A Power Saving Power Strip

The Vampower, a power saving power strip, is an award winning design project that was part of a joint class in product design and development (PDD) co taught by the FW Olin College of Engineering, the Rhode Island School of Design (RISD) and Babson College. The team that worked on this project included two designers from RISD: Will Harris and Danny Kim, two engineers from Olin College: Bennett Chabot and myself, and a Babson College business student: Anand Virmani.

This product design prototype was the result of work in user interaction, design for manufacturing, electrical engineering and many hours of sweat and hard work. It was completed over Fall 2008 with minor work extending into the Spring of 2009.

the background

It all starts with a problem. The problem is that 129 million mega-watt hours of electricity is lost every year due to so called latent power use. This kind of latent use includes obvious competitors like stereos and computers in standby to the cell phone charger that sits on the outlet every second of every year; quietly using power. To understand the magnitude of that power, latent or vampire power we like to call it uses approximately 10% of the residential power used in the US every year. In terms of power generation it is the equivalent of building 6,000 wind turbines that are 600 feet tall. Since monetary figures can also be drivers for purchasing a device that saves power, we estimated that the average home owner loses $160 to this vampire power use. It is definitely a big problem, but some devices like a cable box or an internet modem don’ work right if they are disconnected from power; so the real world impact regarding the amount of energy savings is less but most likely still very significant.

In addition to the green reasons for wanted to build a new power strip; the power strip is one of those items that companies are always trying to redesign. From simply rotating 90 degrees to the more exotic items on the market like the power squid; people have been searching for a better power strip. We decided that since we were looking to solve the green problem with power strips, we would also take a shot at making a more user friendly and more appealing power strip.

The result was the Vampower power strip; a truly different solution…

the problems and our solutions

To really understand the scope of the problems that potential users of the product that we were endeavoring to design would face, we did a large number of observations of people interacting with their power strips as well as a large number of interviews. From that user data we were able to discern a number of unmet physical needs, as well as a desire to save power if it could be done. Through a process of design exercises and a few more rounds of user feedback, we were able to come up with a rather concrete set of requirements.

To share a few of these requirements and the solutions that we devised to satisfy, I will first share a pair of physical/form factor requirements:

The first one I want to share is the idea of modularity, a notion born for the need for flexibility.

We photographed in many places where power strips were used.  In very few of them did we see 6 or 12 receptacles in use (the common number on a strip). When less were needed, it was not a huge problem, but often when someone wanted to have 8 devices attached to a 2 receptacle outlet there was often either a splitter in use or some sort of daisy chaining going on; creating a potentially unsafe and definitely unsightly nest of wires. Our solution to this problem was the introduction of modularity into the power strip.

We considered other alternatives to our final design. From outlet pads to Power-Squid like form factors we settled on a set of rotatable modules that could be connected and disconnected to build a power strip of just the right size. It was one of the ways that we sought to put the right number of outlets in the right place and cut down on the clutter.

The second is the notion of discrete size a solution to the need for more accessibility.

We found through our research that people often tried to fit their power strips out of sight and tucked into small spaces. This creates a problem when using traditional power strip as the AC-DC power converters used in many of our modern electronics take up so much space that only 4 of the 6 outlets are used on a power strip, meaning that a second power strip is needed. Items like the Power-Squid solve this problem but at the cost of taking much more space. Our goal in attacking this problem was to make every outlet on the strip more accessible without increasing the form factor to the point where the item was no longer space efficient.

We looked at a variety of alternatives and settled on making something with rotating plugs. Through this design we were able to avoid increasing the footprint of the power strip dramatically, while at the same time we were able to make it more likely that user would be able to access every single outlet on our power strip.

The next two requirements and solutions have to do with effectiveness as a power saving device. In the most basic sense, the best way to save power would be to simply turn off the power flowing to devices and turn them back on again. By observing people who did this regularly with their power strips to save power, we identified several distinct “pain points” that stood between people wanting to save power and actually doing so. I will share two critical items below:

First, is turning the power strip off after use.

One of the subjects that we encountered wanted to “green (her) lifestyle” and so took great pains to turn off her power strips that were not in use. For aesthetic reasons, she hid her power strips behind other objects. To turn them off she used a walking stick to flip the switches as they were not easy for her to reach. From these observations and others like it, we were able to determine that a device that we wanted to build would likely be placed somewhere where accessing the device would be difficult and that we would need to allow users to easily switch off their devices. Our interviews also provided another design/engineering target, our users want to turn everything completely off. They didn’t want another device that “leaked power.”

We looked through many different ideas on how to turn off the power. While many of our users said that they would have no extra problem taking an extra step to turn their devices on, it was a major problem to remember to always turn them off. We thought of remote hard wired switches, wireless devices, an iphone app and other countless ideas before settling on a self calibrating circuit that sensed current and simply turned off when the current dropped below a % threshold from its peak use. This would prevent users from forgetting to turn off the device, while walling devices from still consuming even a little bit more power.

The second item is the reverse of the previous process. We needed an elegant way to restore power to our devices.

Again we are faced with the same general scenario as above. Our users tended to hide their power strips, so turning them on often involved uncomfortable reaching or use of the walking stick. In this case, doing the turn on operation needed to be remotely activated. There are many AC-DC converters that can sense when they are connected to devices and thus activate and throttle their power that way. Unfortunately, since we aren’t looking to sense connectivity we had for other ways to activate our devices.

Because we did not want our users to have to keep track of a remote, we looked at motion sensors and current sensing mechanisms. Our users surprisingly liked the idea of a clapper as long as they did not have to worry about it accidentally turning their devices off. Since this was going to be an on only mechanism; we decided on using a clapper type sensor to turn the power strip on for 30 seconds after which the current sensors cut power to any device not using enough power to be determined to be “on.”

the product

Once we found our requirements and synthesized our user feedback to the point where we felt like we had solutions to the problems that we wanted and our users expected us to solve. Through several iterations of presenting prototypes to our users, we arrived at the following design:

We decided on three different components that could be plugged into each other. The first was the clapper sensor and timing mechanism, along with more standard tech found in high end power strips like power filtering and a circuit breaker. The second was the “smart power” module with the current sensor inside. This smart module would be the backbone of the product as it fulfills the promise of the product:

An exploded view of the product shows the current sensor inside a housing with a 4 plug connector (pins not shown). The idea would be to use three pins for the standard electrical pins while using the 4th as a signal pin to turn on all of the “smart power” modules. The last component to our system was the “constant power” module, a connection that would always provide power in the manner of a regular power strip while retaining the benefits of modularity and accessibility. We built this component so that our users wouldn’t need another power strip to connect their devices that they always wanted to be on like their DVR or broadband modem.

the business model

After we built the product we kept in mind our costs and figured out that we could offer significant value to our customers at the $30-$40 price point while we would be able to make a significant profit from the device. In terms of surveying our users on what the final package should look like, we settled on a four module basic package of 2 “smart power” and 2 “constant power” modules in addition to the master switch/clapper. The green lines indicate the “smart modules”. (power cord not rendered)

conclusion

We wished that we had the resources to take this further, but as there was no real place for IP (except on the design of which other copies already exist) we did not decide to take this idea further. There are also some problems that were not fully solved in this exercise. There is no way to differentiate between the kinds of modules except for via coloration. One of the ideas that we wanted to implement would have been a way to differentiate the models by shape.

Though the project was not as polished as we wanted it to be, we were able to make prototype(s) for testing and found that the idea was well received. We called this one a success as it was deemed the best design at our expo and photographs of our work were taken to be used in the RISD admissions materials.