Evaluation of PV integrated sliding-rotating overhangs for US apartment buildings

Abstract

The paper evaluates the benefits of integrating PV arrays with sliding and rotating overhangs to both generate electricity and reduce heating and cooling thermal loads for housing units in US apartment buildings. Optimal controls to operate the sliding-rotating overhangs are considered to minimize annual net energy demands with and without the integrated PV arrays. A series of sensitivity analyses is performed to assess the impact of design and operating conditions on the energy performance as well as the environmental impacts of the sliding-rotating overhangs. The analysis results clearly indicate that when integrated with PV modules, sliding overhangs can significantly reduce the energy demand for US housing units especially when they are set at the optimal angles specific to the building location to maximize their electricity generation and solar shading effects. Specifically, it is found that sliding overhangs can not only reduce energy demand but also can achieve net-zero energy conditions for US apartment units with large windows and located in mild climates even when monthly adjustments are applied to operate the shading systems. For instance, 9.2% of the total energy use of an apartment housing unit located in Boulder, CO, can be reduced using the sliding-rotating overhang with no-PV. In San Francisco, CA, more than 100% of the apartment housing unit energy demand can be avoided using PV-integrated sliding-rotating overhangs. To minimize design and operation complexities, it is recommended to consider sliding-only overhangs set at the latitude of the location to reduce both heating and cooling demand as well as increase PV array output. For instance, it is found that sliding overhang set at the latitude angle can be sufficient to achieve net-zero status and even a carbon-neutral operation for an apartment housing unit located in San Francisco, CA, even when adjusted on a monthly basis.