Buildings Energy & Emissions

Green Rehab Experiment: The Feasibility of Solar Powered Student Housing

One component of the Green Rehab Experiment is to determine if a combination of energy efficiency upgrades, solar panel installations, and reduced energy consumption can result in a century-old apartment building that satisfies the annual energy needs of its occupants solely through on-site renewable energy generation. An experimental apartment building was retrofitted to this end, and has now been occupied for over two years. A previous article introduces the project in more detail.

In two years, the experimental building has shown a 16% decrease in energy usage when compared to an identical control building. However, the experimental building is currently averaging 56,600 kWh of yearly energy use, while its rooftop solar array only generates an average of 22,300 kWh per year. Thus, for the solar array to meet the building’s energy needs, residents must reduce their yearly energy use by 60%! In the next phase of the Green Rehab Experiment, team members will engage occupants to introduce them to energy-saving habits and challenge them to meet this ambitious energy reduction target.

Is a 60% reduction feasible? An initial examination of energy usage data collected as part of the project has already yielded insight into opportunities for considerable energy savings. The usage data has shown that a few units account for a significant amount of the total energy use, while other units use drastically less. Figure 1 below shows the total building energy use by category (in blue) and the projected total energy use (in red) for each category if all units matched the usage of the lowest user per category for October 2016.

Figure 1: Energy usage data for October 2016. The blue bars depict the actual building energy usage by category. The red bars show the projected total building energy use by category if all units matched the energy usage of the unit with smallest energy expenditure for a given category.
*Hot water energy consumption is not metered by unit. However, it is expected that significant energy savings are possible for water heating.
**Total (both actual and projected) includes all categories except hot water.

What is most exciting about this phase of the project is its applicability to the entire Washington University community. The plot above details the massive impact that lifestyle and habits can have on energy consumption. A greater than 60% reduction in energy consumption can result by simply matching the habits of the most efficient energy users.

The Green Rehab team plans to explore simple steps that occupants of the experimental building and members of the broader university community can take to achieve and improve upon these extensive reductions in their own energy consumption. Such steps will include hang drying clothes, using low-flow shower heads, washing clothes with cold water, properly adjusting thermostats, and of course, turning off the lights when leaving a room.

This article was written by our Green Rehab Student Associates Sam Emery and Colin Keating.