Hello, New to the forum. Excellent resource for ICF construction (which I love). My question relates to solar heat gain. I'm planning to build my first home and I want to come as close to net zero with it as I can, which may end up being an unrealistic goal however I would really like to explore it to its fullest. I digress. I'm having trouble finding resources that relate to designing around passive solar, principles of heating with it and cooling with it, etc. I originally got hooked when I watched 20 minutes of a show on PBS that mentioned a home that was designed with a prowl front that included an enormous overhang that enabled the home to be heated almost entirely by the sun in the Utah winters. Does anyone have any links to any articles that they could share with me? Thank you in advance, Ryan.

Are you open to books?

http://www.amazon.com/Passive-Solar-Energy-Book-Greenhouse/dp/0878572376/ref=sr_1_5?s=books&ie=UTF8&qid=1439959914&sr=1-5&keywords=passive+solar+house
is really good at describing the technology and calculations

http://www.amazon.com/gp/product/B005OCTJ24?psc=1&redirect=true&ref_=oh_aui_d_detailpage_o07_
is a good read on the overview of techniques.

Passive solar isn't new, and I haven't seen a good resource on how it combines with a lot of your new construction tech, LEED, passive etc, but reading about the two separately ought to lead to a pretty good understanding.

I think that living inside a thermal storage battery is an inherently limited idea. The storage capacity is limited because because the temperature range that people prefer is so limited. And by the fact that the solar heat has to be moved into the passive storage over such a short time period (eg, moving 18 hours of heat into a slab over a 6 hour period - without excessively heating the surrounding air).

Consider adding some PV solar to run a heat pump to move passive solar gain into a large water storage tank. That can be as hot as you want (more btu storage) and is easily controlled (no discomfort). Or just insulate so well that heating/cooling costs aren't an issue.

Net Zero Homes are becoming common, but "passive solar" has inherent flaws (overheating/cooling) which prevented them from becoming common years ago. Your best route is to follow Passive House principles - complete thermal envelope, added insulation, minimize thermal bridging, good triple glazed windows and make the house air tight - less than 1ACH50. All of this is not difficult as long as you pay attention, and if you can stay within the recommended glass limits the house can be comfortable all the time, easy to heat & easily get to net zero. Check out green building advisor.com for lots of suggestions, methods & answers.

I agree. A "thermal Storage Battery" is a good idea, living inside it however, not so much as it takes real carefull design to keep it from over or under performing. PV to Heatpump(havn't looked too much into specifics of that, but it sounds interesting) or even Direct solar hot water into a super-insulated storage tank to be retrieved as dwelling comfort dictates in your VERY well insulated and sealed house sounds like a better option... The cool thing about hot water as a storage medium, is that there are all sorts of ways to make it hot: Direct and hybrid(heat pump) commercial electric, Direct solar, Direct and hybrid Solar electric, Gas, Biomass, waste oil...

Who knows, perhaps in the future, any home without a large water tank will be considered odd - "where do you store thermal energy?". Offpeak rates, wind, solar, wood and air source heat pumps (they are more efficient when it's warm/cool out) should make storage more popular. And water + large radiators is most compatible with low grade heat/cool.

Wow, you guys obviously have not been associated with a properly designed solar home. There are lots of examples of poorly designed solar homes as well as crummy standard homes. The fact is that most homes built fall on this side of the spectrum. Poorly designed, engineered, and executed anything is a fools folly.

This in general means designing a solar home without an understanding of thermal mass, the micro-climate, solar absorption, phase change materials, glazing, shading, thermal solar collection and storage, Solar PV, home siting, flora, seasonal variation, climatic averaging, deep earth temperatures, drainage, etc. etc. is a fools errand.

More is involved in the proper execution of a zero energy passive solar heated and cooled, zero energy home, than a standard home.

That said a properly executed zero energy, passive, solar heated, cooled and dehumidified home makes the occupant healthier, wealthier, more comfortable, as well as sustainable while doing the right thing for the owner and the world. There are no down sides to building them correctly and responsibly. You need to invest in design, engineering, education, and planning with an emphasis on simplicity, comfort, sustainability, life style, and life cycle costs through out.

Built right they are never uncomfortable.

Brian

There are always downsides to every design. But If you know of a "properly executed" passive solar home with WEL (web energy logger) online data, I'm interested.

A solar thermal heated, super insulated stratified drain back water tank system is not that difficult to build and work well. The controls are about as complicated as a good radiant in floor with boiler system. Sized correctly they can provide all the culinary and space heating needs for a home in most areas.

