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Net Zero Energy: Inside the Federal Government's Most Energy-Efficient Building

See the National Renewal Energy Laboratory net-zero energy facility.

Net Zero Energy
As governments push to adopt sustainable practices, one holy grail is creating working environments that achieve net-zero energy consumption. That’s the idea behind a newly opened office building at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) in Golden, Colo. Known as the Research Support Facility (RSF), the structure is designed to create as much energy as it consumes, making it one of the world’s most energy-efficient buildings.

The RSF, while certainly cutting edge, is not some isolated technology wonderland impossible to reproduce. Rather, what makes the building so energy efficient is a combination of thoughtful design, creative architecture, an understanding of the natural environment and clever repurposing of existing materials. Upon seeing the RSF, one is immediately struck by the building’s peculiar footprint. Two long, narrow wings are connected near their center, creating what NREL literature calls a “lazy H” configuration. The lazy H maximizes the RSF’s ability to capture sunlight while complementing the local geography.

Approaching the RSF’s front entrance there are several elements that immediately draw the eye. Most prominently, the doors are surrounded by what look like massive metal mini-blinds, which are surrounded by a highly reflective façade. Both the mini-blinds, actually called light louvers, and the façade serve a specific purpose.

“They take that light and bounce it into the middle of the space,” said Heather Lammers, a public affairs official with NREL. “We’re trying to maximize all of that daylight going into the workspace.”

The RSF is 100 percent day lit, but oddly the natural light at first seems very unnatural. Perhaps the sensation stems from traditional office environments, which are often lit with fluorescent lights. (Though the RSF has artificial lighting, it will only be used at night or during stormy weather.)

In the RSF courtyard, rows of solar panels peek over the roof line. Light-diffusing shades frame all the south-facing windows. LED lights line a walkway made of porous pavers that allow rainwater to seep back into the ground instead of flowing into a storm drain.

There are retaining walls made not of concrete, but of rocks excavated during construction and contained in a mesh made of recycled wire. And all around are landscape features done in a xeric style, featuring vegetation adapted to the extremely dry climate. “Water is king. It’s almost bigger than gold out here,” Lammers said. “Colorado is a very dry, arid climate. And so, because of water loss in Colorado, we can’t retain water onsite to water [the landscape], but we can kind of use the water as it flows through the site.”

The facility uses a clever runoff water collection and irrigation system that combines simple piping from the roof to the ground with intelligently designed terrain.

Other less obvious but equally important elements help make the RSF Leadership in Energy and Environmental Design Platinum certified. Much of the exterior consists of large panels that were preformed before arriving on site. The panels are made entirely of local aggregate and are layered over insulation and interior concrete walls. The panels dissipate radiant heat, preventing it from entering the interior.

“It helps really keep the building at a consistent temperature,” Lammers said. “You think about the old cathedrals that you used to go into made of all that stone … [it’s the] same kind of principle. You get some thermal mass and it helps dissipate the heat, helps slow it down from entering the building, and then at night it naturally cools off.”

A portion of the building’s south side is sheathed in another energy-saving feature — a large swath of corrugated metal. What appears to be decorative metal siding actually is the result of a technology developed at NREL known as transpired solar collectors. The wavy metal is punctured by thousands of tiny holes, which draw in air that’s heated by the sun-warmed metal. The warm air is then pumped underground into the RSF’s unique thermal storage facility. Like most of the structure’s energy-saving features, the transpired solar collectors are completely passive, making them far simpler to duplicate in future structures.

The transpired solar collectors, like the RSF itself, were in development for years before finally gaining traction. Jeffrey Baker, the Department of Energy’s director of the Office of Laboratory Operations at the Golden Field Office, conceived of the RSF 15 years earlier.

“It took that long to get everything lined up, but once everything did get lined up in the budget process … such that we had money and support, the project went very quickly. It was completed in about three years,” he said.

Inside the RSF, there are several elements Baker likes to call attention to. First is the sheer number of windows — sized to match the thermal characteristics of the building and each triple paned and triple glazed. Second is the wood paneling that adorns the building. The wood, a beautiful pine infused with blue and gray, is salvaged from trees killed by a devastating pine beetle infestation. Last, Baker pointed out several ordinary-looking structural support columns that are concrete-filled pipes salvaged from natural gas wells.  
“All the materials and techniques that we used in this particular building are available to anybody today. It all operates passively, so there’s not a lot of very complicated technologies,” Baker said. “What we’ve done here today can be duplicated by others.”

Lammers also pointed out that the floor tiles are made of granite mine remnants mixed with epoxy and the receptionist’s desk is made of ground sunflower seeds and laminate.

On the second and third floors are the office spaces. Scattered throughout these spaces are transparent floor plates, which provide a look at the inner workings of the labyrinth thermal storage facility. The labyrinth, actually just a crawl space, is below the first floor.

From the labyrinth comes a piping system visible below the plates. Water in the pipes is heated by the solar panels and transpired solar collectors. The heat is dissipated into the RSF’s concrete superstructure, which warms the interior. Conversely, to cool the building, the pipes go underground where the water is naturally chilled and again piped back up to cool the concrete, which in turn cools the interior. In total, 42 miles of heating and cooling pipe snake through the building, completely eliminating the need for a forced-air HVAC system. Interestingly the building was engineered with a pink-noise — a variant of white noise — generator that mimics the sound of a forced-air system. NREL research showed that the lack of white noise in an office is distracting.

These office spaces also bear witness to how effective the RSF’s natural lighting scheme is. The sloped, exposed industrial-style roof adds to a feeling of spaciousness. The ceiling and piping are all white and reflect the light directed inside down to the floor, helping to create a refreshing sensation. 

The majority of the many windows also open — something sadly missing from most offices. Most windows are computer controlled, but some employees can open at their choosing.

Also, like most office buildings, there are a host of cubicles with a small number of offices reserved for the bigwigs. Yet none of the offices have ceilings. They’re all open on top. The open offices, together with the sloped roof and the vast number of windows make the space feel large and airy — a truly pleasant working environment.

On the west end of the office floor is a wall of windows that offers a grand view. It’s also in the direct line of the setting sun. Late afternoon in Colorado can often be the hottest part of the day. So like a pair of high-end eyeglasses, the windows automatically tint themselves, letting light in and keeping heat out.

Come winter, 800 employees will fill the RSF and the building will be fully staffed. One might wonder whether the solar-heating systems are enough to heat the building on cold winter days. It turns out the RSF also can capture and reuse the heat generated by its data center.

What’s most striking about the RSF is how energy efficiency is being achieved not with Star Trek-style gadgetry, but with thoughtful repurposing of existing materials and techniques. And by all accounts, the cost to construct the RSF is on par with traditional buildings. Baker said the cost of the building ran about $259 per square foot. So if cost, materials and construction are near-equal to that of a traditional building, the real impact of the RSF is not that it can reach net-zero energy consumption but that it shows anyone else can too — a sentiment Baker shared.

“The lasting value of this building is really demonstrated that we can do projects like this today, using today’s materials and today’s techniques at costs that are comparable to today’s commercial buildings,” he said. “Ten years from now, we want people to look back to the Research Support Facility and say this is where the nation’s move toward highly energy-efficient design started. And these are the folks who actually demonstrated it could be done. I’m here to tell you it can be done today with the right approach, with the right mindset and we’re happy to share our story with everyone so [they] can duplicate what we’ve done.”