A Multidimensional Optimization Approach to Refurbishment Design on a Multi-Building Scale


European countries face a large challenge in retrofitting their aging building stock, which they need to embark on, in order to reach European Union (EU) energy and emission reduction targets. Despite significant policy interventions, refurbishment rates remain low and the refurbishments that are carried out often do not meet the energy savings targeted by the EU, for example nearly Zero-Energy Building standards (nZEB). One of the key reasons for the lower than expected energy savings is that current refurbishment approaches tend to focus predominantly on energy efficiency improvements for individual buildings. The integrated energy systems perspective that can be leveraged at a multi-building scale – and is related to possible interactions between building sizes, scales, and the different systems – is not taken into consideration in most refurbishment concepts. The result are suboptimal renovation solutions which do not reach the full energy demand reduction potential of the refurbished building(s).This paper introduces a methodology for a tool that aims to develop economically and environmentally optimal nZEB refurbishment concepts for multi-building scale refurbishment actions. Increasing the scale of a refurbishment from a single building to a multiple building, or even a building portfolio, will allow to generate economies of scale (both for solution and workforce cost) and facilitate the integration of renewable energy generation. The tool applies the Lifecycle Assessment (LCA) and Lifecycle Cost Assessment (LCC) methods, which makes it possible to optimize refurbishment concepts, both with respect to economic and environmental criteria. Thanks to a multidimensional optimization approach, based on an evolutionary algorithm that can automatically find the Pareto-boarder for a given design space, Pareto-optimal refurbishment concepts are generated. Refurbishment options presented this way can help housing companies prioritize refurbishment needs and actions in their building portfolios, as well as evaluate and select between different refurbishment approaches in line with overarching targets.

Proceedings of World Sustainable Built Environment Conference 2017
Claudio Nägeli
Co-Founder - Sinom

I have long experience in energy and building related fields from a technical, economic, environmental and system level through my work as an energy consultant and researcher. Through my background I have gained broad knowledge in the field of energy in buildings as well as statistics, data analysis and visualization. I am interested in using data and models to speed up the energy transformation in the built environment.

York Ostermeyer
Chief Strategy Officer and Co-Founder at ChillServices
Holger Wallbaum
Holger Wallbaum
Full Professor, Vice-Head of Department and Vice-Dean for Research

Holger is a Full Professor in sustainable building at the Division of Building Technology, research group Sustainable Building, and in the Area of advance Building Futures. Holger works within sustainable building on concepts, tools and strategies to enhance the sustainability performance of construction materials, building products, buildings as well as entire cities.