Whole-House Green

Back in 1971 when this modest, split-level home in Cupertino, Calif., was built, very few people could have envisioned the changes that technology companies would bring to the area over the following 36 years. Today Cupertino is part of the Silicon Valley.

This same house that initially sold in the neighborhood of $20,000, now exists in a zip code where the average home value is $1.14 million. So it stands to reason why the couple who owns the home felt free to invest $467,153 in a whole-house remodeling project. It is also not very surprising—considering the growing interest in sustainable design and green building—that the couple chose to embrace a green approach, and why they ultimately selected Spectrum Fine Homes Inc. of Mountain View, Calif. to design and build the project.

According to Susan Davis CKBR, CGBP, the design principal at Spectrum, the company is well known for sustainable design and green building. Green is not just something they offer as a special item. It is a way of doing business.

“We have been remodeling homes for about 20 years now, and to really make green a focus company wide—in everything that we do and everything that we think—it started about four or five years ago with a project we were involved in,” says Davis. “It got us a lot of attention and everything we have done since has been green.”

Goals and Objectives

Within the spectrum of green colors, this project qualifies as a very dark green. Almost every aspect of the project took on a sustainable design or green building aspect. For the busy couple who own the home, the primary objective was to make the home comfortable and energy-efficient. They wanted healthy indoor-air quality. They also wanted to update their kitchen and bathrooms; to open and update their main floor living space; re-configure their lower-level spaces, which were dark and cramped; and, above all, they wanted use “technologies, materials, and building techniques that did not adversely affect the environment and natural resources.”

With these goals in mind, Spectrum brought in a consulting firm, Sustainable Spaces Inc. of San Francisco, to run a battery of diagnostic tests on the home. In fact, this type of diagnostic testing is now standard operating procedure for Spectrum. Sustainable Spaces gathers air flow and other metrics on the home and compares them with a set of targets established by Energy Star, and the California Home Performance Program.

“With sustainable design, it is different than the traditional way of thinking,” says Davis. “Part of it is a commitment to respect collaboration, and to bring in outside experts. So, when we first begin to design a project, the first thing we do is perform an audit on the home so we can get the right information for designing.”

Sustainable Spaces begins by analyzing energy-bill data from local gas and electric utilities. From this, they map the home’s monthly energy use, specifically the amount of kWh (kilowatt hours) and therms consumed. This analysis showed that prior to any changes, the home consumed 8,537 kilowatt hours and 733 therms each year. From there, Sustainable Spaces measured temperature loads in each room and determined where the home’s energy was used. The tests determined that air leakage consumed 29 percent of the home’s energy: walls, 25 percent; duct leakage, 18 percent; attic, 16 percent; and windows, 12 percent.

Next, a blower-door test was conducted on the home to put some specific numbers to the home’s leakiness. The blower door pulls air through the house and measures the rate of air exchange in the home. By determining the rate of air exchange, a baseline level of efficiency or inefficiency is determined. The lower the rate of air exchange, the greater the home’s efficiency because that reduces the amount of energy used to heat or cool outside air that is coming into the home. This test found a “natural air exchange per hour” of .71. This means that each hour of every day, 71 percent of the home’s air is exchanged with the outside. According to Sustainable Spaces, the maximum recommended level of air change per hour is .35 or 35 percent. Thus, a target leak reduction of 50 percent was established.

The next tests measured the R-values of existing insulation. In the attic, where the recommended R-value is 30 or higher, an existing value of 5.4 was gauged. In the walls, where R-19 is recommended, an R-value of 3.5 was measured. Additional tests quantified extensive leakage in the duct system, measured furnace and water heater loads and efficiency, checked for carbon monoxide safety, and measured humidity and moisture levels, room-by-room. Humidity levels are key determinants of possible mold and dust-mite problems.

After the tests were completed, a series of prescriptions for a healthy home were recommended and incorporated into the remodeling design program. Extra insulation was recommended, including 10 inches of blown-in cellulose in the attic. An aging attic furnace was tagged for replacement. And, along with a number of specific air-sealing remedies, Sustainable Spaces recommended replacing their traditional sheet metal ducts with new insulated ducts with an 8 R-value. For the windows, where 12 percent of the home’s energy load was lost, newer windows were recommended.

“Once we know the places where ducts are leaking or air is coming in,” explains Davis, “we can then seal the existing ducts or maybe there is new duct work to be done. In this case, a whole new HVAC system was recommended because they previously had two different furnaces, one upstairs and one downstairs. We wanted the house to have only one.”

Design & Construction

The entry foyer of the home is between the upper and lower levels. The upper level accommodates the living room, kitchen and master suite. The lower level consisted of a bonus room, three bedrooms and two bathrooms. On the upper level, very few floor plan changes were made. A wall separating the kitchen from the dining and living rooms was removed to open up the space. Also, a dropped ceiling in the kitchen was removed. This allowed lots more daylight into the upper-level living spaces.

The lower level had been even more challenged in terms of available daylight. A back entry to the home was narrow. Dark hallways led to dark hallways. The key change was to open up the back entry by removing a bedroom and installing a set of French doors. This created a well lit, large foyer that fit well with one of the client’s athletic interests, rowing. Soaking wet after her morning rows, the owner needed a place to hang her clothing to dry. A new closet off the large foyer was specially ventilated so her clothes would dry out of sight to guests.

Another lower-level design stipulation was to improve the bathroom and provide a spa-like atmosphere. To that end, the bathroom was fitted with a tall Japanese soaking tub. Since it is tall, as opposed to wide, the tub allows less heat loss because there is less surface water exposure to cooler air.

Lastly, cork, a highly sustainable material was used throughout the lower level for flooring material. A very green product, cork is soft and warm to the touch, says homeowner Gail Brownell. It also cuts down on noise, she says.

Throughout the lower and upper levels of the home, exterior doors and windows were replaced. In the selection of these products, the client, Brownell pitched-in and conducted life-cycle analyses of the different types of window products. Dual-pane, Low-E glazing was the easy part. The hard part was selecting the window material. After much research, an all-fiberglass window from Milgard was selected. In addition to the greenness of fiberglass, Milgard’s California manufacturing location meant that fewer fossil fuels would be used to transport the windows.

Upstairs, re-claimed teak was used for all of the flooring, decking and railings. The source was a local company, Terramai, which participates in a Smart Wood certification program. Further, all of the plywood used for decking and construction was FSC (Forestry Stewardship Council) certified. In this case, the plywood used was constructed using formaldehyde-free binders. In the kitchen, sleek cabinets, built by a local cabinetmaker, were constructed of FSC certified maple.

In fact, all material choices throughout the home were made in favor of green: from efficient appliances to low-VOC paints and sealants. One highly unusual choice was Vulcanite for the countertops. Harvested in Mexico, then trucked in slabs to a tile manufacturing facility, the volcanic rock is fired like a tile. It is green because it is considered to be more renewable than granite.

Perhaps the greenest and most sustainable part of the project occurred before any construction began. The home was de-constructed and older materials were either recycled or disposed of in an earth-friendly manner.

“Everything that could be recycled and reused in the home was kept,” explains Davis. “Anything that could be, was donated.”

After the project was completed, Sustainable Spaces tested again. As a result, the home received a GreenPoint rating by Build It Green, a local certification program.

“Each project is different,” says Davis. “For example, we did not use solar because there were too many trees on the site. But, this project, up to the point we completed it, had more green features and more green ways of thinking than anything we had done before.”