Smart hospital engineering
To operate properly, hospitals need smart engineering, from the HVAC systems to the fire/life safety and electrical equipment. Here, some expert engineers offer advice on smart hospital engineering.
- J. Patrick Banse, PE, LEED AP, senior mechanical engineer, Smith Seckman Reid Inc., Houston
- Benjamin J. Cole, CxA, LEED AP BD+C, HFDP, principal, division director, TLC Engineering for Architecture, Dallas
- Michael A. Crowley, PE, FSFPE, SASHE, senior vice president, The RJA Group, Houston
- John Saad, HFDP, LEED AP, managing principal, R.G. Vanderweil Engineers, LLP, Boston
CSE: What engineering challenges do hospitals pose that are different from other structures?
J. Patrick Banse: Integration of complex mechanical, electrical, and plumbing (MEP) systems/space considerations and increased low-voltage system requirements with Group 1 and Group 2 medical equipment while satisfying a sophisticated and knowledgeable user are challenging. The competitive nature of the healthcare business, with the desire to provide patients as pleasant an experience as possible, has pushed design teams and contractors to find ways to finish a project sooner than they would like to. How to do that without sacrificing quality and the required facility operation and function is an ongoing challenge.
Benjamin J. Cole: The hospital is one of the most challenging types building types from an engineering design, due to the fact that there are so many different types of systems within the building. The different types of areas within the hospital for treating a variety of patients and their ailments (each with its own MEP requirements and systems that are not allowed to fail without serious life and death consequences) are very challenging to the engineers designing the systems.
John Saad: Special filtration, temperature, humidity control, and other life safety elements must be incorporated into the design documents to ensure the safety of the patients, staff, and visitors. Infection control and systems commissioning are critical elements for incorporation as part of the programming, design, and operational life of the facility.
Michael A. Crowley: Operational savings, first cost, and saving money are the main challenges. Total healthcare costs are important to the facility operators and owners.
CSE: How have the needs and characteristics of hospitals changed in recent years?
Cole: Energy costs are affecting the healthcare industry similarly to other markets. Facilities are starting to look more closely at methods to decrease energy use. HVAC systems will be required to still meet the code requirements but at a lower cost; this will require an increase in upfront cost to projects—that is the biggest non-HVAC hurdle. Trying to secure the funds for new and renovation projects will still be a challenge. Facilities will need to learn how to plan and budget future projects based upon lifecycle cost analysis rather than first cost. Once they are able to make this change, the money saved by decreasing energy can be used for expanding services.
Banse: There are higher low-voltage system space requirements: 24/7 HVAC systems demand for IT rooms and radiology/imaging equipment rooms, more rapid changes to diagnostic and imaging equipment requirements, and a call for higher IAQ during construction with reduced infection risk to patients. The addition of reduced water use fixtures has created drain and pipe sizing challenges, and rising construction costs have caused many project functions to be “shelled” in favor of more revenue-producing aspects.
CSE: Many hospitals are choosing to expand and remodel existing facilities rather than construct new buildings. What unique challenges do revamped buildings provide that you don’t encounter on new structures?
Crowley: Maintaining full functionality of the hospital is critical. Also, infection control issues and construction hazards pose challenges to the existing building.
Banse: Challenges include phased construction to maintain operation and required level of functionality, especially in imaging suites and emergency department (ED) renovation and additions. They also include maintaining the required level of life safety during construction while maintaining a high level of infection control.
Cole: A typical renovation in a hospital is revising a non-patient care area into a high-acuity patient care area. These areas of the building do not have the infrastructure required to support such spaces, and it is difficult to upgrade the existing infrastructure. In addition, years of past renovations hide multiple issues in a tangle of existing wiring, piping, and ductwork that must be unraveled to provide an accurate design when these systems are reused.
Banse: One of our recent projects included the expansion of an operation room and catheterization laboratory suite along with a 10,000-sq-ft ED addition and 20,000 sq ft of ED renovation. The new construction was completed in one phase relatively easily. The challenges came in the remaining five phases of renovation. The owner required a minimum number of exam rooms available at all times due to the flu season and their census history. Additionally, maintaining staff and patient flow around the construction zone and existing exiting requirements increased the construction difficulty. Designing the HVAC and electrical systems to provide power and air correctly to all areas while the duct systems were renovated created multiple opportunities to excel. Bi-weekly field meetings and planning with the contractor and owner made the process smoother during the 12-month renovation.
