Stand in the line for the trailhead shuttle on a Saturday morning and you’ll hear, “I’m hot.” “My ankles are sweaty.” “I’m going to have a ridiculous tanline.” “This shirt is not going to last.” “His dog is hot.”
Meteorological summer began on June 1. With daytime high temperatures at or above 100 degrees for much of July, it’s the most appropriate time of the year to look at the relationship between emissions and air conditioning usage in Sedona.
Energy and Emissions
Sedona is home to 6,788 housing units, including homes used as short-term rentals. According to the U.S. Energy Information Administration, the average Arizona household consumes 19,342 kilowatt-hours of electricity in a year, which at Arizona Public Service’s current efficiency produces 9.36 tons of CO2 equivalent emissions.
On this basis, total domestic emissions from electricity consumption in Sedona may be around 63,536 tons CO2e.
EIA data shows that 25% of the energy consumed in Arizona homes is used to run air conditioning systems, so the share of Sedona’s annual emissions resulting from the elective operation of air conditioning in homes may be around 15,884 tons.
Sedona also has 2,789 hotel rooms. If three hotel rooms are equivalent for emissions purposes to one housing unit, those add another 7,832 tons of CO2e.
Sedona’s Climate Action Plan states that 32,402 tons of the city’s emissions result from vehicles being driven within the city limits. Studies by the National Renewable Energy Laboratory and Purdue University have showed that running vehicle air conditioning systems in hot climates is responsible for up to 30% of a vehicle’s energy usage. Their data indicates that up to 9,721 tons of Sedona’s emissions are produced by car air conditioners.
Sustainability Planning
Total emissions resulting from the usage of air conditioning in Sedona are in the range of 33,437 tons, or 18.3% of the city of Sedona’s total estimated annual emissions of 182,380 tons.
Based on APS’s offpeak rate, this represents an amount of energy usage worth at least $3.4 million.
Sedona’s Climate Action Plan states that it is “imperative” for Sedonans “to reduce climate-changing greenhouse gas emissions.”
The city’s current sustainability plan, Climate Action Plan, land development code and Design Review, Engineering and Administrative Manual do not mention reducing air conditioning usage in Sedona to reduce emissions.
City Sustainability Manager Bryce Beck did not respond to inquiries about the steps the city plans to take to reduce its own and private air conditioning use in pursuit of the Climate Action Plan’s objective of cutting Sedona’s emissions 50% by 2030.
Historical Context
Residents of what is now Arizona traditionally dealt with year-round high temperatures with sparse clothing. The Smithsonian Institution’s “Handbook of American Indians” recorded that among members of the Yuman language family, including the Yavapai, Havasupai, Hualapai and Mojave, “the climate favored nudity, the men wearing only the breechcloth, and not always that, while women were content with a short petticoat made of strips of bark.”
Old Technologies
Some ancient Southwesterners also kept cool during the summer by constructing energyefficient buildings with thick adobe and masonry walls that served as thermal masses to absorb heat during the day and release it at night, such as the Hopi pueblos of Northern Arizona. A study in the journal Advances in Applied Mathematics described the adobe houses of the Southwest as providing “an automatic air conditioning effect” due to the 12-hour phase lag of heat transfer through the walls.
The Buildings Technology Center of the Oak Ridge National Laboratory found that replacing traditional framing with massive walls in home construction could reduce a building’s energy needs by up to 18%.
Evaporative coolers in the form of misters were originally developed a form a fire suppression in the late 19th century. They were introduced as commercial cooling technology in 1985 and can be seen throughout Arizona, including at Sedona-area restaurants with outdoor patios.
Modular powered evaporative cooling units, or “swamp coolers,” are one of the most energy-efficient methods of cooling and were the primary form of climate control in Arizona in the middle of the 20th century. In 1951, five Phoenix-area companies were manufacturing half of the nation’s swamp coolers.
According to the Department of Energy, swamp coolers use about 25 percent of the energy that a comparable air conditioning unit does.
Windcatchers and wind towers, consisting of elevated airscoops with appropriate ducting, have been in use in Egypt and Iran for more than 3,000 years to provide cooling and ventilation. Even in still air, wind towers provide cooling via the stack effect as heated air within a building rises and escapes via the tower, to be replaced by cooler air.
Windcatchers can be also combined with a qanat — an underground canal — or another water source to provide additional evaporative cooling. In this setup, hot air passes through an intake, over a water source that absorbs some of its energy and then through the habitable areas of a building.
In modern architecture, this combination is called passive downdraft evaporative cooling. One of the first modern buildings designed with PDEC was the Torrent Research Centre, a large pharmaceutical laboratory in Ahmedabad, India; the laboratory was found to use 64% less energy than an equivalent-sized building equipped with conventional air conditioning. A study of a similarly-designed office building in Seville by De Montfort University found an energy reduction of 75% compared to an air-conditioned building.
The visitor center at Zion National Park employs a mostly-passive downdraft and evaporative cooling system that uses a single pump to supply water to the building’s cooling system.
