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Greenhouse 101 with Andrew Cook: Ventilation

Andrew Cook of European Garden grew up in Holland and he knows a thing or two about greenhouses.  While he was here helping me install my greenhouse he explained why proper ventilation is so important.

Allen: Now Andrew obviously a greenhouse of any size, ventilation is always an important and essential, there are four ways or four places this greenhouse ventilates from.

Andrew Cook: It’s very important. Particularly in the U.S. where the climate is much warmer. Initially the greenhouse concept is an English, northern European concept and many of those greenhouses are not well enough ventilated for the US. We get cold here, but we get easily very warm in the daytime.

Allen: It can get very warm here in the early spring.

Andrew Cook: Exactly, so in a greenhouse like this what we have is two roof windows, you can have maybe one or a smaller one, but the big important thing is a through draft. So this one comes with a very big window in the back wall that can be opened up and be very nice, and then of course the Dutch barn style door with the top open and the bottom closed to keep animals out. And then of course what we have also to the roof windows with automatic window openers that have the paraffin oils in them that expand and contract.

Allen: Now I think that is so interesting the way that works. As the greenhouse environment warms the oil in a tube expands and pushes the windows open and ventilates the warmer air out.

Andrew Cook: Yes. The roof windows open up and they can open up 12-15 inches, and the oil cylinder can be adjusted to how much opening you want, and making sure that in the winter they stay closed. These were closed this morning, and now they’re opening up because the sun is bright.

Allen: Right, last night we dropped down to 37 degrees, and early this morning I came out and they were closed tight. Now we're in the greenhouse and its warmed up to say 70, and they’ve opened.

Andrew Cook: Exactly, and that sort of climate change we usually don’t have in Europe, but here in the US we really have that, and that’s why the automatic window openers are so important.