Optimize your Greenhouse Kit with our multiple ventilation, fan and cooling options
The Growing Dome comes standard with a size-appropriate ventilation system for both passive and active airflow. Greenhouse ventilation is an important feature of your greenhouse to improve temperature regulation, humidity control, air circulation, prevention of pests and diseases, and odor mitigation.
Growing Dome Ventilation System Standard Options
Passive Ventilation
Smaller Growing Dome Kits come standard with automatic vent openers that create passive airflow, bringing in cooler air from the ground and allowing hot air to escape from the top vents. We’ve found that the standard options are adequate for Plant Hardiness Zones 5a or colder.
15′ – two bottom Univents, one top Bayliss vent, and a ½ lite vented door
18′ – two bottom Bayliss vents, one top Gigavent vent, and a ½ lite vented door
22′ – two bottom Univents, two top Bayliss vents, and a ½ lite vented door
Active Ventilation
Larger domes come standard with fans to provide more active ventilation, again drawing air inside the dome from the ground and exhausting air out from the top. Each Growing Dome can be configured to use Solar or Electric power, depending on if your greenhouse will be On-Grid or Off-Grid.
26′ – two bottom Bayliss and one Hybrid Fan for intake. Also, two top Gigavents for exhaust, or upgrade to one top solar attic fan.
33′ – one electric fan, or two solar fans if the solar cooling upgrade is purchased, for intake. One solar attic fan at the top of the dome for exhaust.
42′ – two electric fans, or three solar fans if the solar cooling upgrade is purchased, for intake. Two solar attic fans at the top of the dome for exhaust. Two ½ lite vented doors come standard.
| Air Volume | Intake CFM | Intake Exchange (sec) | Exhaust CFM | Exhaust Exchange (sec) | Net Diff CFM | |
| 26′ + Solar Attic Fan | 3740 | 1217 | 184 | 1875 | 120 | 658 |
| 33′ Standard Electric | 7390 | 2800 | 158 | 2100 | 211 | -700 |
| 33′ Solar Cooling Upgrade | 7390 | 3850 | 115 | 2100 | 211 | -1750 |
| 42′ Standard Electric | 12175 | 5600 | 130 | 4200 | 174 | -1400 |
| 42′ Solar Cooling Upgrade | 12175 | 5775 | 126 | 4200 | 174 | -1575 |
Growing Dome Ventilation Upgrade Options
Automatic vent openers
15′ – one additional upper vent can be added (Bayliss).
18′ – one additional upper vent can be added (Gigavent).
22′ – one additional lower vent can be added (Univent).
26′ – one additional lower vent can be added (Bayliss).
Automatic vent openers can be added to the 15′ through 26′ domes for additional passive ventilation.
Intake Fans
We encourage you to add active ventilation depending on your climate. If your dome is protected from the wind outside, or you don’t get a lot of wind in your area, you may want to consider adding more active ventilation. But if your dome does get natural wind, passive ventilation through the vents and doors is surprisingly effective.
14″ Hybrid Greenhouse Fan (12v DC, 1217 CFM)
The QuietCool Hybrid Solar Cooling Fan will run on solar when the sun is out, and switch to electric (if available) when it is cloudy or at night. Add one or, a few, to your 15′ – 26′ Growing Dome Greenhouse Kits to provide additional cooling, airflow, and ventilation.
16″ Electric Greenhouse Fan (115v AC, 2300 CFM)
The CANARM XFS 16 Wall Exhaust Fan will circulate more air than the Solar or the Hybrid Fan, but will require an electrical connection. These can be added to any size Growing Dome Greenhouse Kit.
14″ Solar Greenhouse Fan (12v DC, 1925 CFM)
The Attic Breeze 12 Volt Retrofit-style Gable Cooling Fan is one of the most powerful solar fans available and can be added to the 33′ or 42′ Growing Dome Greenhouse Kits.
Exhaust Fans
Solar Attic Fan (12v DC)
The Attic Breeze 14″ Solar Attic Exhaust Fan mounts on the top of the large Growing Dome kits for superior ventilation and air circulation. The attic fan is great in areas with high wind loads. The 26′ Growing Dome uses a 45W Fan with 1875 CFM, while the 33′ and 42′ use a 65W Fan with 2150 CFM of airflow.
Desert Cooling Package
The Desert Cooling Package is recommended for hot, dry environments. It includes a misting system and either an extra solar fan or an electric fan depending on your configuration. The evaporative cooling effects of the Misting System and the fans help keep your dome cool during the hot summer months. The low-pressure Misting System easily connects to your garden hose and is custom-sized for each dome.
Climate Considerations
Plant Hardiness Zones 5b through 7b
Adding just one fan to our smaller greenhouse kits will be enough to exchange one full volume of air in less than 2 minutes. These options are recommended for Plant Hardiness Zones 5b through 7b.
| Air Volume (cu ft) | CFM | Air Exchange (sec) | |
| 15′ + Hybrid Fan | 520 | 1217 | 26 |
| 15′ + Electric Fan | 520 | 2800 | 11 |
| 18′ + Hybrid Fan | 1250 | 1217 | 62 |
| 18′ + Electric Fan | 1250 | 2800 | 27 |
| 22′ + Hybrid Fan | 2246 | 1217 | 111 |
| 22′ + Electric Fan | 2246 | 2800 | 48 |
We would recommend having enough active ventilation in larger domes to exchange a full volume of air anywhere between 1 and 3 minutes. Also, look at the Net Differential CFM (Exhaust – Intake) between your intake fans and exhaust fans. Although the dome will never create positive pressure, it is still a good practice to ensure you have almost the same exhaust as you do intake. Lower vents will provide additional intake if you have more CFM through the exhaust fans. But we do not recommend combining top vents and exhaust fans as the fans will just circulate air through the top vents.
