We conducted a search for research studies that specifically focused on exploring relationships between green buildings and health. Inclusion criteria included the following: (1) peer-reviewed paper or government report, (2) evaluation of green buildings, (3) data on indoor environmental quality perception or measurements, and (4) data on health, comfort, productivity, or well-being. Our initial searches were performed using Web of Science and PubMed, with keywords that included the following: green buildings, LEED, WELL, Living Building Challenge, high performance buildings, indoor air quality, indoor environmental quality, and health. The next step in our process was to review the reference sections of the papers identified from the first search and select additional relevant studies. This was repeated again with this second round of studies. Finally, we conducted internet searches for “grey” literature (e.g., government reports) that included original research studies that fit our inclusion criteria. As a result of this search process, we identified 17 studies on green buildings and health for our review. A minimum of three co-authors reviewed each study. We organized our review based on strength of the study design, starting with studies that relied solely on occupant surveys and concluding with studies that included objective measures of exposure and outcomes (Table 1). As the literature currently lacks a study where occupants are blinded to their exposure group (i.e., being in a green environment or a conventional environment), studies with self-reported metrics were deemed weaker than those with objective measures. Due to the widespread adoption of LEED and the fact that it was started 15 years ago, nearly all of the studies of green buildings we identified were focused on LEED buildings. As research is generated on other health-focused certifications and standards (e.g., WELL and LBC), an additional review paper is warranted.
Studies with Only Occupant Surveys
The simplest way to obtain information on both indoor environmental quality (IEQ) and occupant satisfaction is through surveys. While a strength of surveys is that they can be deployed in large cohorts, a limitation is that they are subjective measures of exposure and outcomes and therefore prone to information bias (e.g., misclassification), selection bias (e.g., self-selection bias), and dependent errors .
Several studies of green buildings have used an occupant survey tool created by the Center for the Built Environment at the University of California Berkeley. They conducted initial pre-testing and validation of core questions through a method called “cognitive interviewing” where they assessed respondents’ comprehension of questions and accuracy of answers . This method gave the CBE survey a relatively high level of validity. Over the course of 10 years, 52,980 individual occupant responses were collected in 350 office buildings (49 self-reported as LEED certified) .
We identified four studies that used this database to test occupant satisfaction with various IEQ parameters in LEED and non-LEED buildings [37, 39–41]. All studies found that occupants were more satisfied with indoor air quality, building cleanliness/maintenance, and their workspace in LEED buildings than in non-LEED buildings. The studies were discordant on the effects of other parameters. Huizenga et al., Lee et al., and Abbaszadeh et al. found occupants more satisfied with thermal comfort in LEED buildings while Altomonte et al. did not. Huizenga et al. and Abbaszadeh et al. found no statistically significant differences between building types for lighting and acoustics while Altomonte et al. and Lee et al. concluded that non-LEED buildings performed better. The discrepancies in results are primarily driven by the building inclusion and exclusion criteria used in each study. Each researcher analyzed a different subset of the CBE dataset based on when the study was conducted, what the required response rate was, how the responses were weighted, and which buildings were classified as LEED and non-LEED. For example, Altomonte et al. excluded non-LEED buildings built or renovated before 1998 since they predated the LEED certification system and weighted responses based on the number of responses obtained at each building, although they did not account for the correlated nature of the responses in their analysis.
Using a different survey tool, Paul and Taylor performed a survey of occupants of one green office building and two conventional office buildings on a university campus . The survey measured self-report comfort and satisfaction perception. A critical difference between the green and conventional buildings that could not be controlled for in a study this small is the type of ventilation (natural vs mechanical, respectively). The authors conclude that there were no differences between the buildings, except for occupants in the green building were more likely to report being warm and more likely to describe the work environment as poor; however, detached from the conclusion is an observation that the hydronic cooling system was not working properly in the green building at the time of the study. Therefore, the conclusions regarding thermal comfort were almost certainly a result of a malfunctioning cooling system and not related to the comparison of green versus conventional buildings.
A similar study investigated the same IEQ parameters in a different set of university buildings . Three hundred nine total occupants from two green (LEED Silver) and one conventional building completed surveys on their work environment and health. More occupants reported that the air was fresh and that the air quality was “good” in the green buildings compared to the conventional building, and there were with statistically significant fewer reports of coughs/sneezes and neck/shoulder ache. The occupant surveys in the two green buildings were inconsistent for most environmental conditions investigated, including air temperature, air movement, and noise. Satisfaction with ventilation, air quality, and lighting was significantly higher in the green buildings. The authors concluded that aspects of green building design can result in better perceived IEQ as rated by building occupants. They did not find evidence that the green buildings were more comfortable or productive workplaces.
Thatcher et al. collected self-reported occupant responses related to health and well-being in two groups of employees over the course of 1 year: one which crossed over from conventional offices to a Green-star accredited office after the baseline series of questionnaires and one which worked in conventional offices the entire time . The authors report significantly increased physical well-being and satisfaction with many IEQ parameters for employees in the green building compared to the conventional building. Occupants of the green housing reported better perceptions of ventilation, air movement, and reductions in humidity and stale air. Lighting conditions were perceived as dimmer in the green housing.
The US General Services Administration (GSA) operates the Office of Federal High Performance Buildings [35•]. GSA conducted a survey of 22 sustainably designed buildings from representative areas of the country in order to compare performance against national averages (16 met or exceeded LEED, and 6 met Energy Star or California Title 24 Energy Standard). The survey included information on occupant experience. GSA found 27 % higher occupant satisfaction in the 22 sustainably designed buildings compared to the national average, and reported that the top third of these buildings had even greater margins (78 % higher than average). Higher satisfaction was reported for air quality, general building satisfaction, cleanliness and thermal comfort. There were no differences in satisfaction with lighting, and they found lower scores for sound privacy, but not noise level.
