IN THE GROUND

50˚ today in Plymouth. 

4 mil plastic sheet folded in half to a size of 11' x 12' and then stapled on edge to make it easier to handle while placing it around the sides/bottom of the foundation hole.

It wasn't too difficult to get in the center of the base and walk it up the cellar stairs. Letting it slide down into the hole with the plastic secured in place was also easy. Insulation, heat sink set up and some back filling will be next.

Not bad/close enough

Passive Solar Greenhouse - Updated Diagram

I've started prepping the pieces for the above ground portion of the greenhouse and have made a few on the spot changes. Instead of building a box unit to channel the air down the outside of the under ground insulated box, I plan on running a 1"–1.5" pvc pipe from the warm air collection fan, down through the middle of the back wall of the green house just behind the black absorption surface, and down into the perforated pipe below the rock thermal bank. This method uses up only a little space within the grow bed/wicking bed so its a much simpler compromise. In this diagram I've drawn in some simple pvc vent pipes that when opened will allow outside air into the greenhouse during both winter and summer months.

YouTube Inspiration

These are just a few of the YouTube clips posted by growers and builders/designers that have inspired me to build and test my own system.


https://www.youtube.com/watch?v=pvPVsMGlVVI

A large school built greenhouse in western Canada with pv arrays and an in floor solar thermal storage.






https://www.youtube.com/watch?v=V0M6l3bnzZE

A large wood beam greenhouse in Minnesota focuses on collecting the large mass of sun heated air from within the greenhouse and pumping it through tubes just beneath the grow beds.

Concept of greenhouse, cutaway with foundation box

 This sketch shows the insulated "foundation box" with cut away view of greenhouse on top. 

Foundation Box top view

Here is the top view of the insulated "foundation box". The bottom will also be fitted with a piece of 2" insulation. 

4" perforated corrugated drain pipe will be placed at the bottom, which will receive heated air blown down from inside sun heated air at the top of greenhouse. 

2ft of1.5" rough stone will be placed on top of the perforated pipe and should soak up and store any temperature from the heated air passing through it.

Lower Foundation Box

I made some progress over the past few days. Here you can see the sub-grade insulated box within corner post and sill cap. The posts are 2"x6" p.t. lumber, 32" tall screwed together in an L shape. The sill is made of 2x4 p.t. lumber over posts. 1x5 p.t. lumber is screwed/glued to the outside of the sill to act as an attachment point for posts and frame to be built above.

Cross section of air temp controlled air flow

So in theory this might work. The fans are advertised as waterproof 12v computer fans. Rock isn't the greatest heat storage material, water is but I'd have to include an air to heat exchanger and a water tank beneath the wicking/grow bed. That would break my budget so I'm going with 1.5" dry stone as a winter heat sink.

Air Temp Control Heat Sink Overview

This is the plan anyways. At this point.
2 fans $20 each, 2 monitoring boards $6 each. Wood insulation $20-ish.

The Hole...

After many wheelbarrow loads and one small cave in...

This is the hole for the heat sink, 34" depth, 4' wide x 2.5' front to rear.

 Four 16"x16" concrete blocks leveled in the corners are the footers ready for the 4 pressure treated posts.

SketchUp sketch design

Hello folks, this blog is to document a semi quick build of a 4' x 2' winterized greenhouse. This is the basic mockup done in SketchUp. I plan on including a heat sink below the grow bed which will draw any excess internal warm air down into a dry rock bed beneath the grow bed. I also plan on adding a water bed heating pad just below the grow bed (just above the rock heat sink). I also plan on building a wicking bed into the design and hand water/ fertilize the plants allowing them to soak up nutrients and water as needed.