Principal component analysis of electricity use in office buildings

Principal component analysis was conducted on five major climatic variables—dry-bulb temperature, wet-bulb temperature, global solar radiation, clearness index and wind speed. Twenty-eight year (1996–2000) long-term measured weather data were considered. A two-component solution was obtained, which could explain 80% of the variance in the original weather data. Monthly electricity consumption data recorded during a 5-year period (1979–2006) were gathered from 20 fully air-conditioned office buildings with centralised HVAC systems in subtropical Hong Kong. Electricity use per unit gross floor area ranged from 163 to 389 kWh/m². These consumption data were correlated with the corresponding principal components using linear multiple regression techniques. The coefficient of determination (R²) varied from 0.76 to 0.95 indicating reasonably strong correlation. It was found that the regression models developed could give a reasonably good indication (mostly within 3%) of the annual electricity use, but the monthly estimates might differ from the actual consumption by up to 9%. Attempt was also made to develop a general regression model for the 20 buildings, which had an R² of 0.84 with a maximum mean-biased error of 18.6% and a maximum root-mean-square error of 21.4%.     

Risk factors in heating, ventilating, and air-conditioning systems for occupant symptoms in US office buildings: the US EPA BASE study

Building-related symptoms in office workers worldwide are common, but of uncertain etiology. One cause may be contaminants related to characteristics of heating, ventilating, and air-conditioning (HVAC) systems. We analyzed data from 97 representative air-conditioned US office buildings in the Building Assessment and Survey Evaluation (BASE) study. Using logistic regression models with generalized estimating equations, we estimated odds ratios (OR) and 95% confidence intervals for associations between building-related symptom outcomes and HVAC characteristics. Outdoor air intakes less than 60 m above ground level were associated with significant increases in most symptoms: e.g. for upper respiratory symptoms, OR for intake heights 30 to 60 m, 0 to <30 m, and below ground level were 2.7, 2.0, and 2.1. Humidification systems with poor condition/maintenance were associated with significantly increased upper respiratory symptoms, eye symptoms, fatigue/difficulty concentrating, and skin symptoms, with OR = 1.5, 1.5, 1.7, and 1.6. Less frequent cleaning of cooling coils and drain pans was associated with significantly increased eye symptoms and headache, with OR = 1.7 and 1.6. Symptoms may be due to microbial exposures from poorly maintained ventilation systems and to greater levels of vehicular pollutants at air intakes nearer the ground level. Replication and explanation of these findings is needed. PRACTICAL IMPLICATIONS: These findings support current beliefs that moisture-related HVAC components such as cooling coils and humidification systems, when poorly maintained, may be sources of contaminants that cause adverse health effects in occupants, even if we cannot yet identify or measure the causal exposures. While finding substantially elevated risks for poorly maintained humidification systems, relative to no humidification systems, the findings do not identify important (symptom) benefits from well-maintained humidification systems. Findings also provide an initial suggestion, needing corroboration, that outdoor air intakes lower than 18 stories in office buildings may be associated with substantial increases in many symptoms. If this is corroborated and linked to ground-level vehicle emissions, urban ventilation air intakes may need to be located as far above ground level as possible or to incorporate air cleaners that remove gaseous pollutants.     

Self-reported multiple chemical sensitivity symptoms and personal volatile organic compounds exposure concentrations in construction workers

The relationship between high chemical compound exposure and human health has been an important worldwide issue. High exposure to chemical compounds can make harmful health effect. One of the mostly risky groups to this high exposure to chemical compounds is the construction worker. In this study, their exposure level and self-reported Multiple Chemical Sensitivity were investigated. In the first part of this study, self-reported symptom surveys and personal six Volatile Organic Compounds (VOCs) exposure measurements were conducted with three categories of construction employment, including exterior workers, interior workers, and office workers. The job category with the greatest exposure to VOCs was the interior workers, followed by office workers, and then exterior workers. However, based on the self-reported symptom surveys, office workers demonstrated a relatively high risk for Multiple Chemical Sensitivity (MCS) among the three job categories. From these results, it was uncertain that whether this was characteristic of office workers in general, or only office workers in the construction business. To determine this, the same surveys and measurements were conducted with office workers outside the construction business. University students were also surveyed as a comparison group. The results determined that office workers outside the construction business meeting the operational criteria for MCS were similar to construction office workers. This similarity was not nearly so pronounced when the construction office workers were compared to the university students. High chemical exposure level to interior workers and high MCS symptom of office workers should be considered and improved for each job group's health.     

