The need to minimize and manage the stored electrical energy in the actuated state of an EAM WRB system was identified as critical to producing a safe and robust product. The challenges of implementing the electrical system of an EAM WRB for an entire building envelope were examined. Routes to achieving these improvements were identified and should be readily implemented in future work. Testing at the subscale and prototype scale indicated that additional development is needed to optimize open state permeance and de-actuation of these structures and to insure minimal electrical arcing upon actuation.
Building envelope survey full#
In addition, full scale testing of the permeance of prototypes was completed. Actuation and de-actuation of a prototype was successfully demonstrated. EAM WRB prototypes at a scale relevant to building envelopes (4’ X 8’’) were designed and assembled using a novel fabrication process. Subscale testing of EAM structures demonstrated that permeances in the un-actuated, open state as well as in the actuated, closed state can be achieved which are consistent with the levels specified in hygrothermal modeling of the dual permeance EAM WRB system. Although significant differences in latent heat gains were observed, they were orders of magnitude lower than moisture loads from ventilation and interior loads. The effect of the dual permeance EAM WRB on energy use is small. The preferred permeance level for an EAM WRB in the open state is in the range of 20 to 50 perms. The magnitude of the effect is climate dependent.
conventional single permeance WRB systems.
Building envelope survey software#
Hygrothermal modeling using WUFI® software demonstrated that a dual more » permeance EAM WRB provides reduced water content in the sheathing and reduced mold growth risk vs. EAM technology is capable of 50 to 100X change in permeance between the two states. EAM systems comprise a three component structure which can achieve two significantly different permeance levels on demand: a high permeance level in an open state where moisture transport is facilitated and a low permeance level in a closed state where moisture transport is significantly hindered upon application of an actuating DC voltage. Proof-of-concept demonstration of a Weather Resistant Barrier (WRB) based on Electrostatically Actuated Membrane (EAM) technology was successfully completed in this SBIR Phase 1 program. The paper outlines the need for the analytical approach to moisture control and summarizes the three sessions. The tutorial consists of a Moisture Primer, an Overview of Analysis Methods, and a training session on MOIST, a dynamic model developed by the National Institute for Standards and Technology. Recognizing that practitioners are not generally trained to use available analytical tools, the Building Environment and Thermal Envelop Council (BETEC) has developed a tutorial on moisture analysis for building designers.
These methods can predict condensation, moisture content of layers and surface more » relative humidities dynamic methods also predict the duration of moisture excursions, providing a basis for moisture damage risk assessment. Analytical methods for determining the moisture movement in building envelopes are available. However, cold and warm climates are ill defined, large areas of the United States have warm summers and cold winters, and the rules do not recognize the effects of other materials in the thermal envelope.
Building envelope survey install#
=, number = 5,Īnalytical procedures are routinely used for structural integrity of buildings, but for moisture control, designers still rely on rules of thumb, such as install vapor retarders in cold climates on the inside and in warm climates on the exterior of thermal insulation.
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