Spatial and temporal variations in indoor environmental conditions, human occupancy, and operational characteristics in a new hospital building.

The dynamics of indoor environmental conditions, human occupancy, and operational characteristics of buildings influence human comfort and indoor environmental quality, including the survival and progression of microbial communities. A suite of continuous, long-term environmental and operational parameters were measured in ten patient rooms and two nurse stations in a new hospital building in Chicago, IL to characterize the indoor environment in which microbial samples were taken for the Hospital Microbiome Project. Measurements included environmental conditions (indoor dry-bulb temperature, relative humidity, humidity ratio, and illuminance) in the patient rooms and nurse stations; differential pressure between the patient rooms and hallways; surrogate measures for human occupancy and activity in the patient rooms using both indoor air CO2 concentrations and infrared doorway beam-break counters; and outdoor air fractions in the heating, ventilating, and air-conditioning systems serving the sampled spaces. Measurements were made at 5-minute intervals over consecutive days for nearly one year, providing a total of ∼8×106 data points. Indoor temperature, illuminance, and human occupancy/activity were all weakly correlated between rooms, while relative humidity, humidity ratio, and outdoor air fractions showed strong temporal (seasonal) patterns and strong spatial correlations between rooms. Differential pressure measurements confirmed that all patient rooms were operated at neutral pressure. The patient rooms averaged about 100 combined entrances and exits per day, which suggests they were relatively lightly occupied compared to higher traffic environments (e.g., retail buildings) and more similar to lower traffic office environments. There were also clear differences in several environmental parameters before and after the hospital was occupied with patients and staff. Characterizing and understanding factors that influence these building dynamics is vital for hospital environments, where they can impact patient health and the survival and spread of healthcare associated infections

Indoor Environmental Measurements in the Hospital Microbiome Project: Estimation of Human Occupancy and Occupant Activity

Human occupants have a profound influence on indoor environments, although there is limited information on means to cost-effectively assess occupant metrics in all types of buildings. Multiple methods to estimate occupancy and occupant activity (i.e., doorway movements) were investigated in ten single-patient rooms in a new hospital in Chicago, Illinois, as part of the Hospital Microbiome Project. The overarching goal was to determine occupant characteristics to inform an investigation of interactions between humans, microbial communities, and environmental parameters. A method that utilized data from non-directional doorway beam-break and CO2 concentration sensors produced the most accurate estimates of both occupant parameters. Estimates revealed that daily occupant activity varied less than occupancy, but also reached high levels in certain instances. The dual-sensor methodology investigated in this thesis provides a relatively inexpensive, non-invasive, accurate approach to estimate occupancy and occupant activity in an environment with rigorous privacy and security limitations.M.A.S

Moisture parameters and fungal communities associated with gypsum drywall in buildings

Abstract Uncontrolled excess moisture in buildings is a common problem that can lead to changes in fungal communities. In buildings, moisture parameters can be classified by location and include assessments of moisture in the air, at a surface, or within a material. These parameters are not equivalent in dynamic indoor environments, which makes moisture-induced fungal growth in buildings a complex occurrence. In order to determine the circumstances that lead to such growth, it is essential to have a thorough understanding of in situ moisture measurement, the influence of building factors on moisture parameters, and the levels of these moisture parameters that lead to indoor fungal growth. Currently, there are disagreements in the literature on this topic. A literature review was conducted specifically on moisture-induced fungal growth on gypsum drywall. This review revealed that there is no consistent measurement approach used to characterize moisture in laboratory and field studies, with relative humidity measurements being most common. Additionally, many studies identify a critical moisture value, below which fungal growth will not occur. The values defined by relative humidity encompassed the largest range, while those defined by moisture content exhibited the highest variation. Critical values defined by equilibrium relative humidity were most consistent, and this is likely due to equilibrium relative humidity being the most relevant moisture parameter to microbial growth, since it is a reasonable measure of moisture available at surfaces, where fungi often proliferate. Several sources concur that surface moisture, particularly liquid water, is the prominent factor influencing microbial changes and that moisture in the air and within a material are of lesser importance. However, even if surface moisture is assessed, a single critical moisture level to prevent fungal growth cannot be defined, due to a number of factors, including variations in fungal genera and/or species, temperature, and nutrient availability. Despite these complexities, meaningful measurements can still be made to inform fungal growth by making localised, long-term, and continuous measurements of surface moisture. Such an approach will capture variations in a material’s surface moisture, which could provide insight on a number of conditions that could lead to fungal proliferation

