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Computing Advances Enable More Efficient Buildings

Computers, apps, and visualization tools open up new possibilities to improve the energy performance of buildings.

Computers are becoming ubiquitous devices in the United States: along with countless desktop and laptop computers Americans use at home and at work, more than half of the U.S. population now owns a smart phone, which is essentially a pocket-sized computer. These devices, in turn, open up a world of new possibilities. For instance, the ability for smart phones to use global positioning systems (GPS) to determine their location creates new opportunities for finding a nearby service and determining how to get there.

Computers are also unlocking new powerful possibilities to save energy in buildings, and NREL is at the vanguard of efforts to use design and simulation software—along with tablet computers, apps, massive data storage, and visualization tools—to improve the energy performance of buildings at every stage in their life cycle. As noted by Larry Brackney, NREL's section supervisor for commercial building controls and analysis tools, many decisions go into every stage of building design and operation, and NREL's goal is to help building professionals understand the energy implications of these decisions.

"We're creating the tools that allow architects and designers to assess the tradeoffs that they are making—whether they are aware of them or not—and to visualize and react to the data that's available to them," says Brackney.

One example of such a tool is OpenStudio, an NREL-developed software suite that makes it relatively simple to build a software model of a building and then analyze its energy performance. OpenStudio works with SketchUp, a 3-D drawing tool that architects often use to design buildings. Linking the two tools together encourages architects to analyze the energy performance of their designs before they are set in stone. But for NREL, OpenStudio is a stepping stone to more tools and even greater functionality.

Helping Design More Efficient Commercial Buildings

Consider NREL's work with Xcel Energy, for instance—a utility that operates in eight states, including Colorado, where NREL is located. The utility operates an Energy Design Assistance (EDA) program that offers incentives to companies constructing new commercial buildings or performing major renovations of existing commercial buildings. The incentives are based on how much energy the building will save compared to a building designed to meet the minimum building code requirements.

The EDA program provides energy consultants who help participating companies navigate the process by analyzing the building design, performing energy modeling, and suggesting design alternatives. But the utility struggled to ensure that its energy consultants would perform consistent and cost-effective analyses for its customers, so it turned to NREL for help.

"This is the same problem facing a number of utilities that have EDA programs around the country," says Brackney. "As building codes become more stringent, the viability of these programs is really coming into question, and incentive programs get shut down all the time."

In response, NREL devised a Web service—called the EDA Program Tracker, or EDAPT—that automates the entire process. The system uses OpenStudio software to analyze the energy performance of the building design. OpenStudio, in turn, links to the Building Component Library, an online repository of energy data on individual building components, such as lighting systems and energy conservation measures like increased wall insulation.

Drawing on the Building Component Library, the consultants can examine alternatives to the baseline building design and evaluate their effectiveness. Using the Building Component Library also helps ensure that the energy consultants all use the same assumptions, rather than applying their own "rules of thumb" to the design process.

Once the consultants are done with their analysis, EDAPT automatically generates a report that includes not only all the information that Xcel Energy requires, but also a summary of all the design measures examined by the consultant. In addition, the report flags any findings that seem to deviate significantly from expected results based on best practices. This allows the utility to assess the thoroughness and accuracy of each analysis.

For Xcel Energy, EDAPT also provides a way to monitor their program as a whole. The service provides Xcel Energy with a dashboard that shows the status of all their projects and allows them to analyze whether their EDA program is on track for its energy savings goals.

"We've created a process that reduces the time for the consultant and the time for Xcel Energy," says Brackney. "We've reduced Xcel Energy's administrative costs by at least 20% since this went live, and we've improved the quality."

The project has also gained the attention of the U.S. Department of Energy (DOE), which wants to make EDAPT available to utilities throughout the country. While that will help DOE meet national goals for energy savings, it could also provide an even more powerful tool for DOE: the ability to track EDA programs happening throughout the country.

"Just as the utility has a view of energy performance for their portfolio, DOE is going to have a higher-level dashboard they can look at to see how the country is doing," says Brackney. "Then we can get real impact metrics for our tools and know what measures are being considered, where they're being considered, which measures are not being considered, and how much are measures costing on average. So that's going to help DOE inform their investment in their whole portfolio of emerging technologies."

Such big-picture views could be critical to achieving the aggressive energy saving goals necessary to meet the Obama Administration's greenhouse gas reduction targets, which are part of a global effort to minimize the impacts of climate change.

Operating Buildings Efficiently by Putting Occupants in the Loop

Are you comfortable right now? Feeling a little cold or hot? If you're reading this in an office environment and the temperature seems a bit off, odds are you'll either get up to change the thermostat—and maybe make someone else uncomfortable—or you'll call your building energy manager and complain. But that building energy manager may have no way to judge if you're a lone complainer or an indication of a true problem with the building's comfort control.

At NREL's Research Support Facility (RSF), however, it works differently: each occupant has a desktop application, called the Building Agent, that allows them to provide immediate feedback on their satisfaction with the temperature, lighting, airflow, and noise levels in their area. Occupants can also send a text message.

"What we're trying to do is include people in the control loop," says NREL Engineer Nick Long. "We wanted to have the feedback from the people to also provide some capability of saying, 'It's too hot,' 'too cold,' maybe 'too sunny' or 'too much glare,' 'not enough air movement,' things like that. We want to have that feedback so that we can give that to the building managers in an aggregate, useful way."

