Rome may not have been built in a day, but the DPR Construction’s Phoenix office practically was. It took less than a year for the company to purchase the building—an abandoned cement retail structure—get the permits, complete the design, and build its new regional headquarters. The national contractor proved a quick build could also achieve one of green design’s highest callings—net-zero energy. This is the first building in Arizona to achieve Net Zero certification from the International Living Future Institute, and the largest so far in the world. Here’s how they did it.
DPR Construction tapped Solatube International, whose daylighting systems it had already used in its LEED Platinum San Diego office, to install 82 units that distribute the region’s abundant sunlight throughout the office spaces (1). These provide major benefits, from better circadian rhythms to feeling connected to the outdoors. Best of all, 100 percent of the interior is naturally lit via Solatube Daylighting Systems during daytime hours. The units are even used in the conference rooms, which are fitted with a daylight dimmer that can dial down the brightness to about two percent for presentations.
The original structure of the retail building, which was built in 1972, was intact and played perfectly into the open interior layout DPR wanted. The original walls remain on the south and west elevations, and 13 large glass bay windows with horizontal shading devices were installed on the east and north façades. One of the stated goals of the project was to “bring the outdoors inside,” so three-quarters of the workspaces have exterior views of the surrounding urban area.
Light In, Heat Out
For reducing reliance on electric lighting, it’s hard to beat the cloudless Phoenix sky, but solar heat gain and thermal comfort are another story. On an average of 169 days per year, temperatures in the city hit 90 degrees Fahrenheit or higher. Although glass is limited to the east and north façades, nearly 100 skylights could be installed throughout the facility because Solatube’s daylighting fixtures use Raybender 3000 technology to deflect high-angle sunlight as it passes overhead (2). In addition, the Spectralight Infinity tubing with cool-tube technology filters out the majority of the infrared spectrum of light, preventing heat gain and focusing on delivering only the visible spectrum of light into the workspace.
Unique to the Living Building Challenge program are requirements like Rights to Nature, Beauty, and Equity. Communal outdoor spaces like DPR’s courtyard—accessible to all by a massive operable door on the north side of the building—help satisfy those objectives (3). The courtyard has a defining green wall that cools and shades the area while creating a soft, inviting, flora-filled space for employees to enjoy (4).
Power in Parking
To make way for the Solatube system, no solar panels were installed on the office building’s rooftop. Instead, a parking canopy plays a dual function of gathering energy while shading employees’ vehicles. A 79-kilowatt photovoltaic solar array and solar-thermal system covers the parking canopy. Made up of more than three-hundred 235-watt Kyocera modules, the photovoltaic array produces nearly 150,000 kilowatt-hours annually—more than DPR needed in 2012.
A tempting, palm-sized red button by the main entrance is known as the “vampire switch.” It’s connected to 95 percent of the building’s noncritical plug loads—such as those attached to microwaves, cell phone chargers, and desk lamps. The last person out at the end of the day can just punch it and kill the power leaking out of those outlets. Not only do the employees love the rush, it reduces plug-load energy by 37 percent.
Comfort is Key
A variety of HVAC solutions work in concert to make interiors comfortable even in the desert heat. Operable windows—87 of them on the north and east façades—respond to the outdoor climate, adjusting to ventilate and cool the office. At the same time, a dozen sleek Isis ceiling fans by Big Ass Fans, each with a wingspan of eight feet, circulate the air above the workstations (5). On the exterior, four passive evaporative cooling towers function in tandem with the largest solar chimney in the state to release heat, draw in cool air, and automatically sense and adjust for outside changes like wind speed and temperature.
Focal and Functional
The building’s iconic architectural feature is an 87-foot-high solar chimney clad in zinc. A riff on the adobe chimneys of Arizona’s American Indian architectural heritage, the structure captures heat as it rises in the office interior and releases it via operable louvers. That transfer draws a breeze through the operable windows on the façade, cooling the space and drawing in fresh air. Viewed from inside, the tower—which is fitted with Solatube lenses—raises the ceiling, creating a dramatic, grand hall effect.