Energy benefits from semi-transparent BIPV window and daylight-dimming systems for IECC code-compliance residential buildings in hot and humid climates

Interest in semi-transparent solar cell window systems, also called building integrated photovoltaic (BIPV) windows, has increased worldwide because the windows generate electricity and also provide natural light transmission. This study evaluates the potential energy benefits of integrating semi-transparent solar cell windows and daylight-dimming systems for a 2009 International Energy Conservation Code (IECC) code-compliant residential building in a hot and humid climate. This study used whole-building energy simulation models, a DOE-2.1e BIPV window module created for this study, and an existing daylight-dimming system module. Based on the simulation results, peak demand, energy use, and electricity production from each orientation (east-, west-, south-, and north-facing) were all analyzed. The south-facing window showed the greatest potential to generate electric power and reduce cooling loads/use, whereas the east-facing window resulted in the largest annual lighting energy savings. As compared to the code-compliant base-case model, the BIPV windows showed great potential for energy savings: about 12-21% in annual energy use, and 14-26% in peak cooling demand. In addition, the parametric study varying the window-to-wall ratio (WWR) with the BIPV window resulted that the larger BIPV window provided more savings in annual total energy use.