How does indoor environmental quality in green refurbished office buildings compare with the one in new certified buildings?

A cross-sectional study was conducted in Singapore to investigate whether buildings refurbished to attain the Green Mark (GM) standards present measurable improvements to indoor environmental quality (IEQ) that are also manifested by the occupants with respect to their level of satisfaction and health symptoms. Comparative analyses were performed with buildings that are GM-certified since day one (GMN), buildings refurbished to GM standards (GMC) and conventional buildings which could not receive the GM certification (NGM). A one-week field measurement of selected IEQ parameters and post occupancy surveys of satisfaction and health symptoms of 367 occupants in 14 office buildings revealed that GMC buildings exhibited levels of IEQ, satisfaction and health symptoms similar to GMN buildings. Both categories of buildings had superior IEQ compared with NGM buildings. Apart from parameters affected by limitations of refurbishment related to façade, this study found that enhanced IEQ performance to the level as high as GMN buildings’ can be achieved by converting existing conventional buildings to GM-certified buildings through green refurbishment in the context of office buildings in Singapore. •Indoor environmental quality (IEQ) was measured objectively and subjectively.•IEQ performance of 14 buildings was compared in 3 different green building groups.•Generalised linear mixed model accounting for clustering effects was used.•Green converted buildings achieved IEQ nearly equivalent to new green buildings'.•Green converted building occupants rated improved health and satisfaction with IEQ.