ASHRAE Journal- September 2008

VAV or heat recovery for 100% outside air systems more than 5,000 cfm (2359 L/s). The designer of a sustainable laboratory should consider using both where appropriate. Another way to reduce the actual cooling load is with laboratory equipment consolidation and placement. Laboratories often are designed as flexible spaces with general criteria rather than specific requirements. The actual users and their research program may not be known during facility design and, even if www.info.hotims.com/19354-62 they are known now, they will change in the future. Rather than designing the entire facility with the flexibility to accommodate heavy heat producing equipment, such as ultralow-temperature freezers or centrifuges, this equipment could be consolidated into a few smaller equipment spaces. These spaces could have high watt density criteria, while general laboratory spaces would use lower watt density criteria, ultimately reducing the overall design load. Locating heat-producing equipment in areas where high supply airflow quantities already are required for exhaust fan makeup or minimum air change requirements makes dual use of the supply air and reduces the need for reheat. Reducing the actual cooling load, when using 100% outside air for cooling, is critical in any sustainable laboratory design. Although reducing the actual cooling load is an important first step, once the load is minimized, another approach to reducing the amount of outside air used for cooling is to use non-air sources to meet as much of the cooling load as possible. For example, with the previously discussed consolidation of laboratory equipment into an equipment room, the resultant space could have a tremendous watt density, perhaps 50 W/ft2 (538 W/m2), and a corresponding high amount of cooling air would be required to serve the space. While the consolidation can provide design load reduction savings over a distributed approach, significant energy use reductions can be made by using a small dedicated recirculating unit to cool most of the sensible load. Some outside air is still supplied to the space for ventilation and minimum air change requirements but the majority of the sensible load is cooled with chilled water, eliminating the penalty of using 100% outside air as a cooling source. Another approach, commonly used in Europe, but now gaining popularity in the U.S., is the chilled beam6 (Figure 2). A chilled beam is a ceiling-mounted induction unit. Primary air from a 100% outside air air-handling unit is ducted to the chilled beams and provides latent and some sensible cooling. Blended secondary chilled water at a slightly elevated temperature is piped to the chilled beams. The movement of the primary air past the beam induces room airflow through the beam where it is cooled by the coil. The result is a sensible cooling capacity September 2008 28 ASHRAE Journal http://www.vaisala.com/HMDW6070 http://www.vaisala.com/humidity http://www.vaisala.com/humidity http://www.info.hotims.com/19354-62

Table of Contents Feed for the Digital Edition of ASHRAE Journal- September 2008

ASHRAE Journal- September 2008 Section: Contents Contents Section: Commentary Options for Sustainability Section: Industry News The Silk Route for Energy Solar Thermal Is Unrealized Opportunity Industry Groups Sue City of Albuquerque Section: Letters Letters Section: Meetings and Shows Meetings and Shows Section: Feature Articles Article-Radiant Floor Cooling Systems Article-HVAC Design for Sustainable Lab Article-Mixed Mode Ventilation Article-Single- Design Considerations For Active Chilled Beams Article-Acoustic Design In Green Buildings Article-Teams, Contracts & BIM Section: Building Sciences Some Old Lessons Distilled Section: Washington Report Energy in Federal Buildings Section: Products HVAC&R Product Showplace Section: Emerging Technologies Toplighting & Lighting Controls For Commercial Buildings Section: Special Products Fans & Blowers Section: Classified Ads Classified Ads Section: Advertising Index Advertising Index

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