Wu PC1, Li YY, Chiang CM, Huang CY, Lee CC, Li FC, Su HJ.Author information1Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, Tainan, Taiwan.AbstractOur study conducted serial environmental measurements in 12 large office buildings with two different ventilation designs to obtain airborne microbial concentrations in typical office buildings, and to examine the effects of occupant density, ventilation type and air exchange efficiency on indoor microbial concentrations. Duplicate samples of airborne fungi and bacteria, a total of 2477 measurements, were collected based on a scheme of conducting sampling three times a day for at least seven consecutive days at every study building. Air change rates (ACHs) were also estimated by tracer gas concentration decay method, and measured by continuous Multi-Gas monitor for each building. Most sampling sites were with total fungal and bacteria concentrations higher than 1000 CFU/m(3), an often-quoted guideline in earlier research.

Significantly higher concentrations of fungi and bacteria, as well as higher indoor/outdoor (I/O) ratios across most groups of airborne microbes, were identified in buildings with fan coil unit (FCU) system than those with air-handling unit (AHU) system (Student's t test, P < 0.0001). Older buildings and higher air exchange rates were statistically associated with greater indoor bacteria levels in FCU ventilated buildings (R(2) = 0.452); a pattern not found in AHU buildings. Increasing ACH seemed to be the determinant factor for rising indoor fungal and Cladosporium concentrations in those FCU buildings (R(2) = 0.346; 0.518). Our data indicated that FCU ventilated buildings might have provided more outdoor matters into indoor environments through direct penetration of outdoor air. Results also demonstrated a quantitative association between rising numbers of occupants and increasing indoor levels of yeast in both FCU and AHU ventilated buildings. The regression model identified in this study may be considered a reference value for proposing an optimal ACH, while with adequate filtration of fresh air, as an effective strategy in lowering indoor microbial concentrations in air-conditioned buildings.

PRACTICAL IMPLICATIONS: As control of indoor microbial contamination has become an increasing concern around the world, feasibility and effectiveness of adopting ventilation approach has attracted a significant interest. This field investigation demonstrated, quantitatively, critical variables to be taken into consideration while applying such a measure, including the kinds of microbes to be removed and the types of ventilation system already in place.PMID: 15660566 DOI: 10.1111/j.1600-0668.2004.00313.x [PubMed - indexed for MEDLINE] Publication TypesResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.MeSH TermsAir Conditioning*Air MovementsAir Pollution, Indoor/analysis*Bacteria/growth & development*Bacteria/isolation & purification*Environmental MonitoringFacility Design and ConstructionFungi/growth & development*Fungi/isolation & purification*HumansPopulation Density*Regression AnalysisTaiwanVentilation*Full Text SourcesWileyOvid Technologies, Inc.MedicalIndoor Air Pollution - MedlinePlus Health InformationMolds - MedlinePlus Health Information

The FCU water cassette fan-coils unit is an air-conditioning terminal unit for installation within a false-ceiling with the air distribution flush mounted on the underside of the ceiling. This range of units are particularly suitable for this type of installation due to their minimum height of only 26 cm (except for 80-120 series).reset button gibson ac unit These units are suitable for both summer and winter air-conditioning using ChW and LPHW.dometic air conditioning units for caravansHVAC Acronyms and Abbreviationsinstalling ac unit in casement window Here’s a list we’ve compiled of many of the HVAC acronyms and HVAC abbreviations that are seen regularly. What it stands for … Air Changes per Hour

Association of Energy Engineers Annual Fuel Efficiency Ratio American Society of Heating Refrigeration and Air Conditioning Engineers A Data Communication Protocol for Building Automation and Control Networks Brtish Thermal Units / Hour Cubic Feet per Minute Chilled Water Return Temperature Chilled Water Supply Temperature Cooling Load Temperature Difference Computer Room Air Conditioner Coefficient of Variation of the Root Mean Square of the Error Condenser Water Return Temperature Condenser Water Supply Temperature High Efficiency Particulate Arresting Heating Hot Water Pump Heating Hot Water Return Heating Hot Water Supply Heating Seasonal Performance Factor Heating Ventilation and Air Conditioning Hot Water Return Temperature Hot Water Supply Temperature International Performance Measurement and Verification Protocol Leaving Wet Bulb Temperature Metrix Utility Accounting System

National Electrical Manufacturers Association Net Positive Suction Head Packaged Terminal Air Conditioner Seasonal Energy Efficiency Ratio Solar Heat Gain Factor Millimeter of Mercury (mmHg)Navy Air Handling Units (AHU) Maintain fully supported and fully integrated HVAC systems. DRS’ Navy heating, ventilating, air conditioning air handling units (AHU) are designed to comply with Navy specifications, are first article qualified and, in many cases, are qualified provided listed. Our Navy AHUs are manufactured with proven performance and quality construction, and are fully supported with replacement parts and full integrated logistics support data. Our short manufacturing lead times make our Navy AHUs readily available for both new construction, and overhaul and repair. Navy air handling unit products Self Contained Air Conditioners (SCAC) per MIL-A-19865 Fan Coil Assemblies (FCA) per MIL-A-23798 Fan Coil Units (FCU) per MIL-A-24775