For many people, a greenhouse is only useful for a couple months, at the start of the season. It's too hot in the summer, and too expensive to heat in the winter. I've always thought it's more efficient to put lots of time into the garden, during the season when things want to grow outside.
So how do we turn a greenhouse into a 12-month building?
I was listening to Paul on a video that dealt with wood stove efficiency. He mentioned that people don't use kiln-dried wood. But we could. A greenhouse is not unlike a solar wood kiln. I have dried wood under glass, and it works great. The material dries so fast, that there is more cracking, which leads to even faster drying. Most importantly, it stays dry.
Many people take the time to stack their wood properly and then keep it covered, so the rain doesn't get on it, during the fall and winter.
That system may work on the cold dry prairies. Where I live in coastal British Columbia, the air is often near 100% humidity, during the heating season. Dry firewood is like a sponge, sucking up moisture, as air blows through it. So, the same nice airy pile, that allowed the wood to dry, now helps moisture to reenter the wood.
The solution is to have a really dry place to store it. Although we get most of our rain during the heating season, there are still lots of days when the sun shines and moisture is evaporated from green houses. Wood stored inside, is able to be maintained in a quite dry condition.
Glass and heavy blocks of wood are not compatible. Therefore, we need a fence. Chain link fence stretched along the length of the greenhouse, with a small gap between the fence and the glass, would allow the wood to be stacked without endangering the glass. I used a similar system at one time, without causing any damage. If the greenhouse is large enough, the gap could be a couple feet wide, so that a heat loving vine could be grown there in the summer. Passion fruit, pole beans and luffa are a few examples. After the crop is finished, let the soil dry out, so that it doesn't add moisture to the wood. Don't try to grow things during the period when light and temperature are not conducive. There will still be many days, in the middle of the heating season, when the sun shows itself for a few hours, and moisture is baked out of the wood. It would be important to seal up the gaps, so that moist air or fog are not allowed to flow freely through the dry wood.
This greenhouse does not need to be glass all around. A single south facing wall, will gather lots of heat. We're not trying to grow plants. I like the idea of going three-sided with the glass, and maybe just the length of one patio door, on the Southern portion of a shed style roof. This would allow the summer crop along the fence to get plenty of light.
Patio door glass is available for free in many parts of the world, when thermal units fail or older units are replaced with the latest version. It's the only type of glass I consider for large expanses.
When spring arrives, and you'd like to use the greenhouse for garden starts, haul the remaining wood into the mud room of the house, or to some other dry place. Now it's okay to make the greenhouse moist for a few months.
After the garden starts have been put in, load the back of the greenhouse with green firewood. It will help with greenhouse humidity for a while. It will reach its driest, in the fall, after the vine crops are removed and all watering is stopped. In my area, that's about six weeks before the heating season begins.
I have had good success in drying small dimension wood for a masonry stove , in as little as 2 weeks, when it's placed under glass. A system like this, would allow additions to the wood supply, right up until the beginning of the heating season.
It would be handy to have to door, one on the east and one on the west side of the building. Start loading the place close to the door that is closest to the house. That way, when it's time to start heating, the driest wood will also be the most accessible. Stuff that is added immediately before or during the heating season can be stacked furthest from the house.
Cold frames. We don't all have a nice greenhouse. Many of us have cold frames. It works pretty much the same way. After plants go in the garden, crack the lid for a week or so and let the soil really dry out. Load it with firewood and keep the lid cracked until it's nice and dry. That can be one week in good conditions. Small spaces get incredibly hot, when the sun can get in and there is little air flow.
My first experience with firewood behind glass, was in an attached sunspace. Many hoses get to dry in the winter. Wood that is shedding moisture, helps to alleviate that, as it becomes more useful in the stove.
Old freezers that are given a rubber liner and glass top, are the perfect spot for us Northerners to try raising tilapia or other warm water fish.
If the wood is perfectly dry at the end of August, I suppose the lid could be closed tightly , to lock out any moisture gain.
Diego Footer on Permaculture Based Homesteads - from the Eat Your Dirt Summit