Building façade integrated solar thermal collectors for water heating: simulation model and case studies

This paper presents a dynamic simulation model for the energy and economic performance assessment of a novel building integrated solar collector prototype, for Sanitary Hot Water (SHW) production and space heating. The investigated device is a Flat-Plate Solar Thermal Collector (FPC) with water working fluid, suitably designed to be integrated in the building envelope (Building Integrated Solar Thermal System - BISTS). The developed model was conceived for assessing the active effect of the collector as well as the influence of its building integration on the building thermal behaviour and thermal loads (i.e. overheating). The main differences of the proposed novel collector with the existing technologies consist in the system simplicity and low fabrication cost. The developed simulation model, written in MatLab environment, is implemented in a suitable computer code. Such tool is validated by taking into account the data collected through a suitable experimental analysis recently carried out in Limassol (Cyprus). In order to assess the system performances and to show the features of the developed simulation model, several comprehensive case studies were developed. In particular, they refer to the installation of the examined FPC prototype on south facing façades of different buildings, e.g. characterized by diverse uses and envelope weights, and located in several weather zones. For each weather zone and building typology, a suitable parametric analysis, focused on several system design and operating parameters, is carried out. Suitable reference system layouts are also taken into account for comparison purposes (e.g. buildings without and with stand-alone solar collectors). Simulation results show that interesting energy, economic and environmental advantages are always obtained through the adoption of such prototype. The energy performance and the payback periods strongly depend on the simulated weather zone.