Conduct an energy audit of your greenhouses

An energy audit is a common term used to describe a broad range of energy studies, from a simple walkthrough to identifying major problem areas to a comprehensive analysis of where every Btu of energy is consumed. The areas covered should include heating and electricity use as these are the largest energy bills that you pay.

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A walkthrough audit

Major savings can usually be achieved with a simple walkthrough audit. This will identify losses due to infiltration and areas where insulation can be beneficial. It can also point out maintenance to heating, cooling and control systems that should be done.

Once the audit is complete, corrective measures can be developed, potential cost savings determined and a timetable for implementation established. Assign priority to the different items and someone to implement corrective action.

Comparisons of fuel and electricity use from year to year are also beneficial in that they can identify the energy/demand rate structure. For example, adjusting the controls on a fan cooling system can reduce the electricity demand and save considerable cost. Energy-conservation measures have a shorter payback than installing an alternate energy system. For most energy-conserving measures the payback is usually less than two years.

Walkthrough greenhouse energy audit

Greenhouse No. ____

Reduce air leakage

___________ Do exterior doors close tight? Are they insulated?

___________ Are doors, vents and shutters weather-stripped?

___________ Do fan intake shutters close tightly?

___________ Is there broken glass, torn plastic or cracks around the foundation?

Reduce heat loss

___________ Does the inner layer of the polyethylene film covering have infrared inhibitor and anti-condensate control?

___________ Are knee-walls and non-glazed areas insulated?

___________ Is the perimeter wall insulated to 18 inches below ground?

___________ Are unneeded winter fans and shutters covered with insulation?

___________ Do energy blankets close tight against the sidewall, gutter and frame?

___________ Are windbreaks installed around the greenhouse to deflect the winter winds?

Heating system

___________ Has the heating system been serviced this year? What is furnace efficiency?

___________ Are there leaks in heat pipes, valves or steam traps?

___________ Are the supply and return pipes insulated?

___________ Have the heat pipes and fin radiation been cleaned?

___________ Is there outside make-up air available to the furnace/boiler?

___________ Is the chimney 2 feet above the ridge of the greenhouse? Does it have a cap?

___________ Has root zone heat been installed to allow a lower air temperature?

Ventilation system

___________ Do the ventilating fans have a Ventilation Efficiency Ratio greater than 15?

___________ Have the fans been cleaned and serviced?

___________ Have the vent motors and arms been lubricated?

___________ Is the horizontal-airflow fan system installed to give good air circulation?

Control system

___________ Have thermostat/controller sensors been cleaned and calibrated recently?

___________ What is the thermostat differential between on and off?

___________ Are air temperature sensors located at the plant canopy?

___________ Are soil temperature sensors located in a representative flat or pot?

___________ Are heating and cooling thermostats located together and aspirated?

___________ Have electronic thermostats or controllers been installed?

___________ Has the hot water thermostat been set at 120°F?

Electrical system

___________ Do motors over 5 horsepower have a high-efficiency rating?

___________ Has the wiring system been checked for overloading or corrosion?

___________ Have light bulbs and fixtures been cleaned recently?

___________ Have motion-sensing light switches been installed in storage areas?

Water system

___________ Are water faucets dripping?

___________ Is the hot water tank and piping insulated?

___________ Have water filters and screens been cleaned recently?

Management

___________ Can the night temperature be lowered with a savings of 3 percent for each 1°F?

___________ Can the greenhouse start-up be delayed by a week or more in the spring?

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___________ Is the growing area full of plants?