Reflections on the state of research: indoor environmental quality

A Biophilic Design Approach for Improved Energy Performance in Retrofitting Residential Projects

The existing building stock is recognised as a major contributor to total energy consumption and related carbon emissions around the globe. There is increased attention on the retrofit of existing building stock, especially residential buildings, as a way of curbing energy consumption and carbon emissions. Within this context, human nature connectedness (HNC) has the potential of further amplifying the benefits of sustainable buildings both from an energy conservation practice and tangible improvements to users’ satisfaction, health, and wellbeing. This study attempts to show a case study of the potential of using HNC through the adoption of biophilic design principles to improve a residential building performance. A terrace house located in Sydney, NSW, was used as a case study and proposed retrofit scenarios were simulated with DesignBuilder® and Rhinoceros/Grasshopper with a view of improved daylighting, thermal comfort, and energy consumption. The building performance is improved in terms of daylighting, thermal comfort, and reduced energy consumption, additionally enhancing HNC.

Investigating the plant and air-quality performances of an internal green wall system under hydroponic conditions

Internal green wall systems can be combined with building structures to bring positive impacts on people's quality of life in interior spaces. However, obtaining green wall systems to optimize the performances of these living walls still needs research works. This study was conducted to investigate the plant, and air-quality performance resulted from combining ornamental plants and growing media types in an internal green wall system. The growing media types (mixed based on volume percentage) included cocopeat, perlite, cocopeat + perlite (1v:1v) and cocopeat + perlite + vermicompost (1v:1v:1v). The ornamental species included Peperomia magnoliiaefolia, Kalanchoe blossfeldiana, Aptenia cordifolia, and Carpobrotus edulis. There were significant differences among the plant species and the growing media types for improvement of the plant growth and morphophysiological factors. Organic-rich growing media of vermicompost along with perlite and cocopeat, combined with Aptenia cordifolia as the species can be used to create a horticulturally sustainable internal green wall, and also improve the health index in the building interior environments.

Efficiency and mechanism of formaldehyde removal from air by two wild plants; Plantago asiatica L. and Taraxacum mongolicum Hand.-Mazz

Indoor potted plants played an important role in the removal of air-borne VOCs. According to the difference between plant fresh extracts and boiled extracts on breakdown ability to the added formaldehyde, a simple quantitative evaluation method was used to identify the mechanisms of formaldehyde removal from the air by wild Taraxacum mongolicum Hand.-Mazz. and Plantago asiatica L.. After shoots exposure to formaldehyde (1.28 mg/m³ in the air) for 24 h, the formaldehyde removal rates of P. asiatica and T. mongolicum were 73.18 and 121.20 mg/h/kg FW (fresh weight), respectively. Formaldehyde can be transported from the air to the rhizosphere solution by plants, and the maximum rates of transmission by T. mongolicum and P. asiatica were 23.73 and 83.08 mg/h/kg FW, respectively. Although plant metabolism was responsible for formaldehyde loss in the air-plant-solution system, and the metabolic activity depended on the enzymatic and redox reactions in the plants, P. asiatica and T. mongolicum are still good candidate species for developing phyto-microbial technologies. The redox reaction was the main mechanism used by P. asiatica shoots to dissipate formaldehyde, while the enzymatic reaction was the main mechanism used by T. mongolicum. The higher oxidative potential and lower defensive enzyme activity in P. asiatica shoots led to its higher formaldehyde removal rate compared to T. mongolicum. Meanwhile, the stronger redox reaction ability in the T. mongolicum roots was partly responsible for its lower formaldehyde transmission rate. The results show two plants have strong tolerance to formaldehyde in the air and good formaldehyde removal ability.

Outcome-based ventilation: A framework for assessing performance, health, and energy impacts to inform office building ventilation decisions

This article presents an outcome-based ventilation (OBV) framework, which combines competing ventilation impacts into a monetized loss function ($/occ/h) used to inform ventilation rate decisions. The OBV framework, developed for U.S. offices, considers six outcomes of increasing ventilation: profitable outcomes realized from improvements in occupant work performance and sick leave absenteeism; health outcomes from occupant exposure to outdoor fine particles and ozone; and energy outcomes from electricity and natural gas usage. We used the literature to set low, medium, and high reference values for OBV loss function parameters, and evaluated the framework and outcome-based ventilation rates using a simulated U.S. office stock dataset and a case study in New York City. With parameters for all outcomes set at medium values derived from literature-based central estimates, higher ventilation rates' profitable benefits dominated negative health and energy impacts, and the OBV framework suggested ventilation should be ≥45 L/s/occ, much higher than the baseline ~8.5 L/s/occ rate prescribed by ASHRAE 62.1. Only when combining very low parameter estimates for profitable impacts with very high ones for health and energy impacts were all outcomes on the same order. Even then, however, outcome-based ventilation rates were often twice the baseline rate or more.

