I’m willing to bet that if I asked you to name corporations that use sustainable design, Wal- Mart would probably not be one of the first that popped into your mind. Well, that could all be changing, depending on the success of their new “experimental” Supercenter in McKinney. There are currently two different Supercenter’s in the US that are being utilized to test several different sustainable strategies. This 200,000 s.f. Supercenter is an excellent example of how sustainable design is possible in any facility type.

Starting outside, there are several renewable energy strategies being used to supplement the energy this facility requires to operate. A cutting edge 50-kilowatt wind turbine has been installed in the parking lot. Able to operate in wind speeds as low as 4.5 mph (average wind speed in McKinney is 10 mph), this turbine is estimated to produce 5% of the facilities power requirements. The turbine is mounted 120 feet high, and has a 46-foot diameter rotor. The tail allows the turbine to turn and face the wind, and with only three moving parts, requires minimal maintenance. There is also a more standard windmill that is utilized for pumping water. This windmill circulates water from the retention pond through the artificial wetland (more on this system below).

In addition to wind power, there are also several different versions of solar power employed on site. Solid panels are mounted directly to the south façade of the facility. In addition to generating electricity, these panels also serve as a design element and make up the signature “blue stripe” along the front entry. Not as obvious, solar film is also utilized in the main vestibules and along the Garden Center canopies. This film is laminated between a layer of glass and plastic, and allows natural light to pass through while also generating electricity for the facility. A similar thin film system that adheres directly to the roof membrane is being utilized above the Tire and Lube Express. Together, all these systems will generate over 50,000 kWh of electricity annually, or enough electricity to power 2,000 single-family homes for one day.

Rainwater harvesting is utilized in order to reduce potable water usage for irrigation. There are several collection methods used for diverting stormwater runoff. Runoff from the roof is piped directly into a permanent retention pond on site. The water collected in this pond is estimated to support 95% of the site irrigation water requirements, while also reducing demand on local stormwater infrastructure systems. Additionally, a portion of the stormwater runoff from the parking lot is also collected. Prior to entering the detention pond, the runoff is first filtered through a bioswale. This bioswale is a drainage channel planted with shrubs, grasses and rocks. These plants naturally remove contaminants from the water, and also help slow the water down enough to be absorbed into the ground. After passing through the bioswale, the water then enters another detention pond serving as a natural wetland. This wetland further cleanses the water, while also providing a natural habitat for birds, frogs, insects, and other wildlife.

Lastly, xeriscape plants are also used throughout the site. Xeriscape uses native grasses and plants that create attractive environments while using a minimal amount of water other than natural rainfall. This approach, along with drip irrigation systems, dramatically reduces site irrigation needs compared to a standard facility.

Moving inside the facility, the first thing that you are likely to notice is the quantity and quality of natural light present throughout the facility. Skylights and clerestories allow natural daylight into the store. Light sensors monitor the level of natural light available and dim, or turn off the lights, when sufficient daylight is available. This is supplemented by a lighting system using T5HO lamps. These high output fluorescent lamps are smaller and more efficient, and produce as much light as two of their counterpart T8 lamps (typically used in other Supercenter’s). The color temperature of the lamps have also been increased to 5000K. This color temperature more closely mimics the color of natural daylight, and also has the added benefit of improving the color quality of the merchandise. LED lighting is used inside the grocery cases in place of standard fluorescent strip fixtures. LED lights have longer life spans, produce less heat, and use significantly less electricity as compared to typical grocery case lighting. At night, the light levels in this Supercenter are lowered to help customers’ eyes adjust to the change of light when going in and out of the store, and to reduce energy consumption. All these systems working together are estimated to reduce the total lighting load required by 20% annually, or 300,000 kWh per year.

The other key sustainable element in this facility is the air distribution system. This facility utilized a concept called Displacement Ventilation. Instead of using a traditional hard duct and VAV system, a fabric duct (Duct Sox) is used. The duct is mounted 11 feet above the finished floor, and is perforated with small holes allowing air to be distributed evenly along the duct. Air is supplied at low velocity and moderate temperature (typically 65-68 degrees). The supply air quickly mixes with the surrounding air and slowly falls to the floor level. At the floor level, the air is warmed by the occupants and other heat sources, and rises slowly to the upper levels. The high bay structure allows air to collect that is much warmer above the occupant zone, and focuses on conditioning only the air space that is utilized by occupants. This system is estimated to save approximately 700,000 kWh of electricity annually.

These are just a few of the sustainable design strategies that are being utilized in this new Supercenter. If you haven’t had the opportunity to see this facility in person, I would highly recommend the trip. This facility is also very kid- friendly, and utilizes 34 different educational stations, spread across the site and throughout the facility. Overall, this facility is an excellent example of how sustainable design can be cost effective and utilized in any facility type.