Building certification schemes and the quality of indoor environment

Abstract

Building certification schemes create a new standard for the built environment reflecting the growing environmental consciousness and the need for “green buildings”. They are expected to signify an outstanding quality and excellence. Buildings, which receive a high degree of certification, are consequently presumed to guarantee the outstanding indoor environmental quality (IEQ). There still exists, however, scarcity of data supporting this postulation, especially as regards the ratings and perceptions of occupants of certified buildings. This PhD attempts to shed a light on this topic and supplement with new measuring data. It attempts additionally to formulate recommendations regarding future revisions of building certifications, so that the IEQ requirements, human needs and expectations are sufficiently addressed. These objectives were attained initially by reviewing the scientific literature, providing information on the performance of building certification schemes in relation to IEQ and ratings of building occupants. Then, information was collected on IEQ in existing office buildings certified as green buildings with particular focus on the work performance indicators, acute health symptoms, and perceptions and comfort. Information on IEQ in the existing buildings was collected through field campaigns. They comprised measurements in 6 office buildings in Singapore certified using the Green Mark (GM) Certification Scheme. The measurements were additionally carried out in 6 office buildings that are not certified, and do not qualify for GM certification. The study looked into seven dimensions in a holistic and longitudinal approach. A special on-line software was developed for collecting responses from building occupants. It integrates the questions regarding satisfaction, acute health symptoms, information on the conditions and parameters supporting and distracting from the efficient work, as well as the self-estimated performance and objectively measured performance using different tasks examining various cognitive skills. The data on absence rates was collected, too, and the range of environmental measurements performed. Literature review showed that holistic and transversal IEQ studies comparing Green and Non-Green buildings are rare, with most of the evidence over-represented by post-occupancy surveys. Generally results show that green buildings outperform non-green for most of the IEQ parameters, with exception of acoustic, lighting, and glare. Results of measurements were modeled with statistical methods. They were then correlated with the measurements of IEQ parameters in the buildings. The results and analyses were specifically aiming in examining the differences between Green Mark and Non-Green Mark buildings. Physical measurements did not differ significantly between Green Mark and Non-Green Mark. Occupants´ satisfaction, importance and perceptions of IEQ parameters were observed to be better in GM buildings compared with the NGM buildings and the difference could be caused both by actual exposures and psychosocial factors. Air quality is the most important IEQ parameter for occupants in Green Mark buildings. Acoustical and visual privacy is problematic in Green Mark buildings. The odds of SBS symptoms in Green Mark are half of the odds in Non-Green Mark. Occupant self-assessment performance is better in GM buildings but no significant differences were observed for objective performance between occupants in both types of buildings. Annual sick-leave was lower in the Green Mark buildings; the difference was one day per year. In conclusion, Green Mark buildings have generally a positive impact on occupants, compared with Non-Green Mark buildings. Improvements and future modifications of the building certification schemes are discussed. O.C.E.A.N (Organization, commitment, environment, aesthetics and natural) approach and a metric to integrate human satisfaction responses in certification schemes are recommended. Additionally, experiences collected during the fieldwork are used to upgrade the software for collection of subjective responses with an intent to use it for developing a common standard that can be used for gauging and benchmarking IEQ in buildings, as well as for examining the performance of buildings.