How many climate zones are in Utah?
Yes, there’s a tiny part of Utah that has a zone 9a. However, that’s obviously not what the news report is about. I should have specifically said Northern Utah to avoid your question.
Ogden is zone 6a-7a. I wish the story got more into the heating and greenhouse design…
Exactly! The story is just an intro. For those who want to pursue it further, they can probably find this guy.
Ive been looking at a lot of these greenhouses lately to get my design down. The article reminded me of this guy:https://youtu.be/ZD_3_gsgsnk?si=CaWCtVDoSUccYMB8
From the video,it looks like he makes fairly thick berms,of hay(?),on the outside,to help hold in the heat.
2 WINTER and not winter
The internet is filled with those greenhouse with passive solar…geothermal…climate battery…etc. They look like they work, as long as you don’t expect too much. You can pick up a zone or two, and temper the worst of the winters, but your not going to get that intense tropical sun. I think where I’m at in Northern WI, I’d need a lot of propane to keep citrus even in the best greenhouse, and probably supplemental lighting. I need to build one and find out, because they sure look awesome.
They work with significant limitations in climates with sunny winters. Areas like western Kansas and Colorado. In N WI it’s too cloudy and too cold. Without sun a greenhouse just becomes a very poorly insulated grow room with an enormous heating bill and/or very expensive construction costs. I’d think more in terms of potted citrus in a basement or other insulated structure with LED lighting in winter. Move them outside in summer.
Even in Arkansas where a greenhouse for citrus would be feasible one of our best growers @aap operates that way with great success.
See Duncandog’s video above in Nebraska. It looks like a tropical jungle!
I think your best bet without actual electricity would be a walipini that has actively managed and decomposing organics for heat. It would be a lot of work. A rocket mass heater could be another option… There’s lots of hype about them on permies but I have no real life experience.
That video is incredible and increases my hope for humanity. I may implement these ideas at my new property.
I’m mostly happy with my greenhouse here where we have very little winter sun, but our temperatures are usually only slightly too cold for citrus and avocados (the main things I care to keep happy), so I only need to heat it for a few nights here and there, other than the rare deep freeze like earlier this month. Even on mostly overcast days, the greenhouse usually manages to get a gain of a few degrees from the photons that make their way through the clouds. Though with our low sun angle in winter, even on fully sunny days the gain is only about 15°F to 20°F, so it’s rarely warmer than 65°F in the greenhouse even on those days.
I wish that people with these “passive” heat greenhouses would discuss them in terms of the heat gain (∆°) vs outdoor temperatures, so that people in other climates could get a realistic idea of whether that would work for them. Here’s my ∆°F chart since Dec 1, you can see the “bulge” earlier this month when I was running the electric heater, and the occasional sunny days as blips:
And yes there are even times where it’s negative! Sometimes when a warm front comes in overnight or with very thick cloud cover, the greenhouse lags behind and traps the cold air instead.
Here at 30 north latitude with a sunny climate my greenhouse and sunroom both heat up 40-50F warmer than outside. I’ve had one day since Dec 15 when it didn’t hit 90F in the GH. Most days it’s 90 for 4-8 hours. Outside during that time highs have mostly been 50-60F.
Nights average about 30-35 for a low. I can heat 10F warmer than outside very economically. Trying to heat to more than 20F above outside gets expensive.
Right now my GH is 48 low and 90 high. That costs ~$150 per month for a 1700 sqft GH.