The Mainstream GreenHome should be listed in the Guinness Book of World Records as the residence with the most environmentally friendly features and products. Located on a one-third-acre lot in a conventional, established neighborhood in Raleigh, N.C., the home has the appearance of a traditional residence but uses less energy and water than a typical home, while also providing a healthier living environment.

In addition, it meets Model Green Home Building Guidelines established by the National Association of Home Builders (NAHB), and is believed to be the first home in the country located in a standard subdivision to meet those green guidelines.

Built by Cherokee Investment Partners, a Raleigh-based private equity firm whose principal mission is to acquire, remediate and redevelop environmentally impaired properties, the Mainstream GreenHome was designed to deliver numerous environmental, health and financial benefits to the eventual homeowners. But the builder had another goal in mind as well — to “show that environmentally focused construction is compatible with conventional building,” explains Jonathan Phillips, a Cherokee senior director and the Mainstream GreenHome’s project leader.

In other words, Cherokee set out to demonstrate that residences like the Mainstream GreenHome can be built anywhere, in such a way that they meld easily with the existing homes around them. And in that respect, it’s part of an overall industry trend of taking greenbuilding into the mainstream.

Five Key Areas
When building the Mainstream GreenHome, Cherokee focused on five key areas — the building site and landscaping, energy efficiency, water efficiency, building materials and indoor air quality.

A primary concern with the building site was stormwater management. One of the home’s more impressive — and invisible — exterior features is its stormwater management system, which directs stormwater runoff into underground storage tanks located beneath the driveway and patios. The collected water gradually percolates into the soil while being decontaminated by natural filters. This reduces off-site runoff and erosion while preventing downstream pollution and lessening the chance of local flooding.

Termite control in the foundation was another concern. Nontoxic termite-control techniques utilized metal plates between the foundation and the wood framing to prevent termites from crawling up to the wood portion of the structure. In addition, nontoxic borate was applied to the lower three feet of the structure.

The landscape design was created by staff members of the North Carolina Botanical Garden in Chapel Hill, who planted native species that were selected for their ability to weather drought conditions as well as provide food for people and wildlife.

Energy Efficiency
One of Cherokee’s primary goals was to create a home that uses 50 percent fewer fossil fuels than a conventional home. That effort began with expanding foam insulation. Cherokee chose BASF’s Comfort Foam polyurethane spray foam, which expands to 30 times its original size when applied and thus fills all the nooks and crannies in the building envelope. The foam does not off-gas, and serves as a vapor retardant barrier, preventing moisture migration and reducing the risk of mold.

Beyond that, efforts throughout the house focused on energy efficiency. Basic traditional passive solar strategies were implemented, for instance, with bricks providing thermal mass to hold and radiate heat, as well as moderate interior temperature fluctuations. High-performance, low-e windows from Andersen are not only energy efficient but are also made of sustainable wood certified by the Forestry Stewardship Council.

The home’s attic and crawlspace were sealed, insulated and conditioned, so no outdoor air can infiltrate to cause moisture problems. These spaces also provide better locations for ducts and pipes. Locating ducts in conditioned spaces helps reduce energy loss and improves the home’s efficiency.
A geothermal system with a ground source heat pump heats and cools the house. Five wells with a diameter of six inches each, drilled 300 feet deep, provide 56-degree ground water that circulates through a closed loop. The water imparts heat to the home in the winter and absorbs heat in the summer, which is returned to the ground.

The home’s appliances and ventilation fans are Energy Star-rated models. The lighting is a mixture of compact fluorescent lamps (CFLs) and light-emitting diodes (LEDs), complemented by daylighting. A high-end feature of the lighting system is the automated whole-house shading system, which tracks the sun and automatically operates window shades throughout the home to reduce solar gain and glare while maximizing the availability of natural light.

Up on the roof, a solar photovoltaic system, utilizing Sunslates solar-electric roofing tiles from Sacramento, Calif.-based Atlantis Energy, generates electricity for the home. The solar energy system works in conjunction with a solar water-heating (thermal) system. In fact, there is an interesting symbiosis that increases the efficiency of both systems.

