Rebecca Norman

I don't have a picture or diagram of the trombe wall. It's seen at 1:45 in the video. It's just a half-trombe wall. The downstairs south-facing wall is rammed earth, like the rest of the house, with windows that are not very large since the real winter glazing for the downstairs is the seasonally attached greenhouse. Upstairs, the south wall is largely windows, with a concrete-block wall up to only 2.5 feet high (the half-trombe wall), inside the floor-to-ceiling window, to absorb, store and moderate some of the sun's direct radiation. In the video at 1:10 and 1:45, Rohit is sitting on it. It's about 6 inches thick (because the standard cement or earth bricks in our area are 6x6x12 inches). It's painted black on the outside, facing the glass, to increase heat absorption from the sunlight. There is a 5- or 6-inch gap between the wall and the window -- That might not be ideal thermally, but I've lived with these type of half-trombe walls at our school for over 20 years, and being able to stick your arm inside for cleaning or maintenance is important. The beam above those windows is a reinforced concrete beam, because the roof is earthen and very heavy. All other lintels in the house are wood.

The greenhouse is attached to an iron frame with a type of long wavy wires called "clips" (I'm sure there's an American term but I don't know it) that you wedge into a narrow aluminum gutter that is bolted to the iron frame. It takes a small crew, at least 4 or 5 people, to put it on in November (excuse for a party to invite some of my former students), but only takes 30 minutes if at least one person knows how to do it. You hang the piece of UV-resistant plastic out over the top of the frame, pull it tight along the top, and wedge the "clips" (wavy long stiff wires) into the top edge of the frame, locking the top of the plastic in place. Then it's pretty easy to go down and clip the sides. We fix the bottom with a trench and soil, rather than clips. It is said to be helpful to to attach the greenhouse on a hot midday, when the plastic is as stretched and flexible as it's going to get (though maybe the metal frames expand more so maybe it doesn't matter). It takes only two people to remove the plastic in springtime.

The floors are not vented to each other, especially in winter, when the thermal buffer zone, ie stairwell and the east-west corridor along the north edge of the house, is closed off from the south facing rooms. The upstairs rooms do get a bit too cold at night in winter, these first two years, below 10C, which is not very nice. I was away for January this year, and I slept down in the living room for January last year, as did Rohit this recent January while I was away. I arrived on Feb. 8th and the house started warming up within a few days, and is comfortable even upstairs now, in late February.

The roof insulation is not great and I'm planning to improve it. It's only natural "straw-clay," about 6 or 8 inches thick. There's a gap 8 inches thick between the horizontal joists, hidden by the thin wooden ceiling, and I'm planning to put some more serious insulation in those spaces this year. I think it will make several degrees of difference. If the upstairs bedrooms stay above 12C on January nights, I'll be happy.

I had the exact same idea as you, but I live on a different continent from anywhere that someone I know might have meyer lemon. So I got a friend in California to send a couple of Meyer lemons to me when I was in the USA in August. I took out the seeds, and took them with me to India, and stuck them in the soil of some houseplants. Several germinated within 2 months, and a couple more have germinated now that the weather is warming up.

I know that they won't come exactly true to the parent, but I am hoping that they might be nice small trees that might give some kind of nice citrus. I'll keep one or two in pots to move in and out seasonally. If I get a few established, I'll try one in the ground in my greenhouse, which does go down to -5C every night for at least 2 months of winter, but over 0C every day. It might not last, but I'm eager to try anyway.

Great to know, William! Could you post a picture? I want to do this and if you're doing it successfully I'd try to copy your system to some extent. I think preheating thermal mass above sounds key.

Hmm, then that sounds like there will have to be way too much heat below before there's enough heat above. Pizza needs substantial heat from above, and I can't imagine how that set-up would get enough heat above it without being far too hot underneath. I've tried jerry-rigged versions of this before, and always had the problem you're having. But the box you're using is sold commercially as supposedly working fine over a gas grill, right? So then I'm mystified why it would work over a gas grill. Have you looked at reviews of the item and seen if a significant number of people are actually using it successfully for pizza over a bottom-heat source?

How is the heat transferred to above the pizza?

What I remember from Sandor Katz, the fermentation deity, is that it's usually safe to have a taste, and if it smells or taste yucky, pitch it. Otherwise, give it a go.

What you are describing sounds like it might be fine, or might be going bad (maybe because of low salt as mentioned above).

If I were you I'd try a little taste.

I've killed sourdough several times by leaving it out too long. Currently I am not keeping a sourdough (after 6 weeks away and I could only ask the housesitting housemate to water the garden and keep up with other essentials, so I didn't ask him to feed and tend the sourdough).

I've been getting very nice results from making bread with only a tiny amount of commercial dry yeast and very long rise times. It comes out tasting much like a decent sourdough bread.

My housemate explaining passive solar heating at my house in the high desert. You can ask me for details if you have questions, because being only 3:45 minutes this video doesn't have much detail.

Unscrubbed biogas can have high levels of corrosive gasses that may corrode and damage your propane burner. Scrubbing for this is pretty simple though -- I've read that you include a chamber before or in the middle of the gas pipe, packed loosely with iron filings or steel wool or cheap steel scrubbies that rust quickly. Much of the corrosive gas will do its work by rusting the iron there and turn into less corrosive substances. To reduce moisture in the gas, you can make a condensing chamber before or in the middle of the pipe, and that will happen to work best in winter when you are using the biogas for your greenhouse.

One drawback for biogas for your purpose is that the digesting process as pointed out above needs to be very warm, ideally the temperature of a ruminant's gut, so in the coldest weather when you need biogas the most, the digestion process will be at its slowest. If you want to store the gas for months, you'll need some container that is very airtight and not vulnerable to corroding.

What is your outside temperature and climate? What are the current problem temperatures in your greenhouse and for how many nights? And what is your target, ie how much area do you have in tender plants that need additional heat? Because there may be simpler ways to protect your tender plants or improve the nighttime insulation, etc.

I found it was as successful to plant the cuttings immediately as to soak the bottoms in water for a couple of weeks as local people here recommended. If you have to keep the cuttings for more than an hour between cutting and planting, then by all means do keep the bottoms in water.

We have heavy grazer and browser pressure here, so we plant cuttings that are 2 to 4 inches in diameter, and at least 6 feet long so that 1.5 feet goes underground and ideally 5 to 7 feet above ground. Much shorter above ground would probably be even more successful but we can't do that here. Don't mix any compost or manure into the soil when you plant the cuttings. That makes failure more likely.