A mathematical framework for optimized building refurbishment

Silvia Dematté, Angelo Messina

A building is far more than the sum of its parts: it’s a global system of products and processes, that has to be optimized with a holistic approach in order to increase efficiency and to reduce overall costs. There isn’t just one single optimal solution, but it’s a give-and-take:  none of the objectives can be improved without impairment in some of the others.
A «smart» design approach is required for the achievement of the most efficient exploitation of financial resources. However, there is still a lack of tools to support the consideration and comparison of different design alternatives, so significant time is often spent evaluating only a few points in the design space. Leading to the fact that the task of a human expert is to design something which is “good enough” in relation to the effort.
In order to be approached with an effective and efficient method, the problem has to be translated into a mathematical framework. In this way it is possible to automatically evaluate numerous solutions, and to benefit of the Pareto frontier method, to rapidly compare and optimize numerous design concepts in a multi-objective and multi-variable design space.
Four years ago, this was the context which led, EnginSoft (Italy) to start a two-year research project, BENIMPACT, co-founded by ERDF, with the aim to promote integrated design Computer-Aided Engineering (CAE) and intelligent Digital Prototyping (iDP) in the housing field. The aim was to help designers in checking the quality of their solutions and in quickly finding the “optimal” set of choices between different design alternatives using specific algorithms. Results were methods and a prototype of a software platform: BENIMPACT Suite (Building’s ENvironmental IMPACT evaluator & optimizer): a verticalization of modeFRONTIER which o analyses and optimizes the whole life cycle of a building, or some of its components, from different aspects (Energy, indoor Comfort, Life Cycle Assessment - LCA, Cost).
This paper presents how integrated design praxis and optimization procedures can be applied on building refurbishment in order to obtain good energy efficient solutions at a reasonable pay-back time. A real case-study is provided in order to illustrate the methodology.
The workflow is broken down in the following phases:

  • Data collection: actual characteristics and current energy consumption of the building
  • Identification of the objectives for the redevelopment and the solutions to achieve them
  • Simulations
  • Optimization of the proposed solutions in terms of costs/benefits
  • Proposal of efficient solution to the customer for a more conscious decision making
  • Executive design
  • Construction
  • Monitoring
  • Eventual post-optimization

The added value of this approach is that simulation techniques can strengthen the collaboration in the design team at all stages of the project, which is the key factor to reach the target in an efficient way and to be able to guarantee the performance of the final product.
Indeed they allow for an almost instant analysis and comparison  of the proposed solutions, so that they can be gradually investigated and improved.