have shown that LCA tools are not widely used to guide design development because the analyses are time-consuming, require burdensome data collection, and are poorly integrated with the design process[1]. Since building designs become more difficult and expensive to alter as they are developed, LCAs would be more successful in reducing the impacts of the built environment if they could be done earlier in the design process when much of the design is still uncertain.

Methods and originality

The Building Attribute to Impact Algorithm (BAIA) is a probabilistic LCA method for buildings that accounts for uncertainty in the early design through parametric models that estimate material, process, and use-phase energy requirements based on a flexible definition of building geometry and materials. Uncertain inputs can be defined either with a range (for numerical inputs) or category (for inputs such as material types, which are under-specified by organizing them into a hierarchy of related options). The corresponding uncertainty in the environmental impacts is then captured through Monte Carlo simulation based on the level of detail provided. Further, sensitivity analyses are used to determine which attribute is contributing most to the variability in predicted impacts to guide further building specification. Using the results from these analyses, the building design can be iteratively refined until sufficient detail has been added to the most influential attributes, leaving the rest defined more generally. By prioritizing design development in this way, building practitioners can know which components of the building require detailed data for a reasonably precise life cycle assessment, saving time in data collection and facilitating early-design analysis.

Results

In this presentation, we introduce a new application of BAIA within a simulated design process to better understand how these probabilistic early-design analyses could interact with and influence the development of building designs. BAIA is used to explore different design paths, or sequences of decisions moving the design from uncertainty to higher levels of specification. We present preliminary results showing how BAIA can identify different strategies to improve a proposed building design.  

[1] Saunders, C.L., et al., Analyzing the practice of life cycle assessment: Focus on the building sector J. Ind. Ecol. Journal of Industrial Ecology, 2013. 17(5): p. 777-788.