Impact of Reference Years on the Outcome of Multi-Objective Optimization for Building Energy Refurbishment

Giovanni Pernigotto,Andrea Gasparella,Alessandro Prada,Francesca Cappelletti

doi:10.3390/en10111925

Giovanni Pernigotto, Andrea Gasparella + Show 2 more

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https://doi.org/10.3390/en10111925

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Abstract

There are several methods in the literature for the definition of weather data for building energy simulation and the most popular ones, such as typical meteorological years and European test reference years, are based on Finkelstein–Schafer statistics. However, even starting from the same multi-year weather data series, the developed reference years can present different levels of representativeness, which can affect the simulation outcome. In this work, we investigated to which extent the uncertainty in the determination of typical weather conditions can affect the results of building energy refurbishment when cost-optimal approach is implemented for the selection of energy efficiency measures by means of the NSGA-II genetic algorithm coupled with TRNSYS simulations. Six different reference years were determined for two north Italy climates, Trento and Monza, respectively in the Alpine and in the continental temperate regions. Four types of energy efficiency measures, related to both building envelope and HVAC system, were applied to six existing building typologies. Results showed how the choice of reference year can alter the shape of the Pareto fronts, the number of solutions included and the selection among the alternatives of the energy efficiency measures, for the entire front and, in particular, for energy and economic optima.

Highlights

One of the main goals of building energy simulation (BES) is to characterize the response of the building system to both internal and external dynamic boundary conditions
A preliminary comparison has been performed between the six reference years developed for Trento and for Monza, as shown in Figure 2 for monthly averages of dry bulb temperature, water vapor partial pressure and daily global horizontal solar irradiation calculated for the RYs and the multi-year series
A preliminary comparison has been performed between the six reference years developed for Trento and for Monza, as shown in Figure 2 for monthly averages of dry bulb temperature, water vapor2017, partial pressure and daily global horizontal solar irradiation calculated for the RYs and 9 of the multi-year series

Summary

Introduction

One of the main goals of building energy simulation (BES) is to characterize the response of the building system to both internal and external dynamic boundary conditions. Meaningful transient profiles are often difficult to identify and adopt as inputs. Both occupants’ behavior, on the internal side, and weather solicitation, on the external one, are intrinsically stochastic in nature [1,2]. Provided that BES goal is not to replicate reality but to allow for understanding how a building system works, it is of fundamental importance to specify representative boundary conditions. Their typical time-discretization is hourly but, in some cases, shorter intervals are adopted.

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Conclusion