Adding one extra intake fan and an extra solar attic fan can really improve air flow in the larger domes. These options are recommended for Plant Hardiness Zones 5b through 7b.
| Air Volume | Intake CFM | Intake Exchange (sec) | Exhaust CFM | Exhaust Exchange | Net Diff CFM | |
| 26′ + Hybrid Fan + Solar Attic Fan Upgrade | 3740 | 2434 | 92 | 1875 | 120 | -559 |
| 33′ + Extra Solar Fan + Extra Attic Fan | 7390 | 5775 | 77 | 4200 | 106 | -1575 |
| 33′ + Extra Electric Fan + Extra Attic Fan | 7390 | 5600 | 79 | 4200 | 106 | -1400 |
| 42′ + Extra Solar Fan + Extra Attic Fan | 12175 | 7700 | 95 | 6300 | 116 | -1400 |
| 42′ + Extra Electric Fan + Extra Attic Fan | 12175 | 8400 | 87 | 6300 | 116 | -2100 |
Plant Hardiness Zones 8a or Hotter
In extremely hot or humid environments (Plant Hardiness Zones 8a or greater), we recommend adding maximum ventilation to your Growing Dome. This will optimize airflow within your greenhouse, and help prevent overheating and excessive humidity. In addition, you should consider an evaporative cooler for hot, dry environments and a de-humidifier or an A/C unit for hot and humid environments.
15′ or 18′ – two Hybrid or Electric fans can be added. With two fans, we would also recommend adding the upper vent for exhaust.
22′ – you can add either 3 fans or 2 fans and the extra lower vent.
| Air Volume (cu ft) | CFM | Air Exchange (sec) | |
| 15′ + 2 Hybrid Fans | 520 | 2434 | 13 |
| 15′ + 2 Electric Fans | 520 | 5600 | 6 |
| 18′ + 2 Hybrid Fans | 1250 | 2434 | 31 |
| 18′ + 2 Electric Fans | 1250 | 5600 | 13 |
| 22′ + 3 Hybrid Fans | 2246 | 3651 | 37 |
| 22′ + 3 Electric Fans | 2246 | 8400 | 16 |
26′ – you can add either 2 Solar or Electric intake fans or 1 fan and the extra lower vent. We would also recommend adding an extra Solar Attic Fan. Contact Growing Spacs for the recommended placement of the Solar Attic Fans.
33′ – add 2 Solar or Electric intake fans plus 2 Solar Attic Fans. Talk to Growing Spaces about the best locations for the Solar Attic Fans, and consider mounting solar panels outside of the dome. Contact Growing Spacs for the recommended placement of the Solar Attic Fans.
42′ – add 2 Solar or Electric intake fans plus 2 Solar Attic Fans. Talk to Growing Spaces about the best locations for the Solar Attic Fans, and consider mounting solar panels outside of the dome.
| Air Volume (cu ft) | Intake CFM | Intake Exchange (sec) | Exhaust CFM | Exhaust Exchange (sec) | Net Diff CFM | |
| 26′ + 2 Extra Solar Fans + 2 Solar Attic Fans | 3740 | 3651 | 61 | 3750 | 60 | 99 |
| 26′ + 1 Extra Electric Fan + 2 Solar Attic Fans | 3740 | 5600 | 40 | 3750 | 60 | -1850 |
| 33′ + 2 Extra Solar Fans + 2 Extra Solar Attic Fans | 7390 | 7700 | 58 | 6300 | 70 | -1400 |
| 33′ + 2 Extra Electric + 2 Extra Solar Attic Fans | 7390 | 8400 | 53 | 6300 | 70 | -2100 |
| 42′ + 2 Extra Solar + 2 Extra Solar Attic Fans | 12175 | 9625 | 76 | 8400 | 87 | -1225 |
| 42′ + 2 Extra Electric + 2 Extra Solar Attic Fans | 12175 | 11200 | 65 | 8400 | 87 | -2800 |
Undersoil Ventilation System
All Growing Dome Greenhouses come standard with the solar-powered Undersoil Ventilation System. This unique design circulates air between the above-ground pond and your perimeter garden beds to help maintain the temperature of your soil, and create an additional thermal mass for your greenhouse. We call it a mini climate battery.
Additional Resources
Pro Tip: For even more ventilation, consider adding additional intake fans and reversing them to exhaust fans on the opposite side of the dome to create more cross-ventilation. A total of 5 fans can be installed on the 33′ dome and a total of 8 fans can be installed on the 42′ dome.
Refer to our article on climate zones or talk to one of our experienced Growing Dome Advisors about what ventilation options would work best for your area. You can also download our Air Exchange Calculator to do your own Air Flow calculations.
Is your greenhouse too hot in the summer? Also, refer to our video showing 7 ways to keep your greenhouse cool.