Passive and Active Solar by Milagro Co-housing

Milagro Co-housing is an award-winning community of twenty-eight, energy efficient, passive solar, adobe homes on a 43-acre site in the Tucson mountains – just twelve minutes from downtown Tucson, Arizona. 

The adobe homes are greenbuilt to save energy costs. Their passive solar design features a high thermal mass with 16” adobe walls and concrete floors - slow to heat up and slow to cool down. This is enhanced by having more windows on the south side than the north, to catch the warmth of the winter sun. Overhangs and awnings shield these windows from the higher, hotter summer sun and deep shady porches are placed on the north side of the houses.

Insulated, vented double roofs allow hot air to rise before penetrating the building. The compact shape of our units (joined together in blocks of two to four) reduces exposure to hot or cold outside air, and doors are well sealed. However, on cool summer nights many residents open north and south windows to let the airflow cool their house. A high efficiency heat pump with heat exchanger allows more precise temperature control.

Solar panels on every roof provide very hot water for most of the year, with an electrical backup for cold weather. And in the Sonoran desert, who really needs a clothes drier? Many residents save energy and even time by using a traditional clothesline.

Combining design features with sensible use of power, residents can spend less than $50 per month on power bills! 

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Education and Resources

Arizona Corporation Commission
The ACC adopted the Renewable Energy Standard and Tariff in 2006 which requires electric utility companies to produce 15% of their energy from renewable sources by 2025. Each utility must submit a plan for achieving the standard. The ACC recently approved Tucson Electric Power Company’s (TEP) plan.

The ACC also adopted a general rule for net metering that requires electric utilities to compensate individuals for the excess solar power they feed into the grid. Individuals that install solar panels now have the potential to get paid for the energy they are producing!

Trees for Tucson

If you are a Tucson Electric Power (TEP) customer, you may also purchase 2 trees for $6 through the Trees for Tucson program.

U.S. Department of Energy

Visit the U.S. DOE’s Energy Efficiency and Renewable Energy website for information about how solar electric systemssolar hot water heaters, and solar swimming pool heaters work.

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Community Partners


AzRISE is a global institute created at the University of Arizona with academic and industrial partners to foster, support, and coordinate collaborative efforts between academia, industry, business, national laboratories, local governments, and the public through research and development, economic and public policy analysis, and education at all levels.

Climate Assessment for the Southwest (CLIMAS)

CLIMAS was established to assess the impacts of climate variability and longer-term climate change on human and natural systems in the Southwest. Our mission is to improve the ability of the region to respond sufficiently and appropriately to climatic events and climate changes.

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