Application of Urban Scale Energy Modelling and Multi-Objective Optimization Techniques for Building Energy Renovation at District Scale

Abstract

Nearly-zero energy buildings are now a standard for new constructions. However, the real challenge for a decarbonized society relies in the renovation of the existing building stock, selecting energy efficiency measures considering not only the energy performance but also the economic and sustainability ones. Even if the literature is full of examples coupling building energy simulation with multi-objective optimization for the identification of the best measures, the adoption of such approaches is still limited for district and urban scale simulation, often because of lack of complete data inputs and high computational requirements. In this research, a new methodology is proposed, combining the detailed geometric characterization of urban simulation tools with the simplification provided by “building archetype” modeling, in order to ensure the development of robust models for the multi-objective optimization of retrofit interventions at district scale. Using CitySim as an urban scale energy modeling tool, a residential district built in the 1990s in Bolzano, Italy, was studied. Different sets of renovation measures for the building envelope and three objectives —i.e., energy, economic and sustainability performances, were compared. Despite energy savings from 29 to 46%, energy efficiency measures applied just to the building envelope were found insufficient to meet the carbon neutrality goals without interventions to the system, in particular considering mechanical ventilation with heat recovery. Furthermore, public subsidization has been revealed to be necessary, since none of the proposed measures is able to pay back the initial investment for this case study.

Techno-economic analysis of residential building heating strategies for cost-effective upgrades in European cities

“…Building envelope thermal properties were normalized based on common values found in the literature ( Table 3 ). 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 The normalized envelope system has a value of 0, which indicates that the envelope has the best performance found in literature, with the best thermal insulation for walls, roofs, and fenestrations, 42 while a value of 1 indicates that the building envelope is not well insulated. 43 …”

Environmental Performance of a Cost-Effective Energy Renovation at the Neighbourhood Scale—The Case for Social Housing in Braga, Portugal

“…The calculations generally follow the EU Delegated Regulation methodology [15] and consider 30 years as the life cycle of the building. The methodology uses the global cost method.…”

“…Similar results were also found by another study [14], which showed that this question can constitute a significant barrier for energy renovation implementation at this scale in northern Europe. Other studies approached the problem from the urban scale using multi-objective optimisation techniques and simplified archetypes and found out that for decarbonisation of the building stock, the use of efficient technical systems is crucial [15]. Existing studies also include exploratory approaches to building stocks whose results suggest offsetting a considerable amount (about 65%) of greenhouse gas emissions, taking into account the materials used in the renovation [16] and also that in some contexts, the trade-off between resource efficiency and environmental impacts could be necessary [17].…”