How 8 Commercial Buildings Achieved Net Zero

Story at a glance:

• Net-zero energy buildings generate at least as much energy as they consume annually via onsite renewable energies.
• The Bullitt Center in Seattle was one of the first commercial buildings to achieve net-zero energy status.
• DPR Construction’s Phoenix Regional Office is one of several net-zero energy offices owned and operated by DPR.

On average building operations account for 40% of global final energy consumption and 33% of global energy-related emissions—and commercial buildings are a major contributor. In the US alone commercial buildings generate roughly 826 million metric tons of CO2 emissions annually.

If we as a species hope to keep planetary temperatures from rising 1.5℃ above pre-industrial levels, the AEC sector must prioritize the design of net zero energy structures—or buildings that generate just as much energy as they consume via onsite renewable energy sources rather than the burning of fossil fuels.

In this article we take an in-depth look at eight net-zero energy commercial buildings.

What is Net Zero Energy?

Before we get to the case study examples, let’s take a moment to clarify what net-zero energy status means in the built environment. For a project to be considered truly net-zero energy, it must produce at least as much energy as it uses via onsite renewable energy sources like solar, geothermal, wind, et cetera. Buildings cannot technically be considered net-zero energy if they source a portion of their operational energy via offsite utility providers, regardless of whether that energy is generated from renewable sources.

For the purposes of this article net positive energy buildings—or buildings that produce more energy than they consume via onsite renewable energies—are considered to be functionally the same as net zero energy buildings. To make it easier to feasibly generate enough onsite energy, most buildings aiming for net-zero energy employ strategies to improve overall energy efficiency and drastically reduce electric load requirements.

How 8 Commercial Buildings Achieved Net Zero

Now that we’ve defined what it means for a building to achieve net-zero energy status, let’s take a look at eight net-zero energy commercial buildings from around the world.

1. The Exploratorium, San Francisco

Originally built in 1969 and located in the Palace of Fine Arts, the Exploratorium—a science, technology, and art museum with more than 1,000 exhibits—was relocated in 2013 to Piers 15 and 17 on San Francisco’s waterfront. Redesigned by EHDD, the new Exploratorium was awarded LEED Platinum certification in 2014 and has since gone on to receive Net Zero Energy verification from the NBI in November 2023, making it the largest net-zero energy museum in the country at the time of its opening.

Since opening in 2013 the Exploratorium has generated 85% of its own energy via a 1.3-megawatt SunPower solar grid composed of 5,874 high-efficiency rooftop-mounted solar panels preventing approximately 16,186 tons of carbon dioxide from entering the atmosphere. Today, the museum produces more energy than it uses on a yearly basis thanks to the inclusion of energy efficient systems and features.

The Exploratorium’s hydronic radiant cooling system, for example, drastically reduces HVAC-related energy consumption by using the San Francisco Bay as a heat sink and source for chilled water. “Not only does this innovative use of bay water reduce the overall energy consumption, but it also significantly reduces the building’s water demand by eliminating the need for cooling towers,” Devin Abellon, business development manager for engineering services at Uponor North America, previously wrote for gb&dPRO. “By using the bay water to serve the radiant cooling system, along with a number of other energy conservation measures, it reduced the building’s electrical energy usage for cooling by a staggering 94%.”

Some of these other low-energy design strategies include insulated windows with low-emissivity glass, LED light fixtures, extensive daylighting solutions, and an energy-efficient natural convection-based displacement ventilation system.

2. The Sustainable Energy Fund Office Building, Schnecksville, PA

Designed by Ashley McGraw Architects and TN Ward Company, the Sustainable Energy Fund (SEF) office building is the first energy-positive building in Pennsylvania’s Lehigh Valley. A 149 kWh solar photovoltaic array mounted on the roof generates all of the necessary energy for the building’s operation and is capable of producing approximately 129.33 MWh annually—far more than the ~87.04 MWh used by the office.

