Greenhouse Ventilation Benefits
Mark this down on your checklist of components needed for the construction of your greenhouse- Ventilation is essential to the health of everything you grow.
What is the Purpose for a Greenhouse Ventilation System
1. Controlling the Temperature
If you recall, I pointed out how heat is trapped inside the greenhouse with the help of glass, films, or plastic material covers/panels. This is beneficial for plants to a point, but there needs to be away to stabilize the temperature or the greenhouse will just keep getting hotter, and the plants will wilt and die.
This is where vents and exhaust fans come in to play, and help to maintain an environment of air flow throughout. When properly used, vents will keep cold and warm air stabilized at optimum temperatures, and exhaust fans will force out stale hot air.
2. Fresh Air Circulation
Don’t overlook plant needs for oxygen and CO2 to photosynthesize. Good air flow circulation throughout the greenhouse is essential. Humidity is also needed but under control, or molds, fungi, pathogens and other pests may be a problem.
The plants in your greenhouse depend on windy conditions that spread their self-pollination. Open vents and working fans are needed to provide artificial indoor winds.
Depending on the type of greenhouse design you have, you’ll need to pick between these two ventilation options:
1. Natural ventilation
Also known as curtain ventilation, this system is based on the precept that trivial winds (speeds of only 1-3 mph) flow across the width of the greenhouse, while an arrangement of sidewall vents, usually louvered vents, draw in cool air. This is how it works:
The side vents are near the ground where lower air temperatures rest.
A vacuum is created that sucks in the cool air from side to side, staying colder then air that flows the length of the greenhouse.
The hot air accumulating from sunlight rises and escapes through a roof vent(s). A vacuum is created with the help of wind passing over the roof sucking out heat, and stabilizing the temperature. BTW, roof vents are usually hinged and should be opened to 55° or more during warm weather.
Be aware that the weather plays a part regarding the effectiveness of Natural ventilation systems. When it’s cool outside a favorable temperature difference assists the buoyancy of air. Buoyancy is the effectiveness of warm and moist air rising. However, when the weather is hot, the buoyancy factor doesn’t work. In this case there has been some success raising the height of the greenhouse.
The benefit of using a natural curtain ventilator is energy efficiency that reduces costs since exhaust fans are not needed.
2. Mechanical ventilation (or Fan Ventilation)
This system type uses exhaust fans, and is able to maintain greenhouse temperatures regardless of location and weather circumstances. Ventilation devices should have multiple speeds and control devices to help keep the electricity costs down. These systems are usually implemented in upper latitude regions where weather and temperatures can be extreme.(1)
8. Greenhouse Flooring Materials
Determine which flooring options to use such as:
- Pavers and/or stones- These are appealing and easy to install. They also are good with drainage issues, walking while working, and easy to find (although they are more expensive that other options)
- Concrete- cement is also good at drainage, solid, convenient to move heavy items like tanks and benches, easy to clean off, and durable over time. Can be expensive to pour the concrete.
- Gravel-Inexpensive and easy to drain (use PVC pipes), but not so easy to move things and walking.
- Dirt- The Poor Mans Option.. inexpensive and grades level well, but issues with mud, cleaning, pests, and no drainage.
What about materials to use for the shelving?
- Powdered- coated Metal with mesh facings. The mesh grids are perfect because of the draining and airflow they provide.
- Plastic shelves- Easy to clean and can be configured to allow drainage. Be sure to get heavy-duty plastic as the thin ones
don’t hold up to the high temperatures.
- Wooden shelves are appealing in appearance but have their disadvantages. They can warp and rot wood from moisture. You can stop the decaying by using rot-resistant wood, or paint over them with water-repellent preservatives.
***TIP-Include benches you can use for storage.
It’s a good Idea to have a gutter system for your greenhouse whether its stand alone or grouped together. Don’t waist free water, use your gutter(s) to collect rainwater into tanks and other containers for usage.
Installing gutters is not difficult, it’s just a matter of finding a DIY store that carries the brackets, connectors, and gutter channels that fit the size of your greenhouse.
What you’ll need:
- Lengths of Gutter channels
- End stops and Down-pipes
- Guttering brackets and joining brackets
- A hacksaw to cut the gutter channel to size.
- Screws, a drill, and drill bits
- A catch system that redirects water from the gutter down-pipes to a reservoir capturing water that can later be used for irrigating the plants.