They do take the space of a mechanical room in the envelope. They can be made more efficient with phase change materials. They use the energy produced by a single 300 watt solar panel to provide all the thermal energy needed for the entire home. Again matched with a properly designed home and done right this is a no brainer on payback and sustainability fronts.

Brian

We design, build and install them in our projects. An extreme example is one built by Thorston Klupp in Fairbanks Alaska near the artic circle. There are several talks on line that you can watch in reference to the Passive House homes he is building near the artic circle which use such tanks.

https://www.youtube.com/watch?v=AtHkvpRI6fc
https://www.youtube.com/watch?v=A8ILSHA1_ro

He also works with the Cold Cliamate Housing Reasearch Center in Fairbanks. (CCRC)

His climate is extreme, -50 degrees F in the winter with no usable sun for several months in the winter. There they need to have a wood backup for the middle of winter and thermal shutters on the big windows.

In any climate that is slightly less extreme the backup and shutters are not needed.

Brian

Alas one of the cautions of using this site is to tune out people eager to tell you what you can't do. My house wouldn't exist if I'd heeded the consensus opinion here, and it turned out far better than I had hoped. Go here for help with passive solar: http://builditsolar.com/Projects/SolarHomes/solarhomes.htm

Thermal mass keeps passive homes from overheating. I erred on the side of caution and have yet to overheat in three years of residency. My backup is radiant heat in a concrete slab run by thermostat -- another CAN'T BE DONE on Green Building Talk that works just fine in south central PA. Anyone who has not asked you where you are building is just exercising biases. Orienting your home properly is free and can make a huge difference.

That isn't to say passive solar is all sunshine and roses. No energy strategy is. My house gets too cold with the minsplit set on dehumidify. So, yes, jonr, we have to turn it off after five hours or so or put on a sweatshirt. UCLA's Climate Consultant crunches climate data from the weather station nearest to you building site and ranks energy strategies by how many hours per year of comfort it should provide. You'll find it here: http://www.energy-design-tools.aud.ucla.edu/ Gotta say I ignored this advice as well, but it gives you an idea of the struggle ahead.

No one ever said "Can't"... I know I was just expressing why I don't think passive solar as a primary is necessarilly the best way to go. IE: As a primary, it is typically not as flexible as the environment it typically encounters. You may wind up making a lot of compromises in the design(no hardwood or carpet, need polished concrete to catch and store that heat) to incorporate these features that ultimately prove ineffective or overheat the house.

I think there are a lot of examples of poorly designed passive solar homes because it is so easy to get it wrong. And of course once it is committed to mass it can then be hard to fix. It then needs backups and augmentations and added controls(thermal shutters wood backup ect) to cope and maintain a compromised comfort level. It can ultimately morph into something as complex(if not more) and non-passive than a more conventional design/heating scheme.

As a primary, it also typically calls for very large windows. Windows, even really expensive ones = large thermal holes in the walls that are potentially(depending on climate) loosing energy for most of any given 24 hour period... It is fairly easy to catch solar energy without putting large thin spots in your insulated envelope. Large windows can really make a space appealing though...

Now passive aspects as a secondary to augment an installd primary system that can deal with all conditions including passive gains, can make sense as long as those passive elements remain passive and do not have to be unduly compensated for.

So, You CAN design and build any which way you want(within the limits of your local building department), but myself personally I like stability in my living space...

As always my .02

Posted By ronmar on 22 Aug 2015 05:59 PM
  You may wind up making a lot of compromises in the design(no hardwood or carpet, need polished concrete to catch and store that heat) to incorporate these features that ultimately prove ineffective or overheat the house.

  it also typically calls for very large windows. Windows, even really expensive ones

Not sure where you get that info from?

Windows need only to be 7-12% of the sq footage, so 1000' home needs 70-120 sq ft of south glass they need not be any particular size just total that amount.

Gentlemen, I didn't see anyone had replied, I thought I had subscribed to the post to let me know when people had replied so I never ended up checking back to see what was being said.

A lot of great information shared and I take everything with a grain of salt. It's amazing how vastly different everyone's opinions can be!

I'm looking into buying those books next paycheck to add to my library. There so much that can be learned out there its difficult to pass up a good resource.

Thanks for all the replies. There's so much to think about when making a larger upfront investment for the long term payoff.

Thanks again!

Ryan.

