The advent and application of high-throughput molecular techniques for analyzing microbial communities in the indoor environment have led to illuminating findings and are beginning to change the way ...we think about human health in relation to the built environment. Here I review recent studies on the microbiology of the built environment, organize their findings into 12 major thematic categories, and comment on how these studies have or have not advanced knowledge in each area beyond what we already knew from over 100 years of applying culture-based methods to building samples. I propose that while we have added tremendous complexity to the rich existing knowledge base, the practical implications of this added complexity remain somewhat elusive. It remains to be seen how this new knowledge base will change how we design, build, and operate buildings. Much more research is needed to better understand the complexity with which indoor microbiomes may affect human health in both positive and negative ways.
A mathematical model of an exterior wall covered with climbing vegetation has been developed to evaluate the thermal effects of plants on heat transfer through building facades. This model allows for ...analysis of how various plant physiological parameters such as leaf area index, average leaf dimension, and leaf absorptivity can improve facade thermal performance by reducing the exterior wall surface temperatures and heat flux through the façade. The model has been verified with a set of experiments that measured both bare and vegetated facade thermal performance of an educational building in Chicago, IL, during the summer. A sensitivity analysis was also conducted to elucidate the relative impacts of plant characteristics, weather conditions, climate zones, wall assembly types, and facade orientation on vegetated facade thermal performance. Overall, results herein show that a plant layer added to the facade can improve its effective thermal resistance by 0.0–0.7 m2 K/W, depending on a range of inputs for wall parameters, climate zones, and plant characteristics (particularly leaf area index). These improvements are especially pronounced in predominantly warm climates with high solar radiation and, to a lesser extent, low wind speeds. The model developed herein can ultimately be used both to access facade thermal improvements in existing buildings retrofitted with green walls and to design green walls for optimal energy efficiency in new construction.
•A model simulating the thermal effects of a building facade covered with plants has been developed.•The model was validated with an experiment measuring the existing building's bare and vegetated facade properties in summer.•The model's sensitivity to weather conditions and plant parameters was evaluated.•Facade plants can effectively reduce exterior surface temperature and heat flux through the facade.•Significant improvements to facade thermal performance occur on sunny days with little wind for dense vegetation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
This work describes and applies a methodology for estimating the impact of recirculating heating, ventilating, and air-conditioning (HVAC) particle filters on the control of size-resolved infectious ...aerosols in indoor environments using a modified version of the Wells-Riley model for predicting risks of infectious disease transmission. Estimates of risk reductions and associated operational costs of both HVAC filtration and equivalent outdoor air ventilation are modeled and compared using a case study of airborne transmission of influenza in a hypothetical office space. Overall, recirculating HVAC filtration was predicted to achieve risk reductions at lower costs of operation than equivalent levels of outdoor air ventilation, particularly for MERV 13–16 filters. Medium efficiency filtration products (MERV 7–11) are also inexpensive to operate but appear less effective in reducing infectious disease risks.
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•We modeled the impact of HVAC filters on influenza risks in an office environment.•The model is a modified version of the Wells-Riley model.•Higher-efficiency HVAC filters may yield lower risks of influenza infection.•HVAC filtration appears more cost effective than outdoor air ventilation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Accurate characterization of parameters that influence indoor environments is often limited to the use of proprietary hardware and software, which can adversely affect costs, flexibility, and data ...integration. Here we describe the Open Source Building Science Sensors (OSBSS) project, which we created to design and develop a suite of inexpensive, open source devices based on the Arduino platform for measuring and recording long-term indoor environmental and building operational data. The goal of OSBSS is to allow for more flexibility in synchronizing a large number of measurements with high spatial and temporal resolution in a cost effective manner for use in research projects and, eventually, in building automation and control. Detailed tutorials with instructions for constructing the data loggers using off-the-shelf electronic components are made available freely online. The project currently includes a variety of sensors and data loggers designed to measure a number of important parameters in buildings, including air and surface temperatures, air relative humidity, human occupancy, light intensity, CO2 concentrations, and a generic voltage data logger that can log data from a variety of other sensors such as differential pressure sensors. We also describe results from co-location tests with each data logger installed for one week in an educational building alongside their commercial counterparts, which demonstrate excellent performance at substantially lower costs.