Class separation of buildings with high and low prevalence of SBS by principal component analysis

In this study, we were able to separate buildings with high and low prevalence of sick building syndrome (SBS) using principal component analysis. The prevalence of SBS was defined by the presence of at least one typical skin, mucosal and general (headache and fatigue) symptom. Data from the Swedish Office Illness Study describing the presence and level of chemical compounds in outdoor, supply, and room air, respectively, were evaluated together with information about the buildings in six models. When all data were included the most complex model was able to separate 71% of the high prevalence buildings from the low prevalence buildings. The most important variable that separates the high prevalence buildings from the low prevalence buildings was a more frequent occurrence or a higher concentration of compounds with shorter retention time in the high prevalence buildings. Elevated relative humidity in supply and room air and higher levels of total volatile organic compounds in outdoor and supply air were more common in high prevalence buildings. Ten building variables also contributed to the separation of the two classes of low and high prevalence buildings.     

Comfort of workers in office buildings: The European HOPE project

Previous studies have shown that building, social and personal factors can influence one’s perceived health and comfort. The aim of the underlying study was to get a better understanding of the relationships between these factors and perceived comfort. Self-administered questionnaires from 5732 respondents in 59 office buildings and building-specific data from the European Health Optimisation Protocol for Energy-efficient buildings (HOPE) study were used. Principal Component Analysis (PCA), reliability analyses, and linear regression analysis were performed. The outcome showed that perceived comfort is strongly influenced by several personal, social and building factors and that their relationships are complex. Results showed that perceived comfort is much more than the average of perceived indoor air quality, noise, lighting and thermal comfort responses. Perceived comfort is a phenomenon that deserves more research.     

Levels and sources of volatile organic compounds in homes of children with asthma

Many volatile organic compounds (VOCs) are classified as known or possible carcinogens, irritants, and toxicants, and VOC exposure has been associated with the onset and exacerbation of asthma. This study characterizes VOC levels in 126 homes of children with asthma in Detroit, Michigan, USA. The total target VOC concentration ranged from 14 to 2274 μg/m³ (mean = 150 μg/m³; median = 91 μg/m³); 56 VOCs were quantified; and d‐limonene, toluene, p, m‐xylene, and ethyl acetate had the highest concentrations. Based on the potential for adverse health effects, priority VOCs included naphthalene, benzene, 1,4‐dichlorobenzene, isopropylbenzene, ethylbenzene, styrene, chloroform, 1,2‐dichloroethane, tetrachloroethene, and trichloroethylene. Concentrations varied mostly due to between‐residence and seasonal variation. Identified emission sources included cigarette smoking, solvent‐related emissions, renovations, household products, and pesticides. The effect of nearby traffic on indoor VOC levels was not distinguished. While concentrations in the Detroit homes were lower than levels found in other North American studies, many homes had elevated VOC levels, including compounds that are known health hazards. Thus, the identification and control of VOC sources are important and prudent, especially for vulnerable individuals. Actions and policies to reduce VOC exposures, for example, sales restrictions, improved product labeling, and consumer education, are recommended.     

Risk assessment of exposure to volatile organic compounds in groundwater in Taiwan

The purpose of this study is to assess the risks from exposure to 14 volatile organic compounds (VOCs) in selected groundwater sites in Taiwan. The study employs the multimedia environment pollutant assessment system (MEPAS) model to calculate the specific non-cancer and cancer risks at an exposure level of 1 μg/L of each VOC for a variety of exposure pathways. The results show that the highest specific non-cancer risk is associated with water ingestion of vinyl chloride (VC) and that the highest specific cancer risk is associated with indoor breathing of VC. The three most important exposure pathways for risk assessment for both non-cancer and cancer risks are identified as water ingestion, dermal absorption when showering, and indoor breathing. Excess tetrachloroethylene (PCE), trichloroethylene (TCE), dichloroethylene (DCE), and VC are detected in the groundwater aquifers of one dump site and one factory. However, the study suggests that the pollutants in the contaminated groundwater aquifers do not travel extensively with groundwater flow and that the resulting VOC concentrations are below detectable levels for most of the sampled drinking-water treatment plants. Nevertheless, the non-cancer and cancer risks resulting from use of the contaminated groundwater are found to be hundred times higher than the general risk guidance values. To ensure safe groundwater utilisation, remediation initiatives for soil and groundwater are required. Finally, the study suggests that the current criteria for VOCs in drinking water might not be capable of ensuring public safety when groundwater is used as the primary water supply; more stringent quality criteria for drinking water are proposed for selected VOCs.     

