The breathtaking natural beauty of southern Utah’s Red Rock region makes it one of the country’s most picturesque places to live. But for designer Matt Marten and builder Jake Joines, building homes here requires not only an appreciation of the pristine environment but a healthy amount of respect for it.
While their clients love the region’s spectacular scenery, ethereal cloud formations, and awe-inspiring sunsets, Marten and Joines are more concerned with its blazing-hot summers, cold north winds, and fast-moving storms. Marten, the owner of Gulch Design Group, has spent 20 years exploring the nuances of the local microclimate and how to fine-tune his houses to respond to the harsh—and “moody,” he describes—conditions.
Combating the desert’s grueling temperature extremes—which range from 110-plus degrees F in the summer to the 20s during winter nights—starts with a well-thought-out approach to heating and cooling. For the Terra Numa custom home near St. George, Marten and Joines came up with a zoned system comprised of eight high-efficiency mini-split units with separate programmable thermostats. Thanks to this configuration, a room on the west side of the house can be kept cool even during the hottest part of the afternoon without compromising comfort in other, less sunny rooms.
This strategy cost about one-third more than a traditional HVAC system, Joines says, but will help keep heating and air conditioning costs remarkably low. In fact, the project’s green rater estimates that the home’s annual power bills will run about $328 for cooling and $377 for heating, about half that of a similar-size traditionally built home in the area.
The HVAC system is augmented by a flash-and-batt insulation system that combines two types of wall insulation—2 inches of Demilec spray foam followed by GreenFiber cellulose—to achieve R-28 at a lower price than spray foam alone. “Once we achieve an air barrier with spray foam, we fill the rest up with something less expensive,” Joines explains. He used the same insulation approach under the roof.
Also contributing to the home’s efficiency is its Southwestern-inspired design, which evokes the adobe dwellings of the Anasazi who once lived in the area. Large sections of double-framed walls allow for recessed windows and doors that emulate traditional adobe construction while providing room for extra cellulose insulation (up to 2 feet for R-50 in some areas). The single-level, ground-hugging layout—also favored by Pueblo builders—takes advantage of the earth’s insulating properties.
“The more of the home that can be in contact with the earth the less it’s going to vary in temperature,” Joines says.
To achieve the appearance of a natural adobe exterior, the builder used hard-coat Finestone Stucco and boosted R-value by installing StarRgard 1-inch insulated sheathing board between the stucco system’s water-resistive barrier and fiberglass lath.