• Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education skip experiences global resources cider press projects digital market permies.com pie forums private forums all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • Anne Miller
  • Leigh Tate
  • jordan barton
  • Pearl Sutton
  • Nicole Alderman
stewards:
  • r ranson
  • paul wheaton
  • Greg Martin
master gardeners:
  • Carla Burke
  • John F Dean
  • Jay Angler
gardeners:
  • Nancy Reading
  • Mike Barkley
  • L. Johnson

The Solar Porch- Passive Solar Retrofit

 
pollinator
Posts: 388
Location: Northwest Missouri
131
forest garden fungi gear trees plumbing chicken cooking ungarbage
  • Likes 6
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
The solar porch acts on principles of passive solar thermosiphon to pull up cool air from my basement and deliver warm air into my main living space.  A convection loop with no moving parts (aside from the windows.)

Construction details:
Walls: I enclosed a 17x6 foot area of my south-facing front porch with 16mm R-2.5 triple-wall greenhouse panels. The tops of the panels insert into channel aluminum and are removable in the summer. Bottoms are held with screws and nylon washers. A Metal drip guard guides moisture off the decking.
Door: (not pictured) just a panel set in aluminum channel so that is slides.
Floor: Insulated with 1 inch R-6 rigid foam simply laid on the original decking and covered in 1/2 inch treated plywood, screwed down.
Ceiling: Added R-13 foil backed fiberglass insulation between the existing ceiling joists
Basement air box: a chute covering a basement window constructed with 3/4 treated plywood and insulated with spray foam, 1 inch rigid foam scraps, and foil bubble insulation.

Operation:
Activation: I simply wait until the temps reach around 70 degrees F in the porch, then open the basement window and the top of the main floor window. Upon opening the windows, the air flow starts almost immediately.
Temperatures: Porch temps typically stay around 90 degrees on a sunny day (even with sub freezing temps outside), rising to 104 if I don't open the house windows to capitalize on the heat.
Deactivation: The windows get closed at night at about the same temp of 70 degrees, or just when I get to it.
Main heat: The house thermostat (typical forced air electric heat) is set at 66. I have no way of measuring the heat generated. It just acts as a supplement to the furnace and the furnace runs less. I will be able to compare energy usage after a couple more months.

Other/future uses:
-Makes a great sun sauna and the diffused light through the panels feels great!
-After more time studying the temp swings, I'll decide how useful this is for plants. It does stay at least 10 degrees warmer than outside overnight.
-I'd love to automate the house windows but doubt I could do so aesthetically.
-Maybe a rocket heater could fit into this equation, but only if I can't talk my wife into letting me put one in the main living space :)
-I might add a thermostatically controlled shutter or automatic hydrolic greenhouse vent to dump heat in an emergency overheat situation.
-I completed this with the input from some of you fine Permie folks in other threads, thanks!
Solar-Porch.jpg
Exterior
Exterior
Porch-heater.jpg
Diagram
Diagram
Windows.jpg
Additional plywood and grate have since been added
Additional plywood and grate have since been added
Basement-window.jpg
Delivers basement air to porch
Delivers basement air to porch
Basement-window-interior.jpg
Held open by ratchet rope
Held open by ratchet rope
 
Posts: 1
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

Matt Todd wrote:The solar porch acts on principles of passive solar thermosiphon to pull up cool air from my basement and deliver warm air into my main living space.  A convection loop with no moving parts (aside from the windows.)



This looks great. I saw a video where Matt Walker was explaining that in a rocket mass heater, once the air left the barrel, it would behave like water but upside down.  In your design, the cold air from the basement fills up the lower part (like water) before pushing the warmer air in the window. I wonder if it would work even better if you only opened the top of the porch windows into the house.  

I am not sure if the porch would support it, but if you had some water barrels painted black they might keep the greenhouse warmer for plants in the night

 
pollinator
Posts: 2808
Location: Bendigo , Australia
204
dog gear plumbing earthworks bee building homestead
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
The photo of the ratchet for the rope is not clear, can it be improved please?
 
pollinator
Posts: 749
Location: Boston, Massachusetts
262
4
urban books building solar rocket stoves ungarbage
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

John C Daley wrote:The photo of the ratchet for the rope is not clear, can it be improved please?



The "rope ratchet" doesn't appear to be in this view, probably mounted to the floor/joist above. Visible is the slack end of the rope, and a carabiner clip clipped onto a sash lift handle.

The rope ratchet device, is some sort of cam or chock device that grips the rope (similar to how Venetian blinds operate) with a hook for mounting.
When pulled in one direction, the rope slips through, but is prevented from returning by the cam. It may be released by a redirection of the slack end? (sideways and out of the grip?) or by unloading the cam and moving it aside.

They come in various sizes, for paracord and for ropes.
 
Matt Todd
pollinator
Posts: 388
Location: Northwest Missouri
131
forest garden fungi gear trees plumbing chicken cooking ungarbage
  • Likes 1
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

Tk Gillman wrote:
I wonder if it would work even better if you only opened the top of the porch windows into the house.  
I am not sure if the porch would support it, but if you had some water barrels painted black they might keep the greenhouse warmer for plants in the night



Originally, I did only open the top of the window. Then one day I opened the bottom too so the cat could go enjoy the sunshine and I noticed it only increased the volume of air pushing in.  I figure, as long as the porch air is warmer than the house air it will push in, whether that's at bottom or top window height.  Wish I had more ways to quantify and measure besides just my strip of paper indicator.

I do intend to add water drums at some point, but want to get some extra support under the porch first. Luckily there's an old sidewalk under there which will make a good foundation for support.
 
Matt Todd
pollinator
Posts: 388
Location: Northwest Missouri
131
forest garden fungi gear trees plumbing chicken cooking ungarbage
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

John C Daley wrote:The photo of the ratchet for the rope is not clear, can it be improved please?



I'll let someone elses photo in better lighting show the concept. I love these things! Mine is a smaller version.
Entirely unnecessary here since a hook and nail would do just as well, but I had it on hand and my wife is short so this is easier since she's the one that has to open it every mid-morning while I'm at work  :)
Ratchet-Rope.jpg
[Thumbnail for Ratchet-Rope.jpg]
 
steward
Posts: 12170
Location: Northern WI (zone 4)
3388
3
hunting trees books food preservation solar woodworking
  • Likes 2
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
One way to make it automatic would be the sort of air flappers they use on homemade solar thermal air units (sometimes made from aluminum cans).  They use a very thin piece of plastic (garbage bag) that is draped over a piece of hardware cloth or other mesh.  That goes over the opening.  When the air flows in the direction you want (up into the sunroom), the flap opens and lets the air move.  When it gets cold and the air tries to reverse direction, the plastic is pressed against the mesh and blocks off the air flow.  Basically a check valve for air.

So you could put it on either window (likely the basement one) and just leave the other window open all the time.

Visual for the flapper (called a back draft damper in this link): https://www.builditsolar.com/Projects/SpaceHeating/VacationHome/PipeFreeze.htm
 
On top of spaghetti all covered in cheese, there was this tiny ad:
Work/Trade for the 2022 PDC, PTJ, and SKIP events
https://permies.com/t/166040/experiences/Work-Trade-PDC-PTJ-SKIP
reply
    Bookmark Topic Watch Topic
  • New Topic