Thompson R.H.,SmithGroup Inc.
ASHRAE Journal | Year: 2011
The Mesa Community College (MCC) Physical Sciences Building, Arizona, is a live example of how technology can be combined with architecture to create functional spaces. The building's orientation minimizes the east and west exposures, and takes advantage of the daylighting available from the north and south. A variable air volume laboratory exhaust system allows the building to exhaust only the quantity of air required to maintain indoor air quality, and uses bypass outside air to provide dilution and maintain stack velocity. The building air-handling units are capable of 100% outside air economizer operation, and use variable speed drives for energy efficient operation. High efficiency lighting is provided throughout the facilities. Occupancy sensors regulate lighting, and relay information to the BMS via a secondary contact at the occupancy sensor. This building complies with ASHRAE Standard 55-2004 for thermal comfort.
Dunlap A.A.,SmithGroup Inc. |
Johnson P.G.,SmithGroup Inc. |
Songer C.A.,SmithGroup Inc.
Journal of Testing and Evaluation | Year: 2011
Special building occupancies, those with a high interior relative humidity, have a specific set of performance requirements to control condensation for exterior window and curtain wall systems. High levels of humidity, if not properly accommodated by glazed exterior wall systems, can result in condensation on and within glazing systems and adjacent construction. The performance of glazing has typically been viewed and analyzed based on overall system performance that generally results in a set of values that do not apply to project specific applications. With this approach, important aspects of a system, as applied to specific buildings, are often overlooked. In this circumstance, the result too often is unacceptable levels of condensation. Unfortunately, many within the design, manufacture, and construction communities do not fully understand the importance of treating each building for the unique set of conditions that it is, and the resultant consequence of not analyzing and treating each humidified building as a unique set of materials, systems, and environmental conditions. Similarly, the analysis methods and tools necessary to predict and prevent condensation are even less familiar within the design and construction industry. As a result, deficient systems and materials may often be installed in these applications, resulting in failures ranging from minor inconvenience to complete loss of service. There are, however, methods that can be used to reduce or eliminate such problems. This paper describes methods and procedures that can be utilized to understand and identify the performance levels required for high humidity spaces and analysis methods (including computer modeling) to predict performance of systems and materials, and this paper also describes both active and passive technologies that have been successful in meeting these needs. Passive design, through the use of high performance glazing, and active technologies, such as heat tracing and heated glass, are considered. Benefits, risks, and appropriate uses of each are identified. Examples are included to illustrate these approaches. Copyright © 2011 by ASTM International.