Page 103 - New Trends in Green Construction

NUMERICAL SIMULATION OF THE PERFORMANCE OF GLAZING SYSTEMS WITH SOLAR CONTROL WINDOW FILMS
Henriqueta Teixeira, Júlia Pereira, Maria da Glória Gomes, António Moret Rodrigues
Keywords: Solar control window film, Numerical simulation, Energy consumption, Thermal and optical performance,
1. Introduction
The rapid rise of the world’s population and its lifestyle quality have led to a global increase in energy needs. Today’s energy systems are dominated by fossil fuels which are responsible for the emission of greenhouse gases, primarily CO2, acting as drivers of global climate change. Therefore, a transition to a more efficient use of energy is needed. Globally, in 2015, the building sector consumed 30% of the final energy. Buildings with large window areas tend to have more heat transferred between the interior and exterior through the glazing systems, causing an increase on the cooling and heating loads. Applying solar control window films (SCWF) on existing glazing systems can reduce the heat gain, the annual energy consumption and peak demand load (Yin, Xu, & Shen, 2012). In the present study, an evaluation of the thermal, optical and energy performance of different types of SCWF applied on the glazing system of a non-residential building, in Lisbon, is made. The evaluated results were obtained from EnergyPlus building energy simulations, calibrated with experimental results.
2. Materials and methods
Three adjacent offices located in the first floor of the Mecânica III building (Figure 1Figure 1) of Instituto Superior Técnico, in Lisbon, were used as case study: with an exterior film (RHE20SIERHPR), one with an interior film (R35SISRHPR) and another without SCWF. An experimental campaign was conducted in the offices during heating and cooling seasons (Lourenço, 2016). Before building the EnergyPlus simulation model, the window software Optics6 and Window 7.6 were used to estimate the thermal and optical properties of the glazing system without and with the SCWFs (a list including the two films used during the experimental campaign and 10 new ones with different properties). With SketchUp, a 3D model of the offices was generated (Figure 2Figure 2). The outputs obtained from the abovementioned programs were used as input parameters in the EnergyPlus simulation model and the typical meteorological year climate data of Lisbon was associated. The EnergyPlus model was first calibrated using the experimental data from Lourenço (2016) and then used to perform the simulation of the remaining glazing systems.
3. Results and conclusions
Due to SCWF RHE20SIERHPR’s low visible transmittance (𝜏𝑣=16%) and low solar heat gain coefficient (𝑔=0.2), a comfortable temperature range (18o-25oC) was achieved during 41% of working hours, when installed on the glazing system. Considering the same film, in 43% of working hours the glare comfortable zone (DGI of 18-22) is achieved. From the considered SCWFs, the one referred to above has the highest thermal and optical performance. Comparing
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