Checking out THERMOMASS

Wines & Vines, June, 1994

The wine maker's lot is full of decisions. Which barrels? Which yeast? And on.

Determination of materials for storage/aging facilities may not rank high on the list of decisions to be made, but such determination may be a quality factor. Ask Cloudy Bays in New Zealand.

The winery selected precast concrete panels utilizing the THERMOMASS [R] Building System in 1992 as the wall construction for a facility to control red wine barrel aging, malolactic fermentation of Chardonnay and the secondary fermentation of methode champenoise champagne.

Of primary importance at the above stages is the maintenance of optimum mechanical refrigeration to save large utility costs and the cost of rehumidification. At Cloudy Bays, the temperature required year-round was set at 18 degrees C. (64.4 degrees F.)

Concrete has a high specific heat which enables it to store large amounts of thermal energy. This is referred to as Thermal Mass. On the down side, concrete also has a high thermal conductance of thermal energy which is dramatically increased by the reinforcing steel in structural panels. By insulating concrete in a sandwich construction, without losing the benefit of the insulation through thermal shorts, the high thermal mass can be utilized to create optimum temperature conditions.

Davidson Ayson, Consulting Engineer, recognized the importance of these factors when he specified the THERMOMASS [R] Building System for the concrete panel construction system. The panels were cast off-site using a 2.5-inch fascia concrete layer, 2-inch extruded polystyrene and 6-inch structural concrete layer. The concrete layers were mechanically connected using THERMOMASS [R] composite connector rods placed 16 inches on center in pre-drilled holes in the insulation material. The rods are made from 75% glass fiber in a vinyl ester and have been tested to be at least 200% stronger than mild steel connectors in sheer pullout tests. Of most importance to the system in operation is the connectors thermal performance.

Energy is conducted at negligible rates resulting in close to zero thermal loss. Placement of the rods was performed immediately after the insulation was placed on the still fluid concrete. The structural layer was completed the following day although it is equally normal to cast the entire panel in one continuous operation. In addition to the thermal effectiveness of the connectors, the insulation is placed right to the edge of the panel and the edges of all openings.

A year after construction, the following advantages of this type of structure have been identified:

(1) The target temperature has been achieved, easily, with limited heating. The wine makers have reported that once the room was up to temperature, the variation from top to bottom was one degree C (1.8 degrees F). In the past by comparison, cardboard surrounds measuring 9.8 x 32.8 ft. were employed using fan meters. With this system, the variation from top to bottom was five degrees C (10 degrees F), which created thermal movement within the bottle which results in unsatisfactory sedimentation; (2) Retaining target conditions ensures optimization of secondary fermentation without resorting to specific temperature-tolerant yeast culture; (3) The robustness of the concrete construction results in maintenance-free operation.

The THERMOMASS [R] Building System, is manufactured by Composite Technologies Corporation, P.O. Box 1888, Ames, Iowa 50010.