Reflections on the history of indoor air science, focusing on the last 50 years

The scientific articles and Indoor Air conference publications of the indoor air sciences (IAS) during the last 50 years are summarized. In total 7524 presentations, from 79 countries, have been made at Indoor Air conferences held between 1978 (49 presentations) and 2014 (1049 presentations). In the Web of Science, 26 992 articles on indoor air research (with the word "indoor" as a search term) have been found (as of 1 Jan 2016) of which 70% were published during the last 10 years. The modern scientific history started in the 1970s with a question: "did indoor air pose a threat to health as did outdoor air?" Soon it was recognized that indoor air is more important, from a health point of view, than outdoor air. Topics of concern were first radon, environmental tobacco smoke, and lung cancer, followed by volatile organic compounds, formaldehyde and sick building syndrome, house dust-mites, asthma and allergies, Legionnaires disease, and other airborne infections. Later emerged dampness/mold-associated allergies and today's concern with "modern exposures-modern diseases." Ventilation, thermal comfort, indoor air chemistry, semi-volatile organic compounds, building simulation by computational fluid dynamics, and fine particulate matter are common topics today. From their beginning in Denmark and Sweden, then in the USA, the indoor air sciences now show increasing activity in East and Southeast Asia.

Perceptions in the U.S. building industry of the benefits and costs of improving indoor air quality

How building stakeholders (e.g. owners, tenants, operators, and designers) understand impacts of Indoor Air Quality (IAQ) and associated energy costs is unknown. We surveyed 112 stakeholders across the United States to ascertain their perceptions of their current IAQ and estimates of benefits and costs of, as well as willingness to pay for, IAQ improvements. Respondents' perceived IAQ scores correlated with the use of high-efficiency filters but not with any other IAQ-improving technologies. We elicited their estimates of the impacts of a ventilation-filtration upgrade (VFU), that is, doubling the ventilation rate from 20 to 40 cfm/person (9.5 to 19 l/s/person) and upgrading from a minimum efficiency reporting value 6 to 11 filter, and compared responses to estimates derived from IAQ literature and energy modeling. Minorities of respondents thought the VFU would positively impact productivity (45%), absenteeism (23%), or health (39%). Respondents' annual VFU cost estimates (mean = $257, s.d. = $496, median = $75 per person) were much higher than ours (always <$32 per person), and the only yearly cost a plurality of respondents said they would pay for the VFU was $15 per person. Respondents holding green building credentials were not more likely to affirm the IAQ benefits of the VFU and were less likely to be willing to pay for it.

Factors controlling volatile organic compounds in dwellings in Melbourne, Australia

This study characterized indoor volatile organic compounds (VOCs) and investigated the effects of the dwelling characteristics, building materials, occupant activities, and environmental conditions on indoor VOC concentrations in 40 dwellings located in Melbourne, Australia, in 2008 and 2009. A total of 97 VOCs were identified. Nine VOCs, n-butane, 2-methylbutane, toluene, formaldehyde, acetaldehyde, d-limonene, ethanol, 2-propanol, and acetic acid, accounted for 68% of the sum of all VOCs. The median indoor concentrations of all VOCs were greater than those measured outdoors. The occupant density was positively associated with indoor VOC concentrations via occupant activities, including respiration and combustion. Terpenes were associated with the use of household cleaning and laundry products. A petroleum-like indoor VOC signature of alkanes and aromatics was associated with the proximity of major roads. The indoor VOC concentrations were negatively correlated (P < 0.05) with ventilation. Levels of VOCs in these Australian dwellings were lower than those from previous studies in North America and Europe, probably due to a combination of an ongoing temporal decrease in indoor VOC concentrations and the leakier nature of Australian dwellings.

