Dear Jim,
I was very interested to read about the heated greenhouse in this article. I wondered if people have also tried insulating a greenhouse and designing it to maximize solar gain? I’ve seen a design used in the Himalayas which allows them to grow vegetables throughout the year despite -25C conditions, designed by the charity GERES. I uses a UV-resistant polythene sloping roof facing south, high-mass insulated walls to store the sun’s heat and keep it in, some internal walls painted black and others white to help the solar gain, and finally a manually controller ventilation hatch – though I guess this could be automated if desired. There’s a case study including photos at the Ashden web site. Thanks, – M.
Dear Editor:
Check out this web page: Directory:Walipini Underground Greenhouses.
Regards, – Roman