Has anyone here had any experience with heating greenhouses with geothermal? If so, what kind of load per sq. ft. might a greenhouse have?
Residential or industrial? Your load requirements are strongly product and location prescribed, so you have to fill us in with more details. More often than not, the CO2 requirements dictate fossil fuels.
I ran across this yesterday.... Citrus In The Snow- Geothermal Greenhouse No idea if it's for real or not. I didn't spend the $24 for the report. Claims free heat since 1992 using "geoair".
I'm more wondering if geothermal is an option... I have a couple of people that have asked about it, and I have yet to be able to determine a proper R value. Had I already found it, I could likely do the load. I'll keep investigating. Thanks guys for the replies.
Quick answer - not likely. R- value is easy as it is part of greenhouse design. You need to know your solar gains. Operating requirements are what is needed. Tomatoes or tulips? That plays a big part as well.
Clark, I’m a former hobby greenhouse owner. Your post caught my attention! Virtual Grower is a free computer program from USDA Agricultural Research Service, that I think will help you. It’s described by ARS as: “Virtual Grower is a decision support tool for greenhouse growers. Users can build a greenhouse with a variety of materials for roofs and sidewalls, design the greenhouse style, schedule temperature set points throughout the year, and predict heating costs for over 230 sites within the US. Different heating and scheduling scenarios can be predicted with few inputs.” You can find it here: Application Technology Research Unit Products and Services You can find a review of the program here: Greenhouse Grower: Modeling Greenhouse Efficiency Virtually Current Version 2.5 requires Windows, Version 3, will work on a Mac. I hope the links work! Regards, Masoud
Masoud, Thanks for the heads up. That should work well for figuring out different scenarios they might want to try.
Greenhouse Formula Q=UxSAx(Tin,min-Tout,min) U-overall heat transfer coefficient (Btu Hr Ft *F) SA-total surface area of greenhouse Tin,min-minimum inside air setpoint temp (*F) Tout,min-minimum outside air temp (*F) Q-heat loss from greenhouse (Btu Hr) Overall heat transfer coefficient (U) single layer glass-1.2 single layer polyethylene-1.2 double layer PE-0.8 souble walled polycarbonate-0.6
Solar heat gain may not be applicable, as it needs to cover the required load when there is no sun shining (at night).