Modeling Associations between Principals' Reported Indoor Environmental Quality and Students' Self-Reported Respiratory Health Outcomes Using GLMM and ZIP Models

Background: The aim of this paper was to examine associations between school building characteristics, indoor environmental quality (IEQ), and health responses using questionnaire data from both school principals and students. Methods: From 334 randomly sampled schools, 4248 sixth grade students from 297 schools participated in a questionnaire. From these schools, 134 principals returned questionnaires concerning 51 IEQ related questions of their school. Generalized linear mixed models (GLMM) were used to study the associations between IEQ indicators and existence of self-reported upper respiratory symptoms, while hierarchical Zero Inflated Poisson (ZIP)—models were used to model the number of symptoms. Results: Significant associations were established between existence of upper respiratory symptoms and unsatisfactory classroom temperature during the heating season (ORs 1.45 for too hot and cold, and 1.27 for too cold as compared to satisfactory temperature) and dampness or moisture damage during the year 2006–2007 (OR: 1.80 as compared to no moisture damage), respectively. The number of upper respiratory symptoms was significantly associated with inadequate ventilation and dampness or moisture damage. A higher number of missed school days due to respiratory infections were reported in schools with inadequate ventilation (RR: 1.16). Conclusions: The school level IEQ indicator variables described in this paper could explain a relatively large part of the school level variation observed in the self-reported upper respiratory symptoms and missed school days due to respiratory infections among students.

Health Benefits of Green Public Housing: Associations With Asthma Morbidity and Building-Related Symptoms

OBJECTIVES

We examined associations of several health outcomes with green and conventional low-income housing, where the prevalence of morbidities and environmental pollutants is elevated.

METHODS

We used questionnaires and a visual inspection to compare sick building syndrome (SBS) symptoms and asthma-related morbidity among residents in multifamily units in Boston, Massachusetts, between March 2012 and May 2013. Follow-up was approximately 1 year later.

RESULTS

Adults living in green units reported 1.35 (95% confidence interval [CI] = 0.66, 2.05) fewer SBS symptoms than those living in conventional (control) homes (P < .001). Furthermore, asthmatic children living in green homes experienced substantially lower risk of asthma symptoms (odds ratio [OR] = 0.34; 95% CI = 0.12, 1.00), asthma attacks (OR = 0.31; 95% CI = 0.11, 0.88), hospital visits (OR = 0.24; 95% CI = 0.06, 0.88), and asthma-related school absences (OR = 0.21; 95% CI = 0.06, 0.74) than children living in conventional public housing.

CONCLUSIONS

Participants living in green homes had improved health outcomes, which remained consistent over the study period. Green housing may provide a significant value in resource-poor settings where green construction or renovation could simultaneously reduce harmful indoor exposures, promote resident health, and reduce operational costs.

Study on the interzonal migration of airborne infectious particles in an isolation ward using benign bacteria

Negative pressure isolation wards are essential infection control facilities against airborne transmissible diseases. Airborne infectious particles are supposed to be contained in the isolation room. However, negative pressure may break down by door-opening action or by human movement. Understanding the interzonal transport of airborne infectious particles in the isolation wards can aid the design and operation strategy of isolation facilities. In this work, the interzonal migration of airborne infectious particles by human movement was studied experimentally in an isolation ward. Artificial saliva solution with benign E. coli bacteria was aerosolized to simulate bacterium-laden infectious particles. The interzonal migration of aerosolized bacteria was characterized by biological air sampling. Less than 1% of airborne infectious particles were transported to the higher pressure zone when door was closed. With human movement, 2.7% of the particles were transported from the anteroom to the corridor. From high-to-low pressure zones, as much as 20.7% of airborne infectious particles were migrated. Only a minimal amount of particles was transported from the corridor to the positive pressure nurses' station. Infection risk of tuberculosis of the healthcare workers and other occupants in the isolation wards were also assessed based on the measured migration ratios.

PRACTICAL IMPLICATIONS

Human movement is an important factor governing interzonal migration. It is the main cause of migration of airborne infectious particles to a relatively negative pressure zone. This study provides a set of experimentally obtained particle migration ratios by human movement. Other than serving as empirical data for further studies on the mechanics, these migration ratios can also be used to assess the infection risk for occupants in the isolation ward.