Window+: Electrostatic levitation enabled Polymer-Air multilayer (EPAM) structures for highly transparent energy efficient windows

Abstract

The poor thermal insulating building windows, especially single-pane windows, are wasting ∼ 7% of the total energy consumed by the U.S. every year. This paper presents an electrostatic levitation enabled polymer-air multilayer (EPAM) structure as a highly transparent and energy efficient window retrofitting solution for low-income single-pane window users. To provide controllable and stable suspension force between large size compliant polymer films without deteriorating their visual transmittance (Vt) in the multilayer polymer/air structure, corona discharge (CD) was used to induce quasi-permanent charges for non-conductive polymer films, leading to controllable and long-lasting surface electric potential difference between two sides of CD charged films. Liquid-solid contact electrification (LS-CE) was combined with CD to realize precise control of the electrical potential of each side of polymer films. CD + CE treated films can obtain programmable and stable electrostatic forces to form resilient EPAM structures for cost and energy effective window retrofitting purpose. The resilient EPAM retrofitted clear windows can provide U-factor lower than 3 W·m−2·K−1, Vt higher than 70%, haze lower than 1.6% at cost lower than $79.7/m2, at least 10 times cheaper than double pane windows. The energy saved by EPAM can reach as much as the order of 106 kJ/m2 per year. The CD + CE surface potential programming solution also provides a highly repeatable and controllable way for other electrical potential related technologies, such as energy harvesting and storage.