carried out on a few occasions. The earliest such study was carried out in 1936 by A. M. Simpson, who worked for the van Kannel revolving door company at the time. Simpson's study was followed by a study by Schutrum et al. in 1961, and more recently a study by van Schijndel et al. in 2003. These studies have focused on providing detailed measurements of the quantities of air and heat transferred inside the compartments of a door as it revolves. With the exception of the study by van Schijndel et al., which was purely theoretical, the measurements carried out for the other studies were used to provide design charts enabling engineers to estimate the quantity of air transferred by a door in function of the revolution rate and temperature contrast. Unfortunately, none of these studies appear to be referenced by existing design codes. Although the aforementioned studies provide useful results, these results are also specific to the type of door which they were acquired for, namely 2m x 2m doors with four compartments. Although it appears that these dimensions were standard for four-compartment doors at the time, this is not the case nowadays. A more recent experimental study carried out at Imperial College London's Department of Civil and Environmental Engineering, has provided more insight into the flow physics by which air is transferred across a revolving door. Airflows and energy losses through revolving doors also occur as a result of leakages past the seals of the door. Leakages are common to any type of opening in an otherwise closed space, but have been investigated in the context of revolving doors by Zmeureanu et al. and by Schutrum et al. before that. The first study concluded that to avoid significant leakages, the seals of the doors should be maintained and periodically replaced if needed. The second study produced design charts for estimating the leakage rate through a revolving door. Unlike the curves for estimating the transfer rate also published in this study, the curves for estimating the leakage rate are more generic. As such these design curves still form the basis of the target leakage rates for revolving doors recommended by the ASHRAE standard 90.1 in the US. On May 25, 2006, an MIT Study entitled "Modifying Habits Towards Sustainability: A Study of Revolving Doors Usage on the MIT Campus" was published. In it, B. A. Cullum, Olivia Lee, Sittha