新装修办公楼室内挥发性有机物的测试研究

为研究办公楼装修后室内挥发性有机物的释放特性,利用活性炭吸附采样与气相色谱分析相结合的方法,跟踪监测了天津市某办公楼四个典型房间的室内污染物浓度。得出了装修后室内污染物浓度的变化规律,即污染物浓度随时间推移而降低,其间可能会由于房间温度、相对湿度和气流组织的变化而出现短暂的起伏。     

Relationship between selected indoor volatile organic compounds, so-called microbial VOC, and the prevalence of mucous membrane symptoms in single family homes

Microorganisms are known to produce a range of volatile organic compounds, so-called microbial VOC (MVOC). Chamber studies where humans were exposed to MVOC addressed the acute effects of objective and/or subjective signs of mucosal irritation. However, the effect of MVOC on inhabitants due to household exposure is still unclear. The purpose of this epidemiological study was to measure indoor MVOC levels in single family homes and to evaluate the relationship between exposure to them and sick building syndrome (SBS). All inhabitants of the dwellings were given a self-administered questionnaire with standardized questions to assess their symptoms. Air samples were collected and the concentrations of eight selected compounds in indoor air were analyzed by gas chromatography/mass spectrometry — selective ion monitoring mode (GC/MS-SIM). The most frequently detected MVOC was 1-pentanol at a detection rate of 78.6% and geometric mean of 0.60 μg/m³. Among 620 participants, 120 (19.4%) reported one or more mucous symptoms; irritation of the eyes, nose, airway, or coughing every week (weekly symptoms), and 30 (4.8%) reported that the symptoms were home-related (home-related symptoms). Weekly symptoms were not associated with any of MVOC, whereas significant associations between home-related mucous symptoms and 1-octen-3-ol (per log₁₀-unit: odds ratio (OR) 5.6, 95% confidence interval (CI): 2.1 to 14.8) and 2-pentanol (per log₁₀-unit: OR 2.3, 95% CI: 1.0 to 4.9) were obtained after adjustment for gender, age, and smoking. Associations between home-related symptoms and 1-octen-3-ol remained after mutual adjustment. However, concentrations of the selected compounds in indoors were lower than the estimated safety level in animal studies. Thus, the statistically significant association between 1-octen-3-ol may be due to a direct effect of the compounds or the associations may be being associated with other offending compounds. Additional studies are needed to evaluate these possibilities.     

Associations between indoor CO2 concentrations and sick building syndrome symptoms in U.S. office buildings: an analysis of the 1994-1996 BASE study data

Higher indoor concentrations of air pollutants due, in part, to lower ventilation rates are a potential cause of sick building syndrome (SBS) symptoms in office workers. The indoor carbon dioxide (CO2) concentration is an approximate surrogate for indoor concentrations of other occupant-generated pollutants and for ventilation rate per occupant. Using multivariate logistic regression (MLR) analyses, we evaluated the relationship between indoor CO2 concentrations and SBS symptoms in occupants from a probability sample of 41 U.S. office buildings. Two CO2 metrics were constructed: average workday indoor minus average outdoor CO2 (dCO2, range 6-418 ppm), and maximum indoor 1-h moving average CO2 minus outdoor CO2 concentrations (dCO2MAX). MLR analyses quantified dCO2/SBS symptom associations, adjusting for personal and environmental factors. A dose-response relationship (p < 0.05) with odds ratios per 100 ppm dCO2 ranging from 1.2 to 1.5 for sore throat, nose/sinus, tight chest, and wheezing was observed. The dCO2MAX/SBS regression results were similar.     

Comparison of the equilibrium sorption of five organic compounds to HDPE, PP, and PVC geomembranes

This experimental investigation quantified the sorption uptake of five commonly encountered organic groundwater contaminants, methyl tertiary-butyl-ether (MTBE), benzene, trichloroethylene (TCE), 1,2-dichorobenzene (1,2-DCB), and trinitrotoluene (TNT), to geomembranes made from high density polyethylene (HDPE), polypropylene (PP), and polyvinylchloride (PVC). The organic compounds were chosen to span a range of aqueous solubilities and chemical properties. The geomembranes tested in this study exhibited sorption capacities that were of similar magnitude for each of the contaminants tested, with the exception of 1,2-DCB to HDPE, which exhibited strong uptake in comparison to the other solute/sorbent combinations. In general, the PVC geomembrane demonstrated the highest sorption capacities, while the HDPE geomembrane demonstrated the lowest sorption capacities. Measured partitioning coefficients for the contaminant/geomembrane combinations ranged from S_gf<1 to 160, but most commonly had values between 10 and 75.     

