Abstract:

This video details seven effective strategies employed in the creator's "GAT greenhouse" to maintain cool temperatures, even during peak summer heat. The speaker highlights that while some methods are specific to the GAT system (Ground Air Heat Transfer), others are universally applicable to various greenhouse designs. Key techniques include active air circulation and cooling via underground pipes (GAT), strategic fan usage (fresh air intake, attic fan, both thermostatic), replacing windows with screens for ventilation and pest control, and passive design elements like strategic greenhouse placement for deciduous tree shade, a wood shingle roof designed to block high summer sun, and an optimal orientation that angles the structure away from the sun during the hottest part of the day. The result is a greenhouse where temperatures rarely exceed 95 degrees Fahrenheit, even on 94-degree ambient days.

Seven Ways to Keep a Greenhouse Cool

• 0:00 Introduction to Greenhouse Cooling: The video introduces seven methods for keeping a greenhouse cool, noting that three (points 3, 4, and 7) are applicable to almost any greenhouse design. Despite solar energy's "double-edged sword" nature for greenhouses (often becoming an "oven"), the speaker's greenhouse rarely exceeds 95 degrees Fahrenheit, even on 94-degree ambient days.

• 0:06 Ground Air Heat Transfer (GAT) System:

  • 0:22 GAT Fan for Hot Air Extraction: The GAT fan actively pulls hot air from the top of the greenhouse.
  • 0:24 Underground Cooling: This hot air is then cooled by being circulated six feet below ground.
  • 0:34 Cooled Air Return: The now-cooled air is returned to the greenhouse, lowering the overall ambient temperature.

• 1:43 Additional Ventilation Fans:

  • 1:44 Fresh Air Intake Fan: A dedicated fan brings fresh air into the greenhouse.
  • 1:50 Attic Fan: An attic fan vents hot air from the greenhouse's attic space.
  • 1:52 Thermostatic Control: Both the fresh air intake and attic fans are controlled by thermostats for automated temperature management.

• 1:55 Screen Windows for Ventilation & Pest Control:

  • 1:55 Replaceable Windows: Windows can be replaced with screens, enhancing airflow.
  • 1:57 Half-Inch Hardware Cloth: The screens are made with half-inch hardware cloth to prevent pests, like cabbage butterflies, from entering the greenhouse.

• 2:04 Strategic Greenhouse Location:

  • 2:12 Deciduous Tree Shade: The greenhouse is situated to receive shade from deciduous trees in the morning and later in the afternoon during the hottest part of the day. This keeps the greenhouse cooler for longer periods.

• 2:29 Wood Shingle Roof Design:

  • 2:31 Heat Rejection: The greenhouse features a unique wood shingle roof designed to reject the high angle of the summer sun.
  • 2:41 Summer Sun Blockage: At the peak of summer, the sun's rays do not even reach the back wall of the greenhouse due to the roof's design.

• 2:50 Optimal Greenhouse Orientation:

  • 2:55 South-Southeast Angle: The greenhouse structure is oriented approximately 15 degrees south-southeast.
  • 3:01 Building Turned Away from Sun: This orientation ensures that the building is angled away from the direct sun during the hottest part of the day, further reducing heat gain.