The Building Agent knows where each employee is located, so all the feedback and location information goes into a database, along with data from local sensors and the building automation system, to provide a big-picture view of the RSF's energy performance. The desktop application also allows messages to be pushed out to the building occupants; in the RSF, which has operable windows, it is primarily used to tell occupants when to open and close their windows.

A screen shot of the Building Agent, showing the latest energy message from the Research Support Facility and a comfort level survey for occupants. The message asks occupants to please close their windows.

The Building Agent tells building occupants whether they can open their windows and gives them a means to provide feedback on their comfort levels. Users can also check the building's current energy performance and respond to occasional surveys.
Image provided by NREL

The Building Agent has two primary aspects: gathering data and visualizing it. To give the whole-campus view, NREL has created a Web-based dashboard that displays real-time energy usage as an analog dial, with expected ranges of energy use for the campus as a whole. For the RSF, users can drill down to a lower-level dashboard with individual dials for the energy produced by the building's solar power systems and the energy consumed by heating, cooling, mechanical devices, lighting, the data center, and plug loads—the energy used by equipment that is plugged in, like desktop computers and task lighting.

The clever part of these dials, however, is that the expected range of energy use or production changes with the hour, day, and season. The expected solar power production, for instance, is based on actual measurements of solar irradiance at the site. Other dials draw on a combination of models and historical data. Plug loads, for instance, increase in the morning as workers arrive, then tail off in the evening as workers leave for home. The dials provide real-time information for building managers.

"A lot of things can go wrong in a building like this, and some of them are not very self-evident," says Jake Gedvilas, building manager for the RSF. "Our building automation system does have alerts and alarms, but if something is operating within its parameters, we don't necessarily get alarms, even though there might be a problem.

"For solar power, in particular, the dial might show in the red, but we don't get an alarm, so that's helpful for us as a red flag: an inverter might be down or the snow might be covering the solar panels. So there's an explanation, generally, why things are not working within range."

The benefits of the Building Agent have come to light a number of times since it has been launched. One of the visualization tools is a floor plan that shows which parts of the building are running cool and which parts are too warm. This feature proved useful during a recent winter deep freeze, when NREL had to reevaluate its night setbacks—how much the thermostats were turned down at night.

"We did learn a few lessons from that," says Gedvilas. "There were a couple of areas that had night setbacks that were too low. Night setbacks help to save energy, but the building could never catch up during the day; it was just too darn cold outside, and some rooms never achieved the comfort range. So we had to make some tweaks and adjustments. But we never got any alerts on that because it was operating as programmed and designed."

There are many such anecdotes at the RSF, and to Long, this is the sound of success.

"With Building Agent, we're trying to enhance the communication between the building and the occupant and the occupant and the building; trying to connect those two together to give the facility managers a way to save energy, to look at their energy consumption and see where the issues are," says Long.

Analyzing the Energy Use of Massive Numbers of Existing Buildings

Image of a building floor plan consisting of three long, narrow wings connected by a central corridor. One full wing and one-third of the other two are colored blue.

The Building Agent gathers occupant feedback on comfort for use by the building's energy manager and others. This image shows average responses in several areas on a cold winter day.
Image provided by NREL

So far, we've seen how NREL is helping utilities work with their customers to design and build more efficient buildings—an effort that is slated to go nationwide—and we've seen how NREL is helping building energy managers work with occupants to operate a building more efficiently while maintaining comfort. But what about all those inefficient buildings out there? How can we identify the buildings that waste the most energy in any one area?

That's the question that National Grid, a utility that operates in the Northeast, brought to NREL. And the utility wanted to go big: it wanted to analyze the energy performance of every building in its service area—that's 20 million buildings!

"After we picked up our jaws off the floor, we sat down and thought about it and said, ‘Yeah, we could figure out how to do this with OpenStudio,’" says Brackney.

The result is a program called Customer Optimization for Energy Efficiency, or COFEE for short. NREL started by mining National Grid's customer data for building location, type, and floor space for each of its customers. Using Google imagery to determine the area covered by each building, COFEE makes assumptions about the building and automatically generates a baseline model of the building.

"So we have kind of an OpenStudio-based expert system that makes its best guess at what that building model might look like," says Brackney.

The model is then tweaked to make it fit the billing data for that location, and COFEE compares the model to National Grid's incentive programs and creates a customized sales plan for each customer. The plan may include a few questions for the customer, but once those questions are answered, the program is able to determine which energy saving improvements are appropriate, what incentives are available, and what the payback period is for investing in the improvements.

The approach minimizes the marketing outlay for the utility because it can focus its marketing efforts for its incentive programs on those customers most likely to benefit. It also maximizes the likelihood that the utility will get the benefit it aims to achieve. Looking further out, having energy models for all of the buildings in its service area could allow the utility to generate detailed forecasts of its energy demand. And although COFEE was created for National Grid, NREL and DOE hope to make it available to other utilities.

These examples of the design, operation, and retrofit of buildings all demonstrate a key aspect of the NREL philosophy: to try to have nationwide or even global impacts from relatively small-scale efforts. EDAPT was built to help design efficient buildings for one utility, but it may be adopted nationwide; Building Agent was built for the NREL campus, but it is available for licensing and can be applied to any large building or campus; and COFEE offers a large-scale approach to analyzing the energy performance of buildings. All of these efforts will lead to more efficient buildings throughout the United States and perhaps the world.

—Written by Kevin Eber

Energy Saving Homes and Buildings

Spring 2014 / Issue 6

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