Adaptive Weather Resistant Barrier for Building Envelopes to Control Moisture Ingression and Increase Energy Efficiency

Excessive moisture transport into building enclosures can lead to increased energy use as well as mold growth and structural rot when moisture condenses in wall cavities. Currently, architects and builders must use passive membrane products as weather resistant barriers which exhibit a single permeability irrespective of environmental conditions. Membranes with a single high permeability may allow too much moisture ingression under hot and humid ambient conditions, while membranes with a single low permeability may not allow the building cavity to dry out when condensate accumulates. This project will demonstrate an electrostatically actuated, adaptive membrane for use as a weather resistant barrier. When temperature and relative humidity in the external environment is high as detected by sensors, the membrane exhibits low permeability to inhibit water vapor ingression into the building enclosure; but when humidity in the wall cavity is high, again detected by sensors, the membrane exhibits high permeability to allow water vapor egression to the outside. The membrane changes state by electrostatic actuation using a very low current electrical power supply. EA Membranes’ electrostatically actuated membrane systems have been demonstrated previously in small scale applications including protective apparel for the military. Phase 1 of this project will demonstrate the technology at the scale needed for weather resistant barriers. In particular, 4’ X 8’ prototypes will be fabricated and the power supply needed to safely actuate them in this application will be developed. The prototypes and power supply will be functionally tested. An acceptable installation method will also be identified consistent with building industry methods. In addition, mathematical modeling will be completed using state-of-the-art hygrothermal modeling software to validate the utility of adaptive weather resistant barriers and to quantify the low and high permeability states needed for optimum results from the system in various climates.