Optimised Parametric Model of a Modular Multifunctional Climate Adaptive Facade for Shopping Centers Retrofitting

Abstract

A modular multifunctional façade for the retrofit of shopping malls, capable of adapting to different climates and to the existing building features both by the presence of movable components and by proper sizing of the fixed ones, is under development within the European FP7 project CommONEnergy. In particular, this curtain-wall façade is equipped with a fixed shading system, a photovoltaic panel with a battery feeding the automated openings for natural ventilation. The aim of this work is to define a reliable parametric model for a multi-functional façade system, to support designers with a set of useful data for the holistic design of the façade configuration depending on climate, orientation and building use. Firstly, a reference zone model for the façade was devised; this had to be both representative of reality and smartly defined for simulation software implementation. Besides the definition of the façade model parameters, all unknown design parameters were identified with their minimum and maximum values, depending on different possible applications and environmental conditions in which the façade could be applied. The inputs for the model were defined in a parametric matrix and included: facade module size, façade orientation, climate, window typology (thermal transmittance and g-value), distance between the shading lamellas, tilt angle, and openable window size. The simulation engine was decoupled: visual comfort and artificial lighting use were assessed with Radiance, while the façade thermal behaviour was evaluated by means of building energy simulations in TRNSYS, taking into consideration the daylight assessment results. For each simulated configuration, a set of relevant outputs fields for Indoor Air Quality, thermal and visual comfort, and energy performance were derived. The main considered performance indicators were the long-term percentage of people dissatisfied, the number of hours when CO2 concentration was within the recommended values for each of the categories defined by EN 15251:2007, the illuminance provided by daylight, the energy consumption due to lighting, ventilation, heating and cooling, and the energy generated by the PV panel. Moreover, all outputs were collected in a pre-design support tool comprised of a database accessible through a filtering system to gather the desired performances. This work highlights the role of thermal and daylighting simulation in the design of an adaptive multifunctional façade through the definition of a methodology for the support at the pre-design phase.