Multivariate evaluation of VOCs in buildings where people with non-specific building-related symptoms perceive health problems and in buildings where they do not

Volatile organic compounds (VOCs) were sampled in buildings where people with non-specific building-related symptoms perceive health problems and in buildings where they do not. In total, nine persons and 34 buildings were included in the study. The obtained VOC data was evaluated using multivariate methods, to investigate possible systematic differences in air quality of 'problem' and 'non-problem' buildings. All individual compounds were included as variables in a multivariate partial least squares (PLS) data analysis. 'Problem' and 'non-problem' buildings separated into two distinct groups, showing that air samples of the two groups of building were chemically different. PRACTICAL IMPLICATIONS: The study showed that there was an identifiable systematic difference in the collected VOC data between buildings causing and not causing problems for people with non-specific building-related symptoms (also called sick building syndrome, SBS). This is an important indication that even such volatile organic compounds that can be sampled by commonly used adsorbents are of importance for the presence of such symptoms. By coordination of procedures for sampling and analysis of VOCs in buildings between laboratories, to get large datasets and more general models, the method can become a useful diagnostic measure in evaluating indoor air and to identify chemical compounds and sources that contribute to SBS problems.     

Assessment through environmental and biological measurements of total daily exposure to volatile organic compounds of office workers in Milan, Italy

Personal exposure to total volatile organic compounds (TVOCs), benzene and toluene of 100 Milan office workers was assessed through personal air monitoring at home, in the office, and during commuting. Biological monitoring was performed by measuring blood benzene and toluene concentrations together with urinary trans-trans-muconic acid (t,t-MA) and cotinine at the end of the monitoring period. The geometric means of the total 24-h personal exposure were 514 micrograms/m3 for TVOCs, 21.2 micrograms/m3 for benzene and 35.2 micrograms/m3 for toluene. Daily exposure to the volatile organic compounds was almost totally determined by indoor exposure at home and in the office, with a minor contribution in the transport means. An important factor determining exposure to benzene was found to be tobacco smoke, both for active smokers and for non-smokers exposed to environmental tobacco smoke (ETS). All the mean levels of the biological indicators were significantly higher in active smokers than in non-smoking subjects non-exposed to ETS; urine cotinine and t,t-MA levels were also significantly higher in non-smokers exposed to ETS than in non-smokers non-exposed to ETS.     

Cost effect of earthquake region and soil type for office buildings in Turkey

In this study, the change in the load-bearing system cost of a reinforced concrete office building has been investigated in relation to the earthquake regions and soil types. Three different office projects each with five stories were investigated. The structural design calculations have been made according to four different soil types and four different earthquake regions. According to each combination, concrete, steel and formwork adopted approximations were calculated to reach the rough cost of each office building. The changes in the cost of projects according to the soil type and earthquake region were examined with multiple regression analysis and analysis of variance. In general, the change in cost has been observed around 22% between first and fourth soil type and 14% between first and fourth earthquake region.     

Volatile organic compounds, polycyclic aromatic hydrocarbons and elements in the air of ten urban homes

Ten homes were monitored at regular intervals from June 1994 through April 1995 as part of a Public Health Assessment in Southeast Chicago for exposure to volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), and elements. Simultaneous 24-h indoor and outdoor samples were collected. VOCs were and analyzed using USEPA Method TO-14 with Selected Ion Monitoring Mass Spectrometry (GC/MS). PAHs were analyzed using USEPA Method TO-13 with GC/MS. Elements were collected on quartz fiber filters and analyzed by Inductively Coupled Argon Plasma (ICP) spectroscopy or Graphite Furnace Atomic Absorption (GFAA). Continuous measurements of CO2 and temperature were recorded for each indoor sample. Twenty-four h total CO2 emissions were determined from occupancy and estimated gas stove usage and were moderately correlated (R2 = 0.19) with 24 h average indoor CO2 concentrations. Modeled 24-h air exchange rates ranged from 0.04 to 3.76 air changes h-1 (ACH), with mean of 0.52 ACH. Median particle penetration was 0.89. Emission rates were calculated for each pollutant sampled. Using a detailed housing survey and field sampling questionnaires, it was possible to evaluate associations between housing characteristics and source activities, and pollutant source rates. The data indicate that several predictor variables, including mothball storage, air freshner use, and cooking activities, are reasonable predictors for emission rates for specific pollutants in the homes studied.     

