LEED In Healthcare

By Mr. Kim Shinn

A new guide will help explain how to earn LEED credits for new and renovated healthcare projects.

Healthcare buildings (hospitals, nursing homes and outpatient centers) are unique buildings. They hold a special place in our culture and communities. They are centers for healing and wellness, and places where people and their families gather to receive comfort, celebrate and mourn.

The U. S. Green Building Council's original Leadership in Energy and Environmental Design rating system for New Construction and Major Renovations (LEED-NC®) was designed to be most applicable to commercial office buildings. This market was targeted since it accounted for the greatest annual volume of construction in the United States. While healthcare buildings share a number of features in common with commercial office buildings, they are also very different in design, construction and operation.

Because healthcare buildings have such significant effects on the environment (indoor, community and global) (see Figure 1), the U. S. Green Building Council has recognized the value of providing a tool that is tailored to apply the LEED system to healthcare construction. The LEED Application Guide for Healthcare is currently under development, and is generally based on the Green Guide for Health Care (for more information, visit www.gghc.org).

That is not to say that the current version of LEED-NC is inapplicable to healthcare design and construction. The USGBC estimates that about 50 healthcare buildings are currently pursuing LEED certification, under the current LEED-NC product, and at least one of those is seeking Platinum- level certification. At the time of the writing of this article, two healthcare buildings (Foothills Community Hospital Boulder, Colo., and the Patrick H. Dollard Discovery Health Center in upstate New York) have achieved LEED certification. The Application Guide for Healthcare is meant to provide more credits that are specifically suited for healthcare projects, with particular attention to the improvement of health outcomes associated with those measures.

Some of these healthcare-specific credits, especially those associated with plumbing and HVAC, are highlighted below.

In the Water Efficiency category, The Application Guide pays special attention to the reduction or elimination of the so-called “process” uses of potable water, since it is estimated that more than two-thirds of the potable water used in a hospital is used for these processes (see Figure 2). Some strategies and measures that can be employed to achieve the desired reduction include:

Eliminate the use of potable water for laboratory bench-top or surgical laser cooling. Instead of running potable water continuously to drain to provide “cheap,” local cooling of water baths and the lab and lasers in the operating room, use closed-loop house chilled-water heat exchangers or local electrical-powered coolers.

Use demand-based cooling of sterilizer and autoclave steam condensate. Many facilities use potable water in contact with steam condensate to cool it before it is introduced into sanitary drains. A common practice has been to have this potable water-cooling stream flow continuously. However, because the sterilizers and washers are batch processes, hot steam condensate is only produced intermittently. This means that during times when this equipment is not operating, potable water is wasted to drain. Use demand control devices to control the flow of potable water to maintain drain temperature at a relatively elevated temperature (100-120 degrees F). If the drain temperature is below that setpoint, potable water flow is cut off.

Recover and use air-handling cooling coil condensate. The condensate off air-conditioning unit cooling coils can be used to replace potable water in many areas (irrigation, sewage conveyance, etc.), but one of the most useful is for cooling tower makeup, especially in hot and humid conditions. Up to 20 percent of cooling tower makeup can be replaced by the condensate off cooling coils. Besides saving potable water, this can also reduce the temperature of the cooling tower basin in hot and humid conditions, as well as reduce the need for chemical treatment for hard water, ultimately providing additional savings through reduced evaporation and blowdown.

Reduce the cycles of concentration in cooling tower water to reduce blowdown losses. One method for reducing cycles of concentration, and therefore reducing blowdown losses (as well as reduce the use of chemicals that will find their way into the environment), is to use an electro-chemical water treatment method. This technology uses an electromagnetic field to precipitate out.

Use site-recovered water, such as captured rainwater, for cooling tower makeup or irrigation. Although this will require some level of filtration and additional biological contamination control, using captured rainwater for cooling tower makeup also can serve to reduce the hardness of the basin water, and may reduce overall blowdown losses and chemical use. Another site-recovered water source is backwash from reverse osmosis water treatment.

Use waterless seal vacuum pumps and medical air compressors. Older models of medical vacuum pumps and some air compressors used a continuous stream of domestic water to provide sealing.

