COVID-19 Design Impact Series |
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We recently shared some initial insights into how MEP systems can impact the spread of COVID-19. Our COVID-19 MEP Design Response remains available on our website.
For the next several months, we'll build on these concepts in our Plains Talk newsletter by continuing to discuss important design approaches brought to the forefront by this pandemic. We'll give our perspective on the myriad ways our new "normal" could impact, and be impacted by, MEP design solutions.
In our first edition of the series below, we dive further into HVAC design considerations, including an approachable summary of CDC recommended guidelines, and show how we're using UV in air handling units and isolation room ventilation to support our healthcare clients.
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University of Iowa Hospitals & Clinics AHU Upgrades |
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Maintaining indoor air quality in healthcare facilities is critical. Our country’s ongoing pandemic response has made that fact even more clear as our society has had to learn to take infection control and contaminant isolation to new levels. Some measures, fortunately, have been in place for years, and continue to evolve as allies in keeping our healthcare facilities, essential workers, and patients – safe.
In 2004, we published an article in Plains Talk about adding Ultraviolet (UV) emitters in 17 air handlers at the University of Iowa Hospital and Clinics. At the time, it was a major step forward in improving indoor air quality by reducing contaminants in the air stream and keeping coils clean. When properly designed and installed, ultraviolet emitters can eliminate molds, fungus, and bacteria. Their elimination can, in turn, reduce the level of allergies, colds and other infectious disease exposure to facility occupants. And while the germicidal effects of ultraviolet light had been known for more than 50 years, it was relatively new to the healthcare environment as advancements in lamp technology made it practical within the temperature ranges found inside AHUs.
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Mike Drahos, P.E. is a mechanical engineer and manager of our Cedar Rapids office. For more than 25 years, Mike has worked with healthcare systems across the region as both an engineer and a mechanical contractor, including UIHC and Mayo.
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More than 15 years later, we’re still working with UIHC to upgrade and improve the use of UV emitters in AHUs across the health system.
In fact, these systems are now a required component of UIHC’s mechanical design standard and we currently work to support AHU upgrades as needed system-wide.
In addition to improving indoor air quality and aiding in infection control, UV emitters rapidly improve the cleanliness of the finned coils within each upgraded air handler. The external surfaces of all coils collect both organic and inorganic materials. By killing microscopic organisms and degrading organic materials, ultraviolet lights within air handlers allow the airstreams to actually clean existing coils. As the biomaterials degrade, they flake off the coil and are captured in the unit filters. Cleaner coils increase both the cooling capacities of systems and the overall maximum airflow that an air handler can produce while saving fan energy. In a prototype installation, one air handler at UIHC improved from a static pressure drop of 4.08 inches of water across the coil to 1.37 inches due to the cleaning effect of the retrofitted UV lights. This represents substantial monetary savings due to increased energy efficiency, as well as reducing hours previously required by maintenance personnel for manually cleaning the coils.
Of course, phasing of the construction work in the healthcare environment is challenging due to the potential disruption to users and critical care areas caused by shutting down various air handlers. In recent project, the air handlers affected serve a variety of occupancies, including surgery suites, isolation rooms, radiology clinics, general patient areas, and offices. The construction work was coordinated with multiple departments at the facility to minimize the disruption any single area experienced. Much of the construction inside of the air handlers was performed during nights or weekends and was required to be done in relatively short work shifts.
The UV emitters were designed to be supported in a rack assembly 12 inches downstream of each chilled water coil surface. The vertical spacing of these emitters within each air handler was calculated to provide the required intensity of UV light on the coil surface.
West Plains Engineering also integrates several special features into its designs to improve the safety and maintainability of the system. Door cut-off switches are included to prevent accidental exposure of maintenance personnel to UV energy. Warning signage is also affixed to each access door. A separate emitter switch with pilot light and padlocking case is mounted on the side of each air handler. Each air handler also receives its own hard-wired radiometer to assist maintenance personnel in determining when lamp replacement is required.
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Strategic Direction Report |
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HVAC Measures to Address Virus Spread |
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By: John Huntley, P.E. | Mechanical Engineer |
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In light of COVID-19, there has been a lot of discussion on how virus transmission in our buildings can be mitigated. We shared a few of our insights recently in our COVID-19 Design Response because we feel these discussions need to happen. To date, there have been more than 7 million cases of COVID-19 in the U.S., resulting in over 200,000 deaths. Beyond these startling statistics, the emergence of this latest coronavirus has changed the way we all live, work and approach the future.
As engineers, architects, and construction industry professionals, what can we do to protect building occupants?
It’s important to first understand that COVID-19, and most viruses, are spread primarily through close contact with an infected person (within about six feet). The Center for Disease Control (CDC) also states that it’s possible for infection to spread through contact with infected surfaces and then touching one’s mouth, nose or eyes.
Recently, some discussion has been had on the potential for smaller droplets, which are released through breathing, coughing, sneezing or talking, to become aerosolized and transported through the air currents within a building. As designers of building airflow, this caught our attention. While the HVAC clearly plays no role in mitigating the effects of close contact or surface transmission, there may be ways it can aid in mitigating aerosols which are expelled into a space.
The CDC has offered a number of recommendations, which should be followed where possible, including increasing ventilation air rates, improving filtration, implementing air purification strategies such as UV Germicidal Irradiation or Bi-Polar Ionization, or some combination of these strategies. Information on each is provided below, but the key takeaway here is that anything we can do to improve the air quality in a building, and space between individuals, will help combat virus spread.