Development of New Volatile Organic Compound (VOC) Exposure Metrics and their Relationship to “Sick Building Syndrome” Symptoms

Abstract Occupants of office buildings are exposed to low concentrations of complex mixtures of volatile organic compounds (VOCs) that encompass a number of chemical classes and a broad range of irritancies. “Sick building syndrome” (SBS) is suspected to be related to these exposures. Using data from 22 office areas in 12 California buildings, seven VOC exposure metrics were developed and their ability to predict self-reported SBS irritant symptoms of office workers was tested. The VOC metrics were each evaluated in a multivariate logistic regression analysis model adjusted for other risk factors or confounders. Total VOCs and most of the other metrics were not statistically significant predictors of symptoms in crude or adjusted analyses. Two metrics were developed using principal components (PC) analysis on subsets of the 39 VOCs. The Irritancy/PC metric was the most statistically significant predictor of adjusted irritant symptoms. The irritant potencies of individual compounds, highly correlated nature of indoor VOC mixtures, and probable presence of potent, but unmeasured, VOCs were variously factored into this metric. These results, which for the first time show a link between low level VOC exposures from specific types of indoor sources to SBS symptoms, require confirmation using data sets from other buildings.     

Differentiation of air samples with and without microbial volatile organic compounds by aspiration ion mobility spectrometry and semiconductor sensors

A chemical detector ChemPro100i containing aspiration type ion mobility spectrometry (aspiration IMS), five semiconductor sensors (MOS) and field effect transistor sensor (FET) was used for the detection and monitoring of microbial volatile organic compounds (MVOC). MVOCs were detected from the headspace of glass chambers which contained a specimen of building material in humid conditions. Results regarding particle board as a substrate for mould growth are represented. A specimen kept under sterile conditions was used as a reference. Samples were incubated for 22 days and detector responses as well as air samples introduced into Tenax adsorbent were collected for seven days during the incubation. Air samples were analyzed by thermal desorption gas chromatography mass spectrometry (TD-GC-MS) for identifying the possible MVOCs. MVOC detection was done by comparing the chromatogram peak intensities between the contaminated and the sterile samples. Detector responses were monitored before and after air sampling and data was analyzed by means of multivariate data analysis (MVDA) using SIMCA-P 10.0 software (Umetrics, Umeå, Sweden). Results showed that when incubation proceeded the different samples could be separated by both aspiration IMS combined with sensors and TD-GC-MS and that the results obtained by both methods also had a visible time trend.     

Health risk assessment of personal inhalation exposure to volatile organic compounds in Tianjin, China

Volatile Organic Compounds (VOCs) exposure can induce a range of adverse human health effects. To date, however, personal VOCs exposure and residential indoor and outdoor VOCs levels have not been well characterized in the mainland of China, less is known about health risk of personal exposure to VOCs. In this study, personal exposures for 12 participants as well as residential indoor/outdoor, workplace and in vehicle VOCs concentrations were measured simultaneously in Tianjin, China. All VOCs samples were collected using passive samplers for 5 days and were analyzed using Thermal Desorption GC-MS method. U.S. Environmental Protect Agency's Inhalation Unit Risks were used to calculate the inhalation cancer health risk. To assess uncertainty of health risk estimate, Monte Carlo simulation and sensitivity analysis were implemented. Personal exposures were greater than residential indoor exposures as expected with the exception of carbon tetrachloride. Exposure assessment showed modeled and measured concentrations are statistically linearly correlated for all VOCs (P < 0.01) except chloroform, confirming that estimated personal exposure using time-weighted model can provide reasonable estimate of personal inhalation exposure to VOCs. Indoor smoking and recent renovation were identified as two major factors influencing personal exposure based on the time-activity pattern and factor analysis. According to the cancer risk analysis of personal exposure, benzene, chloroform, carbon tetrachloride and 1,3-butadiene had median upper-bound lifetime cancer risks that exceeded the U.S. EPA benchmark of 1 per one million, and benzene presented the highest median risks at about 22 per one million population. The median cumulative cancer risk of personal exposure to 5 VOCs was approximately 44 per million, followed by indoor exposure (37 per million) and in vehicle exposure (36 per million). Sensitivity analysis suggested that improving the accuracy of exposure measurement in further research would advance the health risk assessment.