[AMc1] CSE: What factors do you need to take into account when designing building automation and controls for a hospital building?
Cole: System integration of HVAC, security, nurse calls, fire alarms, etc., is becoming more commonplace due to lower cost and flexible software and hardware. As the new systems come online, healthcare facility personnel will have better access to the systems to react quicker to emergencies, all from a single room. As the systems are improved, smaller community facilities will be able to upgrade to these systems.
Banse: Factors include system functionality and monitoring of critical care and sensitive patient care areas while adhering to the construction budget. Designing a facility automation system the user can actually use for monitoring and control with appropriate integration of the fire alarm system signals.
CSE: When recommissioning or retro-commissioning hospital control systems, what challenges to you encounter, and how do you overcome these challenges?
Saad: Hospitals are constantly changing. Infection control is critical in healthcare design. Energy and medical costs are skyrocketing, codes are becoming stricter, and construction costs continue to rise. Facility managers and designers need to work together to balance many of these factors to match the programming needs of the factory. For example, air change rates have increased in critical areas like operating rooms, which drive up energy cost. Infection control requirements have mandated many access measures on the hospital facility staff for access/repair into the ceiling cavity space to control contamination of the filtered environment.
Cole: Retro-commissioning returns the systems to the original design intent. In many cases, the system controls and actuators are not functional from lack of proper maintenance or use. Working with the facility to determine the systems that need correction is important to complete before commissioning actually occurs. Working with an experienced contractor with knowledge of the facility expedites this work to allow the commissioning to be done with optimum results.
CSE: How have changing HVAC, fire protection, and/or electrical codes and standards affected your work on hospitals?
Banse: It definitely made it more interesting and interactive with code officials and the authorities having jurisdiction (AHJ). Meeting energy code requirements but not sacrificing patient safety can be a major obstacle, as can keeping up with the updated versions of codes and standards.
Cole: Generally, codes are similar in the various locations. Florida, Texas, and California have unique requirements that must be met, but they are not difficult to apply and typically are common best practices used for design. Specialized system requirements such as pharmacy requirements that continue to change yearly impact operations and designs. This creates additional work by the facility to continually upgrade their systems to meet the current requirements to be certified. Life safety will still be consistent and is not expected to change.
Crowley: The codes adopted by the Centers for Medicare and Medicaid Services (CMS) have remained the same for the past eight years. The nationally published codes have been updated a number of times since then but not adopted by CMS. These updates have many cost-saving items and new design options recognizing the changing healthcare environment. There are conflicts created if you follow the more recent codes.
CSE: How do such codes/standards vary from region to region?
Crowley: The codes are fairly consistent. The applications and interpretations vary widely. This is the designer’s major challenge.
Cole: ASHRAE and AIA have joined forces to develop a more standard approach to HVAC guidelines. This will help in removing conflicting requirements that are currently required to be followed between the various sources. The different requirements from region to region typically have a story behind how they were developed. Working with local officials is important to understand the particular codes and the reasoning behind them. Exchanging knowledge on a particular design issue with the local AHJ typically leads to a better design to meet all parties’ needs.
Banse: Not every state health department, fire marshal, or similar AHJ adopts the same edition of the codes and standards. The life safety code CMS uses is the 2000 edition while many states use the 2003 and 2006 editions. Some state hospital licensing entities write their own regulations while others adopt the AIA guidelines or the FGI guidelines.
CSE: Which codes and standards prove to be most challenging in hospital design?
Cole: Energy codes are becoming more stringent every year. Hospitals are high energy users and are starting to lose many of the exceptions that were used in the past. Systems are being designed to higher efficiency standards, and balancing the need for air change rates with lower electrical cost in fan power can be challenging with today’s tight budgets. Energy modeling early in the design helps to find the best solution for building design and building systems to meet the latest requirements.
