Healing today’s hospitals
Building analysis, energy efficiency, and flexibility are the keys to successful hospital design. This challenge has led administrators to demand more of their healthcare facilities in the way of flexibility, energy efficiency, and codes and standards compliance.
Today’s hospital administrators face an unprecedented challenge. Stuck in the middle of the interplay between technological innovation, economic market forces, rising healthcare costs, patient and staff safety, and the evolving role of government, administrators are looking for new ways to compete for patient business and cut costs. This challenge has led administrators to demand more of their healthcare facilities in the way of flexibility, energy efficiency, and codes and standards compliance.
Chicago’s Rush University Medical Center (RUMC) is a case in point. The first phase of the Center’s 10-year Campus Transformation Project includes a centralized power plant, medical office building, and seven-story parking garage that opened in June 2009. Phase II of the campus reconstruction will include a new 806,000-sq-ft, 14-story hospital building with more than 400 new beds and an emergency room prepared for catastrophic events, set to open in 2012 and targeting U.S. Green Building Council LEED Gold.
While Rush has its own unique set of compliance and design requirements, the principles employed by MEP engineer Environmental System Design Inc. (ESD) can be applied to any healthcare facility.
The first step in creating an energy efficient design is to perform a thorough analysis of the hospital’s goals and functions. Conducting programming sessions with staff and facilities personnel will shed crucial light on typical building operations and expectations for the new facility. The next step is to research all applicable national and local codes and standards; foremost of those for healthcare facilities are NFPA and ASHRAE standards and the American Institute of Architects/Facility Guidelines Institute (AIA/FGI) guidelines. ASHRAE 90.1 and ASHRAE 170, new this year, will play a leading role in any hospital’s design. In addition, knowing the local codes and understanding their intent, and identifying the expectations and current interpretations of the authorities having jurisdiction (AHJ) are also key steps in the planning process.
For example, the lighting requirements of ASHRAE 90.1 standard for energy efficiency can be met with either prescriptive space-by-space or building-wide calculations, the latter of which sets the threshold for hospital lighting density to 1.2-W/sq-ft. Reconciling energy efficiency with the high illumination guidelines of the Illuminating Engineering Society of North America (IESNA), which asks for as much as 50-foot-candles at each office desk or 30-foot-candles in hallway areas, can be challenging.
ASHRAE standard 170 will be the first national standard to specifically deal with hospital ventilation and infection control. Addressing healthcare systems optimization, ASHRAE 170 is expected to push the envelope toward sustainable design, aligning itself with greener practices while maintaining patient comfort and safety and increasing infection control. As this emerging standard is applied over the next few years, its role in healthcare design will become more clearly defined.
Before designing Rush, ESD performed a building analysis that examined energy usage at Rush’s existing hospital. After reviewing utility data, it was determined that energy was being used at a rate of 5.5-W/sq-ft in the 30-year-old facility. Upgrading systems and, therefore, the energy required to operate them, would tend to increase the power usage instead of lowering it. Because the City of Chicago has its own electrical code standards, compliance at Rush involved a synergy of local, state, and NFPA codes, which can be in contradiction. ESD was able to identify and facilitate resolutions to these issues with the AHJ during the design phase. For instance, the City of Chicago electrical code requires two cascading automatic transfer switches (ATS) for a hospital’s critical and life safety systems, while NFPA requires only one. Designing to the “worst case scenario” or in this case, the City of Chicago code, created additional redundancy and resources of power, resulting in the specification of two ATS at Rush, going above and beyond NFPA.
In another example, a compromise with the AHJ was reached by allowing the hospital’s auto doors to be served by the life safety system as well as the use of Greenfield conduit within the air-handling unit plenum. CEC Article 18-27-351.4(b)(11) states that liquid-tight flexible conduit with a non-metallic outer jacket cannot be used in environmental air handling ducts or in spaces where NFPA has no such restrictions. After further discussion with the City of Chicago, ESD received approval in the form of a code variance to use the product per NFPA requirements.
On the power distribution side, ESD worked with the local utility company during Rush’s design phase, chairing weekly meetings with the owner representative and the utility engineers to discuss the vault layout and design a more efficient use of the space for electromagnetic interferences (EMI) to avoid the high cost of shielding vaults. Because of this, ESD was able to provide Rush with substantial cost reduction by eliminating the EMI shielding and minimizing its levels that can interfere with imaging equipment on the floor above. Acceptable EMI levels were established by twisting the primary 12-kV cables and keeping the distribution as low as possible, in addition to transformer secondary 480-V cables installed underground. This type of installation also applies to the power distribution cables on the basement level for the main switchboard, automatic transfer switch, unit substation, and 12-kV incoming service gear rooms.
While it’s no question that hospitals employ more energy-intensive equipment than other buildings, it is still possible to design for efficiency. In fact, when efficiency gains occur in a place where great power consumption is the norm, substantial operational savings can be realized. Sustainable initiatives common to healthcare facilities include daylighting, energy recovery, lighting, and HVAC controls and efficient equipment selection.
