Nonlinear relationships between individual IEQ factors and overall workspace satisfaction

Despite a paucity of rigorous scientific evidence causally linking Indoor Environmental Quality (IEQ) issues to office occupants' productivity, there is a widespread belief that such causality exists; excellent or poor IEQ translate into productivity gains or losses respectively. The aim of this study is to better understand relationship between perceived building performance on specific IEQ factors and occupants' overall satisfaction with their workspace. Kano's satisfaction model, developed originally in the context of marketing, is adapted and tested for its suitability in the context of building occupants' satisfaction. Analyses were conducted on the occupant survey database from Center for the Built Environment (CBE) to estimate individual impacts of 15 IEQ factors on occupants' overall satisfaction, depending on the building's performance in relation to those IEQ factors. These empirical analyses identified nonlinearities between some IEQ factors and occupant satisfaction; some IEQ factors had a predominantly negative impact on occupants' overall satisfaction when the building underperformed. These have been labelled Basic Factors in the Kano Model of satisfaction and include 'temperature', 'noise level', 'amount of space', 'visual privacy', 'adjustability of furniture', 'colours & textures' and 'workspace cleanliness'. Other IEQ factors had a predominantly linear relationship with overall satisfaction - increments or decrements of equal magnitude in the building's performance on these factors lead to a broadly similar magnitude of enhancement or diminution of occupants' overall satisfaction. These were labelled Proportional Factors, and include 'air quality', 'amount of light', 'visual comfort', 'sound privacy', 'ease of interaction', 'comfort of furnishing', 'building cleanliness' and 'building maintenance'.