LEED emphasizes adherence to ASHRAE Standard 90.1-2004-Energy Standard for Buildings Except Low-Rise Residential Buildings. In most jurisdictions, state licensing boards have not required adherence to an energy code (though some jurisdictions require the building envelope meet some level of insulation performance), so the specialized healthcare designer may not know its requirements. One of the most significant power limitations for mechanical systems is the fan power limit. Standard 90.1 limits the total system fan power (includes supply, return, and exhaust fans). For constant volume systems smaller than 20,000 cfm in supply volume, total system fan power is limited to no more than 1.2 hp/1,000 cfm. For constant volume systems equal to or greater than 20,000 cfm, the limit is reduced to 1.1 hp/1,000 cfm. For variable volume systems, the limits are increased to 1.7 hp/1,000 cfm and 1.5 hp/1,000 cfm for the small and large systems, respectively. Systems that use high-efficiency final filtration are allowed a power adjustment based on pressure drop through clean filters. These fan power limitations will mean careful and efficient duct system design to reduce pressure drops.

Another Standard 90.1 power limitation that directly affects the mechanical designer is the limit on lighting power. As can be seen from the chart in Figure 3, the single greatest user of power in a hospital is lighting. Standard 90.1 limits the overall lighting power in a hospital to 1.2 watts per sq.-ft. There are some minor adjustments that can be made to increase this allowance (for decorative or video display terminal lighting and some special space-by-space calculations), but this is probably substantially less than what most mechanical designers have been using to design a hospital lighting load (this designer has used 2 watts/sq. ft.). This lighting power limit could very well result in smaller air-conditioning loads and smaller cooling equipment.

While it may seem that LEED is harder to achieve in a healthcare building, some LEED credits are relatively easy to achieve for buildings that already must comply with a rigorous licensing standard. For instance:

The Indoor Environmental Quality credit for increased ventilation calls for fresh air ventilation rates that are 30 percent higher than those required under ASHRAE Standard 62.1-2004 for indoor air quality. Most healthcare building licensing codes require fresh air change rates that are often 100 percent to 300 percent higher than those required by Standard 62.1.

The Indoor Environmental Quality credit for controllability of systems associated with thermal comfort requires temperature controls for 50 percent of the building occupants. Since most healthcare buildings already require a relatively large number of control zones (for instance, the number of zones in a hospital patient bed tower approaches a 1:1 occupant-to-zone ratio), this may be easily achieved by virtue of the building program requirements.

The Thermal Comfort ASHRAE Standard 55 referenced in the Indoor Environmental Quality credit for thermal comfort in design requires compliance with humidity and temperature regimes that are equivalent to or less stringent than those in healthcare building licensing codes.

The Indoor Environmental Quality credit for indoor chemical pollutant and source control requires exhaust ventilation for housekeeping and laundry areas (janitor closets and utility rooms, for instance) and MERV 13 final filters, which are already required under most healthcare building licensing standards.

The indoor environmental quality credit for construction indoor air quality management during construction mimics the infection control requirements that are already in effect for healthcare construction in occupied buildings - protecting the return air path and equipment during construction and maintaining clean-to-dirty pressure relationships.

One Indoor Environmental Quality credit that may trip up mechanical and plumbing specifiers is the requirement for low-emitting sealants and adhesives. To achieve this credit, any adhesives or sealants that are used inside the conditioned envelope of the building must comply with California's South Coast Air Quality Management District Rule No. 1168. While this requirement has been in force in California since before the turn of the millennium, this may come as a surprise to many non-West Coast mechanical and plumbing installers, particularly those using mastics and adhesives in caulking, firestopping, duct construction and insulation.

The draft mission statement of the Application Guide for Healthcare carries an important message for plumbing and mechanical designers and installers - “By affirming healthcare's fundamental mission of ' … first, do no harm,' the Application Guide for Healthcare recognizes the profound impact of the built environment on the health of occupants, local communities and global ecology, and encourages design strategies that enhance the healing environment for patients, healthy and productive work environments for staff, and responsible ecological stewardship.”

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Kim Shinn is a registered professional mechanical engineer in 14 states and a principal with TLC Engineering for Architecture (www.tlc-engineers.com), as well as TLC's director of Sustainable Design. Shinn is a co-founder and chairman of the Middle Tennessee Chapter of the U.S. Green Building Council (USGBC), and is the Southeast Regional Delegate to the national USGBC Chapter Steering Committee. He has been a USGBC LEED™ 2.0 accredited professional since May 2001, and has been actively involved in the design or commissioning of more than two dozen LEED registered and certified projects. Shinn has helped create the Green Guide for Health Care and is on the LEED committees to draft application guides for laboratories, healthcare and campus combined heat/cooling/power systems. He can be contacted at kim.shinn@tlc-eng.com.