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Top 5 Trends in Lab HVAC Design
Today, as science summons researchers away from the study of molecular structures toward an integrated understanding of complex biological systems, laboratory designers have to follow a parallel path. While lab researchers and their stakeholders pursue collaborative discovery of emergent, big-picture phenomena, lab designers and their stakeholders are collaborating on infrastructure designs that enable such research to flourish in cost-effective ways.
At the center of this activity is HVAC design. With these systems consuming 50 percent of a lab’s energy budget, strategies can save precious dollars. Topping the list of design trends are right-sizing systems, energy-efficiency lab and IT equipment, high-performance fume hoods, chilled beams with water-based cooling, and IEQ-based ventilation and lab management strategies.
1. Right-Sizing HVAC Systems
As outlined in the U.S. Environmental Protection Agency’s Labs21 “right-sizing” strategy, the scrutiny of the design team turns to power measurements of actual connected loads in comparable labs with similar sciences, allowing those loads to shape design criteria and help manage the hefty HVAC portion of the project budget.
For example, this process was used in the design of Lawrence Berkeley National Lab’s Molecular Foundry Building, a 94,500-square-foot, interdisciplinary research facility for the nanosciences. By right-sizing laboratory equipment loads, looking at connected loads and future flexibility, the team achieved a 35-percent reduction in the air-handling load, a 30-percent reduction in boiler capacity, and a 35-percent reduction in chiller load, which reduced the electrical substation by 30 percent – with first cost project savings of about $2 million. All this for a 6-story structure housing inorganic chemistry, organic chemistry, biology, and computational theory research labs, with a nanofabrication clean room and an electron microscopy suite.
2. Energy-Efficient Lab and IT Equipment
Lab equipment consumes about one-seventh of a lab’s energy bill, and virtually all that energy input dissipates as heat that must be removed by the HVAC system. Consequently, every savings in equipment consumption doubles as HVAC system savings.
To this end, the EPA, working with Lawrence Berkeley National Lab, is developing an ENERGY STAR program specifically for lab equipment, recognizing its unique operating conditions and constraints. Currently, energy-intensive lab refrigerators and freezers are the first areas being addressed. Meanwhile, on a smaller scale, some ENERGY STAR-compliant lab products are already available.
A related strategy favors water-cooled lab equipment over air-cooled, since the latter increases the size of air systems operating on 100-percent outside air, with or without heat recovery. Ideally, the water system is cooling tower based vs. chilled water based to avoid the work of compression in a refrigeration cycle. SmithGroup is currently pursuing this strategy for year-round cooling of data servers.
3. High-Performance Fume Hoods
If a lab’s exhaust hood flow rate exceeds its need for cooling air, the building will spend more for reheat, outside air conditioning, and fan energy, as well as installed ductwork. As such, high-performance fume hoods can reduce energy consumption by 50 percent – and maintain or improve containment over standard models – by tweaking the hood’s aspect ratios, airflow patterns, and controls. To gain these advantages, lab designers engage environmental safety staff, plan for appropriate lab modules, and provide optimal hood locations that limit walk-by eddy current risks.
Another emerging trend is the judicious use of ductless fume hoods, which re-circulate air to the room through an activated carbon or other impregnated-media filter package. Today’s application tends to be in areas where the design team can define chemical uses, such as in instructional labs.
4. Chilled Beams and Water-Based Cooling
By using energy-efficient tempered-water or chilled-water systems, chilled beams separate cooling loads from air-system loads. Their European popularity is spilling over to the United States in active forms (using ventilation air to induce more room air through cooling/heating coils) and inactive forms (relying on passive convection). Though chilled beams are simple devices, their ideal application to multiple sciences, and wet and dry lab environments, may involve a combination of HVAC systems allocated by science and building area, with close attention paid to control schemes.
A parallel strategy accommodates high heat gain equipment rooms or labs (possibly as a contingent provision in conjunction with right-sizing) with an integrated design of chilled water fan coils. Unlike chilled beams, however, these devices have fans and filters and wet coils, so allocating floor space for convenient maintenance (in mechanical closets, as opposed to overhead) is key to getting team buy-in to this major energy saver and air-system size reducer.
5. IEQ-Based Ventilation and Lab Management
Yet another trend is rethinking the appropriate levels of air changes per hour (ACH) in the laboratory environment. In lieu of maintaining one recommended flow rate 24/7, new, sophisticated monitoring systems can operate laboratories under reduced ACH for more than 90 percent of the time, constantly monitoring the lab air, and, in case of detecting an IEQ incident, automatically increase the ACH to purge contaminated air. These systems can easily be applied to flexible areas in the laboratory where the need might vary from dry to wet environments. In fact, the recently completed University of Louisville Translational Research Building utilizes one of these systems, which provided an annual savings of $84,564 with a 3.2-year payback.
Green chemistry is a related trend utilizing less toxic substances in the laboratory. The Sustainable Lab Practices Working Group at the National Institute of Health, for example, has identified six target chemicals for reduction, each with an environmentally preferable alternative.
If all else fails, we advocate that less toxic work be done at the open bench, and more be done at a fume hood or ventilated enclosure. Despite some past overuse of point exhaust systems, proper application by an informed team can capture substances that otherwise would contaminate labs.
While these technologies and design approaches show promise, each of these trends requires more than just the motivation of the lab planner or HVAC system designer. As project design teams collaborate to push past integration boundaries, the research and the building operation teams stand to gain significantly. That, indeed, may be the real emergent, big-picture discovery.
George Karidis, PE, LEED AP, is vice president and chief mechanical engineer at SmithGroup (www.smithgroup.com). Victor Cardona is vice president and director of lab planning at SmithGroup.