Additional file 3: Table S3. of Moisture parameters and fungal communities associated with gypsum drywall in buildings

Additional information for critical moisture values to prevent microbial growth defined in the literature. Corresponds to Figs. 4 and 5 in the main text. This table presents the critical moisture values extracted from the literature that were used to generate Figs. 4 and 5, and includes information on temperature, environment, document type, and scenario [95, 91, 96–98]. (DOCX 34 kb

Additional file 2: Table S2. of Moisture parameters and fungal communities associated with gypsum drywall in buildings

Moisture measurement frequency in the literature—additional information for Fig. 3 in the main text. This table presents the moisture parameters measured, categorized by measurement environment, in the 27 studies data used to create Fig. 3 [87–90, 92–94]. (DOCX 23 kb

Spatial and Temporal Variations in Indoor Environmental Conditions, Human Occupancy, and Operational Characteristics in a New Hospital Building

The dynamics of indoor environmental conditions, human occupancy, and operational characteristics of buildings influence human comfort and indoor environmental quality, including the survival and progression of microbial communities. A suite of continuous, long-term environmental and operational parameters were measured in ten patient rooms and two nurse stations in a new hospital building in Chicago, IL to characterize the indoor environment in which microbial samples were taken for the Hospital Microbiome Project. Measurements included environmental conditions (indoor dry-bulb temperature, relative humidity, humidity ratio, and illuminance) in the patient rooms and nurse stations; differential pressure between the patient rooms and hallways; surrogate measures for human occupancy and activity in the patient rooms using both indoor air CO2 concentrations and infrared doorway beam-break counters; and outdoor air fractions in the heating, ventilating, and air-conditioning systems serving the sampled spaces. Measurements were made at 5-minute intervals over consecutive days for nearly one year, providing a total of ∼8×106 data points. Indoor temperature, illuminance, and human occupancy/activity were all weakly correlated between rooms, while relative humidity, humidity ratio, and outdoor air fractions showed strong temporal (seasonal) patterns and strong spatial correlations between rooms. Differential pressure measurements confirmed that all patient rooms were operated at neutral pressure. The patient rooms averaged about 100 combined entrances and exits per day, which suggests they were relatively lightly occupied compared to higher traffic environments (e.g., retail buildings) and more similar to lower traffic office environments. There were also clear differences in several environmental parameters before and after the hospital was occupied with patients and staff. Characterizing and understanding factors that influence these building dynamics is vital for hospital environments, where they can impact patient health and the survival and spread of healthcare associated infections.</p

Variations between floors for hourly average air temperature, relative humidity, humidity ratio, illuminance, and room CO₂ concentration, as well as hourly total IR beam-breaks.

<p>Box plots display median values in the center, bounded by the interquartile range in gray and extreme values at top and bottom. Figures exclude outlier values for clarity.</p

Weekly averages of environmental conditions in the patient rooms and nurse stations measured over the duration of the project: (a) temperature, (b) relative humidity, (c) humidity ratio, and (d) illuminance.

<p>Rooms 101–105 are on the 9^th floor; rooms 201–205 are on the 10^th floor. Room 100 and 200 are the nurse station locations on the 9^th and 10^th floor, respectively. Weeks are counted from the week of hospital opening (i.e., week 0). White areas represent missing values. Values along the x-axes correspond to room identification numbers. Examples time series data at 5-min intervals for one day are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0118207#pone.0118207.s005" target="_blank">S5 Fig.</a></p

Variations between nighttime and daytime periods for hourly average air temperature, humidity ratio, illuminance, room CO₂ concentration, and outdoor air fraction, as well as hourly total IR beam-breaks.

<p>Box plots display median values in the center, bounded by the interquartile range in gray and extreme values at top and bottom. Figures exclude outlier values for clarity.</p

Typical patient room showing locations of built environment sensors and microbial sampling sites.

<p>Sketch of a typical patient room in the hospital. Green shaded areas show microbiological sampling sites; areas circled in blue show locations of the building science measurements sites used herein. The nurse stations, although not pictured, were centrally located to the right of the figure (in the gray area).</p