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Making Energy Savings Easier: Usability Metrics for Thermostats

Daniel Perry, Cecilia Aragon, Alan Meier, Therese Peffer, and Marco Pritoni

Journal of Usability Studies, Volume 6, Issue 4, August 2011, pp. 226 - 244

Article Contents

Future Research Opportunities

Due to the ubiquity of PTs and the dearth of usability metrics in this area, there is a clear need for further work in the field. There were many areas of interest that became apparent during the course of our research that we would like to pursue further.

While the current data shows a strong correlation among our metrics as well as with NIST and an expert’s evaluation, we would like to conduct further studies to demonstrate the repeatability of these results. Because the primary impetus of this research was to provide an actionable test that manufacturers could apply to their own thermostats with minimal cost it is important to ensure third-party verification of results. This is especially relevant given the use of these metrics to inform EPA EnergyStar™ usability standards. There is further potential for the metrics to be applied to a host of embedded systems to reduce barriers to efficient energy usage.

As PTs and similar devices become more advanced, there is also more potential research that can be done regarding the automation of our testing procedure. As an example, manufacturers can capture functions using a simulator that could be uploaded directly into our metric for Path Length. This would require minimal effort on the part of manufacturers. Also, as a growing number of appliances become "smart" in their communications with other systems there is the possibility to measure real-time user performance as the product performs in the commercial market. Several thermostat manufacturers with WiFi enabled devices are already gathering information regarding system states and could easily capture data on the function path as well.

User comments and patterns in common errors provide additional insight into good and poor designs for thermostats. Some of these design choices are already a common part of good usability standards, including font size. As one user commented, “There are very small letters here; I’ll have to get my glasses,” while trying to read the instructions on the cover of the device. Other design choices are more specific to the growing use of small touch screens in embedded devices. This includes confusion regarding the touch sensitivity of icons. One user repeatedly touched blank, non-touch sensitive areas of the HYB screen while trying to complete Task 3. This action was not uncommon. There is much continued work that could be done to document design principles for thermostats and create a possible reference device for use by manufacturers.


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