An existing 60,000 CFM, 100% outdoor air ventilation pre-treat air handling unit (AHU) at Houston Methodist Hospital (HMH) in the Texas Medical Center is located in the 5th floor penthouse above an emergency diesel generator which is located at grade level. The high velocity air-intake louver serving the AHU pulls in unacceptable levels of odorous Volatile Organic Compounds (VOCs) resulting from the operation of the generator during intermittent times throughout the week. Additionally helicopter landings, kitchen exhaust hoods, medical exhaust, a loading dock, trash dumpsters and street level automobile traffic contribute to overall excessive levels of various VOCs being delivered through the AHU and into the hospital. Complaints were regularly generated from patients, nursing staff and doctors, particurally when the generator was running. Existing charcoal filters, originally installed to remediate the odor issues, were found to be ineffective and extremely costly to maintain, leading the engineeringstaff at HMH to select Needlepoint Bi-Polar Air Ionization (NBPI) technology as a better way to reduce objectionable VOC’s as well as keep air-handlers free of microbial growth.
The project revolved around the refurbishment of the existing pre-treat AHU which was supplying code required conditioned ventilation air to various spaces within the hospital, including critical cardiovascular operating rooms. The main scope of the work included an upgrade of existing pre-filters and cooling coils along with the adbandonment of existing UVC lights and charcoal filtration (found ineffective and costly to maintain) in favor of the patented NBPI technology manufactured by Global Plasms Solutions (GPS) and supplied by HTS Texas.
The NBPI system installed at Methodist utilizes a method of artificially generating both positive and negative ions, which are found naturally occurring in the air, without generating an ozone byproduct. These ions have the beneficial property of clustering around and surrounding harmful substances such as airborne mold, virus, bacteria, volatile organic compounds and allergens.
In the past, various forms of gas-phase filtration had been implemented into HMH’s HVAC designs to remove pollutants from the entering outdoor air. Activated carbon had been widely used with varying levels of success. Some carbon filters were found to load quickly with pollutants, leaving them ineffective. In humid areas of the U.S., like Houston, they will absorb water vapor before any other chemicals, which limits their efficacy.NBPI was substituted for traditional gas-phase filtration, eliminating associated air-flow resistance and carbon replacement. The NBPI system requires no replacement parts, virtually no maintenance, and imposes little operating expense. The system design for HMH consumes only 120-watts of power.