ASHRAE Journal- September 2008

Lab Unit System With Heat Recovery Units Temperature Bin 102 97 92 87 82 77 72 67 62 57 52 47 42 37 32 27 22 17 12 7 2 –3 Heat Recovery Temperature (°F) 88.3 85.0 82.6 80.5 78.7 77.0 72.0 67.0 62.0 57.0 52.0 51.0 50.8 49.7 48.0 45.9 42.5 39.1 35.7 32.3 28.9 25.5 Total Gallons Per Year: 879,336.8 Enthalpy Btu/lb Air + Moisture 33.01 34.39 35.07 34.01 33.09 33.10 31.50 27.76 24.40 21.37 OA HR 0.01125 0.01223 0.01378 0.01322 0.01265 0.01307 0.01293 0.01083 0.00921 0.00921 13 136 487 423 311 276 255 243 249 228 166 79 33 13 7 1 1 Time of Day 01 – 08 09 – 16 1 17 103 254 370 353 301 262 248 234 213 200 158 108 57 23 8 3 2 3 32 113 229 350 413 301 286 263 241 222 201 135 80 32 10 7 17 – 24 Supply HR 0.00921 0.00921 0.00921 0.00921 0.00921 0.00921 0.00921 0.00921 0.00921 0.00921 Gallons 132.1 3,917.3 39,970.5 95,286.9 136,596.5 210,192.3 289,942.0 103,299.2 0.0 Table 1: Condensate recovery (Emory Winship Cancer Institute 3/19/2004). This can be achieved via three methods: reducing the actual cooling load, using nonoutside air sources, and creative air distribution. Reducing the actual cooling load in the laboratory is an excellent first step to achieve air-side savings. With smaller loads, a smaller HVAC system may be used, reducing not only energy use but also the capital cost, materials, and energy to install the system. When reducing the actual cooling load, there are some items that are relevant in any building and others that are laboratory facility specific. The general building issues take an added importance in the laboratory due to the hours of operation and the typical use of 100% outside air for supply. Building envelope, especially fenestration and shading, should be carefully considered. Daylighting, using natural light to illuminate a space and reduce electric light use, is a common laboratory feature3 (Photo 1). Reducing the overall illumination levels and using task lighting at work surfaces can also reduce the actual cooling load. With careful architectural design and fenestration selection, heat gain from the envelope and lighting can be reduced. 26 ASHRAE Journal A laboratory specific issue is rightsizing the system. Often laboratory facilities, in the absence of specific criteria, are constructed with a high allowance for user equipment, such as 10 W/ft2 or 15 W/ft2 (108 W/m2 or 161 W/m2). This is done based on historical practice and for flexibility. Research by the Lawrence Berkeley National Laboratory4 suggests that actual equipment loads in laboratories are typically lower, resulting in oversized systems and energy waste. Although designers should meet the user’s criteria and provide the desired flexibility, we should also evaluate what is actually required without undue excess. Variable air volume (VAV) systems should also be used when possible to reduce the laboratory system cooling load by reducing supply airflow to match laboratory space load. While inappropriate for some spaces, such as high containment facilities, VAV is appropriate for many facilities, including those with highly variable cooling loads, low fixed equipment exhaust requirements and low minimum air change rates, and spaces with a high fume hood density.5 ANSI/ASHRAE/IESNA Standard 90.1-2004, Energy Standard for Buildings Except Low-Rise Residential Buildings, Section 6.5.6.1, requires either ashrae.org September 2008 http://ashrae.org

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

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.