[Greenbuilding] Trombe walls are extremely inefficient solarcollectors

[Nick Pine]

"Larry Kinney" <larry_kinney at comcast.net> wrote:

 >... I've been working on insulating shutters for a long time and am 
getting close to solving the myriad problems of snow, ice, air leakage, 
and ensuring good R-values of shutters that open and close automatically 
to optimize energy performance year around.

Good work. What do we do when the lower track on page 19 of your slide 
show at www.SynergisticBT.com fills with bird poop or leaves or ice? 
Wait for spring? :-) Maybe just lean out of the window and brush off the 
track...

IIRC, there's a solar heated homeless shelter in Washington state with 
insulating garage doors, closer to R6 than R15. Then again, they 
automatically roll up out of the way to allow glazing the entire south 
wall of the shelter, with no requirement for sideways space between 
glazings to allow shutters to open.

> I am no particular fan of trombe walls

Storing heat from hot sunspace air requires lots of thermal mass surface 
inside a house. Good shutters would allow sun to shine directly on mass, 
with easier heat storage in less surface (altho we can't see through a 
Trombe wall), but it's still fairly low-temp heat storage, with no way 
to control the heat release, eg to turn off the heat at night or on a 
warm day.

A passive air heater with a vertical duct indoors to avoid mixing 
ceiling and room air can heat shiny ceiling mass (eg shallow trays with 
3" of 120 F water in greenhouse poly film air ducts with radiant barrier 
sheathing beneath) with less collection efficiency and more storage 
efficiency and excellent room temp control using a low-speed ceiling fan 
and a room temp thermostat, in a variation of the Barra system.

>(I prefer smart mass, like water that one can move around  between 
>simple collectors, insulated tanks, and radiant surfaces as a function 
>of need...

We might heat water to 140 F in a 4'x8'x3'-tall plywood tank with a $50 
10'x14' folded EPDM liner and a 0.5% ACI-100 non-toxic (mainly sodium 
silicate) corrosion inhibitor solution from D.W. Davies, using a $35 
1000 Btu/h-F car radiator with its 36 watt electric fans in a sunspace 
or air heater. With 2 foamboard dampers with $10 windshield wiper 
motors, we can avoid a radiant floor and use the same radiator to heat 
the room with the tank water, and we can put a $60 1"x300' 13 gallon 
plastic pipe coil in the tank to heat water for showers. (Wow, what a 
run-on sentence. Ever read Victor Hugo inside all those pretty French 
shutters?)

Nick