The SEF office is also extremely energy efficient and boasts an Energy Star score of 97, meaning it is 97% more efficient than comparable buildings with the same property type. Inspired by Passive House principles, this high degree of energy efficiency is made possible thanks to the building’s airtight envelope, ample insulation, and inclusion of high-efficiency mechanical systems.

Energy recovery ventilation units and variable refrigerant flow air-cooled heat-recovery units, for example, work together to reduce the office’s electric heating and cooling loads, while LEDs drastically reduce the amount of electricity consumed by light fixtures. An integrated building automation system further serves to optimize energy efficiency, ensuring HVAC and lighting are only in use when absolutely necessary.

Passive solar design strategies are also present, influencing everything from the building’s orientation to the size, shape, and placement of its windows. These allow the office to make the most effective use of daylight while simultaneously ensuring that solar thermal energy is only admitted during the winter months when beneficial; window treatments and solar shading devices in turn prevent excess solar energy from entering during the summer.

3. The David and Lucile Packard Foundation Headquarters, Los Altos, CA

Designed by EHDD, the David and Lucile Packard Foundation Headquarters is both LEED Platinum and Net Zero Energy certified through the International Living Future Institute (ILFI), demonstrating the foundation’s commitment to building a healthier, more sustainable future.

Like most net-zero energy commercial buildings, the Packard Foundation headquarters generates all of its energy via a series of rooftop photovoltaic solar arrays. The 285 kW capacity PV system consists of 915 SunPower panels and is capable of producing approximately 418.04 MWh annually—although thanks to the building’s extremely energy efficient design, only about 351.30 MWh of that energy is required for operation.

Cooling loads, for example, are greatly reduced by the building’s usage of a dedicated outdoor air system and chilled beam technology. In warm weather, water is cooled overnight in a compressor-free cooling tower and stored in two 25,000-gallon underground cisterns. During the day this cooled water is then pumped through the chilled beams at variable speeds via pipes angled at 130° instead of the 90° standard. These wider angles allow for more efficient operation as they enable a 75% reduction in the energy needed to pump the water.

Three air handlers pull air in from outside, filter it, dehumidify it, and distribute it throughout the building; as the air passes over the chilled beams, it cools, keeping interior temperatures within a comfortable range. On days where outdoor conditions are favorable, the HVAC system is shut down in favor of passive ventilation. The headquarters’ building management dashboard even tells occupants when to open and close windows and sliding doors to maximize natural ventilation.

During cold weather the building is heated to 74℉ starting three hours before employees arrive through a combination of air handlers and warm water pumped through the aforementioned chilled beams. Once the workday begins, the heating system shuts down, after which body heat and heat gain from office equipment is typically sufficient to keep interior temperatures comfortable.

The building’s orientation, layout, and window placement were also optimized to make the most efficient use of natural sunlight for daytime illumination needs, resulting in a 30% reduction in artificial lighting loads compared to a standard commercial building of similar size. Sensors installed throughout the headquarters measure and monitor daylighting levels, automatically adjusting artificial light as needed, while light shelves help draw sunlight deeper into the building.

4. DPR Construction’s Phoenix Regional Office, Phoenix

Certified in 2013, DPR Construction’s Phoenix Regional Office proves that net-zero energy is possible even in harsh climates. The LEED Platinum and Net Zero Energy-certified building was redesigned by SmithGroupJJR and conceptualized not just as a sustainable workplace, but as a living laboratory for the community at large.

All of the office’s energy is generated on-site via a solar thermal hot water system and 78.96 kW-DC photovoltaic array. The solar thermal system—an extremely efficient choice for projects in desert climates—is a 4,500W Rheem, closed-loop glycol system with an 85-gallon capacity tank. The PV array is linked to the municipal grid and consists of 326 235Wdc Kyocera modules, each mounted at a 10° tilt to ensure optimum performance; a net-metering plan allows DPR to gain credits for any excess power it generates.

