In the wake of Hurricanes Charley, Frances and Ivan, companies in many industries who do business in harm's way are seeking alternative building construction methods that will offer them greater strength against the elements, as well as higher temperature stability, lower operating costs, and energy-saving advantages in the face of rising energy rates.

One such alternative, which is gaining wider acceptance across Florida, is that of insulated tilt-wall sandwich construction. Concrete tilt-up panels have been used for years in the construction of warehouses, office buildings and manufacturing facilities. Owners have benefited from the speed and lower costs of tilt-up construction, as well as, in many instances, lower lending and insurance rates.

But in recent years, a new feature has been developed that enhances the value of tilt-wall construction for temperature-controlled buildings, including food processors and packing companies. Standard load-bearing concrete tilt-up wall panels can be used to incorporate or "sandwich" several inches of extruded polystyrene insulation. The result is a building that offers immediate and significant energy savings, while improving temperature stabilization. This development is proving itself in agribusiness applications throughout the South.

One of the most prominent examples in the agribusiness industry is TKM Farms, located in Belle Glade, Florida. TKM Farms, owned by the Basore family, is the largest supplier of lettuce east of the Mississippi, and prides itself on the quality of its product. The company's continuing success depends on providing its customers with the freshest, leafiest lettuce possible. So when the decision was made for TKM Farms to build a new 79,000-square-foot processing and packaging facility, they turned to Edwards Construction Services, Inc. of Orlando, Florida as their design-builder. Edwards, which specializes in cold storage, food service distribution and food service production, determined that the use of innovative insulated sandwich tilt-wall panels would best meet the specialized needs of TKM Farms.

The facility consisted of a two-story uninsulated tilt-wall office and a large, single-story tilt-wall warehouse that required insulation. The insulating panels used in this project combined the energy-efficient advantages of THERMOMASS® Building Insulation Systems, developed by Composite Technologies Corporation (CTC), and the tilt-wall technology of Orlando, Florida based concrete contractor, Seretta Construction, Inc. Each load-bearing concrete panel measured 15 inches thick, incorporating four inches of enclosed THERMOMASS Styrofoam Insulation between a three-inch outer wythe and an eight-inch structural wythe. Thus the term "sandwich" tilt-wall panel.

Speed of construction was a critical factor to the TKM project. Construction of the building began in July when the season's lettuce crop was already in the ground, and was finished in time for the harvest in November. Seretta delivered a completed concrete building shell for the office/warehouse in five months despite daily, torrential rains that fell over a three-month period.

TKM's insulated sandwich tilt-wall warehouse structure has proven to be beneficial in several ways. In addition to lower upfront construction costs, they provided the owners more precise temperature control, a stronger, more durable facility in the face of severe weather, and significantly higher energy efficiency in the South Florida tropical climate.

Insulated tilt-wall panels also offer another energy-saving feature. The Btu/Square foot ratings of a typical air-conditioned building in Miami, for example, were measured over a 24-hour period for a full year. (Figure 1) reflects the fact that Btu's generated by thermal and solar gain peaked in the 13th or 14th hour daily, as high as 5.37 Btu/Square foot in December.

In a comparable building in Miami, measuring with the same parameters, (Figure 2) an insulated sandwich tilt-wall shifted peak Btu loads to later times in the day, enabling the heating/cooling system to handle these loads during off-peak times, and with off-peak electrical rates.

In 2003, the federal government recognized the need for more effective energy-saving insulation in industry by creating an innovative incentive program. Owners/developers opting to incorporate energy efficient technology such as insulating walls during construction of commercial buildings can receive tax incentives that amount to $2.25 per square foot of building, thanks to passage of the Energy Tax Incentives Act by the United States Congress in 2003.

In the meantime, TKM has discovered other benefits of concrete walls. Smooth interior surfaces, painted with epoxy, are easier to clean, and are more resistant to bacteria and mold than other surfaces. As a result, owners are able to maintain a safer, cleaner work environment in compliance with USDA codes and guidelines.

The advantages of insulated sandwich tilt-wall construction extend to the quality of TKM's product and service to its retail customers as well, better ensuring the delivery of fresh lettuce and other products with less waste due to spoilage.