Mother Earth Living

Can This Home Be Greened? Keeping the Haven Safe

A Phoenix couple wants to green their desert home with low-cost, high-impact improvements.
By Carol Venolia
July/August 2009
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Our projection illustrates how Chrystal and Richard could maximize their outdoor space by expanding their covered back porch.
Photo by Carol Venolia
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When Chrystal Snyder and Richard Otto bought their 1960 concrete-block Phoenix tract house a few years ago, they loved the living room’s cathedral ceilings and wood paneling, the large shade trees, and—thanks to some additions in the 1980s—the “bonus” rooms that accommodate their passions. Chrystal has a ceramics studio off the garage, with north-facing windows looking onto the backyard. At the opposite end of the house, a suite of rooms accommodates Richard’s offices.

After living in the house for a few years, the couple has identified a list of problems they would like to fix: high summer cooling bills; high water bills; dark interiors; little connection with the outdoors; an aging roof; and high levels of indoor dust—especially problematic because of Chrystal’s allergies. With a modest budget, they wanted ideas for “low-cost, high-impact improvements.”

Chrystal and Richard’s project is open-ended, so they can start by addressing the most urgent and least expensive issues, then gradually take on other projects as time and money allow. They can use this master plan to guide their decisions for years to come—preferable to making random changes that may not work well together.

Keep it cool 

1. Reduce water use 

Chrystal and Richard love gardening, and they’ve transformed their once-dreary backyard into an oasis with roses, grapes, vegetables and a little pond and waterfall. But their water bill peaks at $300 in August.

Solutions: A combination of actions will reduce household water use:

■ Practice water-wise gardening. Select locally appropriate, drought-tolerant species for new plantings; assess and repair the existing irrigation system, which delivers too much water in some areas.

■ Reduce indoor water waste. Replace the water-guzzling toilets, faucets and shower-heads with low-volume equivalents.

■ Reuse household graywater. The “waste” water from sinks, showers and laundry can water the yard and help recharge groundwater.

■ Consider rainwater catchment. Chrystal and Richard could capture 12,000 gallons a year from their roof. They’d need to store only 2,500 gallons because rain falls in short bursts most of the year.

Cost: Evolve low-flow showerheads (two at $40 each): $80; Caroma dual-flush toilets (two at $450 plus installation): $1,200; Graywater system: $50 to $5,000, depending on design; 2,500-gallon water storage tank: $1,500 installed

2. Lower cooling bills

The hot desert sun hits the exposed east wall of the house every morning, then beats down on the roof all day. Two aging rooftop heat pumps provide mechanical heating and cooling. With utility bills peaking at more than $400 a month in summer, cooling is a prime target for improvement.

Solutions: A multifaceted approach will maximize natural cooling and minimize mechanical inefficiencies. To cut down on summer heat gain and winter heat loss, my first suggestions are to plant drought-tolerant shade trees and shrubs in the east yard, then seal air leaks by weatherstripping doors and applying caulk or expanding foam around windows, electrical boxes and other penetrations, and at the top and bottom plates of exterior walls. Making the roof more thermally efficient will also help (see item 3). Finally, they can replace the heating/cooling units with a single, high-efficiency model—which can be smaller because of the preceding efficiency measures.

Cost: Air-seal the house: $1,000; High-efficiency heating/air conditioning unit: $8,000

Brighten and breathe easy

3. Reroof for energy efficiency

The roof is typically the most vulnerable part of a house in terms of heat gain and loss. In summer, the sun beats straight down on the roof, and in winter warm indoor air rises to the ceiling.

Solutions: While reroofing, Chrystal and Richard can incorporate several “cool-roof” features. First, they should level out and add to their attic insulation (uneven blown-in fiberglass). A nontoxic option, such as recycled cellulose, is a good choice. Installing a radiant barrier in the attic will reflect solar heat. Richard and Chrystal should also select a new roofing material—such as an efficient, light-reflecting white metal roof—to deflect the sun’s heat. A new fan can replace hot attic air with cool night air.

Cost: Radiant barrier: $900; R-38 roof insulation: $1,900; New roof: $8,000; Attic fan: $500, installed

4. Open up to nature

A house that turns its back on the desert sun may stay cooler, but its dwellers can feel cut off from the outside world. We want to get Chrystal and Richard out of their cave without sacrificing protection from the harsh desert elements.

Solutions: The couple can create indoor/outdoor spaces that let them experience sunshine and breezes while shading the house—a win-win. The house already has little-used narrow roofed porches on the south and north sides. Some alterations could make these spaces more attractive and comfortable.

The south porch could be a nice warm spot in winter, but it’s too open to the street. I encouraged Chrystal and Richard to extend the porch outward, enclosing it with a chest-high adobe wall that provides seated privacy while remaining open to the sky and breezes. A small fountain upwind from the space would supply evaporative cooling while masking street noise. An open structural framework could support movable shading in summer.

On the north porch, I suggested a solid roof and screening to capture breezes, create space for a dining table and chairs, and keep out mosquitoes.

Cost: $8,000 to $10,000 for each porch

5. Bring in daylight

The house’s layout leaves the interior hallway and dining room gloomy, even as the sun shines brightly outdoors. While shade is a great natural cooling strategy, using electric lighting in the middle of the day is wasteful.

Solutions: The trick is to bring in light without adding solar heat. Tubular skylights require only a small roof opening, which minimizes heat passage, but their highly reflective surface maximizes light transmission, turning cavelike rooms into light-filled spaces. The kitchen currently has a large, square, single-pane skylight that lets in too much heat. I suggest replacing it with an energy-efficient model, incorporating double-pane, light-diffusing glazing and a moveable exterior shade for summer. Adding or modifying skylights while installing a new roof will help increase efficiency and reduce costs. Light-colored interior walls would help bounce daylight around.

Cost: Replace kitchen skylight with Velux skylight: $650, installed; Two tubular skylights: $850, installed at the same time as the new roof

Rx at your house

1. Check your water waste. Even if you don’t live in the desert, water issues are coming to a head all over the planet. Nobody benefits from squandering water, so start by trimming waste.

2. Improve your home’s natural cooling and heating before you invest in mechanical solutions. For cooling, this means providing shade (via deciduous plantings, awnings, trellises, blinds or other shade structures) and taking advantage of breezes, indoors and out. For heating, it means letting the sun into your living spaces in winter and storing its heat in thermally massive materials such as tile, earth or stone.

3. Let the sun light your house. If you’re turning on electric lights during the day, consider adding a well-placed window, glass blocks or a tubular skylight to reduce electricity use and bring in the sun’s biologically preferred, dynamic, full-spectrum light.

4. Create outdoor rooms. Instead of adding a room that needs mechanical heating and cooling, consider lightly enclosing an outdoor space next to your house. You might like a glassed-in sunspace on the east or south side; a screened porch on the north or west side; or a trellised patio shaded by a deciduous vine in summer and warmed by the sun in winter. 

Resources:

Arizona Cool Roof Council
(623) 878-7117

Arizona Gray Water guidelines
(800) 234-5677

California Energy Commission
(800) 555-7794
cool roof information

California Urban Water Conservation Council
household water efficiency information

Cool Roof Rating Council
(866) 465-2523
information and product directory

HarvestH20.com
online rainwater harvesting community

Oasis Design
graywater resources

Salt River Project’s “DesertWise” guidelines 

Carol Venolia is an eco-architect, author, teacher and frequent contributor to Natural Home


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