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Automotive Parts Maker Uses Solar to Cut Gas-heating Costs

Injection molding firm combines a wall-mounted solar air heater with heat recovery to reduce CO2 emissions by 15 tons/year.

Injection molding firm Plastech Inc. recently combined a wall-mounted solar air heater with heat recovery to reduce CO2 emissions by 15 tons/year. The thermoplastic parts manufacturer wanted solar technology to eliminate the $5,776 ($6,000 CAD) annual natural gas-energy costs of heating its shipping area, but without the expense of altering its ivory color building's aesthetic exteriors or painting it a darker, more absorbing color. A recently developed solar technology uses a patented perforated glazing on wall-mounted solar air heaters to make solar possible without bearing dark paint costs—or in this case altering the 26,000-sq-ft building's exterior aesthetics.

The solar air heater appears more like a wall of windows than a solar collector for Plastech, a Sherbrooke, QC division of the MI Integration Group that supplies injection-molded interior and sealing parts to the automotive industry. Plastech's Lubi wall-mounted solar air heater manufactured by Enerconcept Technologies (Magog, QC) is an efficient solar collector rated at 80.7% efficiency by the Canadian Standards Association. On a black surface, the Lubi is said to be 20% more efficient than other wall-mounted solar glazing or metal collectors. On a white wall such as Plastech, however, the Lubi is rated 58% more efficient than competitors.

With darker colors, the collector can provide air temperatures of up to 81°F above ambient outdoor temperatures and maximum outputs of 254 Btuh/ft2 (800 W/m2). Since its installation at Plastech in late 2010, a 45°F was measured on sunny days, a performance that was previously unheard of in the solar industry for a white collector. Lubi's performance statistics are certified by the National Solar Test Facility, a Mississauga, ON-based third-party laboratory that tests and rates solar technologies under controlled temperature/sunlight/wind and is sanctioned by the Solar Rating and Certification Corp., Cocoa, FL.

"For Plastech, solar air heating has been a good method of reducing energy costs and CO2 emissions, preserving the environment and maintaining a comfortable workplace for our employees," said Stephane Tremblay, General Manager, Plastech.

Using dark walls as an absorber is recommended for optimum solar-performance efficiency, however the inherent performance disadvantages of Plastech's light-colored wall were offset with a 40-percent larger collector. After incentives from Natural Resources Canada and a rebate from the Energy Efficiency Fund of natural gas utility Gaz Metro, the payback on the project is four years. Besides the annual savings, the collector reduces Plastech's CO2 emissions by 15 tons/year.

How it works
Installed by Sherbrooke, QC-based metal contractor RTSI, the 90-ft x 24-ft wall-mounted solar collector has clear glazing that from a distance appears like windows. Sunlight radiates through the glazing where it is absorbed by the building's corrugated steel wall. The Lubi's efficiency is attributed to its patented design featuring 906 perforations per 3-ft x 1-ft panel. As the indoor ventilation fan draws collected warm air through the 6-in.-deep collector, ambient air draws through the perforations and cools the panels. Unlike other wall-mounted solar collectors that suffer significant heat loss through the glazing or metal facade, the panel's airflow cooling minimizes heat loss and increases efficiency.

When Plastech's 5,500-sq-foot, three-door shipping area calls for heat, the plant's indoor mixing plenum box's motorized damper opens and its 7,000-cfm fan draws solar collector heat to the area via ductwork. Heated air is distributed via 36-in.-diameter DuraTex, a non-porous fabric air-dispersion system manufactured by DuctSox, Peosta, IA. The lightweight duct has no diffusion through the plant until it enters the shipping area where the High-Throw array of linear diffusion orifices located at 6 o'clock disperses the air evenly. The fabric ductwork is hung with a cable suspension system approximately 2 ft below the 24-ft-ceiling.

If the shipping area doesn't reach its set point temperature of 69°F from solar collector heat, a second motorized damper opens to add recovered ambient production floor machinery heat through the same duct system. Heat from the injection molding process is ample enough that Plastech’s exhaust surpluses and does not need a dedicated heat source for the production area during winter. If the combination of solar and heat recovery still cannot satisfy the shipping area's set point temperatures, then the propane gas-fired heater, by Reznor, Memphis, TN, acts as a back-up source. Typically the solar collector and heat recovery supply all the shipping-area heating needs and therefore reduce the firm's future gas-fired heating consumption to near zero, according to Yann Rouleau, Plant Manager.

Milwaukee, WI-based Johnson Controls, direct digital controller monitors the heating process and controls the Belimo Aircontrols USA (Danbury, CN) dampers and the mixing box's 7,000-cfm fan manufactured by the LFI division of Canarm, Brockville, ON.

Leprohon, a Sherbrooke, QC-based mechanical contractor that offers design, installation and service to its industrial, commercial and residential customers, solved several challenges as the project HVAC contractor. Leprohon custom-fabricated sheet-metal ductwork to circumvent a machinery crane that shares a common surrounding wall area with the solar collector. In addition, the north side shipping area required fabric ductwork installation traversing the entire building's width to the collector's south side optimum solar exposure location.

The shipping area's IAQ, which is affected by idling trucks, now receives a minimum of two air changes per hour, twice what the local code requires, but at no fossil fuel energy expense to Plastech.
The addition of wall-mounted solar heating offers multiple advantages to Plastech. Throughout its minimum 15-year lifecycle, it will reap significant annual energy savings and eliminate more than 300-tons of CO2 emissions from the environment, while it simultaneously provides employees with better indoor air comfort.

For more information, visit, e-mail or call 866-829-1690.

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