Green home building has the potential to save homeowners a significant amount of money in energy costs, but many buyers question whether the savings are worth the upfront investment. Developer Nathan Day decided to test his new green homes to determine if the added expense of building to the National Green Building Standard--which for his homes can be up to 12 percent--is worth it.
His project, Sterling at Silverleaf in Scottsdale, Ariz., is the state’s first single-family, new construction project to achieve Gold-level certification to the National Green Building Standard. Located in the Sonoran Desert, the custom home community features a collection of 16 villas designed by architect Bing Hu. Created in partnership with Sterling Collection Development Group and Luster Custom Homes, the spacious three- and four-bedroom floor plans average 3,000 square feet and are priced from $1.36 million. 
Day recently hired a certified home energy rating team to compare a Sterling home’s energy performance against that of a similar traditionally built home in the same climate zone. The testing found that the certified home saved 74 percent in energy costs per month, translating to $256 in monthly savings compared to the traditional home. Heating, cooling, hot water, lighting, appliances, and photovoltaics were all factors in the test. Here, EcoHome checks in with Day about the findings of his energy testing.
Developer Nathan Day
Developer Nathan Day

Did you learn anything new about how best to build high-performance homes? 

It all comes down to the details and how each system you implement assists the others in efficiency. For example, it wouldn’t be wise to install top-of-the-line windows and not use spray-foam technology for your insulation, or to install the most efficient HVAC system and use incandescent light bulbs that produce considerable amounts of heat and energy loss. 
How much more does a high-performance home typically cost? 
On average, a high-performance home will run 9 percent to 12 percent more. However, the longevity of the home is considerably longer than that of a traditional home. Our buyers will not need to change a light bulb in the first 15 years they own their homes. Our air filtration is eight times more effective than a HEPA filter. Quality of life is better in energy-efficient homes, and that’s what we market to our buyers. 
Are luxury-home buyers wooed by energy-saving features?
A luxury buyer might not be as concerned with the overall cost of the electricity but an overwhelming majority of them are concerned with the environment. And they feel that the pride of owning the most efficient luxury home in Arizona sets them in a class of their own.
What are the top energy-saving features you put in your homes?
• Spray-foam insulation. The No. 1 element that contributes to a green home is developing a seamless air barrier. With traditional fiberglass insulation, air easily passes through the spaces in the wall studs and the insulation batts. Open-cell spray polyurethane foam insulation has no seams or cracks because it immediately expands to fill every nook and cranny. It also doesn’t settle or sag over time, so it never has to be replaced. We use Gaco Wallfoam, which reduces our buyers’ monthly energy bill by up to 40 percent, creates a comfortable, draft-free home, and controls exterior and interior noise levels.
• LED lighting and dimming app. In addition to specing LED bulbs, we offer a proprietary iPad app, developed by Crestron, that dims the home’s lighting to 85 percent power, an easy way to lower energy costs and extend bulb life. Studies show the human eye cannot tell the difference between lighting at 100 percent and 85 percent so there is no inconvenience on the part of the residents and they can save up to 15 percent on their lighting bills.
• Hybrid water heater. We like the Eternal hybrid water heater, which is 98 percent efficient, durable, and leaves almost no carbon footprint. This can result in large energy savings, since up to 80 percent of the energy used by a traditional heater is used to reheat the stored water. Tankless heaters also conserve space and will last 20 years or more, compared to 10 to 15 years for a traditional water heater. 
• Dual-pane, low-E windows. In the average single-family home, 20 percent of all heat loss occurs through windows. Single-pane windows are especially problematic as they let out 20 times more heat than nearby walls. Replacing them with dual-pane, low-E windows will cut this heat loss in half. The effects can be dramatic; depending on its age and construction, a typical home could save up to 21 percent on annual heating bills by installing low-E windows.