M/E Roundtable: The Power of Medicine
Engineers look to evolving technologies for the unique power needs of health-care facilities
When it comes to issues of electrical power, health-care facility administrators have alot to be concerned about. With tight budgets and the need to control costs, their facilities are especially susceptible to volatile energy prices. When trying to protect life-saving missions and sensitive equipment from power events, hospital administrators must look to the engineering community for answers. In this month's M/E Roundtable, consulting engineers who specialize in health-care work describe how they are helping these clients.
M/E Roundtable Participants
Richard Hermans, P.E., electrical department, Ellerbe Beckett, Minneapolis
Kenneth L. Rigby, P.E., vice president, Vanderweil Engineers, Maitland, Fla.
Steven Yanke, P.E., vice president and chief electrical engineer, OWP&P Engineers, Chicago
Scott Siddens, moderator
CONSULTING-SPECIFYING ENGINEER (CSE): What are the most common challenges in designing power quality and reliability into medical and laboratory facilities?
YANKE: Cost is the big challenge. Everyone understands the needs, but when it results in extra cost, it's difficult to justify to those funding the project.
Other challenges include finding space for engine/generators, uninterruptible power supplies and extra distribution equipment; getting the utility's response to redundant services and future transmission and distribution upgrades; and long lead times for equipment delivery in a world of ever-decreasing construction schedules.
RIGBY: The amount of reliability designed into a system must be evaluated for each project, because each project has its own unique requirements. Factors that must be considered for all projects are utility reliability, environmental considerations (earthquakes, hurricanes, lightning) costs and evaluation of the equipment requirements being served in a facility. For example, can the equipment or procedure tolerate a momentary loss of power, or no power loss under any conditions?
HERMANS: A common challenge for most designs is the sensitivity of medical equipment to power abnormalities. Some of the newest radiology equipment, for example, has low tolerance to voltage sags or spikes. This goes beyond the normal requirements for computer power, because some equipment provides direct clinical treatment and other equipment performs critical diagnostic functions by direct patient connection.
CSE: Magnetic field interference (MFI) has been identified as a source of medical equipment failure. What can designers do to prevent equipment failure caused by MFI?
RIGBY: The majority of problems due to MFI can be alleviated by having a good grounding system. Most equipment problems are the result of not having a properly designed grounding system.
YANKE: It's true that design professionals must make sure to observe proper grounding methods, but getting the electrical engineer involved during the space planning effort is the best thing one can do. Keep any sensitive equipment away from electrical equipment, including switchboards, transformers and feeders.
Where there is no choice but to locate sensitive equipment in close proximity to electrical equipment, the designer must provide appropriate shielding. Various shielding methods can be explored with the manufacturers.
HERMANS: There are technical solutions to blocking interference from generation, or from speed controllers. Most, if not all of them are expensive and might not be specified because of their cost.
Backup Options: Designs and Degrees
CSE: In what way, if any, has electrical deregulation had an impact on your electrical designs for medical facilities?
HERMANS: Some utilities are beginning to cut back on their energy conservation rebate programs as a result of a more market driven philosophy by public utility commissions. The loss of rebates as an incentive for energy conservation measures limits the designer's options.
YANKE: We are looking into more means of on-site energy production for clients and are exploring alternative service and billing arrangements (for example, curtailable and interruptable power). This is based on the uncertainty of prices in the future. We are also seeing a greater use of natural gas engine/generators for backing up non-essential loads.
CSE: What degree of redundancy is expected by facility managers? Have anxieties about central power generation and transmission led them to ask for greater redundancy?
YANKE: Yes, it has. Facility managers are looking for a minimum of two utility services. Cooling systems are being backed up by natural gas or diesel engine/generators. Essential loads (those required by code) are being backed up by diesel engine/generators. Many times, loads not required by code are being placed on a separate emergency branch of the essential system. We are generally providing a spare engine/generator in case one is down for service.
RIGBY: The degree of redundancy varies from project to project. The reliability of the utility plays a big role. The cost impact vs. additional reliability must be evaluated for each project. If the utility has reliable power in an area, the anxieties about central power generation and transmission are lessened and the owner is less apt to want to incur the cost for greater redundancy.
HERMANS: Those facility managers who have experienced lengthy interruptions of service will require more redundancy than is presently mandated by building codes in health-care settings. The most frequent requests involve emergency power for cooling systems.
CSE: In what way are medical and laboratory facility administrators focusing on issues of on-site power generation and distributed generation?
HERMANS: Most health-care administrators are focusing on the cost/benefit issues of combined-heat-and-power systems, or on peaking power generators to limit demand. Distributed generation is an issue in some large campus facilities.
YANKE: These facility managers are really focusing on reliability at the least cost. If we are working with a medical campus, the individual facility managers are sometimes working together to share engine/generator capacity or develop a central electrical plant that each facility on the campus can use.
RIGBY: Generally, generators are provided to serve as a backup source of power to the utility for the critical loads of a facility. In areas where the utility provides reliable power at a reasonable cost, on-site power generation and transmission for the total facility load is usually not a viable option.
