School of Architecture + Design

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Browsing School of Architecture + Design by Subject "1202 Building"

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    Counteracting high winds with low pressure: Development and testing of a new roof vent system
    Grant, Elizabeth J.; Jones, James R. (College Publishing, 2011-01-01)
    Roof system failures are common during high wind events. In locations subject to high wind conditions, membrane roofing systems must typically be either physically attached or fully adhered to the substrate or ballast may be added to weigh down the membrane. An alternative to these installation approaches could be to use aerodynamics principles such as the Bernoulli and Venturi effects to create a low-pressure region beneath the membrane roof that is lower than the ambient pressure and thus counteracts the uplifting force. A new omnidirectional vent has been designed and tested that takes advantage of these aerodynamics principles to induce low pressure under the membrane layer. This new vent operates with no moving parts and was tested in the high-speed stability wind tunnel at Virginia Tech to wind speeds up to 233 km/h. The results demonstrate that this new vent generates pressures lower than the ambient when subjected to high wind conditions. This paper presents the design principles and performance test results for this new roof vent system and other applications for roof vent technologies.
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    A Decision-Making Framework for Vegetated Roofing System Selection
    Grant, Elizabeth J.; Jones, James R. (2008-04-01)
    Design frequently involves making tradeoffs to obtain the “optimal” solution to a design problem, often using intuition or past experience as a guide. Since vegetated roofing is a relatively complex and comparatively new technology to many practitioners, a rational, explicit method to help organize and rank the tradeoffs made during the design process is needed. This research comprises the creation of a framework diagramming the decision process involved in the selection of vegetated roofing systems. Through literature review, case studies and interviews with experts, the available knowledge is captured and organized to determine the critical parameters affecting design decisions. Six important evaluative categories are identified and parameters within these categories are addressed in the context of a decision support system for green roof designers. A summation of the total importance of the advantages represented by each alternative is used to determine the most feasible green roof system for a particular project. The framework is demonstrated and compared with green roof designers’ decisionmaking processes and conclusions are drawn regarding its effectiveness.