There are no visible rooftop collectors for the solar water heating system. Instead, half-inch PEX tubes, which carry an anti-freeze solvent, run under the roof decking. The liquid in the tubes picks up heat from the roof, which is then transferred to water in a storage tank located in the basement.
This works to the benefit of the solar energy system, since photovoltaic tiles are less efficient when they get hot. By sucking up heat and keeping the roof cooler, the solar water-heating system actually increases the efficiency of the photovoltaic system.

The solar water-heating system also provides heated water to the home’s Warmboard radiant floor heating system. The Warmboard system consists of aluminum-coated plywood with integrated piping that negates the need for pouring concrete around the delivery pipes.

The roof holds another secret: Areas not covered by the photovoltaic tiles have shingles with highly reflective granules. As a result, the shingles, from ElkCorp, reflect three times more sunlight than conventional shingles, which helps keep the roof cooler.

Water Efficiency
In addition to a stormwater management system, the Mainstream GreenHome has a rainwater catchment system that collects and filters rainwater, which is used for landscape irrigation and flushing toilets. The rainwater is even used for cold-water cycles in the washing machine.
Water-efficient appliances and fixtures are used throughout the home. The washer, for instance, is a front-loading Duet Sport model from Whirlpool. It can determine the correct water level and optimal energy usage for each load, which results in an 85 percent improvement in efficiency over conventional washers.

Building Materials
Many of the building materials and products used when building the Mainstream GreenHome contain significant amounts of recycled or reused content. IceStone countertops in the kitchen, for example, are made from recycled glass and concrete, while the garage doors, from Ankmar, contain 86 percent recycled content.

Cape Fear Riverwood of Wilmington, N.C., provided reclaimed pine wood flooring, which was milled from trees salvaged from local rivers and old tobacco warehouses. Due to the local proximity of Cape Fear Riverwood to the building site, transportation-related energy costs and pollution were minimized. This was also a consideration when selecting some of the other building materials used in the home, such as the bricks, which were fired only 40 miles away.

Indoor Air Quality
The home’s ventilation system uses finer air filters than are generally found in homes. Using the MERV rating system (a number from 1 to 16 that is relative to an air filter’s efficiency), the GreenHome’s filters are MERV 12, whereas commonly used filters are MERV 4 to 6. This finer filter does a much better job of preventing pollen, dust mites, pet dander and other airborne pollutants from entering the home.

The paints, glues, stains and caulks used in the home were selected because of their no or very low volatile organic compound (VOC) content. For instance, Henkel’s OSI Green-Series adhesives, with only five grams of VOCs per liter, greatly improve on the 200 grams per liter allowable for for low-VOC designation.

Attention was even paid to the air quality in the garage. In addition to being tightly air-sealed to prevent car emissions from infiltrating the house, the garage is equipped with an exhaust fan that turns on automatically when a vehicle enters or leaves, drawing out tainted air.

An Unconventional Project
These are but a few examples of the myriad green features in the Mainstream GreenHome. Incorporating all of these green and efficient materials and systems into a conventional house was not without its problems, notes Cherokee’s Phillips. The company encountered unexpected delays due to the unconventional nature of the project, as well as inefficiencies in the green-product supply chain and the fact that some subcontractors were experiencing a new approach to homebuilding.

But in the end, all that proved to be beneficial, Phillips notes. Beyond acquiring basic knowledge of the products and techniques Cherokee and its contractors used, they learned something about the process of greenbuilding itself, and how to better manage building green within an industry that is still learning this new approach.

The building of this exemplary home is the first step in a process Cherokee Investment Partners intends to be a catalyst in the marketplace. As Phillips states, “We want to signal to the manufacturing sector to start their engines. We will have approximately 400,000 homes built at our sites in the next four to six years.” And the Mainstream GreenHome is leading the way.

What’s more, when complete, the GreenHome project will serve as a “living laboratory.” Cherokee will continue to measure indoor air quality, water conservation and energy usage once the residence is occupied, ensuring that this showcase house will have a significant ripple effect into the greater housing industry.