Indoor Environmental Quality in WELL and LEED Certified Buildings

WELL and LEED certification systems are globally recognized standards that promote the design of healthy and sustainable buildings. The WELL standard provides innovative design criteria for human health, comfort, and well-being, while the LEED standard champions indoor environmental quality and building sustainability. The two certification systems are complementary due to their differences in intent. The collective benefits of both standards might explain why some buildings have achieved WELL and LEED certification (i.e., dual certification).

As building scientists, we are often asked if certification through systems like WELL or LEED improves occupant satisfaction with the workplace. Studies have compared certified and non-certified buildings (for example, with and without WELL certification) or buildings with different certification systems (for example, WELL and LEED certification). However, the results between these studies are inconsistent when it comes to differences in occupant satisfaction. In other words, it is unclear whether certification leads to higher satisfaction with indoor environments.?

One challenge with interpreting these findings is that the methods typically used have notable drawbacks. For example, comparing occupant satisfaction between pre- and post-certification in the same buildings prevents interventions from being concealed and does not allow for controlling for unknown or uncontrollable confounders. Any comparison between occupants in different buildings should also consider potential differences in their features (for example, time in the building. These challenges might confound reported differences (or similarities) in occupant satisfaction in WELL- and LEED-certified buildings.

To address this, we used a statistical matching approach to pair responses in the CBE Occupant Survey database from WELL- and LEED-certified buildings. The matching process was based on features of the building and workspace, such as the certification award level and proximity to a window and resulted in an even number of responses from buildings that had achieved either WELL or LEED certification. This lets us fairly compare satisfaction with indoor environmental quality (temperature, visual comfort, noise, and air quality) by removing the influence of other variables not of primary interest to the outcome.

General satisfaction with the building and workspace was high in WELL- (94% and 87%, respectively) and LEED-certified (73% and 71%, respectively) office buildings (Figure 1).

Satisfaction with 14 other aspects of indoor environmental quality was higher in buildings with WELL certification (Figure 2). The largest difference in satisfaction was for sound privacy, and the smallest difference was for the amount of space.?

It is difficult to establish the exact reasons why we see higher occupant satisfaction in WELL-certified buildings with our approach. Perhaps it could be attributed to the WELL standard focusing on human-centered design. Other plausible reasons could be the age of the building or the different certification versions, variables that we could not match in our analysis. A causal link should be established in the future.

The pathways to verify compliance for some credits have been offered as part of collaborations between WELL and LEED. This enables designers to select credits that are similar to those offered by either of these two standards. Given that higher occupant satisfaction was found in WELL-certified buildings, compliance pathways could offer opportunities to bridge the gap in occupant satisfaction by leveraging WELL-credits that exhibited the largest difference (e.g., acoustic performance) with satisfaction to indoor environmental quality. This could serve as a viable alternative when dual certification is not possible for some buildings.

Acknowledgments

This work was supported by the Republic of Singapore’s National Research Foundation through a grant to the Berkeley Education Alliance for Research in Singapore (BEARS) for the Singapore-Berkeley Building Efficiency and Sustainability in the Tropics (SinBerBEST) Program. BEARS has been established by the University of California, Berkeley as a center for intellectual excellence in research and education in Singapore. This research was (partly) funded by the industry consortium members of the Center for the Built Environment (CBE), University of California, Berkeley. We would like to thank Professor Gail Brager, Dr. Seema Bhangar, and David R. Lehrer for their careful review of this paper.

Reference

Kent, M.G., Parkinson, T. & Schiavon, S. Indoor environmental quality in WELL-certified and LEED-certified buildings. Sci Rep 14, 15120 (2024). https://doi.org/10.1038/s41598-024-65768-w