Building Water Systems Research Articles

Optimizing the topologies of heating, ventilation, and air-conditioning water systems in supertall buildings: A pilot study

The vertical topologies of HVAC water systems in supertall buildings are one major concern, which yet has been determined in experience-based manners. Therefore, the current article proposes a computational optimization procedure to search optimal design of system topologies, as well as component sizing and control settings. To reduce the computational efforts, the vertical topologies are simplified by considering only major components (e.g., air-handling units, heat exchangers, and chillers).Since both electricity consumption and capital cost are primary concerns for system design, the optimization problem has been solved using a two-objective solver, Nondominated Sorting Genetic Algorithm II. This optimization problem is then validated using a supertall building in Shanghai, and it is concluded that the generated solutions are superior in terms of both electricity consumption and capital cost. Finally, parametric analyses are conducted to provide insight into the uncontrollable variables (i.e., building location, building characteristics) with the hope that system design can be facilitated.

Implementation of a Legionella Ordinance for Multifamily Housing, Garland, Texas.

Context:The incidence of legionellosis has sharply increased in the United States as a result of contaminated water systems. Jurisdictions across the country are considering whether to develop and implement regulations to protect individuals against Legionnaires' disease with its associated high morbidity and mortality.Objective:This article sheds light on the implementation and effectiveness of a 2005 citywide Legionella testing mandate of multifamily housing cooling towers in Garland, Texas. This ordinance has been in place for more than 10 years and represents the first of its kind in the United States to mandate routine testing of cooling towers for Legionella in multifamily housing.Design, Setting, and Population:We utilized a mix of both qualitative and quantitative methods to explore the development, adoption, and implementation of the ordinance. Phone interviews were conducted with individuals from the City of Garland Health Department and apartment managers. Quantitative data included public health surveillance data on legionellosis.Main Outcome Measures:Barriers and facilitators of implementation, number and percentage of cooling towers from multifamily housing units that tested positive for Legionella by year, and number of legionellosis cases by year in Garland, Texas.Results:Study outcomes highlight key themes that facilitated the successful implementation of the Legionella testing mandate, including the importance of timing, leadership support, stakeholder engagement, and education and outreach. The number of contaminated cooling towers was reduced over time.Conclusion:Mandatory monitoring for legionella in a local jurisdiction may result in reduced risk of legionellosis from cooling towers through raising awareness and education of building owners and managers about the need to prevent, detect, and remediate legionella contamination in their building water systems. Garland, Texas, broke new ground in the United States in moving toward primary prevention of legionellosis. The ordinance may be useful both in serving to educate and increase awareness about the need for Legionella prevention and to monitor effectiveness of maintenance procedures.

Carbon Dioxide Reduction Targets of Hot Water Showers for People in Hong Kong

Improving water and energy efficiency in buildings is one of the best ways to reduce greenhouse gas emissions. This study examines various energy-related carbon dioxide (CO2) reduction measures, including the use of water efficient showerheads and shower drain water heat recovery, in order to distinguish the significance of user influence on the water usage of a shower. The probability of taking a hot shower and the number of showers taken by an occupant per day, which can be evaluated from open literature data, are used as the parameters of user responses to water conservation measures in this study. A Monte Carlo model of water consumption and CO2 reduction for showering is adopted to determine the contributions of user responses. The results demonstrate that the influence of users on CO2 reduction is significant and compatible to the influence of water efficient showerheads. This study can be used as a reference to enhance water and energy incentives and to facilitate continuous improvement in building water systems.

Building Water and Wastewater System Resilience to Disaster Migration: Utility Perspectives

AbstractThis paper leverages expert knowledge from leaders in water and wastewater utilities to anticipate water and wastewater infrastructure impacts in communities that host populations displaced...

Vital Signs: Health Care-Associated Legionnaires' Disease Surveillance Data from 20 States and a Large Metropolitan Area - United States, 2015.

