Paper Conference

Proceedings of BSA Conference 2022: Fifth Conference of IBPSA-Italy


Energy Performance Evaluation and Economical Analysis by Means of Simulation Activities for a Renovated Building Reaching Different Nzeb Definitions Targets

Riccardo Gazzin, Jennifer Adami, Mattia Dallapiccola, Davide Brandolini, Miren Juaristi Gutierrez, Diego Tamburrini, Paolo Bonato, Martino Gubert, Stefano Avesani

Abstract: The nZEB target is increasingly becoming one of the main objectives in building renovation, but a unique nearlyZero Energy Building definition is not explicitly available in the 31/2010 EU directive, the so-called “Energy performance of buildings directive”. Nevertheless, the technical implementation of the nearly-Zero Energy Building concept into defined constraints and requisites is a determining factor for the consequences of energy-economic performance . In fact, in the renovation process of a building, different technical requirements lead to different design solutions that affect investment and operative costs, as well as energy performance. Through an optimization process based on dynamic simulations for energy and economic performance assessment, a comparison between different approaches for the nZEB building retrofit for a demo-case building has been performed. First, an energy target which is stricter than the nZEB standard is examined. In particular, the so-called “Positive Energy Building” approach, consisting of the design of a building that produces more energy than it consumes in the overall year, is evaluated. Then, the results of the Positive Energy Building target are compared to a nearly-Zero Energy Building approach in which self-sufficiency is promoted, instead of the energy production/consumption balance. Also, the nearly-Zero Energy Building target promoted by the Italian legislation has been evaluated, comparing the result of a plausible implementation with the other more stringent approaches. The simulation work has been aimed at comparing significant Key Performance Indexes, regarding both energetical and economical aspects. In particular, initial investment costs, expected net present value of the investment after 25 years and energy performance indexes have been evaluated. The discussion demonstrates that, according to the assumptions adopted for the investment and energy costs, the Positive Energy Building target is excessively economically inconvenient for a renovation intervention of this type. Moreover, designers should prioritize the self-sufficiency of the building energy system with respect to the production/consumption yearly ratio. Finally, the discussion demonstrates that a renovation design in accordance with the Italian nearly-Zero Energy Building target is economically sustainable but the PV system size to meet the minimum requirements could be non-optimal.
Pages: 367 - 375