Singh et al. followed employees who transitioned from conventional to two LEED-certified green buildings . A pre- and post-move survey was administered (two case studies; n = 56 and n = 207). Unlike the studies described previously, the questions focused on absenteeism and productivity rather than environmental perceptions. They compared results using paired t-tests and found that, after moving into green buildings, employees reported significantly (p < 0.05) lower absenteeism attributable to asthma and respiratory allergies, fewer work hours affected by asthma and respiratory allergies, fewer work hours affected by depression and stress, and increased productivity related to improved IEQ. Combining these impacts together resulted in 42.75 more work hours per year per occupant (greater than one whole work week) in the LEED building compared to the conventional building.
Studies with IEQ Measurements + Occupant Surveys
To reduce misclassification, dependent error, and bias, subjective measures can be augmented or replaced by objective measures of IEQ and occupant well-being. Several studies have complemented occupant satisfaction with the built environment with objective measures of IEQ. Liang et al. combined a variant of the CBE survey with IEQ measurements in three green buildings in Taiwan (EEWH-certified) to two conventional buildings . They found improvements in thermal conditions, indoor air quality, noise, and lighting, all of which contributed to higher occupant satisfaction scores. Ravindu et al. conducted a case study of self-reported survey results in a LEED-certified factory and a second factory used as a control in Sri Lanka . They report thermal quality and ventilation as less satisfactory in the green factory and no difference in acoustics or air quality. The survey was performed on 35 workers randomly selected from each facility, but then matched based on work location and type of work. Matching was not performed for age or other potential confounding variables (gender, years worked, supervisor). Newsham et al. matched 12 green buildings to 12 comparable conventional buildings . At each building, an IEQ assessment was conducted and occupants completed a questionnaire about their well-being. The green buildings performed slightly worse for noise and better for indoor air quality, with other IEQ parameters being largely consistent. Occupants in green buildings reported higher satisfaction with access to outside views, better mood, better sleep quality at night, and fewer visual or physical discomfort reports.
Several studies in public housing have used self-reported health metrics in conjunction with occupant satisfaction with IEQ to better characterize well-being. Jacobs et al. combined the use of validated surveys of physical and mental health with objective measurements of allergens [49•]. Measurements were taken at baseline and 1 year after study subjects moved to a renovated space certified LEED Gold. Cockroach allergen (Bla g1) and mouse allergen (Mus m1) registered significant sustained reductions 3 months after the intervention. The 58 participants who participated in both measurements reported an overall improvement in their health of 8 %. Another study followed tenants in an affordable housing for 18 months after moving into a LEED-certified complex . The extent of the renovation included the substitution of gas stoves for electric units, integrated pest management as well as the use of biodegradable cleaners; no smoking is permitted in the complex premises. The main finding from this study was a significant decrease in daytime respiratory symptoms and nighttime asthma symptoms after moving into the LEED-Platinum certified complex.
Breysse et al. used validated surveys from the Centers for Disease Control and Prevention and the National Institute of Environmental Health Sciences to study the effectiveness of green renovations in public housing [51•]. Significant decreasing trends in the number of reported non-asthma respiratory problems (e.g., emphysema, hay fever, sinusitis, and chronic bronchitis) prevailed for 18 months after moving into the renovated space, both in children and adults. The overall health status of adults and children also improved, although the effect was only significant for the adults. The authors suggest that the improvement in respiratory health outcomes was not stronger presumably because ventilation levels were lower than expected (982 ppm CO2 mean annual concentration) in the green housing. One considerable limitation of this study is that pre-renovation information relies on the participants’ recall once they had already moved to their renovated unit.
Colton et al. investigated the difference in IEQ parameters and self-reported health between tenants of conventional housing and affordable green housing [16••]. The study also included a subset of residents transitioned from conventional to green housing. Although thermal comfort was perceived less satisfactory and air changes per hour were lower in the green homes, there was a 47 % reduction in the reported sick building syndrome symptoms among green housing tenants [16••]. Environmental sampling also showed significantly lower PM2.5, NO2, and nicotine in green homes compared to conventional apartments, despite AER being lower in the green homes. CO2 concentrations in green units (median = 1204 ppm) were considerably higher than benchmark values of adequate ventilation. Other benefits include lower reports of pests, fewer water-related issues, and fewer inadequate ventilation issues [16••].
Studies with Objective Health Outcome Measures
Objective health metrics are even more important than objective measurements of IEQ because the relationship between building design and IEQ is currently better understood than the relationship between building design and health. Thiel et al. compared a newly constructed LEED-certified hospital to a conventional hospital in Pittsburgh, PA [52••]. Because of their unique focus on hospitals, they had the most objective health assessment of the studies reviewed; hospital records on both the patients and employees were compared at the two hospitals. A key strength of this study is that the authors had 10 and 3 years of objective, standardized hospital metrics in the conventional and green hospital, respectively. The green hospital had a 19 % decrease in mortality despite an 11 % predicted increase based on the severity of cases drawn to the new facility. Employees were generally more satisfied with the newer facility based on an increase in employee tenure, a decrease in employee turnover, and a decrease in the length of open staff positions. The quality of care also improved in the new facility: blood stream infection rates declined 70 % and number of corrections to the Medication Administration Record declined 49 %. The authors conclude that the results, “lead to a reasonable observation that the facility did in fact contribute to the overall improvements.” Without measurements of IEQ in this study, it is not possible to identify the specific green building attributes that were responsible for the improvements.