Energy Efficient Design Features


Location Sunnyvale, California
Geographical coordinates 37.8° N, 122.4W
Occupancy Type Commercial
Typology Retrofit
Climate Type Dry-summer subtropical
Project Area 31759 ft2
EPI 42.6 kWh/m2/yr
Installed PV capacity  113.2 kW


435 Indio Way is an over 50-year old single-story tilt-up in Sunnyvale, California, that was renovated to achieve net-zero energy. The building incorporates innovative design strategies for climate-response as well as occupant wellness while reducing costs by as much as $100.83/sft as compared to similar minimum-code buildings. The energy-efficient building in fact exceeds its design goals and supplies energy back to the grid. 435 Indio Way’s most outstanding feature is that it’s cooled only by passive strategies, with a backup HVAC system that is 22% smaller than conventional systems.

435 Indio Way

Passive Design Strategies

1. Envelope

  • The walls are insulated with 127- 15.875mm (5-5/8”) thick polystyrene and have an RSI of 3.5 (R-20)
  • The roof uses foam insulation, along with a cool roof coating above it and a 254mm (10”) batt insulation and has an RSI of 7 (RSI-40)

2. Daylighting & Lighting

  • The building remains daylit for approx. 80% of the occupancy hours.
  • The roof has been fitted with 43 skylights that are tilted southwards to bring diffused daylight into the building.
  • The windows have been fit with self-tinting or electrochromic glass
  • Light fixtures used are LED and are wired to occupancy motion and infrared sensors
  • Acoustic fabric ceiling ensures an even distribution of light inside the building

3. Night cooling

  • The building uses night ventilation of its interior thermal mass to tap the site’s high diurnal outdoor temperature swing for passive cooling. The building’s skylights and ground-level windows automatically open during nights so that the interior walls, slab and the deliberately uncarpeted concrete floor are exposed to absorb the ‘coolth’ of the night breeze.
  • Meanwhile, the hot indoor air is flushed out with the help of high-volume low-speed ceiling fans. In the daytime, the skylights and windows close to keep out the outdoor heat. Thus, the building stays cooler during the daytime, using mechanical cooling systems only as a backup.
435 Indio Way

Active Strategies

1. The building uses 2 air-source heat pumps as backups for heating and cooling. The HVAC system is 22% smaller than traditional systems.
2. An omni-controller monitors the performance of passive strategies
3. Actuators operate the skylights and windows to automatically open and close for the night ventilation
4. Occupants who work late nights were identified and their workspaces were mapped. This helped determine which windows needed to be opened to facilitate night purge without causing discomfort to the late-night occupants

435 Indio Way

Renewable Energy

  1. The Solar PV generates 83.7 kwh/sq/yr while the energy performance index is 42.6 KWh/sqm/yr making is a energy positive building
  2. Solar thermal system on the roof top generates 500 kwh of energy per year for hot water heating

Disclaimer: This website is made possible by the support of the American People through the United States Agency for International Development (USAID). The contents of this website are the sole responsibility of Environmental Design Solutions and do not necessarily reflect the views of USAID or the United States Government.