Banse: Generally the most stringent requirements apply, so each code and standard has to be read and discussed to be sure the correct documentation is produced. NFPA 99: Standard for Healthcare Facilities, which requires nonrecirculation of smoke in an anesthetizing location, coupled with NFPA 101: Life Safety Code and the building codes with their fire and smoke damper requirements, require careful design and component control which creates a project’s own unique challenges.
Crowley: Proper application of NFPA 99 and its reference standards covers many areas of hospital design from medical gases to electrical to emergency planning. It takes a team of people to address NFPA 99 requirements. It is too big of a job for one person.
CSE: Describe how you’ve tackled ASHRAE Standard 90.1-2007 in a recent project.
Banse: “Carefully” comes to mind—making the best use of the climatic conditions for both air and water economizers, using variable air volume systems with airflow measurement to maintain required minimum outside air changes and total air changes while maintaining space and building pressurization are areas projects need to focus on.
Cole: A heat recovery chiller was used to capture waste heat to provide domestic hot water for the facility. The use of the waste heat helped to reduce the natural gas used to heat water by 50% during operation. In addition, to decrease fan power requirements of the air handling systems, filter velocities were decreased down to 200 fpm and coil velocities were decreased down to 350 fpm. The challenge at these low velocities is to provide adequate unit control to prevent systems from dropping below minimum velocities for heat transfer.
Saad: For one recent major urban hospital a 110,000 cfm air-handling unit (AHU) was located on the seventh floor of a 23-story tower. This unit served the entire tower and could not be replaced due to room space/availability. The existing unit had one supply fan; it was a single wall unit with exposed internal lining and no humidification. The return air was not ducted to the unit and experienced many motor failures. We investigated the installation and recommended the use of a newly installed AHU on the lower roof as a temporary energy unit. We installed 68-in. supply/80-in. return mains up the side of the tower and back-fed the existing risers. They allowed our design team to install a new 145,000 cfm custom AHU that meets all of the current code requirements, energy, and operational improvements the owner desired for a first-class facility.
CSE: What’s the one factor most commonly overlooked in electrical systems in hospitals?
Cole: Selective coordination is the one item that seems to be considered too late in the design process, especially in renovation projects. The engineer must take into account the existing electrical distribution’s overcurrent devices upstream from any new devices/panels and any overcurrent settings that these devices are set at. These settings will be the starting point for performing a selective coordination study for any new electrical distribution added to the existing distribution. Selective coordination provides for a systematic way to trip electrical events such as short circuit or over-current events to trip over-current devices downstream before any overcurrent devices upstream.
CSE: What types of electrical products do you most commonly specify in a hospital, and why? Describe the UPS system, standby power, generators, etc.
Cole: That will include the standard equipment you see in most commercial buildings, such as fluorescent lighting, electrical panels, switchboards, and transformers. In addition, hospitals also use some very unique products to meet their requirements, such as isolation panels for operating rooms (OR), emergency generator and automatic transfer switches to provide backup power, and hospital-grade and tamper-proof receptacles in patient areas. The above electrical equipment meets unique requirements for a hospital environment not found in other building types.
CSE: How have sustainability requirements affected your approach to electrical systems?
Cole: The lighting power totals allowed have been decreasing in order to meet sustainable requirements and improve the overall energy efficiency of the hospital. New technologies such as T5 lamps, LED for OR exam lights, and automatic lighting controls in nonpatient areas are becoming baseline requirements for hospital projects trying to become more sustainable.
CSE: What types of lighting retrofits are existing building owners requesting?
Cole: As hospital are renovating, they are looking for the lighting to be upgraded in the space to provide for more energy efficiency as well as quality of light. Many hospitals have been reviewing the use of 28-W T8 lamps in fixtures to help reduce energy usage without a great loss of lumen output. Larger hospital projects have been going to T5 and T5HO lamps as the source in the lighting fixtures as a way to reduce energy usage and use fixtures that have a higher fixture efficiency.
CSE: What trends, systems, or products have affected changes in fire detection/suppression systems in hospitals?
Crowley: Mandatory automatic sprinklers for all new construction and most renovations is a trend started in the 1990s. It is a major factor in the recent NFPA fire data report on healthcare. From 2003 to 2006 there was an average of one death per year in a hospital setting due to fire. Quick-response sprinkler technology also has contributed to this performance.
