SIP homes net zero?

I've been toying with the idea of designing a home using structured insulated panels(as well as solar passive) and I'd like to be able to make it a net zero energy home, I can't really find a lot of info on the internet about people who have been using these and have net zero homes, well I should say not too many numbers on them.

I'm curious what kind of heating source people are typically using and how much power it requires, it would be nice to run a ground source heat pump or maybe just a sub floor insulated hydronic floor system perhaps off a solar/wind setup but I can't quite figure out how much power these things draw.  I realize they probably draw quite a bit of power but seeing how the home is designed so well using SIP and solar passive I'm wondering how much heat/cooling would actually be required for such a home.  It would be in Iowa FYI, maybe 800 SQ FT and no basement, just a slab.

So I'm curious if anyone knows how well these work in the wild and what kind of systems people are using and what sort of results they have achieved with said setups.

Thanks

Here are some links to informative websites:

http://greenedmonton.ca/MillCreekNetZeroHome
http://www.greenbuildingadvisor.com/
http://www.builditsolar.com/
http://www.buildingscience.com/

Brian, I'm also from Iowa and just completed my certification as a Home Energy Rating Systems (HERS) Rater.  This is where you use equipment that either pressurizes or depressurizes homes, allowing you to determine how "leaky" a house is or if there are leaks  in your ducting system.  My instructor used an example of a SIP house he rated in Wisconsin. 

One of the things you do when testing a house is to turn off furnaces (to prevent blowback or flame rollout during the test).  You then put your car keys on the furnace to remind you to turn the furnace back on before you leave.  My instructor was talking with the owner after finishing the test, got distracted, and pocketed his keys without turning the furnace back on.  In September.  Just before a Wisconsin winter.

Six months later the builder was doing a checkup on the house.  The first thing the owner did when letting the builder into the home was to compliment the builder.  "I have never lived in a house that was so comfortable and draft-free, and so energy-efficient," the owner said.  It was when the builder was in the basement checking out the heating systems that he noticed the furnace had been turned off.  The house had been heated through the entire winter using nothing but the heat from appliances (stove, oven, water heater, light bulbs) and the body heat of the occupants.

So, yeah, it's possible to make an SIP house net zero.

Hi Brian
Glad to hear you want to build an efficient home. Don't start with "SIP", even if you choose that technology in the end.
I'm in the middle of reading Heating, Cooling, Lighting by Norbert Lechner http://www.amazon.com/Heating-Cooling-Lighting-Sustainable-Architects/dp/0470048093. Probably the best resource I've seen in one place.
One of the first points Lechner makes is that buildings should be designed with three tiers
Tier 1: Basic Building Design (Heat retention, Heat rejection, Heat Avoidance)
Tier 2: Passive Systems (Natural Energies)
Tier 3: Mechanical Equipment (Heating & cooling equipment, renewable energy, lighting equipment)

"Right design choices in tier one can reduce the energy consumption of buildings as much as 60 percent. The second tier involves the use of natural energies through such methods as passive heating, cooling, and daylighting systems. The proper decisions at this point can reduce the energy consumption another 20 percent. Thus, the strategies in tiers one and two, which are both purely architectural can reduce the energy consumption of buildings up to 80 percent. Tier three consists of designing the mechanical equipment to be as efficient as possible. That effort could reduce energy consumption another 8 percent. Thus, only 12 percent as much energy as needed in a conventional building."

Your SIP idea fits into tier 1, but you should look at the other options available too.

Another good book, but somewhat less practical slightly less up to date is http://www.amazon.com/Passive-Solar-Primer-Sustainable-Architecture/dp/0764330705 a reprint of his 1970's book, which is very likely in your library system somewhere.
At a minimum, do a bit of reading before you build. Make it a house worth building and living in for generations.

The April edition of The Journal of Light Construction had an article on Super Insulated Slab Foundations that was a decent read. http://www.jlconline.com/cgi-bin/jlconline.storefront/4c3e60a401e31d5c27180a32100a05e1/Product/View/1004sup
You can find the author's web site here http://gologichomes.com

Those tiers are a really good idea.  We are in the middle of our passive solar home now.  With out knowing your location look into what the location offers as far as passive approaches.  Ours had a natural spring so we built the house below it...aimed it south , bermed etc.  Maybe a nook from a previaling wind? Maybe orient house long ways towards south?

One caution that I do not hear enough people bring up is air exchanges.  Those air tight homes will become sick homes in time.  You need fresh air.  If you have high medical bills that will wipe out any heating savings fast.

