NREL scientists have developed a mesoscopic building energy model to compare next-generation building glazing technologies. They have found that PV glazing technologies can be easily integrated into existing double- or triple-glazed substandard windows to significantly reduce building energy use and carbon emissions.
The team created glaze units using three types of PV window technology: a non-wavelength-selective technology using perovskite-based thin-film; a wavelength-selective technology, or so-called transparent PV; and dynamic PV technology, which is a recent innovation combing dynamic glazing technology with PV conversion.
They reportedly translated the nanoscopic glazing unit simulations to large-scale building energy simulations using the EnergyPlus and OpenStudio physics-based building energy simulation tools. They used weather data inputs from the Typical Meteorological Year database to simulate the energy consumption profiles of buildings in terms of heating, cooling, and lighting in 15-minute intervals over the course of a year.
The results showed that “PV glazing with a power conversion efficiency as low as 6% reduces energy use by more than 30%,” according to the researchers. They said increases in efficiency translate into additional energy use reduction. At efficiencies of 12.5%, perovskite thin-film and transparent PV technologies reach 42% energy-use reduction when integrated into double- or triple-glazed windows.
Dynamic PV glazing reaches almost 50% energy savings and “has the highest potential savings amongst PV technologies,” according to the researchers. However, they noted that the technology has only achieved an efficiency of 11% in a lab setting, so it needs further development to reach its full potential.
The results also showed that dynamic PV glazing generates more electricity in hotter months, with more than 1,200 gigajoules (GJ) of generation in June and September, but less than 200 GJ from December to January.
“In contrast, static wavelength-selective PV consistently generates more than 500 GJ each month but never exceeds 1,000 GJ for any single month,” said the researchers, who shared their findings in “Photovoltaic windows cut energy use and CO2 emissions by 40% in highly glazed buildings,” which was recently published in One Earth.
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