BackgroundLegionnaires’ disease, a severe pneumonia, is typically acquired through inhalation of aerosolized water containing Legionella bacteria. Legionella can grow in the complex water systems of buildings, including health care facilities. Effective water management programs could prevent the growth of Legionella in building water systems.MethodsUsing national surveillance data, Legionnaires’ disease cases were characterized from the 21 jurisdictions (20 U.S. states and one large metropolitan area) that reported exposure information for ≥90% of 2015 Legionella infections. An assessment of whether cases were health care–associated was completed; definite health care association was defined as hospitalization or long-term care facility residence for the entire 10 days preceding symptom onset, and possible association was defined as any exposure to a health care facility for a portion of the 10 days preceding symptom onset. All other Legionnaires’ disease cases were considered unrelated to health care.ResultsA total of 2,809 confirmed Legionnaires’ disease cases were reported from the 21 jurisdictions, including 85 (3%) definite and 468 (17%) possible health care–associated cases. Among the 21 jurisdictions, 16 (76%) reported 1–21 definite health care–associated cases per jurisdiction. Among definite health care–associated cases, the majority (75, 88%) occurred in persons aged ≥60 years, and exposures occurred at 72 facilities (15 hospitals and 57 long-term care facilities). The case fatality rate was 25% for definite and 10% for possible health care–associated Legionnaires’ disease.Conclusions and Implications for Public Health PracticeExposure to Legionella from health care facility water systems can result in Legionnaires’ disease. The high case fatality rate of health care–associated Legionnaires’ disease highlights the importance of case prevention and response activities, including implementation of effective water management programs and timely case identification.

Eco-efficiency analysis of non-potable water systems in domestic buildings

Energy efficiency in water systems contributes significantly towards achieving sustainable water management. Decentralized anaerobic fluidized bed membrane bioreactor (AFMBR) systems with energy recovery have been proposed for greywater recycling in domestic buildings for non-potable uses, such as toilet flushing. This study developed an eco-efficiency analysis (EEA) framework with the integration of life-cycle assessment (LCA) and economic analysis for the evaluation of different water systems. Four water management scenarios including (1) freshwater flushing system, (2) seawater flushing system, (3) greywater flushing system adopting aerobic membrane bioreactor (MBR), and (4) greywater flushing system adopting AFMBR, were analyzed in a case study in Hong Kong. The EEA results reveal the AFMBR greywater reuse scenario to be the most eco-efficient option as the system is capable of energy recovery, recycling of water resource and reduction of sewage treatment loadings. This study has demonstrated that the EEA framework is an effective tool to guide water management towards sustainability and provides a basis for further research on the application of greywater recycling systems on a larger scale.

On-filter direct amplification of Legionella pneumophila for rapid assessment of its abundance and viability

Guidelines and regulations to control Legionella pneumophila in cooling water systems of large buildings are evolving due to the increasing number of outbreaks. Rapid, on-site, simple, and sensitive quantification methods that are also able to assess viability may be extremely useful in monitoring and control. Culture-based methods for measuring L. pneumophila may take 4–10 days and qPCR-based methods are also slow, requiring at least a day from sample to result, albeit mainly due to the need for sample transport to a centralized laboratory. This study reports a rapid isothermal amplification method for L. pneumophila concentration and detection with live/dead differentiation under field conditions. Using an on-filter direct amplification (i.e., amplification of cells without DNA extraction and purification) approach with propidium monoazide (PMA), and a real time isothermal amplification platform (Gene-Z), L. pneumophila could be detected in 1–2 h at ∼1 cfu/100 ml of tap water. Signature sequences from 16S rRNA and cadA genes were used as genetic markers for L. pneumophila and loop-mediated isothermal amplification (LAMP) primers were designed using Primer Explorer V4. Result were also compared with direct amplification of cells spiked into distilled, tap, and cooling water samples as well as extracted DNA by qPCR. This method may be useful to managers of cooling water systems in large buildings for rapid detection of L. pneumophila. The overall approach of on-site sample concentration, on-filter amplification, and live/dead differentiation may be extended to other organisms where analytical sensitivity and speed are equally important.

