Phoenix residents are transforming their homes to save energy and conserve water as climate scientists warn of an ever-worsening crisis

• Phoenix is a hot spot for housing innovation, including energy-saving homes.
• Its desert climate inspires builders whose designs prioritize conserving both water and energy.
• One homeowner explains how he's tackling the climate crisis in his backyard — literally.
• This story is part of Advancing Cities, a series highlighting urban centers across the US that are committed to improving life for their residents.

The United Nations just released yet another report about the devastating consequences of climate change, urging world leaders to take immediate action to contain the global rise in temperatures. This time, its recommendations are being described as a "final warning" from scientists.

Phoenix residents are all too familiar with sweltering heat — temperatures are consistently over 100 degrees for about 140 days a year — and other extreme weather. The arid capital city has already experienced major environmental issues, including a diminishing supply of fresh water, reduced air quality, and unusually high energy consumption.

For years, architects and homebuilders across the American Southwest have worked to integrate sustainability into new-construction homes to lessen their impact on the environment. But in Phoenix, one of the fastest-growing cities in the country, the problem is particularly acute.

Its metropolitan area of about 5 million continues to draw in people of all ages and professions with its mountainous beauty, food and wine scene, and relatively low cost of living. So builders and residents alike are realizing that it's more crucial than ever to focus on design that makes as little impact on the environment as possible, while still providing enough space and comfort to occupants.

Arizona is a hot spot for sustainable building. It started with simple construction with adobe mud bricks, used for centuries, before modern materials and construction methods were adopted. In the 1930s, the famed architect Frank Lloyd Wright built Taliesin West, his live-in architecture school and studio, which was inspired by primitive building techniques that used large rocks and trees to create a low-slung campus that felt like it's built into the earth.

In 2021, of the more than 120,000 Energy Star-certified homes that were built in the US, Arizona built the highest share, 17%, or 20,140 homes. Arizona builders that tout their energy-efficient homes include Fulton Homes, Maracay Homes, and Meritage Homes. Phoenix has even offered free preapproved plans to residents who want to build a net-zero home.

Insider spoke with a Phoenix sustainable-construction consultant and homeowner taking strides to not only incorporate the latest tech into new homes but also use safe, natural building materials whenever possible.

What it takes to build a sustainable home in Phoenix

Making a home sustainable in Phoenix requires more than simple upgrades like solar panels or electric-car chargers, said Lucas Johnson of Vali Homes, a company that consults with homeowners and builders on sustainable development.

Typical homebuilders will construct the same few home models across the country, Johnson said, but because of Phoenix's extreme heat and water concerns, new homes should be "desert-optimized," or designed with these considerations in mind. The city and its suburbs are in a low-desert valley known for its extreme heat and dryness, but there are also unique challenges during monsoon season in the middle of summer.

"Buildings will get wet but have no ability to dry well. That's the recipe to create mold and rot, which is a way bigger issue here than you'd think," said Johnson, Vali's self-described "chief science nerd" who researches sustainable building materials and designs to apply to projects.

Phoenix homes need to be properly insulated because of the extreme heat and weather conditions, and it's common to find long, low-slung single-story ranch houses in the area, which helps prevent heat from rising and stifling additional floors.

Take, for example, a four-unit townhouse complex dubbed Vali Mews that Johnson's team is working on in north Phoenix.

The team selected a site that was not raw, untouched desert and sought to build on a site that had already been developed at some point. It used wool for interior insulation instead of toxic spray foam and chose pricey Gutex wood-fiber boards imported from Germany for exterior insulation.

While the "desert-optimized, future-proofed" homes offer sustainability and functionality, they aren't cheap: A three-bedroom, 2,350-square-foot floor plan starts at $1.65 million.

Making a home sustainable can come with challenges

Last year, Gerald Leenerts, a Phoenix-area homeowner, set out to make his home more sustainable.

One of the first things Leenerts did after buying his house was get rid of the lawn. The increasingly popular "anti-lawn" movement in the Phoenix area has been a way to address the region's looming water crisis by opting for a yard that's more suitable for a desert climate — think rocks and cacti — instead of a lush, water-consuming space lined with green grass and flowers.

Leenerts wanted to go further: He was looking to do a full sustainability-focused renovation of his home. Right away, he faced a major challenge. He lives in a historic district in Scottsdale, a suburb of Phoenix known for its pricey homes, so a planned addition to the house was struck down by the city because it was determined to be too aesthetically intrusive.

Instead, the compromise with the city was that Leenerts could build a new 1,000-square-foot accessory dwelling unit — essentially a tiny guest house — on the property, and he hired Vali Homes to help with planning and design.

The under-construction ADU contains many of the same "desert-optimized" features and natural materials as the Vali Mews project, Leenerts told Insider, but there's an emphasis on conserving water.

"Water is, by far, the biggest resource concern that we have here, so we needed to prioritize that as the first and foremost thing in our ADU addition," he said. "It's not energy consumption but water consumption."

The new ADU has a metal roof that directs rain to water-collection barrels that Leenerts can then use for gardening. Inside, the tiny home has high-efficiency showerheads and faucets to reduce water consumption.

Instead of using drywall to build out the interior, Leenerts opted for plywood, which can be reused or recycled if a wall is damaged and needs a repair or replacement. Leenerts also opted for natural wool and wood fiber for insulation to keep the interior temperature stable without overburdening the heating and air-conditioning systems.

The total cost of the project is north of $400,000, Leenerts told Insider, though he said it could be done for closer to $300,000 — or less — if cheaper materials were used for construction. Both Johnson and Leenerts said the use of natural materials was not only more sustainable and environmentally friendly but also healthier for the occupant.

It's this holistic approach to the environment and health that will be the key to addressing climate concerns and waste — especially in this moment, when we're quickly running out of time to reverse course on the climate crisis.

"We've taken a long time to address climate impact, so we don't have a ton of time for efficiency to create payback periods," he said. "What's incredibly important is that buildings are made out of good ingredients in the first place. One of our sayings is that the ingredients create the results."