Sustainable Design

Light colors, such as white or ivory, are rarely recommended for most solar collector absorbers. However, recently-developed solar technology using patented perforated glazing on wall-mounted solar air heaters made solar possible without bearing dark paint costs or altering the 26,000-square-foot building's exterior aesthetics. The solar air heater appears more like a wall of windows than a solar collector for Plastech, a Sherbrooke, Quebec division of 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, is rated at 80.7 efficiency by the Canadian Standards Association. On a black surface, the Lubi is 20 percent more efficient than other rated wall-mounted solar glazing or metal collectors. On a white wall such as Plastech’s, however, the Lubi is 58 percent more efficient.

RTSI personnel install Lubi solar collectors on the Plastech facility in Sherbrooke, Quebec.

With darker colors, the collector can provide air temperatures of up to 81 degrees F (45 degrees C) above ambient outdoor temperatures and maximum outputs of 254 BTU/h/ft2 (800 watts/m2). Since its installation at Plastech in late 2010, a temperature rise of 45 degrees F (25 degrees C) was measured on sunny days, a performance which was previously unheard of in the solar industry for a white collector. Lubi's performance statistics are certified by the National Solar Test Facility (NSTF), a Mississauga, Ont.-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. (SRCC).

"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 (EEF) of natural gas utility, Gaz Metro, the payback on the project is four years. Besides $6,000 in annual savings, the collector reduces Plastech's CO2 emissions by 15 tons/yr.

How the System Works

Installed by Sherbrooke, Quebec-based metal contractor RTSI, the 90 x 24-foot-high 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 x 1-foot-long (900 x 320-mm) panel. As the indoor ventilation fan draws collected warm air through the six-inch-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.

Visible-light and infrared images of the Lubi solar heater in operation on a winter day at the Plastech facility in Sherbrooke, Quebec.

When Plastech's 5,500-square-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-inch-diameter DuraTex, a non-porous fabric air dispersion system manufactured by DuctSox. The lightweight duct has no diffusion through the plant until it enters the shipping area where a high-throw array of linear diffusion orifices along the bottom of the duct disperse the air evenly.

The fabric ductwork is hung with a cable suspension system approximately two feet below the 24-foot-ceiling. If the shipping area doesn't reach its set point temperature of 69°F (21°C) 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 exhausts surpluses and doesn't need a dedicated heat source for the production area during winter.

If the combination of solar and heat recovery still can't satisfy the shipping area's set point temperatures, then a propane gas-fired heater, by Reznor, acts as a back-up source. Typically the solar collector and heat recovery supply all the shipping area heating needs and therefore reduces the firm's future gas-fired heating consumption to near zero, according to Yann Rouleau, plant manager.

A Johnson Controls direct digital controller monitors the heating process and actuates the Belimo Aircontrols dampers and the mixing box's 7,000-cfm fan, manufactured by the LFI division of Canarm.

As the project HVAC coordinator, Leprohon, a Sherbrooke, Quebec-based mechanical contractor, solved several challenges. Leprohon custom fabricated sheet metal ductwork to circumvent a machinery crane that shares a common surrounding wall area with the solar collector. Plus, 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 indoor air quality (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.

Courtesy of sustainableplant.com

Office:	(800) 424-7175	300 Carlsbad Village Drive	3912 Battleground Avenue
Fax:	(866) 850-5111	Suite 108A176	Suite 195
Sales:	Contact	Carlsbad, CA 92008	Greensboro, NC 27410
Support:	Contact
Webmaster:	Contact		www.fwdinnovations.net

Sustainable Design and Construction.

Solar Air Heater Cuts Gas Heating Costs for Thermoplastic Parts Plant.