Since we are all about being as passive as possible we have used earthtubes other options include heat recovery air exchange units.  The heat recovery units cost a bit ($1,500?)  to install and then they need to maintained, they also use electric.  We are hoping convection will power the earthtubes.  You might want to check out John Haits book, Passive Annual Heat Storage.
good luck in your venture it's an awesome goal!. 

Silver wrote:
Hi Brian
Glad to hear you want to build an efficient home. Don't start with "SIP", even if you choose that technology in the end.
I'm in the middle of reading Heating, Cooling, Lighting by Norbert Lechner http://www.amazon.com/Heating-Cooling-Lighting-Sustainable-Architects/dp/0470048093. Probably the best resource I've seen in one place.
One of the first points Lechner makes is that buildings should be designed with three tiers
Tier 1: Basic Building Design (Heat retention, Heat rejection, Heat Avoidance)
Tier 2: Passive Systems (Natural Energies)
Tier 3: Mechanical Equipment (Heating & cooling equipment, renewable energy, lighting equipment)

"Right design choices in tier one can reduce the energy consumption of buildings as much as 60 percent. The second tier involves the use of natural energies through such methods as passive heating, cooling, and daylighting systems. The proper decisions at this point can reduce the energy consumption another 20 percent. Thus, the strategies in tiers one and two, which are both purely architectural can reduce the energy consumption of buildings up to 80 percent. Tier three consists of designing the mechanical equipment to be as efficient as possible. That effort could reduce energy consumption another 8 percent. Thus, only 12 percent as much energy as needed in a conventional building."

Your SIP idea fits into tier 1, but you should look at the other options available too.

Another good book, but somewhat less practical slightly less up to date is http://www.amazon.com/Passive-Solar-Primer-Sustainable-Architecture/dp/0764330705 a reprint of his 1970's book, which is very likely in your library system somewhere.
At a minimum, do a bit of reading before you build. Make it a house worth building and living in for generations.

Sorry I took so long to respond to this post, not sure why I didn't get an email telling me someone replied but anyway, I didn't mean to imply that the only thing I was looking into was simply using SIPs and that was it.  I had already planned on using a slab for a thermal mass and using over hangs on the windows and facing the home to the south with small or no windows on the other walls.  I thought about using a GSHP but I think the systems designed today are far too large, expensive, require too much electricity for a home that small and I think going with a mini split ductless system is the best way to go.  I realize in the winter/colder months their efficiency goes way down so I thought maybe using a removable housing to insulate it during the colder/winter months and putting it where the sunlight can hit it(and painting it black of course) to warm up the removable housing to increase efficiency.  If all else fails I could just get a propane back up, build a rocket mass stove, or perhaps install some sort of evacuated tube solar thermal radiant floor system.  I planned on collecting water anyway so why not just use that water in the ground cistern as a place to dump excess heat etc.

Anywho as you can tell I have put some thought behind this and wasn't just looking at one area to solve all the issues of energy production/consumption during home ownership.

Mostly what I was getting at was I think SIPs are the best material you can use to get your home to net zero if you were going to try that, by best I mean commercially available, customizable, very high R value, easy to assemble and readily available, and proven.  So what I would like to know is if other people have come to this conclusion and what results are they getting to see if what I think produces real world results and doesn't just sound good on paper.  So far it looks that way.

speedfunk wrote:
Those tiers are a really good idea.  We are in the middle of our passive solar home now.  With out knowing your location look into what the location offers as far as passive approaches.  Ours had a natural spring so we built the house below it...aimed it south , bermed etc.  Maybe a nook from a previaling wind? Maybe orient house long ways towards south?

One caution that I do not hear enough people bring up is air exchanges.  Those air tight homes will become sick homes in time.  You need fresh air.  If you have high medical bills that will wipe out any heating savings fast.

Since we are all about being as passive as possible we have used earthtubes other options include heat recovery air exchange units.  The heat recovery units cost a bit ($1,500?)  to install and then they need to maintained, they also use electric.  We are hoping convection will power the earthtubes.   You might want to check out John Haits book, Passive Annual Heat Storage.
good luck in your venture it's an awesome goal!. 

You know I have been thinking about HRVs for a while, and I'm not quite sold on the idea just yet, I'd like to see some data on how effective they are or aren't. 

After all weren't they invented on the premise that homes like these are so tight that you are going to get sick because of all the germs in them etc and not because they are so tight people were getting sick so someone invented them?

