Cover fans and shutters are not needed for winter ventilation.
Photo: John Bartok, Jr.

As I conduct energy audits, I often see obvious energy losses and discounts that the grower walks by every day as not very important. The following are a few that can add up to a sizable amount over the course of a year.

1. Room lighting – Failing to turn off the lights in an office, storage room, work area or restroom when leaving can add a significant amount to the electric bill. Installing a motion sensing or programmable switch will shut the lights off after a predetermined amount of time. The cost is from $30 to $60.

2. Outdoor area lighting – Nighttime security lighting adds up to several thousand watts of electricity in most greenhouse operations. The lights are on from dusk to dawn. Research has shown that a better method is to have the lights illuminate by detecting the motion of intruders. The savings can be significant. Regulations in some states limit the amount of up-light and glare. High-intensity discharge lights should not be used as lamp lighting. LEDs are a better choice.

3. Tears in double-poly glazing – Besides requiring energy to replace the air that is lost, the cold make-up air increases the heat loss from the greenhouse, requiring additional fuel. Patch tape is available that will seal small tears.

4. Doors left open – Whether they be exterior doors or doors between a warm and cool areas, additional heat is needed. Door closers, springs or simply a sign reminding employees to close the door can solve this problem.

5. Loading dock doors – Dock seals and dock shelters will reduce heat loss and keep rain, snow and insects out of the loading area. Seals are designed for a one-size truck body, whereas a shelter will accommodate several sizes.

6. Infrared (IR) poly – I am surprised at the number of growers that are not using IR poly as the inner layer on hoophouses. This proven technology saves a minimum of 10 percent in fuel use at a cost of only a couple of cents extra per square foot of material. Payback is always less than one year. The plastic should also have an anti-condensate feature to help control moisture.

Insulating boiler room supply/return pipes reduces wasted heat.
Photo: John Bartok, Jr.

7. Fan shutter closure – This is a major source of heat loss in many greenhouses. Shutters get out of adjustment, have sticky blades or get bent from high winds. Maintenance or replacement before winter can save significant heat. Shutters and fans that are not needed during the winter should be covered with poly or removable insulation panels.

8. Boiler piping – Adding insulation to hot water pipes, especially in boiler rooms, can save considerable heat. It is better to insulate the pipe and add a small thermostat-controlled unit heater that provides heat as needed. Supply and return pipes that run through greenhouses should be insulated so they are not overheating the greenhouse once the room thermostat is satisfied. An inch of foam or fiberglass insulation is usually adequate. An insulated 2-inch diameter pipe will save $3 to $6 per linear foot in yearly heating cost as compared to an uninsulated one.

9. Clean fin radiation and pipes – To get good heat transfer, brush or vacuum dust and cobwebs from fin radiators or bare pipes. Furnace blowers and ducting should also be cleaned. A ?-inch coating of dust will decrease heat transfer by 10 percent.

10. Water heater temperature – The recommended domestic hot water temperature is 120 degrees Fahrenheit. This prevents burns when used for washing hands. The thermostat is easy to adjust. Supply pipes should be insulated.

John W. Bartok Jr. is an agricultural engineer, an emeritus extension professor at the University of Connecticut and a regular contributor to Greenhouse Management. He is an author, consultant and certified technical service provider doing greenhouse energy audits for USDA grant programs in New England.