The builders of the Cottle Zero Energy Home say their newly build luxury house was recognized as one of the highest-performance, greenest and most energy efficient homes in the entire California. It was certified LEED Platinum, Passive House, EPA Indoor Air Plus, Net Zero Energy, and was awarded a special commendation by the California Energy Commission.

It boasts all the modern style and luxury one would expect in a custom luxury Silicon Valley home plus a plethora of ground-breaking performance standards for indoor air quality, comfort, energy, and water efficiency. Being a “Net Zero” home it has virtually zero energy costs (produces all the energy it needs via renewable sources on site) but the home turned out to be a tough sell to the locals at its $2.2 million price tag.

It took the builder almost a year to sell the property for a final price of $1,768,000, which is painfully close to what a standard custom home sells for in the neighborhood with similar square footage. That’s a $432,000 pay cut for a very ambitious project.

Allen Gilliland, builder of the Cottle Home and founder of One Sky Homes, admits “You have to tread carefully as we’re looking at the early adopter market; it’s not a solid one yet.” As Allen painfully found out, even though Silicon Valley people are generally tech savvy and can appreciate sustainable building concepts, not everyone is ready to pay the 15-percent premium for a net-zero energy house.

As a Realtor, I can confidently attest – people buy entry level homes because they need a place to live but with higher end homes they are looking for value. In other words, they want to know what exactly they are caching out those millions for.

It is hard to say what went wrong with the sale of Cottle home. It could have been the lack of education of potential buyers or it was simply overpriced from the get go which would have encumbered the sales process. The builder may never know.

Nevertheless, it shouldn’t stop us from learning a bit more about the project and enjoying this marvel. The Cottle home truly excels in building performance with highly advanced technologies, both inside and out. This means excellent air quality, thermal comfort, acoustics, durability, and energy-efficient plants and xeriscaping.

Allen says, “I lived in the house for four months and experienced completely even temperatures throughout the whole building pretty much all the time. It’s a marvelous tranquil environment with super fresh air.”





A full energy efficiency, systems and features rundown:

Indoor Air Quality

  • EPA Indoor Air Plus certified; highest residential standard achievable
  • Zehnder (Swiss) continuous (.33ACH) ventilation system w/heat recovery & allergenic air filtration (Merv 13)
  • NightBreeze night ventilation cooling w/allergenic filtration (Merv 13)
  • Zero VOC paints/low-VOC wood finishes

Thermal Comfort

  • Guaranteed even temps: avg +/- <1degF everywhere
  • Guaranteed 70-74 deg continuously; you choose your comfort zone
  • German Triple pane tilt/turn windows & doors …no drafts, no cold spots
  • Continuous Heat Recovery Ventilation = even temps & fresh air everywhere
  • Solar awnings & shades …no hot spots
  • NightBreeze natural, night ventilation cooling
  • Lennox heat pump heating/cooling


  • Ultra quiet acoustics w/super-insulated walls & triple-pane windows
  • Premium sound isolation layers between floors
  • Ultra-quiet HVAC systems
  • Ultra-quiet dishwasher


  • Solar PV & Hot water systems
  • $0 utility bills* …guaranteed by OSH
  • Surplus solar power for EV charging; up to 20,000 miles/yr free driving!!
  • Amazing $10,000/yr in combined home/transportation energy costs avoided …$300,000 over 30 years!
  • Guilt-free long, hot showers! …water heated by the sun, then goes to grey water system to water landscaping
  • Energy Star appliances; efficient lighting & controls; ultra-efficient heat pump, etc., etc
  • Real time energy monitoring system, the meter runs backwards!


  • Grey water system recycles shower, vanity, clothes washing water to landscaping
  • On-demand hot water system …always hot water in 3 secs, no water/energy waste
  • Salt-free water softening: Nuvo H2O
  • EverPure dual-cartridge drinking water system


  • Old-growth recycled porch columns from Del Monte cannery
  • Premium wide-plank bamboo floors
  • Lutron Maestro digital, soft on/off lighting controls
  • Great natural lighting and upstairs views
  • Bio-ethanol wall-mounted eco fireplace
  • Recycled tile floor
  • Electric solar shade screens
  • Eco-friendly, recycled composite decking



As you see, the builders spared no costs or systems; they really went all out with the project. On the outside, an untrained eye will only see a beautiful but an average looking home but little do they know they could heat the place with a hair dryer and save tens of thousands of dollars of the years. This time Allen’s company took a financial hit but they are not disparaged. A new California law requires that by the year 2020 all new homes to be Net Zero. By that time, Allen will be way ahead of the pack of other builders learning about sustainable building practices.

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