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The Zen of Passive Solar Heating Panel Design (2010)

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Re: The Zen of Passive Solar Heating Panel Design (2010)

#31

Post by cellularmitosis »

dboreham wrote: post #9

Very interesting. I live in a place where we have significant issues with ice build up on roof surfaces, gutters, etc. One way to deal with this is to electrically heat the roof and gutters. This of course is expensive (very!). So I had the ideal that one could use the available solar energy (it is reasonably sunny in winter here) to melt the ice. My idea is not to use PV panels and restive electrical heating but to…

You could also wait until it stops snowing and then throw a large piece of black fabric (think black woven nylon like a trampoline) over the snow.

Automating the black fabric deploy would be an interesting project :)

Re: The Zen of Passive Solar Heating Panel Design (2010)

#32

Post by GoToRO »

maxerickson wrote: post #16
themartorana wrote: post #14

Earlier quoted context omitted.

So what's stopping a setup like this becoming standard? It's obviously generally superior, at least for new construction that's well-insulated. Right?

They won't work very well when they don't have good southern exposure, they won't circulate a lot of heat if you have rooms and doors. Meanwhile, the direct operating costs for natural gas heat aren't all that high.

"good southern exposure".

In which case you can fit normal windows and achieve the same or better.

Re: The Zen of Passive Solar Heating Panel Design (2010)

#33

Post by redtexture »

GoToRO wrote: post #32
maxerickson wrote: post #16

Earlier quoted context omitted.

They won't work very well when they don't have good southern exposure, they won't circulate a lot of heat if you have rooms and doors. Meanwhile, the direct operating costs for natural gas heat aren't all that high.

"good southern exposure". In which case you can fit normal windows and achieve the same or better.

No, windows fail, as can be seen by reviewing the linked pages.

Windows are not the same:

- Windows do not passively aid circulation of warmed air, which the panels are particularly designed to do.

- Windows also do not passively reduce or eliminate overnight-losses of energy (heat) on a cold night (consider negative-centigrade temperature or less), which the linked-to design does do, by passively preventing circulation of air that would cool the building overnight

The design linked-to is specifically designed to passively deal with the prevention of the transfer of heat outside on a cold night, among other things, including limited cost, simple construction, and rapid payback over the life of the building in a cold winter environment. Windows fail as a passive solar source.

Diurnal intervention required for windows.

Re: The Zen of Passive Solar Heating Panel Design (2010)

#34

Post by redtexture »

Retric wrote: post #24
maxerickson wrote: post #16

Earlier quoted context omitted.

They won't work very well when they don't have good southern exposure, they won't circulate a lot of heat if you have rooms and doors. Meanwhile, the direct operating costs for natural gas heat aren't all that high.

Inserting something like this into the duct work of a normal heating or cooling system is fairly simple. The real issue is they increase construction costs and most buildings are built by people that don't use them. Further, they don't look like something out of a Norman Rockwell painting.

A problem of insertion into ductwork of a passive-design system component, is that when the heating system runs at night, it will cause air to pass through the panels, and thus cool the building at night in winter.

Since the solar panel-system is passive in design, insertion into ductwork would be a new design issue.

Re: The Zen of Passive Solar Heating Panel Design (2010)

#35

Post by redtexture »

pinko wrote: post #25
WalterBright wrote: post #21

Earlier quoted context omitted.

> How to ensure snow does not cover the panel/solar heat collector is also a potential problem. Mount the panels vertically.

Not always sufficient! http://c8.alamy.com/comp/D0DG83/stop-sign-covered-in-snow-du...

Not an insulated capture point. Backside of the example metal sign always cooled on backside by low temperature air.

Re: The Zen of Passive Solar Heating Panel Design (2010)

#36

Post by redtexture »

devenson wrote: post #29
gvb wrote: post #27

Earlier quoted context omitted.

Efficiency. The black box surface and vanes maximize the conversion of light into heat. The construction with the airflow traps and chimney effect maximize the transfer of the heat into the building while minimizing the heat transfer out of the building when the sun isn't shining. Windows are not nearly as efficient because the material behind the windows is not optimized to convert light into heat (see his section o…

You're right about the airflow traps preventing the heat transfer out at night. However, I think windows will trap the heat from incoming sunlight as well as the black vanes since a window allows the light to reach farther into the building and get absorbed by the floor (or opposite wall). Ultimately he wants the heat in the floor anyway, so it's best to get it there via radiation. Not much of it will be radiated bac…

The key difference between windows and the solar panels, as designed, is the passive design of the solar panels. No need to close curtains on these panels, as windows would require, for reduction of heat loss on winter nights.

The black vanes are cooled, during the day, by induced air flow, such heated airflow going into the building (passively), and results in heating the building, without further action. The panels are designed to prevent winter-night cooling via the panels. Thus you're missing the passive intent heating intent of the design: windows fail as a passive heat source, because of the need to actively insulate them in some fashion in the winter night.

Re: The Zen of Passive Solar Heating Panel Design (2010)

#38

Post by redtexture »

imaginenore wrote: post #23
rzzzt wrote: post #11

Earlier quoted context omitted.

Some people build these with painted beer can columns on the inside serving as air ducts, see this video for an example: https://youtu.be/nuxanLdtwZQ They also tend to install it on the side wall; it doesn't get that much sunshine in the summer, but it becomes more efficient in the winter when the Sun stays at lower angles. External circulation of air is still required and is usually done by using an electric fan.

Yeah, I'm fully aware of that design. I've seen tests of it against a much simple design with the sheet of fabric in the middle, and there's basically no difference. Cutting so many cans' tops and bottoms is actually not an easy task, I had tried.

A couple of pieces of plywood, for each window, and some foam strips for air-flow sealing would do. This is not a big effort, just more than your (exceedingly short-lived) cardboard design contemplates.

The gain in creature-comfort in the apartment, might be more than the money saved in avoided heating, as a renter of the apartment.

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