Posted on 09/25/2014 11:16:29 AM PDT by Prophet2520
Fairly expensive, does the system have a series of pipes wending through underground troughs or is it using a well? Return on investment can be fairly lengthy, over a decade, but heating and cooling from a constant 56 degrees does reduce load considerably.
Lots of south facing glass and lots of mass inside glass to retain the heat produced. Super insulation or house built into hill side on north. Save $$.
I thought years a good design was a thick north wall of sand bags covered in adobe on both side that sun hit through south facing glass would be very efficient and inexpensive to build.
Can you think of anything in the world more conservative than designing buildings to be well-suited to their climate, thus "conserving" energy and money?
Instead of being so stupid as to build a home that is utterly dependent on fragile infrastructure?
1) what do you do in the dead of winter when the sky is overcast for several weeks in a row, and outside temps below zero?
Build a fire in the woodstove?
Proper passive solar design minimizes solar heat gain in the summer, while maximizing it in the winter.
How this is accomplished depends utterly on the climate and location. There are lots of locations where roasting in the summer is just not an issue.
3) why not tell us about the technology rather then give us a bunch of promises? how does it work?
Well, mostly I was hoping interested parties might actually do some research on their own rather than my writing a book. Many have already been written.
1) what do you do in the dead of winter when the sky is overcast for several weeks in a row, and outside temps below zero?
I don’t know where you live, but several weeks in a row is unheard of in the United States. Several days in a rows when a big storm system moves through, but that is about it 99.9% of the time. More on that later though.
2) what do you do in the dead of summer when you have the hot sun beating down on you all day, our side temps in the high 90’s?
That is the easiest question of all. In the summer for most of the US, the sun rises to a much higher angle in the sky. A small roof overhang that will easily let winter sun in, will block summer sun. Passive solar can also be used to INCREASE natural ventilation. an over the top example is here http://ottp.fme.vutbr.cz/laboratore/e-komin.php, or search solar chimney venitlation under images for some simple drawings.
A. Earth sheltering: It is not required but is the most efficient, cost effective strategy for controlling temperature swings. Google it. There are a zillion ways to do it from really simple to really elaborate. A walkout basement on the south side with the north side in the ground and most or all of the East and West sides in the ground is a simple example that add no cost to the building. A little bit of rigid insulation placed properly in the ground significantly increases performance.
B. Cost. There are plenty of Governemnt studies, and the consensus is that passive solar adds 0-2% to the construction budget. The three solar houses I built, added 0% to the budget. Due to other sensible techniques it was actually well under budget of homes in the area for $/sq ft.
C. Insulation - A highly insulated building costs a little more but will absolutely save the money, especially when combined with active solar. Smoggy Wallasey England had a school built in 1961 at the latitude of approximately Southern Alaska. They only get a VERY low 1500 hours of sun per year. Yet this well insulated passive solar school removed their heating system after decades of never using it. So that answers your question about overcast. In decades it was never overcast enough to need an additional heat source. BTW, they never even asked for passive solar, the guy just built it that way in budget.
2/3 of the mortgage life, payback is what I would consider VERY expensive passive solar.
We have brutal Northeast winters, but with passive solar they did not seem brutal. On sunny days we would let the house heat up to whatever our toleration level was(usually about 90 degrees) then open some windows. We could have designed it to not heat so much or use curtains more but we liked the sunshine. When you are toasty warm and go outside and it is 15 degrees, the cold does not seem anywhere near as bad as when you are in a fossil fuel heated home trying to save money with the temperature at 68-70.
Battery bank, converters etc, are ACTIVE PV electric systems, NOT passive solar. They can be great to but the payback is long. You are essentially buying 10-20 years of energy in advance.
As mentioned in another reply, you can build it with ZERO extra costs if you want. I did three homes that way. But spending a little more on insulation and thermal mass will pay back in 1-3 years.
For the self sufficient type I would recommend a large aquaponic system instead. You get the thermal mass, you get vegetables, and you get fish. Win, win, win.
Passive solar is not a bad idea, but you will get better returns from using a high R-value insulation in walls, attic space and even basement walls. I would also use a reflective roof matting under shingles at least on west facing roofs. Energy efficient windows, doors and a high efficiency HVAC system should round out your construction.