Cole: Fire system designs have been stable over the years. Atriums are becoming more common in hospital common areas that require specialized systems and specialized modeling to insure the proper airflow for pressurization and smoke exhaust is provided. Minimizing special systems within the hospital is the best option.
Banse: We have seen more requirements for pre-action and dry-pipe fire suppression systems for imaging suites and operating rooms than before. Typically these systems have been used in main electrical rooms and elevator machine rooms (EMR). Additionally, with the expansion of EMR and their support systems, server rooms and file storage rooms are now protected with clean agent or similar fire suppression systems.
CSE: What are some important factors to consider when designing a fire and life safety system in a hospital, and what things often get overlooked?
Crowley: Lifecycle costs of maintaining systems often are omitted. Each smoke detector or heat detector added to a new design has a lifetime of testing and documentation required. NFPA 101 and the International Building Code have a minimal set of requirements for smoke detection. Too often I see a hospital with full corridor smoke detection that was not required by the code. The owner is paying for the devices and the lifetime of testing and maintenance. Coordination with other systems is most often overlooked. The fire detection and alarm system is used to release doors, shut down fans, start stair pressurization fans, control operating room fan responses to fires, sound the alarm, send a voice command, summons the emergency responders, operate on battery power, and other emergency responses. These functions and equipment are installed by different vendors and contractors. The integrated testing is sometimes overlooked.
CSE: What unique requirements do HVAC systems in hospitals have, and how have they changed in the recent past?
Banse: Many requirements unique to HVAC systems involve filtration, minimum air change rates—both outside air and total air—along with specific temperature and relative humidity ranges. Being more aware of infections, the unknown diseases, and bacteria entering the ED and the needed involvement of the hospital infection control staff have opened a good dialogue that makes HVAC design more positive and balanced in the building. Patient procedures are now taking place in exam/procedure rooms rather than operating rooms, and can be deemed invasive procedures by either the hospital or the licensing regulatory body, which have required higher air change rates as well as more laminar airflow. What was good engineering practice is now code required.
Cole: Humidity control in critical care areas has always been a challenge to maintain, monitor, and control. In recent years, these requirements have been relaxed and may be decreased in the future. Research on humidity and the impact of patient safety should continue to better refine actual design values that are needed to make systems more efficient.
CSE: How has ASHRAE Standard 170-2008 affected your infection control systems in hospitals?
Cole: The requirements in Standard 170 have been typical design requirements for our projects for years. The standard is good to provide a common requirement for all designers to meet the minimum standards because in many locations, these were not followed.
Banse: I do not think Standard 170 has caused a significant change to infection control. The AIA guidelines that many jurisdictions adopted required similar levels of filtration, positive and negative pressure relationships, air delivery and removal direction, and air change rates. Studies by the Centers for Disease Control and others have influenced HVAC design regarding potential infection by establishing minimum air change rates, airflow direction, and exhaust requirements. What has occurred, though, is the identification of more specific room types in Standard 170 and in concert with the 2010 Facility Guidelines Institute guidelines makes it a more coherent document. Infection control risk assessments have previously been suggested for renovation projects but are now required in renovation projects. Additionally, duct cleanliness and system start-up procedures to maintain system integrity are mandated in the document.
CSE: Describe the use of fans and ventilation equipment in a recent hospital project.
Banse: Several fan types were used in a recent hospital project. In factory-built AHUs, the higher static pressure requirements due to increased filtration requirements and component air pressure drops required the use of some plenum and plug fans to meet the air delivery requirements. The exhaust fans used to remove air from the building in the form of excess air or relief air used a centrifugal fan or mushroom-type fan. Other contaminated air, such as from an infectious isolation room, required a vertical discharge belted vent set utility fan to discharge air vertically at a high velocity (2000 to 3000 fpm) at a safe height above maintenance personnel. Still other fans for smoke removal required high temperature construction mixed-flow fans that used high air volume and high discharge plume to minimize any air entrainment back into the building.
