Laboratories: Solving the Challenge of Water
- By Gerald Williams
- April 1st, 2013
Increasing demands for high-performance and sustainable designs are challenging laboratories and research facilities to consider their energy and water usage. Laboratory design is constantly evolving and outdating previous methods due to new building and energy codes, and lab designers are seeking game-changing ideas. This makes innovative design solutions more imperative than ever.
This imperative requires, among other things, a shift in thinking from merely air conditioning buildings to developing integrated strategies to heat and cool the people, equipment, and processes within the building. Instead of simply pumping hot or cold air into a box, a new approach is required where mechanical systems are designed to meet specific needs of the individual research facility and then dynamically respond to the rapid evolution of those facilities. The building itself can serve as an extension of the education or research instead of an obstacle to that research.
A robust building utility spine that includes “plug-and-play” connections for an abundance of power, communications, exhaust air, and process-cooling water allows new equipment installations without extensive disruptions or costs. Laboratories can recognize additional significant cost savings as well as improved sustainability by utilizing existing chilled water systems with newly developed, innovative technology, such as a water-to-water heat exchanger.
Water Is the Next Challenge
Water usage is taking over at the forefront of designer considerations in laboratories. New water use regulations for federal agencies that mandate 26 percent reduction in potable water by 2020 relative to a 2007 baseline are already in place (Presidential Executive Order 13514). This puts great stress on laboratories that are dependent on water for cooling and other processes but now must conserve. Executive Order 13514 mandates reducing federal agency industrial, landscaping, and agricultural water consumption 2 percent annually or 20 percent by the end of fiscal year 2020, relative to a 2010 baseline.
States like California have legislation that sets an overall goal of reducing per capita urban water use by 20 percent by Dec. 31, 2020. Starting in 2016, failure to reduce water consumption by at least 10 percent could result in the loss of eligibility for state water grants or loans for urban retail water suppliers. All of these regulations are working to resolve the fact that literally millions of gallons a year of potable or conditioned water are being wasted. This is particularly true in research facilities.
With the plug-and-play utility spine, lasers, mass spectrometers, thermal analyzers, specimen freezers, spot coolers, and even ice makers can be installed wherever and whenever needed without being required to purchase additional unitary chillers to cool the equipment. These unitary chillers can often use up to 10 times the amount of electricity to generate cool water than a central building chiller system and often reject large amounts of heat back into the lab, forcing the building HVAC system to work even harder to remove the heat. Some unitary chillers and analytical equipment still use tap water to cool their equipment and then dump that water down the drain. According to the EPA, a single device using this process, known as single-pass cooling, can waste more than 700,000 gal. of fresh water every year.
Using a water-to-water heat exchanging system that can provide cool water to the equipment or process at the appropriate temperature, pressure, and flow rate can eliminate single-pass cooling using tap water. A system like this isolates laboratory equipment from the building’s chilled water loop, with a secondary closed loop of cool water, and then uses the main building chilled-water loop to reject the heat outdoors. The equipment heat is then removed from the lab space using the building’s process cool-water loop. This type of heat exchanging system protects the equipment from potential problematic characteristics of the cool-water loop that may operate at pressures, temperatures or water quality that is not optimal or appropriate for the lab equipment. Advantage is also taken of the cool-water loop’s positive characteristics including high efficiency, low maintenance, low first cost, and redundancy.
California Institute of Technology: Revolutionizing Laboratory Cooling
The California Institute of Technology (Caltech) has taken a revolutionary approach to cooling buildings using captured rainwater for its newly renovated Linde + Robinson Environmental Science Laboratory building. This high-tech laboratory building is capturing water from rain and air-handling unit condensation and storing the water in an underground tank. Then, at night, when the outside air temperature is cool, the building pumps the captured rainwater throughout a cooling tower that uses natural evaporative cooling to reduce the water temperature to below 60°F. During the day, this evaporative cooled rainwater is pumped throughout the building to fan coil units to provide sensible air conditioning for the building and equipment for much of the year, without running compressors or traditional chillers.
Although Caltech found this was an efficient way to reduce HVAC costs, it discovered that a large percentage of the building’s electrical use now went to provide energy for “plug loads,” or electricity for equipment that is plugged in and used after the building is constructed. Research equipment that produced large amounts of heat needed to be cooled, sometimes constantly, for the equipment to perform. The traditional method of providing this cooling was to purchase small, unitary air-cooled chillers that produced cool water and rejected the heat to rooms they were in. These mini-chillers often have poor energy efficiency as compared to central cooling systems and can take up a large amount of valuable lab space.
Instead of using mini-chillers, Caltech found a better solution in extensive use of a water-to-water heat exchange cooling system. Ten heat exchanger units have been installed specifically designed to provide cooling for lab equipment with high plug loads using the evaporative cooled water system. An independent engineering firm’s study revealed the lab would experience 87 percent reduction in energy use for equipment cooling using the combination of heat exchangers and evaporative cooled water as compared to traditional unitary process chillers.
Working in collaboration with scientists at Caltech and the building design engineers at Rumsey Engineering, Cannon Design Products Group developed awater-to-water heat exchanging interface system that allowed the scientific equipment to be cooled indirectly by the highly efficient and evaporative cooled central cooling loop. By isolating the precision equipment with a system of plate and frame heat exchangers, pumps, and PLC controls, the system supplies a constant supply of water at precisely 60°F (+/-0.1 degree), at the proper pressure, water quality, and flow rate that research equipment requires for peak performance. The system also uses the evaporative cooling loop as a heat sink to cool down the lab water, while always keeping the two water streams separate, protecting the equipment’s internal components from damage and eliminating the risk of flooding the lab if a hose leaks.
Gerry Williams, PE, LEED-AP, is a vice president at Cannon Design and leads its Products Design Group. He is also an adjunct professor at the Missouri University of Science and Technology where he teaches graduate courses on Environmental Systems Design and Control. He may be contacted at email@example.com.