Rather than mount the solar array on top of the office’s roof, the design team elected to install the system over top of the site’s structural parking canopies. The reason behind this decision was twofold—doing so would shade employees’ vehicles and free up space on the roof for additional daylighting opportunities. Ultimately, this allowed SmithGroupJJR to fit 82 tubular skylights from Solatube on the roof, greatly reducing artificial lighting requirements and saving energy.

In addition to daylighting, the building employs several other strategies designed to improve overall energy efficiency, including:

• HVLS fans. Because the office’s acceptable interior temperature range is higher than most commercial buildings—reaching up to 84°F during the summertime—high-volume, low-speed (HVLS) fans from Big Ass Fans were used throughout the open office space to facilitate air movement and improve perceived comfort.
• Climate-controlled operable windows. Large operable window walls line the office’s North and East facades, automatically opening when the ideal conditions for natural ventilation are detected.
• Passive cooling. An 87-foot-tall solar chimney helps facilitate passive cooling by funneling warm air up and out while simultaneously drawing cooler air in, while four evaporative shower towers direct water-cooled air inside, further serving to regulate interior temperatures.
• Vampire switch. At the end of each work day, a kill switch connected to 95% of the building’s non-critical plug loads is pressed to turn off “vampire” loads, or appliances that continue to use electricity even when not in use; the vampire kill switch helps the office achieve a 37% reduction in plug loads.

Combined, these features allow the DPR office to perform much more efficiently than similarly-sized commercial buildings and even operate at an energy net positive. At the end of the initial 12-month reporting period, the office only used 129,624 kWh of the 142,871 kWh of energy it generated.

5. Indigo | Hammond + Playle Office, Davis, CA

West Coast architecture and design firm Indigo | Hammond + Playle’s Davis office is an inspiring example of how net zero energy can be achieved in the context of adaptive reuse. Originally built in 1967 as a Dairy Queen, the structure was expanded and converted into an office/studio workshop but still retains the lines, character, and spirit of the midcentury modern landmark.

And while net-zero energy usage was always part of the conversion plan, the firm’s primary goal was to design a super sustainable and incredibly energy-efficient office that could rely almost entirely on passive strategies for heating and cooling. What little electricity the building does require—about 16,389 kWh—is produced onsite by an 11.4 kW photovoltaic system, capable of generating approximately 20,200 kWh annually.

Energy efficiency was built into the project from the ground up, informing every aspect of the building’s renovation and expansion. New walls with an insulating capacity of R-40 were constructed from straw bales locally sourced from nearby rice farms, while the design as a whole works to harvest energy from the environment through passive heating, thermal storage, night ventilation cooling, and daylighting strategies.

Unwanted heat gain is minimized during the summer through the strategic placement of overhangs on the building’s south-facing windows; these solar shading devices do not prevent daylight from entering and still admit solar thermal energy from the low-angled winter sun, allowing the office to rely partially on thermal heat sinks for warmth throughout the winter months. All-LED fixtures with advanced controls—like photocell detectors and motion-detection sensors—installed throughout ensure that electric lighting is only used when absolutely necessary.

In summer automated louver windows—positioned to facilitate natural cross ventilation—open at night to pass cool air over the aforementioned heat sinks, pre-cooling them for use the next day. A natural conditioning system operated by sophisticated controls integrates the building’s thermal mass, 1,250-gallon storage tank, hydronic radiant heating and cooling system, and backup air-to-water heat pump to further ensure interiors remain comfortable year-round.

6. archimania’s Office, Memphis

When architecture and design firm archimania relocated their Tennessee office, they purchased a pair of existing buildings and renovated them using two very different approaches. One was equipped with geothermal and solar capabilities to achieve dual Zero Energy and Zero Carbon Certification by ILFI, while the other was outfitted with conventional systems and serves as a “control” building of sorts—together, the two properties expertly showcase the possibilities of carbon-neutral design.

All lighting in archimania’s net-zero energy office is part of a Crestron programmable LED lighting control system powered by a 49.4 kW PV solar array mounted on the building’s roof; the array generates ~54,384 kWh annually, though the office only used 51,371 kWh during the initial 12-month performance period. The lighting system itself consists of occupancy sensors, daylight sensors (for exterior lights), daylighting harvesting sensors, plug load controllers, and a subdivided electrical panel for component energy monitoring.