•OSBSS is an inexpensive open-source platform for logging building environmental data.•Sensors include air temperature, relative humidity, occupancy, light, CO2, and more.•Tests alongside commercial counterparts demonstrate excellent performance.•Tutorials for constructing the data loggers are online at www.osbss.com
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
High efficiency particle air filters are increasingly being recommended for use in heating, ventilating, and air-conditioning (HVAC) systems to improve indoor air quality (IAQ). ISO Standard ...16890-2016 provides a methodology for approximating mass-based particle removal efficiencies for PM1, PM2.5, and PM10 using size-resolved removal efficiency measurements for 0.3 µm to 10 µm particles. Two historical volume distribution functions for ambient aerosol distributions are assumed to represent ambient air in urban and rural areas globally. The goals of this work are to: (i) review the ambient aerosol distributions used in ISO 16890, (ii) evaluate the sensitivity of the mass-based removal efficiency calculation procedures described in ISO 16890 to various assumptions that are related to indoor and outdoor aerosol distributions, and (iii) recommend several modifications to the standard that can yield more realistic estimates of mass-based removal efficiencies for HVAC filters, and thus provide a more realistic representation of a greater number of building scenarios. The results demonstrate that knowing the PM mass removal efficiency estimated using ISO 16890 is not sufficient to predict the PM mass removal efficiency in all of the environments in which the filter might be used. The main reason for this insufficiency is that the assumptions for aerosol number and volume distributions can substantially impact the results, albeit with some exceptions.
This work demonstrates an open-source hardware and software platform for monitoring the performance of buildings, called Elemental, that is designed to provide data on indoor environmental quality, ...energy usage, HVAC operation, and other factors to its users. It combines: (i) custom printed circuit boards (PCBs) with RFM69 frequency shift keying (FSK) radio frequency (RF) transceivers for wireless sensors, control nodes, and USB gateway, (ii) a Raspberry Pi 3B with custom firmware acting as either a centralized or distributed backhaul, and (iii) a custom dockerized application for the backend called Brood that serves as the director software managing message brokering via Message Queuing Telemetry Transport (MQTT) protocol using VerneMQ, database storage using InfluxDB, and data visualization using Grafana. The platform is built around the idea of a private, secure, and open technology for the built environment. Among its many applications, the platform allows occupants to investigate anomalies in energy usage, environmental quality, and thermal performance via a comprehensive dashboard with rich querying capabilities. It also includes multiple frontends to view and analyze building activity data, which can be used directly in building controls or to provide recommendations on how to increase operational efficiency or improve operating conditions. Here, we demonstrate three distinct applications of the Elemental platform, including: (1) deployment in a research lab for long-term data collection and automated analysis, (2) use as a full-home energy and environmental monitoring solution, and (3) fault and anomaly detection and diagnostics of individual building systems at the zone-level. Through these applications we demonstrate that the platform allows easy and virtually unlimited datalogging, monitoring, and analysis of real-time sensor data with low setup costs. Low-power sensor nodes placed in abundance in a building can also provide precise and immediate fault-detection, allowing for tuning equipment for more efficient operation and faster maintenance during the lifetime of the building.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Numerous studies have reported that ambient air pollution, which has both
local and long-range sources, causes adverse impacts on the environment and
human health. Previous studies have investigated ...the impacts of
transboundary air pollution (TAP) in East Asia, albeit primarily through
analyses of episodic events. In addition, it is useful to better understand
the spatiotemporal variations in TAP and the resultant impact on the
environment and human health. This study aimed at assessing and
quantifying the air quality impacts in Japan and South Korea due to local emissions and TAP from sources in East Asia - one of the most polluted
regions in the world. We applied state-of-the-science atmospheric
models to simulate air quality in East Asia and then analyzed the air
quality and acid deposition impacts of both local emissions and TAP sources
in Japan and South Korea. Our results show that ∼ 30 % of
the annual average ambient PM2.5 concentrations in Japan and South
Korea in 2010 were contributed to by local emissions within each country, while
the remaining ∼ 70 % were contributed to by TAP from other
countries in the region. More detailed analyses also revealed that the local
contribution was higher in the metropolises of Japan (∼ 40 %–79 %) and South Korea (∼ 31 %–55 %) and that minimal
seasonal variations in surface PM2.5 occurred in Japan, whereas there was a
relatively large variation in South Korea in the winter. Further, among all
five studied anthropogenic emission sectors of China, the industrial sector
represented the greatest contributor to annual surface PM2.5
concentrations in Japan and South Korea, followed by the residential and
power generation sectors. Results also show that TAP's impact on acid
deposition (SO42- and NO3-) was larger than TAP's impact
on PM2.5 concentrations (accounting for over 80 % of the total
deposition), and that seasonal variations in acid deposition were similar
for both Japan and South Korea (i.e., higher in both the winter and summer).
Finally, wet deposition had a greater impact on mixed forests in Japan and
savannas in South Korea. Given these significant impacts of TAP in the
region, it is paramount that cross-national efforts should be taken to mitigate air
pollution problems across East Asia.