Power and Air Quality
CSE: Hospitals and laboratories are faced with the twin concerns of power reliability and air quality. Describe how electrical and mechanical engineers can coordinate efforts in an integrated approach to both issues.
HERMANS: Power reliability and air quality are not mutually exclusive goals. Collaboration between electrical and mechanical engineers will achieve both creative solutions of generator siting and equipment selection.
RIGBY: I agree. Electrical and mechanical engineers need to work closely together to identify methods of improvement in areas of power reliability and air quality. Usually, improved air quality results in more energy usage.
YANKE: Reducing electrical consumption and peak consumption will help to reduce greenhouse gases. If utilities are not forced to run their least efficient power plants, the overall air quality (and not just air within one building) is improved.
When dealing with batteries for backup of systems, care should be taken in the selection of the batteries and the design of the ventilation system for the battery room. Daylighting can be used to reduce the electrical load, minimizing the impact of the electrical system on the mechanical design.
Hybrid ventilation systems utilizing natural ventilation can be used to minimize the electrical energy needed to support the ventilation systems. The engineering team must work in close collaboration to determine which areas need complete backup, and which do not. Let's not make the engine/generator larger than it needs to be.
CSE: What are some of the other promising technologies and strategies for a high degree of both power quality and energy efficiency?
HERMANS: Combined-heat-and-power plants offer reliable and clean power while returning the initial investment in a short time through high energy-use efficiencies. Future technologies to watch include fuel cells and microturbines.
YANKE: Low-harmonic-distortion electronic ballasts and variable-frequency drives [VFDs] used to control building systems offer both energy efficiency and power quality. [One should] provide input line reactors as required to mitigate the harmonic effects of the VFD on the electrical distribution system. Also, remember to use dv/dt filters, sometimes called reflected wave traps, for 480-volt motors with long leads between the VFD and the motor terminals. Energy-efficient transformers and harmonic canceling transformers are also significant in this respect.
RIGBY: Even though, at present, many owners cannot justify the additional costs, as these technologies continue to develop and the costs decline, they will be implemented in more and more projects. Promising technologies include solar photovoltaic systems and fuel cells.
CSE: Describe some of your recent designs, and how the design team used innovative approaches to address concerns and solve problems.
YANKE: One recent design used a hybrid ventilation system taking advantage of an atrium and heat stacks to drive airflow through the building. Working closely with the architects, the HVAC system designers also took into account the exposed thermal mass of the building. When outside conditions allow these features to be utilized, the electrical load will be significantly reduced.
We have used ice storage and steam absorption to reduce electrical loads during peak hours. Other projects have taken a more straightforward approach, using natural gas engine/generators to back up systems and equipment that are not required by code to be backed up.
HERMANS: Recent designs continue to use traditional generation and variable-speed drives for motors. The quality of the power has been maintained by using active and passive noise filters.
RIGBY: On one project, a gas-engine driven chiller was used in conjunction with electric chillers. This cut operating costs during peak electric-rate periods and provided added reliability to the system. A heat-recovery system was utilized to lower costs by reducing boiler input requirements.
Occupancy sensors are used in labs to control lighting and fume hood exhaust for energy efficiency.
CSE: What do you think will be the greatest concern in the future for electrical design in medical and laboratory facilities?
RIGBY: The greatest challenge will be to provide a flexible electrical system for the changing needs of a facility. As technology changes, the electrical requirements of the facility will change. The electrical system in a facility must be able to serve these changing technologies.
YANKE: Availability of reliable source of electricity (utility, multiple levels of generator redundancy, UPS for key systems, equipment and experiments) will be a great concern.
The need for reliable electrical power is increasing while the infrastructure of the utility transmission systems is aging. Moreover, the need for power quality is increasing because of equipment sensitivity.
Construction budgets are coming under greater scrutiny, while the time to develop appropriate design is decreasing. Accelerated schedules force the engineer to select equipment before all of the load analysis is completed. Oftentimes, equipment has already been purchased and delivered to the site before all of the calculations are complete.
Reducing Hospital Power Costs
The shake-up in the electric utility industry isn't affecting only California. More than 20 states already have electric deregulation, with many more proposing the same.
In many cases, deregulation has caused the cost of electricity to skyrocket, particularly during the high-demand months.
Health care facilities have been hit particularly hard. Already dealing with squeezed budgets from rising medical costs and shrinking reimbursements, they are struggling to pay the bills and balance budgets. So they're turning to engineering firms for help.
BSA Design in Indianapolis is working with several health care companies to design new systems that minimize energy costs. For example, the firm's engineers are designing and installing new hybrid power generation systems in some facilities. These systems run on electricity and natural gas, which allows health care facilities to decide, hour by hour, whether to buy electric power or natural gas, depending on the market price of each. These generation systems allow hospitals and other health care facilities to buy as little electric power as possible during price spikes.
These systems are gaining in popularity in states where deregulation has taken place. However, some facilities in regulated states are already bracing for the future. In Illinois and Indiana, for example, a few hospitals already have installed these cost-cutting systems.
By ADAM HOOVER