The aim of current research study was to investigate the association of indoor air quality with the occupants’ health and wellbeing. It has also compared BREEAM and LEED in terms of inclusion of indoor air quality in green buildings. The literature has mentioned that LEED is more inclusive for quality of indoor air in comparison to BREEAM.  In order to fulfil the research aim, the current study has relied don mixed research methods. The quantitative data was obtained through online survey and data was obtained from 200 respondents. On the other hand, qualitative data was obtained through structured interviews. The interviewees were conducted from the professionals of sustainability buildings and data was obtained from 18 respondents. The data of survey was analysed through visual representation by figures and results have provided that there is significant association of indoor air quality with health and wellbeing of occupants. Along with this, the interviews were also analysed through visual representation. The responses of most of interviewees have provided that BREEAM are LEED are similar in terms of indoor air quality. The results of open ended questions have highlighted that BREEAM is more inclusive for health and wellbeing of occupants, as all of interviewees had experience of BREEAM rather than LEED. Along with this, results have also highlighted that WELL building standard is more important in terms of occupants’ health and wellbeing and expected merger of BREEAM and WELL can improve the health and wellbeing aspect of BREAAM further. The results of the current research were highly important for both practice and theory.

1.    Introduction

1.1 Background

The indoor air quality (IAQ) is one of the most important aspect of green buildings that may have direct influence on living quality and health and wellbeing of humans. It has been recommended by the researchers that poor quality of indoor air can have negative impact on health of occupants both psychological and physical (Edwards, 2006). The IAQ is one of the important aspects of indoor Environment Quality (IEQ) as provided by prior researchers (Zuo and Zhao, 2014)and it provides that air should be free from any contaminants that cause harm and discomfort to people (Miller, Pogue, Gough and Davis, 2009). The high quality of air is ensured by adequate ventilation within green building and it offers greater assurance of occupants’ health and wellbeing. The IAQ has been considered as the most important measure of indoor environment quality as it can be measured quantitatively in comparison to other criteria that are mainly perception based(Chatzidiakou, Mumovic and Summerfield, 2015).It has been mentioned in the study of Edwards and Torcellini (2002) that in US and UK higher percentage of people are suffering from respiratory allergies and asthma that are mainly caused by indoor environmental conditions, such as poor quality of air.

It has been asserted by the prior researchers that main emphasis of green buildings movement is on effective maintenance of IAQ with an aim to offer healthier living environment and ensure health and wellbeing to occupants. The evidences from past research has provided that occupants of green buildings are likely to be more satisfied with the high IAQ and they have better health and wellbeing than occupants of traditional buildings (Chuck and Kim, 2011). The same has been acknowledged by the study of Kibert (2016), carried out in perspective of Leadership in Energy and Environmental Design (LEED) and its association with occupants’ health and wellbeing. The results of the study have revealed that building with high LEED ratings and improved IAQ were mainly having a positive influence on better health and wellbeing of occupants. Moreover, the evidences from various researches have provided that occupants have placed significant importance to the IAQ in terms of their comfort and satisfaction with indoor environment (Fisk, 2000). The satisfaction is mainly the indicator of psychological wellbeing and it also hinders the anxiety, stress and depression among occupants(Ferreira, Pinheiro and de Brito, 2014; Chuck and Kim, 2011).Therefore, the notion of green buildings and high IAQ are largely associated with occupants’ health and wellbeing.

Along with this, it has been highlighted in the study of Chuck and Kim (2011) that there is considerable difference in the IAQ consideration of BREEAM(Building Research Establishment Environmental Assessment Method) and LEED. The present study will conduct the comparison and offer more recent insight. It is important to note that prior studies have mainly suggested that LEED has higher level of inclusion for quality of indoor air than BREEAM in preocc