Air Ventilation
Outdoor air ventilation should be increased as much as possible. One method is to use the air-side economizer mode of the existing HVAC system, which simply uses the equipment connections to the outside air to provide as much cooling as possible through ventilation air. However, this approach would require close oversight in our upper Midwestern climate where the humidity in the summer and cold of winter may not make 100 percent economizing advisable.
Air Filtration
Improving central air filtration, using MERV 13 or higher, can help capture particles which have been aerosolized and brought back into the AHU, reducing the quantity of particles that are recirculated back to the occupied zone.
Air Flush
Running systems at maximum outdoor airflow for two hours before and after occupied times will improve fresh air changes in the space, and purge contaminants from the occupied space.
Air Movement
Generate clean to less clean air movements by moving diffusers and return grills to impact how air moves through a space or the building as a whole. The goal is to move air from staff environments (clean areas) to areas that don’t necessarily need as much clean air such as unoccupied or visitor reception spaces. Creation of isolation rooms is another option to keep air moving in the desired direction.
Ultraviolet Lighting
The Food & Drug Administration has stated that UVC radiation has been shown to inactivate the COVID-19 virus. How well UV lighting will work in the HVAC system on viruses such as COVID-19 isn’t clear at this time however. The wavelength, dose and duration must all be evaluated further to gain a clear understanding of their efficacy. One concern is that the effectiveness of UV lights diminishes over time. These lights need to be replaced at set intervals and building owners may only get between one and three years of adequate performance before they need to be replaced. Additionally, within an HVAC system, UV lamps require a length of straight ductwork and an appropriate air velocity to provide enough exposure time for the lights to kill pathogens. In some built environments this simply isn’t possible. However, other facilities such as healthcare, have been able to introduce UV lighting into their AHUs or even into select spaces as standard design procedure.
Needlepoint Bi-Polar Ionization (NPBI)
NPBI is a relatively new technology which generates an ion plasma field inside the HVAC equipment. These ions are then distributed throughout the building by fans and ventilation ductwork. NPBI releases charged ions into the air, which then attach to microscopic particles. In the case of COVID-19, these ions strip away hydrogen and leave oxygen, which neutralizes the pathogen threat. According to a report published by Global Plasma Solutions, NPBI was shown t have a 99.4 percent reduction rate on SARS-CoV-2 (Covid-19) surface strain with 30 minutes of exposure. These systems can be installed in any major HVAC equipment and some terminal units. They also don’t require much power, so changes to the infrastructure are minimal.
Download Other Strategic Direction Reports
engineer-authored white papers from West Plains Engineering.
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John Huntley, P.E. is a mechanical engineer who supports both our Rapid City and Casper offices. John has been designing HVAC systems for all types of building environments for 25 years, and has been with West Plains Engineering since 2009.
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Similar isolation room completed by West Plains Engineering |
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IHS Emergency Department Expansion & Upgrade |
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Isolation rooms within emergency departments and health care facilities have always been key to patient and caregiver safety. As we face the current coronavirus pandemic, their importance has become even more critical to slowing the spread, and containing this highly contagious illness.
In 2019, West Plains Engineering designed the mechanical and electrical systems for the new Emergency Department expansion for the Indian Health Services hospital in Pine Ridge, SD. Less than a year after being built, the isolation rooms from that project are now being used to house patients recovering from COVID-19.
To minimize the risk of transmission of contagious diseases, special attention must be paid to maintaining airflow and proper humidity levels in isolation rooms. Humidity in particular impacts the survival of infectious disease organisms and viruses. When we began this project, we understood there had been humidity and air flow issues at other IHS facilities, so it was an area of emphasis for the owner. Our team underwent an extensive analysis of the humidity levels of the isolation rooms at the Pine Ridge facility to assure they continue to maintain appropriate levels at all times.
Another interesting component of this project was that it was created as a flexible use space. Although critical when needed, isolation rooms are only required a limited amount of time. To allow these rooms to be used as standard rooms and reduce overall energy consumption, we took a unique approach and designed the rooms to operate in two modes - isolation and normal. This was achieved with a simple wall switch that the facility end users can change, allowing the room to be converted seamlessly from one mode to the other.
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Michael Heinrich, P.E. is head of the Mechanical Department in Rapid City. He has been the lead mechanical engineer on several recent projects to expand and update the IHS Hospital in Pine Ridge, SD.
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West Plains Engineering News |
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Speaking of Michael! He recently celebrated a pretty important milestone with WPE in August. :) We've been so fortunate to have his incredible talent, leadership and sense of humor for two decades! Happy anniversary Michael (and thanks for the article)! |
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WPE Sponsors State AIA Events |
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West Plains Engineering is proud to support our architectural partners across the Upper Midwest. We annually sponsor statewide conventions for groups in Iowa, South Dakota and Wyoming. In September, all three of these events were held, with Iowa and South Dakota opting for virtual conferences and Wyoming creating a socially distance in-person opportunity.
We appreciate getting to be a part of them all, and hope the AIA professionals enjoyed learning, networking and growing in the industry!
PS - check out the video below that we used to (virtually) introduce the AIA-SD luncheon keynote speaker, Matthew Kreielich, FAIA of Snow Kreielich Architects in Minneapolis.
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Rapid City, SD | Sioux Falls, SD | Bismarck, ND | Casper, WY | Cedar Rapids, IA |
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