Mechanical heating and cooling is supplied by two high-efficiency geothermal HVAC variable speed fan and variable speed compressor heat pumps. One heat pump serves the office and conference room areas in a zoned variable air volume (VAV) configuration and is equipped with zone dampers allowing it to service four separate subzones. The other heat pump services the open office seating area and operates in a single zone VAV configuration. Each pump only runs when its associated compressor runs, ultimately helping to conserve pump energy. Waste heat from the geothermal system is then repurposed to heat the building’s hot water.

The firm also made several energy efficiency improvements to the existing building, including the construction of overhangs to help prevent solar heat gain, improving the roof’s solar reflective index, adding R12 wall and R30 roof insulation, and replacing the original window glazing with low-e insulated glass units.

7. Bullitt Center, Seattle

Completed in 2013 and designed by Miller Hull Partnership, the Bullitt Center—one of the first net-zero energy commercial buildings in the United States—is a masterclass in both efficiency and resource conservation.

All of the building’s electricity is produced on-site via a 14,000-square-foot rooftop photovoltaic solar array consisting of 575 solar panels. The panels themselves are sensitive to the amount of sunlight they receive, meaning their actual production values are dictated by sky conditions and solar intensity. This means that, in summer, the PV grid generates much more energy than is actually used, whereas in winter the building produces less energy than it uses.

The key to the Bullitt Center’s net zero status lies in its connection to Seattle’s electric grid, which essentially functions as the building’s battery. All surplus electricity generated during the summer months is transferred to the city’s municipal grid, where it is “stored” until the winter when energy production is low, at which point the building takes the electricity back for its own operational needs. As long as the surplus energy produced during the summer meets or exceeds the winter deficit, the building is considered to be a net zero energy property.

Such a surplus may not at first seem feasible given that the Bullitt Center possesses a relatively small PV array for its size—but when you factor in the building’s extremely energy efficient design and systems, it no longer seems so far-fetched. Artificial lighting requirements are greatly reduced by the extensive implementation of daylighting and solar shading strategies, while heat recovery ventilation and a geothermal hydronic radiant heating/cooling system drastically reduce the energy required to maintain a comfortable indoor environment. The building also boasts a regenerative elevator that recovers a portion of its own kinetic energy as it slows down, resulting in up to a 60% reduction in energy compared to traditional elevators.

An extensive building management system automates and controls many of these features, optimizing them for peak efficiency and occupant comfort. Together, these systems help the Bullitt Center operate at an impressive EUI of just 16—much lower than the typical EUI of 92 that most commercial office buildings operate at.

8. Floating Office Rotterdam, Rotterdam, Netherlands

Serving as the headquarters for the Global Center on Adaptation, Floating Office Rotterdam (FOR) is one of Europe’s most impressive net-zero energy commercial buildings and boasts incredible resilience in the face of both climate change and rising sea levels.

Designed by the Powerhouse Company—an international architecture firm whose office is also located in the building—FOR generates all of its electricity via an 870 m2 rooftop-mounted solar array with an annual capacity of 154 MWh. This is roughly 109% of the energy the building actually uses in a year’s time; the surplus energy is then diverted back to the municipal grid for the City of Rotterdam’s benefit.

FOR is moored in Rijnhaven port on the south bank of the Nieuwe Maas river and uses its waters for heating and cooling purposes. Heat pumps transform water ranging from -7 to 55°C to 35°C for the central heating system and 12°C for the chilled water pipes. A pitched roof and overhanging terraces provide passive shading while the office’s green roof helps insulate against unwanted thermal heat loss and gain.

Large floor-to-ceiling triple-insulated glass panels flood the interior with natural sunlight, greatly reducing daytime electric lighting loads; all artificial lighting systems in the building are optimized for energy efficiency, further reducing energy consumption. Certain sections of the glass facade can also be opened to facilitate natural ventilation.