In July 2014, a group of us from Lake|Flato drove three hours west of San Antonio to Uvalde, Texas to install an energy-monitoring device on a newly completed ranch house. The occupants, retired full-time residents, had moved in over a year ago and loved the house and the lifestyle they had on the ranch but felt that their utility bills were, in their words, “a little higher than [they] had expected.” Before the trip to the site, we had attempted to figure out the source of their high electricity bills but were not sure what to make of them. This was not a project that was loaded up with “green gadgets,” but from a sustainability perspective we had virtually done everything right. The house was small – just over 2,000 sf – had limited, well-shaded glazing, and was oriented for ideal solar access. The clients had opted for an efficient ground source heat pump for space conditioning and water heating, and the project had been zoned so that the bedroom and living space could be set to different temperatures. The occupants are energy-conscious people who described unplugging kitchen appliances when not in use to avoid phantom loads, as well as keeping the house cool and wearing sweaters in winter.
Despite these efforts, the house was using about twice the energy that we had anticipated, and the goal of our trip was to find out why. The device we were installing was an eMonitor, an energy monitoring system that tracks and logs the energy for every circuit in the home. The data is uploaded to the Internet in real time via the home’s Wi-Fi and is accessible from anywhere in the world.
Circuit-by-circuit monitoring allows us to study both energy end uses and time-of-use, helping us understand both where and when energy is used. This information can help us study patterns and diagnose problems and can provide us with a deeper understanding of the project’s performance. At Uvalde, we installed 44 current transformers in the main electrical panel, hooked the system up to the Internet, and waited for the data to begin to upload. Within five minutes, we discovered where all the energy was going: the pool.
Though many, if not most, of our residential projects have pools, before this day we had not thoroughly explored pools from an energy perspective. Pool pumps are not included in typical residential energy models, and most of the design, specifications, and scheduling of the system is traditionally left to the pool contractor. The Uvalde pool pump was pulling a constant 3,000 watts, or 72 kWh per day – more than the 62 kWh per day that an entire typical Texas house consumes. Not long after the installation of our energy-monitoring system, we were able to re-program the pool pump to run only five hours a day, and the total energy use of the project dropped by 40%, saving the occupants almost $2,000 per year in electricity. We have since learned a great deal about pools and have developed and implemented officewide pool energy design guidelines with the goal of making our pools as efficient as possible.
Since our trip to Uvalde, we have installed eMonitors on several additional homes, and by studying these projects along with the LEED for Homes certified Hacienda Ja Ja, a project that has been logging energy since 2011, we have expanded our understanding of the forces that drive residential energy. A major lesson learned is that we need to understand what systems are using the most energy so we can devote our time and resources where it will be most effective. The Uvalde pool, for example, used 50% of the whole building’s energy, yet most of our sustainability effort was spent on the envelope, a system that used significantly less. Our study of the Hog Pen Creek residence really furthered this line of thinking when the occupants began receiving $1,000/mo. electric bills.
Hog Pen Creek, a full-time home on Lake Austin, is another project where we are using an eMonitor to analyze and reduce energy consumption. This project is similar to Uvalde in that, from a sustainability perspective, we did virtually everything right. The project is small, around 2,500 sf, compact in its organization, and limited in its glazing. It is divided into two wings, one full-time and one guest, each equipped with systems designed to limit energy based on use patterns. The main house is conditioned and supplied with hot water via an open loop geothermal system that draws cool water directly from Lake Austin. The guest wing is conditioned by efficient split systems that can be easily turned on or off depending on occupancy. Similarly, the hot water system is instantaneous to prevent tank losses during periods without guests.
The energy model had predicted a high-performing project, but unlike Uvalde, which was using twice the energy we had expected, Hog Pen Creek was using four times more energy than was modeled. This time, when we hooked up the eMonitor system and waited for the first bits of data to upload, we knew the pool energy would be significant but also that something else must be causing such high energy use. The pool pumps and heaters were pulling a constant 7,000 watts, 60% of the total energy of the house, but we also found significant and unexpected energy use from the lighting control system, the security system, and the irrigation. These systems were not included in the energy model and little to no time was spent thinking about their potential energy use yet, combined, the systems accounted for 85% of the project’s total energy.
The problem with our energy models was not one of depth, but one of breadth. We had the details to predict the energy use of the systems that were being modeled, but we were not modeling the systems that were using most of the energy.
Reflecting on our research, it was clear to us that we live in a new reality of residential energy use. Like many firms, we are exploring what it means to design and build high-performing projects in an era where traditional solutions matter less, and new solutions are becoming less and less architectural. A glass box, though a poor architectural solution, might perform better than an otherwise efficient project with a pool. Determining which project would be more “sustainable” is a question that we are still tackling. One thing we know for sure is that there is a need to broaden thinking and design considerations from “designing a high performing house” toward “encouraging a high performing lifestyle.” The pools matter; the set points matter; and the lights that are on when the occupants aren’t home matter. Our research has shown us that all of these things seem to matter more than the R-value of the roof, the window-to-wall ratio, or the rest of the features that many of us, as architects, are more comfortable talking about. The new reality of residential energy use can feel both intimidating and liberating — intimidating, because we need to learn about all of these systems that have traditionally been outside our scope, but liberating, because traditional “design” is beginning to have less of a correlation with actual performance than we had once believed. This frees us to orient and glaze the building to optimize daylight and space, knowing that energy won’t be affected significantly.
Overall, the biggest lesson has been the value of staying engaged. Uvalde, Hog Pen Creek, and Hacienda Ja Ja are all good performers today, not because we are design geniuses, but because we remained engaged. This is true for all projects, not just residential. As an architect, if you don’t know how your project is performing, it’s not performing well. Many in the profession have caught on to this idea, including the AIA, which now requires actual energy data to be submitted with most design awards. Our strategy for engagement is to make energy monitoring devices standard for the vast majority of our residential projects. When the project has been completed, we teach the occupants how to use the eMonitoring web interface and encourage them to check their energy use regularly and even experiment by switching things on and off to see their relative energy use in real time. After six months, we analyze the data and prepare a personalized “energy user’s guide”, a report that shows how energy is being used and a series of strategies that can be implemented to run the home more efficiently. Our goal with this initiative of following up with residents is not to tell our clients how they should live, but to empower them to understand the energy implications of their decisions. Research has shown that occupants who track their own energy use consume up to 20% less energy than comparable occupants who do not, another significant savings not picked up in traditional energy models, but one we are happy both to implement and to take advantage of.
Corey Squire is Sustainability Coordinator at Lake|Flato.