Sanitary evaluation of domestic water supply facilities with storage tanks and detection of Aeromonas, enteric and related bacteria in domestic water facilities in Okinawa Prefecture of Japan

To provide for temporary restrictions of the public water supply system, storage tanks are commonly installed in the domestic water systems of houses and apartment buildings in Okinawa Prefecture of Japan. To learn more about the sanitary condition and management of these water supply facilities with storage tanks (hereafter called “storage tank water systems”) and the extent of bacterial contamination of water from these facilities, we investigated their usage and the existence of Aeromonas, enteric and related bacteria.Verbal interviews concerning the use and management of the storage tank water systems were carried out in each randomly sampled household. A total of 54 water samples were collected for bacteriological and physicochemical examinations. Conventional methods were used for total viable count, fecal coliforms, identification of bacteria such as Aeromonas, Enterobacteriaceae and non-fermentative Gram-negative rods (NF-GNR), and measurement of residual chlorine. On Aeromonas species, tests for putative virulence factor and an identification using 16S rRNA and rpoB genes were also performed.Water from the water storage systems was reported to be consumed directly without boiling in 22 of the 54 houses (40.7%). 31 of the sampled houses had installed water storage tanks of more than 1 cubic meter (m3) per inhabitant, and in 21 of the sampled houses, the tank had never been cleaned. In all samples, the total viable count and fecal coliforms did not exceed quality levels prescribed by Japanese waterworks law. Although the quantity of bacteria detected was not high, 23 NF-GNR, 14 Enterobacteriaceae and 5 Aeromonas were isolated in 42.6%, 7.4% and 3.7% of samples respectively. One isolated A. hydrophila and four A. caviae possessed various putative virulence factors, especially A. hydrophila which had diverse putative pathogenic genes such as aer, hlyA, act, alt, ast, ser, and dam. Many bacteria were isolated when the concentration of residual chlorine was below 0.1 mg/l and the water temperature was above 20 °C. These results suggest that elevated water temperature and mismatch between tank size and water demand lead to loss of residual chlorine in tap water. Therefore, to minimize growth of aquatic bacteria such as Aeromonas spp. and Pseudomonas spp., we recommend that an appropriate size tank and/or volume of stored water is always used, and also suggest installation of some means of reducing water temperature such as shading.

Assessment of antibiotic susceptibility of Legionella pneumophila isolated from water systems in Poland.

Several studies have reported therapy failures in patients with legionnaires'disease; however, antimicrobial resistance of clinical and environmental isolates of Legionella spp. has not yet been documented. Routine susceptibility testing of Legionella spp. is not recommended because of difficulties in determining standard minimal inhibitory concentration values. The purpose of this study was to analyze the antimicrobial susceptibility of Legionella pneumophila. strains isolated from a water supply system. Twenty-eight isolates of L. pneumophila (16 - L. pneumophila SG 1, 12 - L. pneumophila SG 2-14) obtained from water systems in public buildings in Poland were tested. Susceptibility testing was performed using the E-test method. The tested antibiotic were azithromycin, ciprofloxacin, and rifampicin. The medium used for the susceptibility testing was BCYE-, a special medium for Legionella cultivation. Among the tested strains, L. pneumophila was the only one resistant to azithromycin. It was a strain of L. pneumophila SG 2-14 isolated from the water system in a sanitorium. All isolates were found to be sensitive to ciprofloxacin and rifampicin. However, the azithromycin-resistant strain exhibited higher ciprofloxacin and rifampicin MIC (1.5 μg/ml, and 0.19 μg/ml, respectively). The MIC50 for azithromycin, ciprofloxacin, and rifampicin were 0,032, 0,125, and 0,003 μg/ml, respectively. The MIC90 for azithromycin, ciprofloxacin, and rifampicin were 0,032, 0,125, and 0,003 μg/ml, respectively. Azithromycin resistance was found in one strain of L. pneumophila SG 2-14, but the resistance mechanism is unknown and needs further study. It is possible that therapeutic failures in Legionnaires' disease may be associated with bacterial resistance which should be taken into account. The antibiotic sensitivity testing described in this study could be helpful in detecting the resistance of clinical L. pneumophila isolates. Ciprofloxacin and rifampicin have good in vitro activity against environmental L. pneumophila SG 1 and SG 2-14 in Poland.