Saad: Provision of the correct amounts of outside air is critical to maintaining proper pressurization and promoting a healing environment inside the hospital. The larger amounts of ventilation air required in a hospital coupled with the high cost of conditioning outside air present an opportunity to incorporate energy recovery systems. We recently incorporated total energy recovery systems in the outside air conditioning units for a major hospital in Jeddah, Saudi Arabia. This resulted in a 30% reduction of the total cooling load for the hospital and over $300,000 in annual operating cost. Due to the 24/7/365 operation of HVAC systems, energy associated with ventilation fans is often the single largest electrical consumer in a hospital (20% to 35%). Successful strategies to improve the operating efficiency include application of variable speed drives on fan motors, use of arrangements containing multiple fans, reduction of air pressure losses due to friction (larger ducts, coils, filters, etc.), and application of dynamic pressure rest controls.
Cole: Patient floors require an isolation room for infectious patients. In a high-rise patient tower, providing exhaust to the patient rooms can be a challenge. On one project, there were two rooms on a 10-floor patient tower. To prevent maintenance of fire dampers within the ductwork, each floor required a dedicated riser to the roof through individual shafts. On the roof, the ducts were manifold together to common plenum served by a dual fan exhaust system designed to maintain a constant negative pressure in isolation ductwork. All fan components were out of the airstream so the entire system could be maintained without special biohazard suits, a cost savings to the owner.
CSE: Have low-flow plumbing fixtures become the norm in your hospital projects? Why or why not?
Banse: We use 1.6 gpf water closets consistently and have many projects to 1.28 gpf with owner consent. Sensor-type faucets and flush valves are generally used, but it depends on the region of the country. The staff encourages the hands-free no-touch features, but sometimes very young users get surprised by an auto-flush water closet. Dual-flush units are being cautiously used but require owner buy-in. Waterless urinals have been used in several facilities, but usually in combination with low-flow fixtures. Recovering and recycling grey water and reusing it for nonpotable use can lead to drier and sometimes blocked branch or site drainage piping due to the absence of water flow on a regular basis that is needed to carry away solids.
Cole: Low-flow fixtures have not been a factor in recent projects. Infection control personnel and facility medical staff are typically resistant to the lower flow systems for hand washing. More research will be required before more facilities will start to use the lower flow fixtures. Low-flow water closets have been used in several projects with mixed results. Patients tend to flush inappropriate items, which give the lower flow units problems in performing correctly.
CSE: Discuss chiller and/or boiler plants in a project you recently worked on.
Cole: In southern climates, steam is not a common requirement for heating. A typical boiler plant system will have a hot water boiler for generating heating hot water with stand-alone steam boilers for providing steam to central sterile and associated sterilizers. This allows smaller equipment to be used and eliminates heat exchangers for generating heated hot water from steam that increase maintenance and future replacement cost. Efficiency is increased by eliminating steam losses.
Saad: On a recent healthcare project in the Middle East, we were challenged to incorporate the mechanical system equipment into one large mechanical floor of approximately 100,000 sq ft. This mechanical floor was located at the top floor of the main podium diagnostic and treatment block. Two patient towers were designed to sit on top of the podium building (floors 7 to 16). Due to the region-specific issues in the Middle East (extreme temperature, humidity, filtration/sand, etc.), Vanderweil designed a 100% outdoor air AHU system to pretreat the fresh air needs for the facility. This treated air also incorporates latent and sensible heat recovery systems. Individual AHU, pumps, medical gas systems, and electrical distribution networks also complement the large mechanical and electrical floor. Special fire and smoke separation was provided to meet code requirements. Fan wall technology along with N+1 capability was also provided. A complete air cooled chilled water system was installed to provide emergency cooling for the operating suites.
Banse: A recent project involved the addition of almost 200,000 sq ft of critical patient care services to an existing hospital facility. To avoid significant downtime in the existing central plant making piping connections and relocating a boiler, the owner and design team agreed on a stand-alone cooling and heating plant for the new building. High-efficiency variable primary flow chillers with modular cooling towers were planned. As the building required very little steam, modular high-efficiency heating water boilers were used to provide space heating requirements and domestic hot water through double wall plate/frame heat exchangers.