At Rush, daylighting was used in all offices, workrooms, and interior and exterior corridors as well as the café and family waiting areas. Daylight and wireless occupancy sensors with manual override switches were installed in most of these spaces with on-off controls set to conserve energy when no occupancy is detected. Additionally, Rush used a centralized inverter system to serve all LED down-lights within the operating room (OR) suites and eliminated the required battery pack to save money on maintenance. Integrating different types of room controls through the BAS, as in these examples, allows for maximum efficiency gains.
Artificial lighting at Rush was also optimized. The ASHRAE standard 90.1 whole building method was used to meet the 1.2-W/sq-ft lighting power density (LPD) requirement, which takes an average of W/sq-ft over the entire facility, instead of demanding that each space fulfill the standard individually. In common areas, a LPD of 0.7-W/sq-ft was achieved, or a 45% reduction in energy use below LEED requirements, which helped offset the increased LPD for spaces that require more lighting such as procedure areas. This significant reduction allowed Rush to pursue utility grants that would offset the upfront cost of the LED fixtures.
Employing efficient lamps and ballasts helped meet the 45% reduction at Rush. Because they are easily dimmable, have a longer life, use less power, and generate significantly less heat, LEDs can help minimize the HVAC cooling requirements. The ESD design team went to the Philips factory to test 20-W LEDs and verify their lumen output prior to specifying them at Rush. Subsequently, ESD provided Rush and architect Perkins+Will with an in-depth lamp cost of ownership evaluation based on the standard 28-W, T5 lamp compared to the proposed 25-W, T8 Philips. As the T5 lamps could only be used in conjunction with a 1.03 ballast factor, the price for programmed start ballast would increase by 64% to $29.41 in lieu of $18.71 for T8 ballast with 0.88 ballast factor specified for RUMC.
Although the T8 and T5 lamps have different specifications, the light output per unit length is almost identical due to lamp behavior in different ambient temperatures. For instance, T5 lamp light output will reach its maximum when the lamp ambient temperature is at 35-C, while the standard T8 lamp maximum performance is at 25-C, ambient temperature. On the other hand, the alternate 25-W, T8 XEW and XLL lamps react to heat the same way a T5 lamp does. Figure 2 shows lumen output for a standard 32-W, T8 versus a standard 25-W, T5 XEW/XLL. Through a cost analysis study, ESD estimated that incorporating these efficiencies will reach payback for Rush in just five to six years.
The lighting industry has always used 25-C ambient temperature when it comes to lamp lumen output evaluation and the above data clearly shows that the T5 lamp lags behind the T8 lamp in performance. The 28-W, T5 lamp’s price is 230% higher than the price of a 25-W, T8 XEW and 400% more than that of a 32-W, T8 lamp. Additionally, life expectancy of the T5 lamp is approximately 20,000-h versus the 30,000- to 40,000-h of the T8 lamp. This can result in a significant savings when it comes to hospital maintenance. Refer to manufacturer cost ownership worksheets for annual cost and estimated life cycle savings for each lamp.
After reviewing all of the parameters for both the T5 and T8 lamps, it is apparent that the T8 lamp provides flexibility and cost savings for hospitals without compromising the IESNA light level values. The 25-W, T8 XEW lamp is a great alternative in 35-C temperature applications because its lumen output is as high as the 32-W, T8 and it consumes 7-W less. The 32-W, T8 lamp has the best performance in 25-C temperature conditions with lumens output of 2800. In addition, the 25-W, T8 XLL provides the same lumen output as the XEW and a lamp life of 40,000-h, which translates to over $90 in savings over the life of the lamp.
With the rate of technological innovation doubling every two years, creating a state-of-the-art hospital can be challenging. Flexible design is the answer. Using applicable codes and standards and the hospital’s energy-efficiency goals as baseline parameters, mechanical, electrical, and plumbing infrastructure for areas such as imaging should be up-sized by 5% to 10% over current equipment load requirements. This will provide adequate support for the new equipment, typically chosen as close to 6 to 18 months prior to move-in. Designing a robust, flexible, and modular infrastructure will also provide a hospital with the ability to alter room functions as its patient base grows and evolves. This might mean that an office space will change into a labor and delivery suite, for example.
At Rush, ESD provided the same number of normal and critical power outlets on each patient headwall, which goes beyond code requirements to maintain the same quantity of equipment should there be a failure of the ATS units serving the critical outlets in the room. ESD built extra capacity into the HVAC distribution system serving the electrophysiology, interventional radiology, and catheterization laboratories so that the hospital can easily convert these rooms into OR suites in the future and provide the code-required air changes. The added pressure losses associated with using laminar flow diffusers with integral high efficiency particulate air (HEPA) filters was also considered in the design of the air-handling systems.
