Winter Project – Solar Heat (?) for Scrounging BTUs

In a perfect world, 1) all the bents of the barn would be equally spaced, and 2) if #1 is not the case then the larger of the side bents, the one where my shop resides, would be on the south side of the building.  Alas, such is not the case.  When the barn was assembled and erected, what I got was what I got.  My shop is on the north side of the barn, and in the winter vis-a-vie the sun nary the twain shall meet except for perhaps three hours after dawn (east-ish wall) and four hours before dusk (west-ish wall).  As for the smaller space in the south side of the barn, the one ostensibly dedicated for a classroom, the solar/thermal gain is immense with full wall exposure to sunlight and a complete row of clerestory windows all the way around.  Given enough motivation I could probably move my shop there, but it is a smaller space and the heating stove is underneath the current shop, the classroom is entirely uninsulated…  I just had not experienced the alpine winters (near-zero lows are common) before setting up shop or things might be different.  Sigh.

Between my propane wall furnace keeping the overnight shop temps in the upper 30s for about $2/night (no real desire to heat more aggressively with it through the day as delivered propane is topping $5/gallon!), my kerosene heater (frankly astonishingly effective; I am pretty certain I could heat my shop with it alone for about $5/day, but that open flame thing…) and my wood/coal stove in the basement under the shop I can keep the temps congenial 99% of the time.  Nevertheless, my ongoing hunt for BTUs remains, well, ongoing.  The other day when it was single digits with a stiff breeze outside it was a challenge despite 3″ XPS insulation in the walls and ceiling, new tighter doors, and a relentless hunt for crevices to caulk.

Many years ago my friend Tred told me of a set-up whereby direct solar heat could be harvested and introduced into the interior space via a ducted “greenhouse” panel.  This video shows the concept.  My plan is to modify that construction to build and install a couple of solar thermal collectors, one on the northeast corner of the barn (near the vise end of my Roubo bench) and the other on the wall nearest my Waxerie at the other end of the shop.  For the former I expect I can harvest BTUs two or three hours each morning, and the latter perhaps four hours each mid-day and afternoon.  Any BTUs I can garner without ongoing effort is a winner to me.  A few years ago I made a solar oven to melt beeswax and it wound up melting the case for the digital thermometer (!), so I am optimistic that these units can be useful.

I think I just might start this project later today.  I’ll check to see if I have all the materials on hand that I need.