The microorganisms that inhabit hospitals may influence patient recovery and outcome, although the complexity and diversity of these bacterial communities can confound our ability to focus on ...potential pathogens in isolation. To develop a community-level understanding of how microorganisms colonize and move through the hospital environment, we characterized the bacterial dynamics among hospital surfaces, patients, and staff over the course of 1 year as a new hospital became operational. The bacteria in patient rooms, particularly on bedrails, consistently resembled the skin microbiota of the patient occupying the room. Bacterial communities on patients and room surfaces became increasingly similar over the course of a patient's stay. Temporal correlations in community structure demonstrated that patients initially acquired room-associated taxa that predated their stay but that their own microbial signatures began to influence the room community structure over time. The α- and β-diversity of patient skin samples were only weakly or nonsignificantly associated with clinical factors such as chemotherapy, antibiotic usage, and surgical recovery, and no factor except for ambulatory status affected microbial similarity between the microbiotas of a patient and their room. Metagenomic analyses revealed that genes conferring antimicrobial resistance were consistently more abundant on room surfaces than on the skin of the patients inhabiting those rooms. In addition, persistent unique genotypes of
and
were identified. Dynamic Bayesian network analysis suggested that hospital staff were more likely to be a source of bacteria on the skin of patients than the reverse but that there were no universal patterns of transmission across patient rooms.
Recent studies have greatly increased our knowledge of microbial ecology of the indoor environments in which we live and work. However, the number of studies collecting robust, long-term data using ...standardized methods to characterize important building characteristics, indoor environmental conditions, or human occupancy – collectively referred to as “built environment data” – remain limited. Insufficiently described built environment data can limit our ability to compare microbial ecology results from one indoor environment to another or to use the results to assess how best to control indoor microbial communities. This work first reviews recent literature on microbial community characterization in indoor environments (primarily those that utilized molecular methods), paying particular attention to the level of assessment of influential built environment characteristics and the specific methods and procedures that were used to collect those data. Based on those observations, we then describe a large suite of indoor environmental and building design and operational parameters that can be measured using standardized methods to inform experimental design in future studies of the microbial ecology of the built environment. This work builds upon the recently developed MIxS-BE package that identifies high-level minimal built environment metadata to collect in microbial ecology studies, primarily by providing more justification, detail, and context for these important parameters and others from the perspective of engineers and building scientists. It is our intent to provide microbial ecologists with knowledge of many of the tools available for built environment data collection, as well as some of the constraints and considerations for these tools, which may improve our ability to design indoor microbial ecology studies that can better inform building design and operation.
•This work reviews recent literature on indoor microbial community characterization.•Studies can be grouped into three categories of built environment data collection.•Insufficiently described built environment data can limit utility of these studies.•We describe tools and methods to improve built environment data collection.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Mechanical ventilation systems are used in residences to introduce ventilation air and dilute indoor-generated pollutants. A variety of ventilation system types can be used in home retrofits, ...influencing indoor air quality (IAQ) in different ways. Here we describe the Breathe Easy Project, a >2-year longitudinal, pseudo-randomized, crossover study designed to assess IAQ and adult asthma outcomes before and after installing residential mechanical ventilation systems in 40 existing homes in Chicago, IL. Each home received one of three types of ventilation systems: continuous exhaust-only, intermittent powered central-fan-integrated-supply (CFIS), or continuous balanced system with an energy recovery ventilator (ERV). Homes with central heating and/or cooling systems also received MERV 10 filter replacements. Approximately weeklong field measurements were conducted at each home on a quarterly basis throughout the study to monitor environmental conditions, ventilation operation, and indoor and outdoor pollutants, including size-resolved particles (0.3–10 μm), ozone (O3), nitrogen dioxide (NO2), carbon dioxide (CO2), carbon monoxide (CO), and indoor formaldehyde (HCHO). Mean reductions in indoor/outdoor (I/O) ratios across all systems after the intervention were approximately 12% (p = 0.001), 10% (p = 0.008), 42% (p < 0.001), 39% (p = 0.002), and 33% (p = 0.007), for CO2, NO2, and estimated PM1, PM2.5, and PM10, respectively. There was a reduction in I/O ratios for all measured constituents with each type of system, on average, but with varying magnitude and levels of statistical significance. The magnitudes of mean differences in I/O pollutant concentrations ratios were generally largest for most pollutants in the homes that received continuous balanced with ERV and smallest in the homes that received intermittent CFIS systems, with apparent benefits to providing ventilation continuously rather than intermittently. All ventilation system types maintained similar indoor temperatures during pre- and post-intervention periods.
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•Measured indoor air quality impacts of residential mechanical ventilation retrofits•Evaluated continuous exhaust, continuous balanced, and intermittent supply systems•2-Year crossover study with quarterly weeklong field visits pre- and post-retrofit•Ventilation (and filtration) retrofits reduced indoor/outdoor pollutant ratios.•Continuous ventilation systems were more effective than intermittent.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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