Another current healthcare trend is to create dual-purpose rooms that can, for example, house imaging and OR services in a single space, creating a hybrid OR. Driven by a desire to increase patient comfort and shorten hospital stays, these rooms will have both diverse and energy-intensive infrastructure requirements. They may necessitate lighting or equipment to be ceiling- or floor-mounted, to allow for easy rotation and movement.
The Hybrid OR at Rush presented the design team with numerous challenges from light fixture placement to avoiding interference with the floor and ceiling-mounted C-arms, sprinkler heads, laminar flow diffusers, and more. Provisions were made for dual voltage isolation transformers to accommodate 120-V and 240-V equipment and finally the use of pedestal- and ceiling-mounted receptacles in lieu of the traditional boom design.
While today’s hospitals face unprecedented challenges from new economic market forces, rising healthcare costs, and government regulations, there has never been a more important time to design for the future. From building analysis to designing energy efficient and flexible infrastructures, innovative engineering is rising to meet the needs of medical facilities head-on.
- Kos is a senior associate and mechanical engineer and is involved in a variety of healthcare, commercial, residential, and tenant development projects at ESD.
- Quadi is a senior associate and electrical engineer responsible for designing efficient and cost-effective electrical systems for a wide variety of healthcare, commercial, residential, and industrial facilities at ESD.
The Low-Hanging Fruits of Hospital Energy Savings
Mechanical, electrical, and plumbing (MEP) systems account for a significant portion of any hospital’s energy expenditure. The following are some of the low-hanging fruits hospitals can incorporate to reduce their MEP expenditure:
Lighting retrofit: Employing T8 and LED lamps and/or new longer-lasting ballasts will conserve manufacturing resources and cut down on waste, while reducing daily operational expenditure. In fact, replacing incandescent lamps with an Energy Star-qualified bulb can reduce energy consumption by as much as 75%, according to Energy Star.
Lighting controls: Specifying lighting controls, including occupancy sensors, daylight sensors, and time clocks in non-emergency areas can minimize operating expenditures. Sections of the hospital that aren’t populated 24/7 (offices and gift shops, for example) can be programmed by the BAS or set to turn off or dim with reduced occupancy and increased daylight.
Temperature controls: Integrating the building operations and patient management software with the BAS will lead to reduction of the airflow exchange rate below the required values when a room is not occupied.
VFDs on motors: Variable frequency drives (VFDs) can be installed on most motors to operate based on actual load, slowing down or speeding up the motor as needed, instead of running at a constant speed 24/7.
Constant volume fans: Employing VFDs on constant volume fans for balancing purposes can reduce the energy consumption of the fan at its required operating conditions. In addition, it allows hospitals that are constantly renovating and upgrading to rebalance systems more effectively.
Airside economizer: An airside economizer can reduce energy costs in cold and temperate climates while also improving IAQ. Energy can be saved by using cool outside air to condition and ventilate the building when the enthalpy of the outside air is less than the enthalpy of the recirculated air. When the outside air is sufficiently cool and dry, no additional conditioning is required and therefore the load on the building chiller system is reduced.
Waterside economizer: Hospital process loads, such as imaging equipment, require chilled water all year. During the winter months, the waterside economizer uses outside air to remove heat from the chilled water system. Instead of producing the chilled water with the chiller, cooling towers are used via a heat exchanger to produce wintertime chilled water.
Variable discharge air temperature: Increasing the air handling unit discharge air temperature by just two to three degrees on moderate days, from 55- to 58-F for example, will provide for a reduction in operational expenses while still maintaining the same level of patient and staff comfort. This exercise also increases the available time for operation of the airside economizer mode.
Energy recovery of exhaust airstreams: Required outside air can be precooled during the cooling season and preheated during the heating season by transferring energy from the exhaust airstream to the incoming outdoor airstream. This can be accomplished with an air-to-air heat exchanger, which requires the exhaust and outside airstreams to be in close proximity. An alternate method to recover energy from the exhaust air steam is a run-around loop, which accomplishes the transfer of heat by installing connected coils in the exhaust and outside airstreams and circulating a fluid.
Boiler heat recovery: In order to make steam, the boiler must raise the temperature of the make-up water to its boiling point. Capturing otherwise wasted heat from the boiler’s combustion exhaust to preheat the incoming make-up water will reduce the boiler’s load.
Low-flow plumbing fixtures: Using low-flow faucets and showers can significantly reduce the water consumption of a healthcare facility as well as reduce the energy required to operate the building’s domestic water pumps. Designers must review fixture selections with the facility’s infection control authority to get complete owner buy-in.
Condensate recovery: During the cooling season, make-up water to the condenser system represents a significant portion of domestic water use. During the same period of operation, condensate from the air-handling unit cooling coils tasks the sanitary system and represents a potentially large resource of clean water that is otherwise wasted. Recovering condensate from cooling coils is an easy way to offset the large water demand of hospitals while significantly reducing that building’s sanitary system outfall.