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?
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?
3) why not tell us about the technology rather then give us a bunch of promises? how does it work?
A quick wiki copy and paste:
In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design or climatic design because, unlike active solar heating systems, it does not involve the use of mechanical and electrical devices.[1]
The key to designing a passive solar building is to best take advantage of the local climate. Elements to be considered include window placement and glazing type, thermal insulation, thermal mass, and shading.[2] Passive solar design techniques can be applied most easily to new buildings, but existing buildings can be adapted or “retrofitted”.
People have built passive solar homes successfully in less than ideal climates. There is still solar heat gain even on overcast days. Heat loss through a lot of glazing in a very frigid climate is mitigated by decorative insulated panels placed over much of that glazing.
How you go about it will vary depending upon your climate, that is only logical. The high ceilings and large shade trees of the subtropical south that are so good for passive cooling would be miserable in the climate you describe.
If heating is your primary concern, having an earth berm for greater insulation makes sense. Taking full advantage of a southern exposure for maximum sun exposure makes sense. Triple pane glazing facing that southern exposure with dark stone or tile flooring to absorb the solar heat gain makes sense. Lower ceilings to keep the heat closer to occupants rather than rising well above their heads makes sense. Radiant heat circulated under the floor whether it’s plumbed in circulating heated water from a boiler or electrical makes sense. Planting a fairly dense row of deciduous trees to block the sun in warmer weather makes sense.
This is passive solar. All it takes is a little forethought and ingenuity to adapt your dwelling to local conditions to minimize undesirable heat loss or heat gain. What is sort of dumb is building the same house all over the place, willy-nilly with no regard for exposure to the sun. That makes some houses hot and miserable with excessive cooling costs. It also makes some houses cold and expensive to heat.
That’s all passive solar is, paying attention to local conditions and idealizing the structure to take advantage of what exists locally for comfort and economy. It’s different in different locales.
Answer: Freeze.
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?
Answer: Roast.
3) why not tell us about the technology rather then give us a bunch of promises? how does it work?
Answer: because that's the way Enviro-nut social policy works. How it works -- indeed, whether it works -- is besides the point. You can feel good about yourself while you are freezing or roasting because you are "doing something" about the environment.
It’s cheaper to cool a home than to heat it.
Here’s what I did......
My house if more-or-less square. What that means is for the same amount of living space (~3400 sq ft), my house has less exterior wall than a comparable “golden rectangle” home.
My house also faces to the south—where the highest proportion of windows on an exterior wall is on most homes.
I live in NC and while we don’t have the brutal winters experienced in the northeast, the fact that my home faces south means I can take advantage of the sun while it’s in the southern hemisphere during the winter. During the summer the sun simply beats down on an asphalt shingle roof. The thicker insulation in the attic means my house keeps that warmth out of the living space. (as with most others)
During the winter the southern sun (when it’s out) means my heat rarely runs during the day.
We had a passive solar super insulated home built in 1984 and still live in it. BUT we are in Michigan, not a great state for sunshine. We have some heat gain but depend on a woodstove which can heat the whole house both floors with just 9 or so logs a night. LP gas furnace for the rest of the time. The super insulation was our best move back then. It has saved us a bundle.
1. Switch to traditional forms of energy.
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.
One of the main things you do is the length of your overhangs. This way in the summer and the sun is high the overhangs block the sun coming into the windows. Then in the winter when the sun is lower the sun comes more directly into the window.
Planting deciduous trees(trees with leaves) on the south side of your house helps too. They shade your house in the summer and when the leaves drop in the fall they let the sun come through.
Another method is to create heat sink. This would be an area/space/room on the south side of the house with all windows and some kind of masonry floor. It should have doors to close it off if it gets too hot or cold. The walls should also be made out some dark colored masonry product. I have also seen people put large dark colored barrels filled with water. The idea behind this is to absorb the heat from the sun during the day and then let it flow via natural convection(heat rises)to warm the surrounding rooms. Greenhouses work the same way.
None of these things will keep your house 70 degrees on a January day when it is 20 out and snowing. However, they will help when its 45 and sunny. The most important thing for heating or cooling is you have a well sealed and insulated house. If you have single pane windows, doors with cracks around them and 3” of insulation in your attic, your waisting your time.
This is an *awesome* website. No envirofreaks, just tinkerers experimenting with different concepts and configurations and often measuring and posting their temperature data.
That site is what solar is meant to be. If you can’t find some great tips there for your home I’ll be shocked.
This is not some new-fangled tech some greenie-weeines made up. House designers have used these techniques for hundreds of years. They just fell out of fashion with on demand forced-air HVAC systems becoming cheap and efficient.
I read an article about a passive solar, earth berm house in NH - owners went away in dead of winter for two weeks and when they came back it was still 50 deg inside.