Anyone have any definitive data on this?

Silver wrote:
The April edition of The Journal of Light Construction had an article on Super Insulated Slab Foundations that was a decent read. http://www.jlconline.com/cgi-bin/jlconline.storefront/4c3e60a401e31d5c27180a32100a05e1/Product/View/1004sup
You can find the author's web site here http://gologichomes.com

I'd love to read it but they want me to subscribe(see: pay), and I'm not doing that to read one article.

Brian, I don't know if this helps or not, but we're building a bermed house using icf's from ARRX.  Fiddled around with alot of ideas and settle on this one.  I'm currently trying to get the areas that need insulation done so we can determine how much of a heating system that we will need.  We live outside of Corning NY.  Outside temperature today is around 19 with about a 10-12 mph wind out of the west. 50/50 clouds/sun mix.  Temp at the back wall was 45 degrees, and the temperature in the sunny area was 70 at around 13:00.  Now I haven't finished insulating the ceiling yet in the section where I took the temperature, and the other section has no insulation in the ceiling or walls (above the ARRX blocks).  When all this done we should be able to do a whole better, but we won't know that for another couple of weeks.
We have pex tubing in the floor, and I found some info on direct wind to hot water, thought I wish I could find more.  We have a 550 watt 12 volt  PV system ready to go in.

There are pictures in The Hill House Becomes section of: http://luckydogfarm.wordpress.com/
If you are interested I can share costs, problems and you can have the drawings if you want to mess around with it.

Best

Ed

Hi fellow Brian with an I. Congrats on your project planning, its obvious you've done some good research. I agree with your assessment of SIPS. Its a great place to "start" because an airtight, continuously insulated building envelope is the most important factor when it comes to efficient heating and cooling. Of course SIPS arent the only way, but to me they offer a great balance of the many considerations that go into the most permanent part of a home or building.

I can understand your trepidation with using ERVs and HRVs. Its tough to present convincing data or studies that back up their effectiveness when it comes to health claims. This is true with any product that involves claims about health. The fact is that a vast majority of Building Science experts from around the world advocate their use with tight envelopes in heating and cooling environments. It comes down to control. Tight envelopes offer more control of conditioned air and indoor air quality. Outdoor air is almost always healthier than indoor air. Rather than building a leaky envelope that doesnt leak enough when you want it to, or too much when you dont, is not a good way of conserving energy or introducing healthier outdoor air.

ERVs and HRVs are the easiest, safest and most efficient ways of ventilating a home. Expect to pay 600-800 for a basic unit but a model with an ECM motor is highly recommended which doubles the cost. My most recently installed HRV uses only 13.5 watts. Thats about the same as a compact fluorescent lightbulb. Usually they are programmed to run for 20 minutes out of every hour but can be turned off or up depending on the conditions... Fresh Air Control!

If the moderators allow, http://www.springtimehomes.com/green_building_science#BuildingEnvelope is an elaboration of some of this discussion with some good pics and diagrams.

I agree with your assessment of Ground Source Heat Pump not being the right fit for your project. With such a small, well insulated home, the payback will be a very long time. I would also caution your plans on using solar thermal to heat a radiant slab. Those heating systems tend to be expensive, complicated and troublesome. Especially if your are going passive solar, you wont get much more usable BTUs anyway. Solar thermal for your domestic hot water is tough enough but possibly a good fit for you.

I think a mini-split is a great fit for your project and if you want to go even cheaper (with a sacrifice in noise and aesthetics) check out PTAC heat pumps. I wouldnt worry too much about the drop in efficiency in cold months. Their efficiency is still amazing even at temps below freezing and decent at sub zero temps.

I saved my most controversial (to permies readers) comments for last. Be extremely careful with earthtubes. They are notorious for moisture and humidity problems. The best earthtube scenario is one that feeds the intake for the HRV/ERV. I think there are many problems even with this best case scenario. Money spent on detailing proper earthtube design and construction is better spent on a higher efficiency ERV/HRV.

Be careful with woodstoves and especially RMH. Wood is the cheapest fuel available for heating. Its also one of the dirtiest and most pollution causing devices you can introduce to the home. A mini-split heat pump combined with a net-metered PV system is one of the cleanest and most efficient heating systems available. Its also much better for your neighbor's air, reduces the community's energy footprint by reducing peak demand and keeps firewood where it belongs; building topsoil or hugelkulture beds