No HVAC is needed if you spend approximately the equivalent amount in thermal mass and natural ventilation.
Yes, use high insulation, but that can be a health problem as well. Ensure you have good air handling. NASA has hsown that a normal leafy potted plant will purify a 10ftx10ft room. An aquaponics system would purify your whole house.
Of course energy efficient windows are a must, especially on the north side. South side be careful not to use ones that block the suns heat, as many do.
It is very inefficient to convert heat to electricity. It is really a different topic.
active geothermal heating systems are VERY efficient, but VERY expensive. A new construction well designed passive solar house should NEVER use one of those in my opinion. Even if you don’t want to spend a little more to never need a heating system, then for the little bit of supplemental heat you do need, a super cheap small system, or wood stove is ample.
“Planting a fairly dense row of deciduous trees to block the sun in warmer weather makes sense”
This is NOT recommended.
1. Deciduous trees have many branches that block sun all year round. A dense row is even worse. If you have existing adult trees at the construction site that may be of use, then trim all the lower branches that will block the winter sun, and leave only high branches that will block the summer sun.
2.Just be aware that large trees near houses are a common cause of death, injury, and property damage in storms from wind and or ice.
3. New plantings will take many, many years to get high enough to only block the summer sun, and meanwhile they will block winter sun.
I recommend landscaping that gradually slopes up in height on the southern side as it goes away from the building, such that no winter sun is ever blocked. A well designed permaculture garden landscape is of great benefit.
Using slightly extended roof overhangs, and one floor overhanging another is cheap and very effective.
“My dad claims that it never paid for itself but I skeptical. All of their hot water needs were covered “
NO, NO, NO. That is not passive solar. That is solar hot water. It is expensive. It is theoretically possible to make a completely passive solar hot water set up, but it is seldom done because the heat exchange is so poor.
There are do it yourself ways to do solar hot water which can be more cost effective, but they tend to be “red-neck” :-) or less professional.
“1. Switch to traditional forms of energy.”
That simply doesn’t apply to this threads main point, PASSIVE solar. No extra cost, just sensible house and window orientation.
“2. You have a lot more hot water. Longer showers, cleaner dishes, etc. :)
3. It can be expensive. Best to do an ROI analysis. It may never pay for itself.”
Again these apply to ACTIVE PV and solar hot water systems. Not passive solar. Yet both of these systems will normally pay for themselves. What a strict ROI does not tell you is all the other benefits like still having electricity and hot water when that ice or wind storm comes that takes out all your neighbors power. How do you put a price on that or self-sufficiency?
The sun is lower on the horizon in winter and higher in summer. Planting deciduous trees to shelter a southern exposure in summer is a time-honored way of managing sun exposure and solar heat gain. So, if you want to recommend against it you’re certainly free to do so, but it goes against a lot of accumulated experience and wisdom.
Just because a lot of people say something does not make it right. There have been a number of studies on this. http://carmelacanzonieri.com/library/6123/Heisler-IndividualTreesSolarRadiationSmallBuildings.pdf
This one for examples shows 40% shading by a maple in winter. That is VERY bad. My point is not to use trees, but to do so with awareness a good sense. Just willy nilly, “Oh trees lose their leaves in winter and shade in summer” so it make good sense to plant “dense rows” of them could lead to efficiency disaster. A dense row of maples could block 70% of your winter sun.
Two of the three passive solar homes I built used existing site trees for shade. The best was three trees only on the south side, close to the house. The lower 30-40 feet of these trees had no branches whatsoever. Even then however, it was noticeable when the shadow of the trunk rolled across, and it increases the risk of property damage.
So I wasn’t, and am not, trying to slam your recommendation, but rather to refine it with extra knowledge so that someone will not misapply it to their own demise. :-)
Whatever. You clearly have a vested interest in appearing expert, whereas I do not. So, have at it.
system is yet unplanned, so....i like the idea of the use for air conditioning as well.
thanx for the explanation. turns out i am already at least contemplating many of these concepts. house will be in north-eastern Maine
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