Approaches to evaluate sustainability of modular building systems

Abstract

Besides the many well-known economic advantages, such as cost, time and material savings offered by modular design, there are other less considered advantages on a social and environmental level, which have to be addressed. Since modular buildings strongly depend on the chosen system and are based on a repetition of individual modules, their representation and assessment by the traditionally used sustainability indicators only work to a limited extent.

For this reason, a framework for analysing the sustainability, especially of modular buildings, is developed within this work, which does not prescribe a set of rules, what sustainable modular construction is, but serves as a support for context-dependent decision making during the early design stage. The development process is accompanied by a comprehensive literature review, expert interviews and case studies.

The framework is an extension of today's standard sustainability analysis methods, where the early design stage indicators, based on the triple bottom line of sustainability, are supplemented by the so-called system level. The system level examines the specific properties of the modular design and consists of two main categories: The complexity, which deals mainly with the construction of the modular building, and the flexibility, which addresses both the freedom and diversity of the system and the simplicity of changing the structure during the use phase.

Subsequently, the developed indicators from the proposed framework were reviewed based on eight case studies, which were then compared to each other. The comparison revealed no apparent right solution in terms of sustainability, and decisions must always be made according to the context. It requires a balance between different sustainability indicators, as they are often positively or negatively interlinked. Several suggestions were made regarding what should be considered within each phase of the design process while keeping the whole life cycle of the building in mind from the beginning. Since sustainability is a matter of definition, it is necessary to question the common definitions and adapt them constantly.