In 2015, AP+I Design helped transform a 1,328.5-square-meter dark office into a bright workspace. 11 years later, it remains Mountain View's first commercial zero-energy building

An old concrete office in Mountain View, California, has taken on a very different role. Instead of being replaced, the dated building was redesigned as a modern workplace built around energy efficiency. The project became Mountain View’s first commercial zero net energy property, giving an aging office a new purpose.

The transformation focused on reducing energy use before relying on renewable power. The building received an insulated envelope, which helps control heat moving in and out. Electrochromic windows can automatically adjust their tint as sunlight changes. Skylights and natural daylight also reduce the need for artificial lighting during the day.

Inside, LED lights work with occupancy sensors to avoid wasting electricity in empty spaces. Recycled building materials were also used as part of the renovation. These choices may sound simple on their own, but together they helped create a workplace designed to use energy far more carefully.


The project also had a human side. AP+I Design, the new owner and occupant, was directly involved in turning the dark, dated concrete building into a brighter and more open office. The result shows that reaching zero-energy goals does not always require starting with a new building. Sometimes, an older structure can be given a second life through smarter design.

Mountain View’s First Zero-Energy Pioneer Holds Firm: What makes this a zero energy building?

“Zero energy” does not mean the building never uses electricity. That is an easy misunderstanding. It means the building can balance the energy it consumes with renewable energy production over a defined period, depending on the certification and accounting method being used. The U.S. General Services Administration describes a zero-energy building as one that balances its energy needs with renewable energy, while the Department of Energy has also established a common framework for measuring zero-energy performance.

The 117 Easy Street project received International Living Future Institute Zero Energy certification, according to the World Green Building Council. Its reported energy use intensity was 18.5 kilowatt-hours per square meter per year, while its onsite renewable production intensity was 18.6. That tiny numerical margin illustrates the basic idea: the building was engineered to keep demand extremely low and then meet that demand with renewable energy.

Why do the windows matter so much?

One of the less obvious features is the building's electrochromic glass. These windows can change their tint in response to conditions, helping control how much sunlight enters the building. That matters because sunlight is useful for daylighting, but too much solar heat can make an office hotter and increase the need for cooling.

The project combined those windows with skylights and extensive natural daylight. Instead of treating lighting, windows and temperature control as separate problems, the design connected them. LED lighting with occupancy sensors could reduce unnecessary electricity use, while the building envelope helped limit unwanted heat transfer.

Could an old office really be the starting point?

That may be the most relevant part of the project for American cities. Much of the country's commercial building stock already exists, meaning climate goals cannot depend entirely on constructing new buildings with the latest equipment. AP+I's project began with an older concrete structure and reused parts of the existing building rather than simply replacing it.

The transformation also extended beyond energy systems. AP+I says pieces of concrete removed from the building's facade were reused for the reception desk and entry partition, while the redesigned workplace added collaborative areas, a garden, outdoor space and a living green wall. Hillhouse Construction also reports that the project incorporated automated building-management systems and real-time energy-performance monitoring.

What did workers notice after the transformation?

The project was ultimately about people as much as electricity. AP+I says employees quickly noticed the difference created by natural light, fresh air and the building's thermal characteristics. The firm later described the workplace as a place where staff became more conscious of how their own energy use affected the building's overall performance.

That detail matters because highly efficient buildings still depend on how they operate once people move in. Computers, appliances, lighting and other equipment create what building professionals call “plug loads.” AP+I's experience suggested that occupants who understood the building's energy goals could become part of the solution rather than simply another source of demand.

What does the Mountain View project tell us now?

The building does not prove that every aging American office can become zero energy at the same cost or with the same design. Climate, building orientation, roof area, occupancy patterns and available renewable energy all affect what is possible. And “zero energy” is not automatically the same thing as having zero environmental impact across a building's entire life cycle.

Still, 117 Easy Street demonstrates an important principle: energy performance can come from a collection of relatively understandable decisions rather than a single futuristic invention. The World Green Building Council records the building as a verified net-zero operational-energy/carbon project, while AP+I continues to describe the Mountain View office as its zero-net-energy home.

For U.S. communities facing older offices, rising energy costs and pressure to cut building emissions, that may be the more useful takeaway. The next generation of efficient buildings may not always begin with an empty construction site. Sometimes it begins with an old concrete box that someone decides is worth saving.