Vital Signs: Deficiencies in Environmental Control Identified in Outbreaks of Legionnaires’ Disease—North America, 2000–2014

Background The number of reported cases of Legionnaires’ disease, a severe pneumonia caused by the bacterium Legionella, is increasing in the United States. During 2000–2014, the rate of reported legionellosis cases increased from 0.42 to 1.62 per 100 000 persons; 4% of reported cases were outbreak-associated. Legionella is transmitted through aerosolization of contaminated water. A new industry standard for prevention of Legionella growth and transmission in water systems in buildings was published in 2015. CDC investigated outbreaks of Legionnaires’ disease to identify gaps in building water system maintenance and guide prevention efforts. Methods Information from summaries of CDC Legionnaires’ disease outbreak investigations during 2000–2014 was systematically abstracted, and water system maintenance deficiencies from land-based investigations were categorized as process failures, human errors, equipment failures, or unmanaged external changes. Results During 2000–2014, CDC participated in 38 field investigations of Legionnaires’ disease. Among 27 land-based outbreaks, the median number of cases was 10 (range = 3–82) and median outbreak case fatality rate was 7% (range = 0–80%). Sufficient information to evaluate maintenance deficiencies was available for 23 (85%) investigations. Of these, all had at least one deficiency; 11 (48%) had deficiencies in ≥2 categories. Fifteen cases (65%) were linked to process failures, 12 (52%) to human errors, eight (35%) to equipment failures, and eight (35%) to unmanaged external changes. Conclusions and Implications for Public Health Practice Multiple common preventable maintenance deficiencies were identified in association with disease outbreaks, highlighting the importance of comprehensive water management programs for water systems in buildings. Properly implemented programs, as described in the new industry standard, could reduce Legionella growth and transmission, preventing Legionnaires’ disease outbreaks and reducing disease.

Legionnaires' Disease

Abstract Almost 40 years ago, Legionella pneumophila was initially recognized as the cause of a major respiratory outbreak. Since the first description of Legionnaires' disease, surveillance schemes have been implemented worldwide; however, legionellosis is still an underdiagnosed and underreported entity. Legionella pneumophila causes a severe inflammatory pneumonia that primarily affects susceptible patients as a result of advanced age, underlying debilitating conditions, and immunosuppression. Organ-specific and extrapulmonary manifestations have also been described. Cooling towers and water systems in buildings and hospitals have been reported to be environmental reservoirs that commonly harbor this pathogen. Numerous prevention guidelines vary in scope, and effective surveillance and detection systems are required for early clinical intervention. Various diagnostic tests are available, but they do not offer the desired sensitivity. To date, urinary antigen testing is still the most rapid and inexpensive method used in the diagnosis of Legionella infection. Culture and isolation of L. pneumophila from clinical specimens are not as cost-effective as other diagnostic methods, but they continue to be the criterion standard for the diagnosis of Legionnaires' disease. The newer macrolides and respiratory tract fluoroquinolones are highly effective in the treatment of Legionella infection. Current understanding of Legionnaires' disease is crucial in the identification and management of major outbreaks.

Investigation and modelling of the centralized solar domestic hot water system in residential buildings

The solar domestic hot water (DHW) system is applied as a building energy saving technique. The centralized system, which is considered to provide both energy efficiency by exploiting solar energy and high-level services to the customers as the occupants could have access to the hot water at any time during the day, is widely used among the various forms of solar DHW systems. The real performance of a centralized solar DHW system is measured, based on which a model describing the solar energy collection, water supply, and terminal water use is built. The simulation reveals that the actual energy performance of the centralized DHW system is closely related with the occupant behaviour, i.e., the water use patterns of the occupants residing in a building. This study concluded that whether the DHW system is energy efficient or not could not be evaluated without considering the water use patterns of the occupants.

Vital Signs: Deficiencies in Environmental Control Identified in Outbreaks of Legionnaires' Disease - North America, 2000-2014.

