Six California buildings, renovated to zero net energy.

Every one an existing building, kept and remade, and every one more profitable than it would have been renovated to code. Together they are about 245,000 square feet that produce as much energy as they use.

435 Indio Way, Sunnyvale.47951 Westinghouse Drive, Fremont.640 Clyde Court, Mountain View.380 N. Pastoria, Sunnyvale.117 Easy Street, Mountain View.415 Mathilda, Sunnyvale.

435 Indio Way

Sunnyvale. 31,759 square feet, 2014. A commercial building renovated to zero net energy in 2014, and the proof project. South-facing skylights and electrochromic glass light it every day of the year; the exposed concrete, operable windows, and fans keep it comfortable. ASHRAE named it the most innovative sustainable building of the year in the United States.

47951 Westinghouse Drive

Fremont. 82,408 square feet, 2017. A manufacturing building renovated to zero net energy while the tenant ran two shifts, sixteen hours a day. The load came down first: LED lighting, a tuned HVAC system, insulation, window film, a reflective insulated roof. Then a 1.02 megawatt system on the roof and over the parking lot took the bill to zero.

640 Clyde Court

Mountain View. 36,982 square feet, 2019. A fully renovated envelope and a 200 kilowatt solar system gave the building a new face and a net zero energy bill, at a price point more profitable than renovating to minimum code.

380 N. Pastoria

Sunnyvale. 45,383 square feet, 2016. Every light, fan, window, and skylight actuator is powered over Ethernet, and the lights are tuned to the color of the sun through the day. A watertight bifacial solar canopy makes a protected outdoor workspace with filtered light and about a third of the building's power.

117 Easy Street

Mountain View. 14,852 square feet, 2015. The smallest of the six. The scale made the roof and the ceiling the whole design: skylights, solar, solar thermal, and HVAC above; lights, fans, ducts, and cable trays below. Walls that open all the way.

415 Mathilda

Sunnyvale. 33,750 square feet, 2015. A forty-year-old racquetball court with almost no glass; eighty-six windows were cut in. A 660 square foot living wall, accordion doors to the patio, and dynamic glass keep the occupant connected to outside. The tenant chose where to sit by the light.

$49.84added to the cost, per square foot, over a standard renovation

$100.29added to the value, per square foot, the day after occupancy

91 → 22.5energy use intensity before and after, kBtu per square foot per year

93%of the demolition reused

4.67 yearssimple payback for the owner

21.4%return on a net cost of $1,966,453 after incentives

$0the tenant's cost of power, set for the next twenty years

$6.15Mincrease in building value

200 kWof solar on a renovated envelope

$0energy bill

2019the most recent of the six

1/3of the building's power from the solar canopy over the patio

100%of the covered patio leased at full rental rate

98.5%of the demolition reused

92.5%of the demolition reused

14,852square feet, the smallest building to reach zero

86windows cut into a building that had almost none

660 sfliving wall, two stories tall

2016Silicon Valley Business Journal Structures Award, best green project

The building where the method was worked out, and the one the numbers on this site come from.

A 1970s tilt-up with a conventional dropped ceiling and almost no daylight. The envelope came first: six inches of insulation outside the walls, ten in the roof, and operable electrochromic windows and south-facing skylights cut into the shell. Inside, the concrete slab was exposed to do the cooling, the ceilings were upholstered in theater fabric for the acoustics, and the fans and the windows were put under a management system that opens the building at night. Community gardens and a usable patio draw people outside to work.

Renovating to those goals instead of to code cost $4,021,522 against $2,438,801 for a standard renovation of the same building, $49.84 a square foot more. The budget for that work had been set before the design, from the operating savings, at $48.48 a square foot. The day after occupancy the building was worth $100.29 a square foot more than the standard one would have been, and 93.5 percent of what was demolished was reused.

  • ASHRAE, most innovative sustainable building of the year in the United States, 2017
  • Silicon Valley Business Journal Structures Award, best reuse and rehab project, 2015
  • Acterra Business Environmental Award for the sustainable built environment, 2015
  • County of Santa Clara, certificate of commendation for outstanding achievement in the sustainable built environment, 2015
  • Special congressional recognition for outstanding and invaluable service to the community, 2015

What the renovation cost, and what it is worth, per square foot.