Posted By gosolar on 22 Aug 2015 06:34 PM

Posted By ronmar on 22 Aug 2015 05:59 PM
  You may wind up making a lot of compromises in the design(no hardwood or carpet, need polished concrete to catch and store that heat) to incorporate these features that ultimately prove ineffective or overheat the house.

  it also typically calls for very large windows. Windows, even really expensive ones

Not sure where you get that info from?

Windows need only to be 7-12% of the sq footage, so 1000' home needs 70-120 sq ft of south glass they need not be any particular size just total that amount.

Last I recall anything between the sunlight and the storage mass being heated is called insulation:) Window size like overhang is one of those things that can be over or under designed. Too much and you get overheat, then you have to add and control blinds and shades to compensate, all of a sudden not so passive anymore.

Posted By ronmar on 22 Aug 2015 10:50 PM
 Window size like overhang is one of those things that can be over or under designed. Too much and you get overheat, then you have to add and control blinds and shades to compensate, all of a sudden not so passive anymore.

I don't agree, not sure you researched solar all that much based on your posts herein.

If it was over or under designed then you're referring to a incompetent designer, these things are really cut and dry today.

Overhangs today are very simple to design there are online apps that can do it.
Or what I did was hire a pro for 1 hour of his time to double check my calcs and adjust perfect as needed.

When the models are run they are spot on, no guess work

Thing is, Ronmar, there are many places in the mountain west where passive solar/high mass can do most of the work. At a minimum, you should get some specifics first. My house cost less than std practice in this area, mostly because slab on grade is cheaper than a basement (at a substantial cost in storage space.) Yes, the windows dominated my design, but I was heeding Frank Lloyd Wright's admonishment that good architecture invites the outside in. Granted it is more difficult today to find sites where there aren't people outside looking in.

One more caveat, rpm. You may not be able to pass the energy code with aggressive glass. Again, this depends on where you are. Some states allow alternative permit paths. And BIs in states where passive solar is common often acknowledge the inanity. Still worth checking before you get too deep in the homework.

When the models are run they are spot on, no guess work

As long as they don't try to predict the temperature or the amount of sun on any specific day in the future. That is guess work.

Todd. Passive solar does most of the work, what does the rest? Just curious what works for you and how your home is put together, like how much mass, what kind of insulation, what kind of floors...

Yes, Gosolar, it is the result of design errors, but that seems to be more prevelant than less in my experience, because IMO, it is more difficult to get it right. Since the OP was asking about design information and not designers, I get the impression he wants to design and build it himself? In the interest of full disclosure, there is more potential risk, or more expense paying for it to be properly engineered...

Todd brought up an excellent point, RPM, if you are looking at doing this yourself, goto your local building department and get a building permit application package. It will have all the permit requirements including any energy efficiency requirements. For instance the state of washington has an online energy calculation that you must complete and print out to be included with your permit application. It has you fill in all your wall floor and ceiling areas and insulation values. It also has you lay out all your window areas and their U factors to gauge heat plant requirements and overall energy efficiency. You need certain numbers as a result to meet their energy standards...

Jonr asked a very good question a while back in this thread about a proper passive design with an energy logger. I wonder in the overall picture of energy consumption if the savings are all that great compared to say a very well insulated conventional design with a drainback solar system feeding a large insulated thermal storage tank in the basement or buried under the slab? When you factor in the possible inconsistencies created by living inside the solar collector, and the compromises to allow the most efficient energy collection, I am not convinced it is the best way to build a place to live.

But to each his own...

Well, ronmar, I live in Pa so passive solar doesn't do most of the work for me. Instead, I have a little of everything in the European multifuel style: a 2-ton minisplit heat pump, solar hot water, a British indoor wood stove boiler and a 200-gallon storage tank heated by solar and the stove. Because things here come down to firewood in the crunch, Jonr shouldn't wait for me to install a WEL monitor. Last time I checked, the cost came down to about a year's worth of utility bills.

Remember how location is everything? I'm living in a forest with two chain saws. GBT pros told me that sloth would ruin my plans to heat with wood. I set out to minimize my use of wood and I did. I usually make one flat-out fire per day regardless of ambient temperature. Passive solar is the reason. Lapse conditions on the coldest days mean the sun is shining brightly. Clouds are the problem in the east, but that means ambient temps are moderate.

Why not increase storage and active solar? Stupid question. By the time you have an array that meets Jan demand, you'll have a monumental heat dump problem in August and capital costs that won't be amortized in your life time. Active solar shortens my stove duties by a month or so in spring and fall but its btu contribution pales in comparison to passive solar in the depth of winter. Even in a marginal climate.

In a good climate like Utah, you'd be silly to ignore it.