The number of reported cases of Legionnaires' disease, a severe pneumonia caused by the bacterium Legionella, is increasing in the United States. During 2000-2014, the rate of reported legionellosis cases increased from 0.42 to 1.62 per 100,000 persons; 4% of reported cases were outbreak-associated. Legionella is transmitted through aerosolization of contaminated water. A new industry standard for prevention of Legionella growth and transmission in water systems in buildings was published in 2015. CDC investigated outbreaks of Legionnaires' disease to identify gaps in building water system maintenance and guide prevention efforts. Information from summaries of CDC Legionnaires' disease outbreak investigations during 2000-2014 was systematically abstracted, and water system maintenance deficiencies from land-based investigations were categorized as process failures, human errors, equipment failures, or unmanaged external changes. During 2000-2014, CDC participated in 38 field investigations of Legionnaires' disease. Among 27 land-based outbreaks, the median number of cases was 10 (range = 3-82) and median outbreak case fatality rate was 7% (range = 0%-80%). Sufficient information to evaluate maintenance deficiencies was available for 23 (85%) investigations. Of these, all had at least one deficiency; 11 (48%) had deficiencies in ≥2 categories. Fifteen cases (65%) were linked to process failures, 12 (52%) to human errors, eight (35%) to equipment failures, and eight (35%) to unmanaged external changes. Multiple common preventable maintenance deficiencies were identified in association with disease outbreaks, highlighting the importance of comprehensive water management programs for water systems in buildings. Properly implemented programs, as described in the new industry standard, could reduce Legionella growth and transmission, preventing Legionnaires' disease outbreaks and reducing disease.

Robust optimal design of chilled water systems in buildings with quantified uncertainty and reliability for minimized life-cycle cost

Conventional design of chilled water systems is typically based on the peak cooling loads of buildings, while the cooling load reaches its peak level for only a small proportion of time in a year. This results in that design flow of chilled water system could be significantly oversized in actual operation and it thus causes significant energy wastes. In this paper, a robust optimal design based on minimized life-cycle cost is proposed to optimize the design of chilled water pump systems while concerning the uncertainties of design inputs and models as well as the component reliability in operation. Monte Carlo simulation is used to generate the cooling load distribution and hydraulic resistance distribution by quantifying the uncertainties. Markov method is used to obtain the probability distribution of the system state. Under different control methods, this proposed design method minimizes the annual total cost. A case study on a building in Hong Kong is conducted to demonstrate the design process and validate the robust optimal design method. Results show that the system could operate at a relatively high efficiency and the minimum total life-cycle cost could be achieved.

In-situ implementation and evaluation of an online robust pump speed control strategy for avoiding low delta-T syndrome in complex chilled water systems of high-rise buildings

The low delta-T syndrome is one of the major faults that affect the operation and energy performance of the chilled water systems in practice, particularly for the complex chilled water systems. Low delta-T syndrome refers to the situation where the measured mean temperature difference of the overall terminal air-handling units is much lower than the expected normal value. The conventional pump speed control strategies lack the ability to handle the low delta-T syndrome. This paper presents an online robust control strategy for practical applications to avoid the low delta-T syndrome for chilled water systems including complex systems. On top of the conventional control strategies, a temperature set-point reset scheme is developed aiming at providing the reliable temperature set-point for enhancing the operation reliability of chilled water pumps. In addition, a flow-limiting control scheme is employed to perform the function of actively eliminating the deficit flow in the bypass line by a feedback mechanism. This robust pump speed control strategy has been implemented and evaluated on a real complex chilled water system in a high-rise building. The site test results show that the temperature set-point given by the proposed strategy is reliable and the system temperature difference is significantly raised by eliminating the deficit flow problem. When compared to the conventional control strategies, 78% of the total chilled water pump energy was saved in the test period. The actual pump energy saving percentage could be 39% in a year after implementing the robust control strategy in the studied system.

Investigation and Modelling of the Centralized Solar Domestic Hot Water System in Residential Buildings

The solar domestic hot water system is currently widely applied as a building energy saving technique. Various forms of the system exist, which should be properly applied in practical engineering. It is significant to study the adaptability of the solar domestic hot water system as it accounts for the building energy consumption in a non-negligible proportion, which is still scarcely studied based on field measurements in current research. This study figured out the performance of the centralized solar domestic hot water system through field measurements, as well as built a sub-hourly simulation model, which has been validated with the field measurement. The model was used to analyse the influence of several factors on the energy consumption of the system, such as the water supply strategy, the use modes of occupants, the thermal insulation of pipes, and the forms of the system. The adaptability of the system was concluded.

