Greenhouse Construction Updates

Winter 2017-2018 - basic shell completed !

Entire covering is standard greenhouse 6mil film, all double layer to slow down heat loss at night.

Perimeter footing and underneath floor are insulated to retain direct solar gain and radiant heat floor. To add thermal mass, 24 cuyd clean fill was added above grade to floor area. Tubing for hydronic radiant floor (the white PEX) was added into the same thermal mass.

January 2018 - 20 cubic yards of compost loaded into our "compost bunker". Recipe is based on blend of fresh wood chips from local arborist and spent grain from local brewery. All free, by the way. The tricky part is getting the optimal ratio of chips to grain. Considerations include, carbon to nitrogen ratio, pile density (to allow it to breath and conduct heat), moisture and potential for generating unwanted odors that will ..... ummmmmm.... displease neighbors.....

Once materials are all delivered, it takes two men, two days to load the bunker.

January 2018 - Compost Heat Source for Greenhouse Radiant Heat Floor -

blue PEX tubing buried in compost to absorb heat

Simple recirculation pump powers

closed loop hydronic system: through compost pile then to radiant floor and then back to pile. To optimize heat exchange, we found this cool little variable speed Taco pump ($200) that includes sensors for measuring temperature of Supply (S) and Return (R) water. The difference between the S and R water governs the pump speed (aka, flow rate).

Fast-forward to early Spring 2018.

The bare deciduous trees let in lots of sunlight.

Seasonal adaptations.

From struggling to retain heat in Winter, to struggling to release heat in Summer !

About 1/3 of floor space (120 sqft) was opened up in form of vents. About 40% of roof was covered in 40% opaque shade cloth.

On hottest days, wetting the floor during hottest part of the day (2pm) made about a 4-5 F difference to help cool things off !

Donated paving stone added a nice touch. This is just temporary: we now have to set them in sand/soil to make it permanent.

Notice shade from trees. After about 3pm, Summer sun is blocked by trees. While we knew that this was an ultimate constraint for this Greenhouse's location, we really got a chance to feel how it effects plant growing conditions. In turn, this will really drive future crop choices....

OK: now to Food Safety !!

Cement Board for floor, all graded towards drain.

SS Sink for washing up to sanitize.

Two more - separate - sinks needed for hands and washing produce for post-harvest handling.

Experimental kale and cress grown in larger, deeper containers.