Architecture and engineering, with the mechanical engineer integral to the design
$2.42
Hard costs, including city fees and commissioning, less the HVAC, ceiling, and framing the design made unnecessary
$37.05
Soft costs: more legal work on the lease, but a carry of twelve months instead of eighteen
($0.50)
Solar system
$10.87
Additional cost over a standard renovation
$49.84
Operating expense savings, $0.45 a square foot a month, capitalized
$89.78
Above-market rent, $0.20 a square foot a month, capitalized
$36.92
Rent from leasing in 3 months instead of 18
$22.81
Leasable area added by the exterior insulation
$7.32
Additional value the day after occupancy
$100.29

An occupied manufacturing building, renovated to zero net energy without stopping the line.

The tenant ran two shifts, sixteen hours a day, through the whole renovation. So the work was sequenced around them: LED lighting, an optimized HVAC tune-up, insulation, window film, and a reflective insulated roof to bring the load down, then a 1.02 megawatt solar system on the roof and over the parking lot, generating about 1.6 million kilowatt hours a year, to take the bill to zero.

For the owner it was a 4.67 year simple payback and $6.15 million of value. For the tenant it set the cost of power at zero for twenty years, a real advantage when pricing long-term manufacturing contracts, and cut the maintenance on the roof, the lights, and the HVAC. Over those twenty years the system offsets the burning of more than 95 million gallons of gasoline.

The owner's return.

Total investment
$3,332,988
Less tax incentives
($1,366,535)
Net cost after year one
$1,966,453
Annual utility savings
$421,000
Return on net cost
21.4%
Simple payback
4.67 years
Increase in building value
$6,153,846

The most recent of the six, and the plainest version of the method: fix the shell, then add the solar.

A fully renovated envelope gave a tired building a new face and a much smaller load. A 200 kilowatt solar system then covered what was left, for a net zero energy bill. It was done at a price point significantly more profitable than renovating the same building to minimum code, which is the test every one of these projects has to pass.

Where the building's systems went onto one network, and the patio started paying rent.

Every light, fan, window actuator, and skylight actuator at 380 N. Pastoria is powered over Ethernet, so the whole building runs on low-voltage wiring and one management system. The lights are tuned to the color of the sun through the day, which helps keep the occupants' circadian rhythm in step with it.

Outside, a watertight canopy of bifacial solar panels covers the patio. It makes a protected outdoor workspace with filtered light, generates about a third of the building's power, and leased at the full rental rate on every square foot under it. The outdoor space, in other words, earns the same as the indoor space. 98.5 percent of what was demolished was reused.

The smallest of the six, where the roof and the ceiling had to carry the whole design.

At 14,852 square feet there is no spare roof. Skylights, solar panels, solar thermal panels, and the HVAC equipment all compete for it, and below it the lights, fans, skylight wells, ducts, and cable trays compete for the ceiling. So the two drawings that matter are the roof plan and the reflected ceiling plan, and they were drawn together, by everyone, in the second charrette.

Walls that open completely blur the line between the indoor and outdoor community space, and private rooms were still designed into a densely populated building. 92.5 percent of the demolition was reused.

A forty-year-old racquetball court with almost no glass, turned into a building people chose their desks in by the light.

The building was a partial two-story racquetball court, and racquetball courts have no windows. Eighty-six were cut in. Once the electrochromic glass and the light sensors were tuned, the occupant decided where each person would sit by their preference for light, which is not a decision most buildings allow.

A 660 square foot living wall rises two stories beside the stair, accordion doors open the floor to an outdoor patio, and the dynamic glass keeps the view clear. The point of all three is a constant connection to outside. 93 percent of the demolition was reused.

  • Silicon Valley Business Journal Structures Award, best green project, 2016
  • Acterra Business Environmental Award for the sustainable built environment
  • County of Santa Clara, certificate of commendation for outstanding achievement in the sustainable built environment
  • Special congressional recognition for outstanding and invaluable service to the community