Survey of green building water systems reveals elevated water age and water quality concerns

Widespread adoption of innovative water conservation strategies has potential unintended consequences for aesthetics and public health.

Geostatistics - a tool applied to the distribution of Legionella pneumophila in a hospital water system.

Legionnaires' disease is normally acquired by inhalation of legionellae from a contaminated environmental source. Water systems of large buildings, such as hospitals, are often contaminated with legionellae and therefore represent a potential risk for the hospital population. The aim of this study was to evaluate the potential contamination of Legionella pneumophila (LP) in a large hospital in Italy through georeferential statistical analysis to assess the possible sources of dispersion and, consequently, the risk of exposure for both health care staff and patients. LP serogroups 1 and 2-14 distribution was considered in the wards housed on two consecutive floors of the hospital building. On the basis of information provided by 53 bacteriological analysis, a 'random' grid of points was chosen and spatial geostatistics or FAIk Kriging was applied and compared with the results of classical statistical analysis. Over 50% of the examined samples were positive for Legionella pneumophila. LP 1 was isolated in 69% of samples from the ground floor and in 60% of sample from the first floor; LP 2-14 in 36% of sample from the ground floor and 24% from the first. The iso-estimation maps show clearly the most contaminated pipe and the difference in the diffusion of the different L. pneumophila serogroups. Experimental work has demonstrated that geostatistical methods applied to the microbiological analysis of water matrices allows a better modeling of the phenomenon under study, a greater potential for risk management and a greater choice of methods of prevention and environmental recovery to be put in place with respect to the classical statistical analysis.

An ontology-based decision support tool for optimizing domestic solar hot water system selection

In an effort to tackle climate change most countries utilize renewable energy sources. This is more pronounced in the building sector, which is currently one of the major consumers of energy, mostly in the form of heat. In order to further promote the use of domestic solar hot water systems in buildings, an ontology-based decision support tool has been developed and is presented in this paper. The proposed tool aids non-technical consumers to select a domestic solar hot water system tailored to their needs, containing up-to-date information on its components and interrelationships, installation costs etc., in the form of an ontology formulated in OWL (Web Ontology Language). The optimum system configurations are computed based on various specific parameters, such as number of occupants, daily hot water requirements and house location. The backbone of the proposed system is an ontology that represents the application domain and contains information regarding the various domestic solar hot water system components along with their interrelationships. Ontologies are a rapidly evolving knowledge representation paradigm that offers various advantages and, when deployed specifically in the domestic solar hot water systems domain, deliver improved representation, sharing and re-use of the relevant information. As a conclusion, this paper presents an ontology-driven decision support system for facilitating the selection of domestic solar hot water system, which delivers certain advantages, such as sustainability of the decision support system itself, due to its open and interoperable knowledge-base, and its adaptability/flexibility in decision making policies, due to is semantic (ontological) nature.

Legionellosis on the Rise: A Review of Guidelines for Prevention in the United States.

Reported cases of legionellosis more than tripled between 2001 and 2012 in the United States. The disease results primarily from exposure to aerosolized water contaminated with Legionella. To identify and describe policies and guidelines for the primary prevention of legionellosis in the US. An Internet search for Legionella prevention guidelines in the United States at the federal and state levels was conducted from March to June 2012. Local government agency guidelines and guidelines from professional organizations that were identified in the initial search were also included. Federal, state, and local governing bodies and professional organizations. Guidelines and regulations for the primary prevention of legionellosis (ie, Legionnaires' disease and Pontiac fever) have been developed by various public health and other government agencies at the federal, state, and local levels as well as by professional organizations. These guidelines are similar in recommending maintenance of building water systems; federal and other guidelines differ in the population/institutions targeted, the extent of technical detail, and support of monitoring water systems for levels of Legionella contamination. Legionellosis deserves a higher public health priority for research and policy development. Guidance across public health agencies for the primary prevention of legionellosis requires strengthening as this disease escalates in importance as a cause of severe morbidity and mortality. We recommend a formal and comprehensive review of national public health guidelines for prevention of legionellosis.