How Can I Keep My Residential Greenhouse From Overheating?

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As summer approaches and the outside temperatures begin to rise, the temperature inside your greenhouse will begin to rise with it.  How do you combat overheating inside your greenhouse? Here are four things you can do to keep those temps down.

Passive Ventilation 

Open any windows and doors and leave them open (even overnight)! Consider removing any screens on your windows to allow pollinators inside.

Change the setting on your GAHT® System  

Consider manipulating your thermostat settings so that the system starts working for you earlier than you think you might need it. For example, if your cooling thermostat is set to 75°F, try 70°F. Another trick with the GAHT® system is change the thermostat settings so that the system is running overnight. This will essentially flush the stored heat in the soil, bringing down the outlet temperatures and amplify the cool effect of the system. 

If you do not have a GAHT® system to start with, consider adding an external GAHT®. This system essentially turns the soil next to the greenhouse into additional thermal mass, storing the excess heat the greenhouse generates for later use. 

Learn more about how a GAHT® system works

Change the Setting on your Exhaust System

This system is intended to flush any heat that the GAHT® system cannot cope with. A typical thermostat setting for an exhaust system is around 90-95°F. In the heat of the summer, try setting the thermostat to 80-85°F.

Shade paint

Once you begin to see exterior temperatures of 90-95°F, we need to consider how to cut the solar heat gain of the greenhouse. Enter shade paintWe prefer shade paint to shade cloth for a few reasons:

It is safer for your glazing. Shade cloth can scratch the polycarbonate and remove the protective coatings, thereby increasing the degradation rate.

Shade paint is much more customizable. Each coat is estimated to cut only 6% of incoming light and 15% of incoming heat. You can apply multiple coats, and apply it to all of your glazing, including any windows.

Some people install shade cloth on the inside of their greenhouses. This is a great way to avoid the potential risk of damaging the glazing. However, it is important to note that with this technique, heat is still allowed inside the building, and therefore this technique is negligible.

Additional techniques

  • Install blinds on the South facing windows of the greenhouse. This will block sunlight from entering and heating the greenhouse.
  • Hang insulation at the ridge or peak of the greenhouse. This serves to insulate against the high summer sun and additionally helps to retain heat in the winter as well.
  • Consider evaporative cooling systems, such as misters. Be cautious with high levels of humidity in your greenhouse. If you choose a technique such as this, be sure to use a circulation system as well, set on a timer so that it runs for a few hours every morning.
  • Install plant reaching or vining plants along the South wall and up a trellis attached to the rafters during the summer months for natural shade!

Contact us to learn more.

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