Section 6: Methods of Heat Conservation
Greenhouse design
Minimizing the exposed surface area can reduce heat loss. This is primarily accomplished through the use of gutter-connected designs.
Glazing selection
Heat loss can be reduced by selecting glazings with low thermal conductance values.
Wall insulation
Heat loss may also be reduced by including insulated curtain walls along the lower three to four feet of the greenhouse walls. In northern climates, the entire north wall is converted into a curtain wall since the light loss is minimal and heat savings significant.
Thermal screens
Polyester, cloth, or polyethylene screens that can be pulled closed at night reduce heat loss through the roof panels of the greenhouse.
Windbreaks
Windbreaks reduce the effect of wind on heat loss and thus can reduce heat loss from the greenhouse. However, windbreaks (i.e. high walls or trees) can also reduce light entering the greenhouse if placed too close to the structure.
Close air leaks
Broken panels, loose panels, poorly sealed doors, and other openings in the greenhouse structure increase the mass air flow (infiltration and exfiltration) and increase heat loss.
Equipment Maintenance
Regardless of the type of heating system utilized, proper maintenance of the entire system is critical. Not only will maintenance maximize efficiency of the heating system but will protect against a malfunction that can result in the release of ethylene and/or carbon monoxide into the greenhouse. Maintenance should include appropriate cleaning, checks of the air intake, checks of the exhaust system, checks of the fuel line, checks of fans, checks of the burner system and the heat exchanger, calibration of the thermostat, and any other maintenance items prescribed by the manufacturer.
You are now at the end of Unit 5: Heating Systems. Click here to take the self-exam.
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