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@Larry Weingarten : "Yup, 80%! If you could get anywhere near that number, any flavor of solar works and is easier to accomplish."

I agree very much with the general sentiment. I'll add that a well-insulated house is just more pleasant: more comfortable, quieter and less dusty. I like to say that an ounce of insulation is worth a pound of hydronics when it comes to comfort.

But I have to disagree with the statement that "any flavor of solar works." There are lots and lots of failed attempts at passive solar and heat storage out there, what Joe Lstiburek calls "mass and glass." Sometimes they work, a lot of times they don't, and when they do work it's mostly because of the conditions at the site, particularly the climate.

Installing one of these systems isn't like putting a deck on a house, where you just have to follow some basic guidelines and it's going to work, and the design involves mostly deciding whether you like deep and narrow better than wide and shallow, or whether a square works best for how you see yourself using it. I'd say it's more like building a hydro-electric generator on your property. Before you even begin, you have to ask, do you have water flow? How much? And how much does it drop? And do you have the right to build on it? Because if you don't have those things, there's no way to make up for the lack.

This is what's behind the questions I asked three posts ago. Without knowing specifics of the energy use in this house, in this climate, it's impossible to do any of the calculations that would tell if some sort of heat storage would make sense at all.

Fair enough. Have you calculated your current heating loads? Either through modeling or the process outlined in this article?

https://www.greenbuildingadvisor.com/article/replacing-a-furnace-or-boiler

Do you know your heating and cooling design temperatures, and heating and cooling degree-days?

Have you looked up average monthly insolation for your location?

Without that information you can't even begin to look at a design.

Hi All, I'm probably about to sound silly, but please bear with me. My experience is the most cost effective things you can do to make any heating/cooling system perform is to have a superior shell, so the loads remain small. It's hard, but possible to reduce the loads by 80% with good design, air sealing and insulation. Yup, 80%! If you could get anywhere near that number, any flavor of solar works and is easier to accomplish.

My climate is predominantly heating, but by reducing South and West facing glass, and thinking about low-E glass appropriate for each orientation, I've minimized the problem of overheating. A reason I like to use water as my thermal mass is it can be moved around, but importantly, I don't want to live inside of a solar collector with its temperature swings. I live in a low-mass house.

I have played with a variation of solar cooling, but never completed it because the house works without. The cooling was to have unglazed solar collectors placed higher than a well-insulated storage tank, and filled with an antifreeze mixture. The tank is placed just above the living space and tied into finned tube baseboard elements. Both fluid flows are driven by convection. Thermostatic control for the finned elements is given by a wax filled piston operator, driving a ball valve. It's the same system I use for controlling a gravity driven heating system that I did build, and it works. During the day, the collectors get sorta hot, but do nothing. On a clear night, they radiate heat and convection moves the resulting coolth into the tank.

I got ridiculed when I started to build my place 25 years ago because I used SIP panels, which people didn't seem to understand, and because I used 8" walls, 10" floors, and 12" roof. They told me I was nuts to be that well insulated. I was building for the life of the structure, not current energy prices. Anyway, it doesn't seem so crazy now, and my energy use per square foot is 10% of normal. Hope some of the above is useful.

Yours, Larry