Lots of brains in this place that I hope to be able to pick! - Though not entirely sure where this belongs...
Anyway here is the challenge, I am about to take over a large, glass, green house roughly 18m x 7m, normal peaked roof shape. I need the most energy efficient ways of keeping the interior at 12-15C, I also need to regularly exchange the air inside. So that means heating sometimes and cooling others. Natural light is not needed, humidity is not an issue. South UK, I have a small budget but lots of DIY/electrical/electronic/mechanical skills...!
For insulation the original plan was to paint all the glass with an opaque white paint, use mineral wool and chicken wire to insulate the vertical walls and create an insulated horizontal false ceiling on wood frames, leaving the apex above empty but with whited out windows, thus hot air in the roof would have to travel downwards before even getting to the insulated ceiling - and I could vent the roof space in summer to stop it heating up.
First idea is to rent a JCB and bury a bunch of IBCs at 4m deep, fill with a water/glycol solution and pump the resulting 11-12C water directly through a water/air exchanger (most likely a salvaged cold room evaporator!) in the insulated room - this of course would provide almost the right temp all year, but probably won't cope with the loss's through the insulated walls and air exchange when it's 0c or 30c outside!
For air exchange I plan to run room exhaust air through long pipes "contraflow" inside the incoming air duct as a sort of MVHR heat exchanger
For cooling I was thinking of building an evaporative cooler.
For heating I am scratching my head a bit, the air exchange will again go through the long tube heat exchanger to minimise losses but then I have a number of options. For winter sunny day heating, a black air pipe in the apex of the roof circulating into the room would probably do it but there is no thermal store for night or cloudy days. A big set of solar vac tubes hooked up to insulated IBC's outside could provide enough heat store but it is expensive. I could hook a GSHP up to those buried IBC's but I assume there is a reason they normally bury lots of pipe, plus again expensive. Thought about building a home made collector under the glass roof or even a trickle down black pad version, again under the existing glass.
Most stuff I see is aimed at providing living room temps so any ideas on any of this welcome.... please!!
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