ASHRAE Journal- September 2008 - 25

Expenditure Dollars (In Billions) institutes compete for the same small group of talented researchers and use new and better facilities to recruit. Given the large number of laboratory facilities that will be constructed in the next decade, it is essential to minimize the energy use of these facilities to reduce operating cost, energy dependence, and greenhouse gas emissions. Water—The Other Resource 350 300 Other 250 200 150 100 50 Private Industry Federal Government Although HVAC energy use is often the 0 primary focus, another important part of sustainability is water conservation. In a sustainable facility, water use is mini- Figure 1: Research spending adjusted to 2006 constant. Courtesy AAAS. mized and water recovery is a priority. Sustainable features such as low-ﬂow plumbing ﬁxtures, dual- make up the cooling tower needs, the domestic water system ﬂush ﬂush valves, extensive circulation of domestic hot water, provides the necessary ﬂow. As an added beneﬁt, the condensate and rainwater recovery for nonpotable reuse are appropriate for is cold, lowering the condenser water temperature and cooling nearly every building type. Some features of laboratory facilities tower fan energy required to reject chiller heat. offer additional water-saving opportunities. Two speciﬁc areas Cooling coil condensate could also be used for irrigation, are process cooling and cooling coil condensate recovery. sometimes in conjunction with rain water capture and reuse. An Many laboratories house equipment such as nuclear magnetic attractive aspect of the condensate ﬂow is that, in humid climates, it resonance spectrometers, environmental room lasers, condens- is available even in a drought when irrigation needs are highest. ing units, and vacuum pumps that require process cooling water. Many locales permit the use of once-through domestic Air-Side Savings water—where domestic water is used and then discharged The most signiﬁcant opportunities for reducing the environinto the sanitary system—for process cooling. This should be mental impact of laboratory facilities are in the air-side design. avoided in new facilities and should be given high priority for Given the number of variables of function, user criteria, climate, upgrade in existing facilities. In lieu of once-through water, a and systems, it is impossible to cover all the features or ways to recirculating process water system using building chilled water design a sustainable laboratory. The design must be customized directly, a blended secondary chilled water loop, a dedicated and tailored for the speciﬁc application. However, with respect process chiller and loop, or condenser water, should be con- to laboratory air-side systems, a sustainable design should focus sidered based on the process water loads and other building on three main goals: infrastructure. Providing domestic water as an alarmed backup 1. Reduce the amount of outside air used to meet cooling and system is a reasonable approach to increase redundancy and ventilation requirements; reliability for sensitive or critical loads. 2. Recover energy from the outside air that must be used; With high quantities of outside air and 24 hours per day and operation, the cooling coils in laboratory facilities can provide 3. Minimize the amount of energy required to distribute air. a signiﬁcant source of water, which can be used for a variety of purposes including irrigation or a nonpotable water supply Reducing Outside Air Used for Cooling and Ventilation for toilet ﬂushing and/or cooling tower makeup. For example, Nothing reduces the long-term energy use and environmental in a recently built laboratory in Atlanta, four 30,000 cfm (14 impact more than reducing the amount of outside air used to 158 L/s), 100% outside air air-handling units were located in a meet the cooling and ventilation requirements. In a typical ofﬁce penthouse. Using weather bin data information and an estimated building, the amount of outside air is dependent primarily on the cooling load proﬁle, the estimated condensate recovery from the ventilation requirements for people. In a typical laboratory facilcooling coils exceeded 800,000 gallons (3 million L) per year, ity, on the other hand, the amount of outside air has three drivers: with a maximum ﬂow of 19 gpm (1.20 L/s) (Table 1). cooling load, exhaust makeup, and industry-expected minimum In this project, the cooling towers were located at a lower air change rate. With each of these drivers, several ways exist to elevation than the air-handling units. The collected condensate attack and optimize the system. Each must be addressed, since the could gravity drain to the cooling tower basin, where a three-way amount of outside air used is dependent on all of these items. valve directed condensate to the tower basin to make up losses from evaporation, drift, and bleed. If condensate production ex- Reducing the Cooling Load Reducing the cooling load that is served with outside air ceeds the cooling tower needs, the excess condensate is directed to the sanitary sewer system. If the condensate is inadequate to should be the highest priority in a sustainable laboratory. 1953 1957 1961 1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 September 2008 ASHRAE Journal 2005 25

ASHRAE Journal- September 2008

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