Passive solar design also takes into account summer heat gain - different solar angle, shaded windows, insulated roof, light colored roof.
I always figured the best use of solar panels was to run the AC in summer heatwaves.
There's really no "technology" or moving parts involved - that's why it's called "passive". No solar panels, no electricity, no water pipes. It is not meant to replace artificial means of heating and cooling - it supplements them.
It involves three important concepts that are really just common sense: the changing angle of the sun with the seasons; orientation of house and features (especially closets and other 'dead air' and windows); solar gain/ storage mass.
Here are the keys to making it work:
1. siting the house so that the long axis faces south or slightly east of south. If possible, the south side should be longer than the north. Our house was a symmetrical trapezoid.
2. minimizing glass on all sides but the south side, and placing 'dead air' like closets, hallways, etc. on the north.
3. design roof overhangs to shade the interior in the summer but allow light into the home in the winter(there's actually a calculation based on latitude). The equinox is the normal crossover point, but you can vary that depending on your local climate. In the South, we opted to have light enter the interior for a shorter period during the year.
4. build a "solar mass" (we poured a huge concrete cube that formed the dining room/ solarium floor) that will absorb heat during the day and radiate it at night
5. insulate like MAD - we framed up with 2x8s and 10s instead of 4s or 6s, and had additional R-MAX outside the studs as well. Roof was super-insulated, and ice dams are not a consideration here.
We had a conventional HVAC system, but it ran very little. Our total cooling costs for the hottest month in Georgia (the main consideration) hovered around $100 in the 1980s. We also had a manufactured fireplace and a whole-house ventilation fan that would pull the stripes off a pussycat.
So . . . in answer to your questions:
1. you let the furnace or the fireplace run a little more.
2. superinsulated roof helps a lot, shade helps a lot, you run the A/C a bit more but you don't need much.
3. there isn't any technology. That's the beauty of it.
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.
I would do several of the suggestions by Freepers on this list before I installed a Geothermal system. The return on investment is just too long. As stated by several others, many of the passive solar designs can easily be incorporated into new construction without any added major costs.
The most important thing is insulation. Energy costs will continue to rise. Therefore, limiting the energy it takes to heat and cool your house will always be your best ROI.
I built a center chimney cape in 1989 in southern NH. I used the best low E glass window that Anderson made. I framed it with 2x6 walls, Tvyec wrap, and R 40(12” bonded cellulose) in the ceiling. I had a small Jotul woodstove in the center of the house up against the stairway to the second floor. I did not have big overhangs because capes do not have those. However, in the summer I would open the windows at night , close the shades on the south side of the house during the day and when I came home after work the house was still 72 degrees. In the winter I could heat the house with that small woodstove.
Since then I have owned two houses that were built in the early 70s. On both of them, I insulated, changed exterior doors, caulked, etc. They will never be as good as the house I built in ‘89. I just installed a Harman pellet insert. Heating oil here is now $3.49/gal. It costs about $3500 now to heat my house in the winter. I figure it will take about 3 years to pay off the pellet stove. I am in the process of replacing all the exterior doors. Replacing the windows is too expensive.
Lots of other good answers; but I feel compelled to throw my depreciated $0.02 in.
The real point of passive is to take a realistic look at what the outer limits are, and design the house accordingly. Most homes are _not_ designed this way, and throw in a costly HVAC system to compensate for not spending the same cost (or much less) on doing it right from the beginning.
First off, realize that sufficient insulation will mitigate most HVAC needs outright. Thicker walls with better insulation will stabilize indoor temps; an earth-berm home with feet of dirt on 5 sides and a sensible front will stay around 50 degrees. A more normal home design can still reduce temperature standard deviations and change rate by just putting in better/thicker insulation during build.
Once you’ve got the standard deviations and “extreme temps for weeks in a row” covered to your satisfaction (say, 1 degree per day internal temp change for 2 standard deviations extreme outdoor temps), then of course you’ll have to include active HVAC. But since you’ve already covered nearly all conditions with passive systems, the active systems have to address a far smaller range & load: one carefully-chosen decorative wood stove/fireplace solves the “outside temps below zero”, and one modest AC unit solves the “outside temps in the high ‘90s” - with each only having to supply HVAC for a much smaller range of rare conditions outside the range of passive systems.
The technology is very well understood for decades (centuries? millennia?). Short answer is: run the numbers on insulation, wall exposure (size & orientation vs solar impact), air circulation, thermal mass, and expected temperature fluctuations. A double-walled exterior with good circulation, thick insulation, and latitude-appropriate southern wall arrangement will go a LONG way to cutting HVAC costs close to nil.
Random example: George W Bush’s ranch home in Texas is largely a “passive” design, requiring very little HVAC costs (for 4000 sq ft!) despite fairly extreme conditions.