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Behavior and Usability: At the Interface of Human-Building Interaction

Posted by Lester Shen  |  Date March 1, 2013  |  Comments 3

Of course, behaviorism works. So does torture. Give me a no-nonsense, down-to-earth behaviorist, a few drugs, and simple electrical appliances, and in six months I will have him reciting the Athanasian Creed in public.

- W. H. Auden


figure-28.pngIn the 1970s, Princeton’s Twin Rivers Project found that the behavior of the occupant is a determining factor of the energy used in a home. Families living in identical units (floor plans, furnaces, and appliances) had widely varying energy use. In fact, when new occupants moved into previously occupied units, their energy use was “nearly unrelated to their predecessors.” Clearly, if we seek to reduce energy use, we need to address how people use energy in their homes.

In the ‘80s and ‘90s, trying to change occupant behavior was known as client education and was an aspect of the low-income weatherization process. The approach was didactic using the strategy of commitment to induce behavior change. Since this was part of a larger weatherization package, it was difficult to assess the impact of these efforts and given the time and effort involved in the audit process, often client education was given a lower priority. Retrofitting the shell and mechanical equipment were things that we actually could do to get big energy savings.

report.pngIn the early 2000s, social psychologist Robert Cialdini and Wesley Schultz looked at social norms to promote energy saving behaviors. Opower developed a program with the Sacramento Municipal Utility District to provide customers with feedback reports that were based on this social norming strategy. Energy savings were found to be around one to three percent.

However, given the large variations in energy use found forty years ago in the Twin Rivers Project, one would think that the savings potential based on behavior might exceed a couple of percent.
 

Usability

teapot.jpegConsider the noble teapot. You fill it with water and place it on the burner. Its whistle serves as a clarion call that the water is ready to make tea and that you can now turn off the burner. The teapot whistle is a very usable, energy efficiency device. It is so usable that we probably don’t even think of the teapot as an energy efficient appliance.

Now let’s take a look at the programmable thermostat, the device that is at the center of the heating and cooling of your house. Alan Meier at Lawrence Berkeley National Laboratory performed a study of the use and usability of programmable thermostats. In a survey of homeowners, he found that half of the homes had the thermostats set on continuous hold, meaning that no savings from setback were being obtained. Twenty percent of the houses had the wrong time set on the thermostat. Clearly a gap exists between functionality and usability. The issue with ththerm.jpege technology is with the design. The programmable thermostats were not designed to be usable. This is an example where we can not expect behavior to change in order to comply with the technology but should look toward how the technology is designed so that the user can employ it properly for the energy saving purposes that it was designed for.
 

Human-Building Interaction

nest-(1).jpgIn the computer engineering and design fields, there is a field of study called human-computer interaction (HCI) that involves the planning and design of how humans use and interact with computers. As Alan Meier’s work with thermostats has shown, there currently is a need for a field of study dealing with human-building interaction (HBI). We need to apply user-centered approaches to the design of the appliances, technologies, and equipment that consume the energy that we use in our homes and workplaces.

The Nest thermostat is a great example of how usability and design has led to a rethinking of the programmable thermostat. It is little wonder that the designer of the Apple iPod is behind the Nest. They are using a design approach that should (will) be extended to the rest of the building.

Smart power strips are another example of a design where users must conform to the technology. While they are intended to help eliminate phantom loads for entertainment centers or computer systems, adjusting them to work properly can lead to frustration and eventual abandonment. Wouldn’t it be easier to simply have a switched outlet on the television to control the power to the other devices in the entertainment system? How about having a wall outlet that has a switch on the wall that turns off the power to the entertainment system?

powerstrip.jpeg
In my house, we use a power strip that has a remote control switch that can shut off the power to any devices plugged into it. We have the remote control switch adhered to the wall and our five year old can turn off our entertainment center with the touch of the switch. This is a great example of user-centered design. No need for me to fine tune a smart power strip (and I have had to go through that frustration before.) We don’t need to use multiple remote controls to turn off devices nor do we need to bend down to turn off a power strip. Did we change our behavior? Yes, but it was no more than turning off the lights in the room and in fact it provided convenience.

Another great example of usability can be found in the Salt River Project (SRP) M-Power pre-payment plan. Using a tried and true technology from the UK where pre-paid electricity plans are common, pre-pay.pngSRP customers use an M-Power smart card to buy the energy that they plan to use. They can buy more energy as needed or budget their use to keep within the amount they’ve purchased. According to SRP, “the average M-Power customer reduces energy usage by 12% annually. More than 90% of M-Power customers believe they use energy more wisely on this plan.” Contrast this to online bill payment, where customers become so removed from their energy bill that they lose awareness of how much they spend and use.

We need to make it easier to use products that will help us save energy. Behavior and usability are two sides of the same coin. Changing behavior conforms the user to the technology while usability conforms technology to the user. It is time to enlist designers and human factors experts to help us apply usability to instill energy efficiency habits.
 

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3 Comments

great post Les. "Changing behavior conforms the user to the technology while usability conforms technology to the user." That concept opens up a lot of possibilities...
Nice blog but I have to disagree with the claims about the size of occupant effect on energy use - nearly unrelated? I have lots and lots of data showing that gas usage in heating climates is dominated by the building - the correlation across occupants is very high (with some outliers). I also have similar data for cooling loads in hot climates. Occupancy effects are much larger for plug loads and other baseloads, but not so much for heating in cokd cliates or cooling in hot climates in most cases. Also, there were several evaluation of energy savings from in home education combined with weatherization back 20 years ago. They found added savings on the order of 6% in pilot programs but it didn't seem to replicate in large scale efforts.
Michael, thanks for the insights from your analyses. The Twin Rivers project was such a seminal work at the time that many of its findings have become gospel to people like me. I was chatting with Martha about it and she had some thoughts and questions. It would be great to get more information on your findings. Perhaps a guest blog post for us? ;-)

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