BISBEE — Exurbanization: A large scale settlement by urban people in non-metropolitan areas beyond typical suburban commuting distances.

Stephanie Kopplin, a NASA Space Grant intern at the University of Arizona, discussed that topic with Cochise County Board of Supervisors members Pat Call and Paul Newman during a work session Tuesday afternoon.

A rendering of a design by University of Arizona students showing environmentally-friendly pod housing.

Kopplin explained that such developments are the fastest-growing type of residential development in the United States. And it could be the wave of the near future in Cochise County, thanks in part to the growing retiree community that will be boosted in numbers even more as the Baby Boomers reach retirement age.

While that was a preliminary vision of what the university student panel on a different study project would be discussing, the crux of Kopplin’s study was to determine the difference in cost to the county when unregulated lot splits — aka wildcatting — and planned developments are compared.

Are single-family residences on larger parcels up to five acres in size worth as much as a single-family home on a half-acre parcel in a subdivision?

Her focus area was the Three Canyons area, and she looked for homes that matched relatively in square footage and then researched the assessed value. The lot splits came in with the lowest assessed value.

“There is a difference in assessed valuations of otherwise equal units depending on whether they are in formally subdivided or non-subdivided developments,” Kopplin said. “Higher assessments of homes in formally subdivided areas might be attributed to amenities such as paved roads, open space and fire service infrastructure. Sticking with status quo policies that permit lot split development and uninhibited exurban expansion will result in the continued loss of revenue to the county.”

However, as County Assessor Phil Leiendecker pointed out, some of those assessed values are on lands lying on slopes and so they are worth more. Kopplin said that aspect was not considered in the study.

In the second part of the work session, University of Arizona students presented a hypothetical project for a 43-acre development on Astro Road near Carr Canyon Road. Their shared-wall design for single-family residences employed ideas that will reduce impermeable surfaces, save on construction materials, provide graywater systems and rainwater-harvesting measures.

Wade Wietgrefe, one of the students, said the site’s topography was challenging since the development was beneath a steep hillside. Rather than build on the slopes and invade the scenic view, the students clustered the housing at the bottom of the hill in what they called pods. Each pod was actually a community in itself with eight adjoining homes, each with a separate roof, that have front doors that exited into a common open area about 100 feet across. The homes also were staggered so everyone had a view of the mountains.

Another student, Aaron Lien, gave an overview of the rainwater-harvesting system that would dump all the water from one pod into a 2,500-gallon tank that could be used for landscaping and could even be piped indoors for use flushing the toilet to save potable water.

Lien also presented the group’s recommendations on recharging the aquifer with rainwater harvesting from sheet flow. As for a wastewater system, that treated effluent could be used to sustain a wetlands that would also act as a recharge source.

The developer of the 43-acres, Charles Crowell of GreenLight Inc., liked the concepts and said they followed what he had in mind. If the development goes through as planned, it would be the first conservation subdivision in a TR-36 zone. That zoning designation establishes a transitional residential density of one home per 36,000-square-foot lot. But as a conservation subdivision, it leaves 50 percent of the property as open space, that density can be doubled.

“There is a market for this type of community development,” Crowell said. “We are identifying snowbirds that live here and don’t want the maintenance work associated with a separate home.”

Shade Tree consultant Jim Huff added, “The new design is toward this type of shared community. People want to get back to a community feel.”

Though going green in building design is voluntary in the county right now, Call expects to have a policy on conservation standards some time in the future. “This has been a great prelude that will push the county toward a green building policy,” the county supervisors said. “I want Cochise County to be the most welcoming county in the state when it comes to green development.”