I am in the process of designing a new home that will be about 3400 square feet - one story. I like the idea of ICF construction for all its reasons. I would also like a standard, open, wood burning, fireplace, but hear that due to the tightness of the ICF construction, and heat retention, there could be problems with back draft and overheating the house. Does anyone on this forum have any experience with this? Thanks!

The words, "standard, open, wood burning, fireplace" and "energy efficient" should NEVER be in the same sentence. Standard wood burning fireplaces are an abomination when it comes to energy efficiency. You might as well leave a 3' wide hole in your wall and call it a day.

Dump the fireplace as it will be a huge energy penalty for the life of the home. You are building an ICF home, it makes no sense to introduce items that negate the efficiency of the wall assembly.

I understand the conflict and would like to know if there is a way to work this out - hence my posting. It doesn't sound like you know of a way to handle this scenario. If you, or anyone else, can offer any workable advice, I would appreciate it.

Posted By JonHoebelheinrich on 22 Jul 2014 09:47 AM
I am in the process of designing a new home that will be about 3400 square feet - one story. I like the idea of ICF construction for all its reasons. I would also like a standard, open, wood burning, fireplace, but hear that due to the tightness of the ICF construction, and heat retention, there could be problems with back draft and overheating the house. Does anyone on this forum have any experience with this? Thanks!

Regardless of the type of construction you use, you need to provide a combustion air supply from outside. Your only challenge is to figure out how the best way will be to pipe in fresh air from outside to the fireplace and control it so it doesn't flow into the house when you're not using the fireplace. I believe it's a code requirement so is not limited to ICF construction.

Posted By JonHoebelheinrich on 22 Jul 2014 03:31 PM
I understand the conflict and would like to know if there is a way to work this out - hence my posting. It doesn't sound like you know of a way to handle this scenario. If you, or anyone else, can offer any workable advice, I would appreciate it.

You are lucky in that you have that option.  In california, we can't have any wood burning fireplaces inside, so one decision less for us.

you have to excuse lbear, he can only criticize people and their actions.  he doesn't like to provide suggestions except to do the same as he is doing.

Jon,
It is unlikely that a  conventional fireplace will overheat your home.  They tend to be very inefficient at producing heat.  A open fireplace generally draws as much as 150 cfm of room air when it is going.  That is a fair bit of air to make up.   If the net combustion efficiency was 10% I would be surprised. On very cold days it is often negative. I lived in a house that you couldn't run the fireplace when it was below 0°F  because the furnace could not keep up with the extra heat loss.

There are substitutes that work better- but they definitely don't have the same aesthetics.  

You may indeed have problems with backdrafting, especially if you have a large range hood.  Any thing that depressurizes the house more that a couple of Pascal's  will cause problems with lighting a fire.  Think dryer, range hood, bath vents, all can cause problems if you really build a tight house.  Mostly you overcome this by not running exhaust vents when you are starting a fire, or opening a door or window.   It makes a big difference where the chimney is, put that sucker right in the middle of the house so the stack  stays warm.  If you have it on an end wall on the outside it is much more likely to backdraft on start up. You should also realize that a ICF house is not necessarily a tight house, just like a stick built house is not necessarily leaky.

You can get a fireplace with outside combustion air that looks fairly normal and eliminate a lot of the issues.  Some fireplace inserts(and some wood stoves) are rated to be run with the door open (run it with the door closed when you want heat, run it with the door open for ambiance)
 
The bigger issue is continuous air leakage up the chimney due to stack effect.   I have yet to blower door test a house where the chimney was not a significant air leak.   Dampers suck, most glass  fireplace doors suck, 

To summarize- overheating not likely, smoking, backdrafting  and difficulty starting a fire is a possibility, continuous air leakage due to stack effect is  probable


2009 iecc (international energy conservation code) states in section 402.4.3 Fireplaces New wood burning fireplaces shall have gasketed  doors and outdoor combustion air.

Do you know what code applies to your location?


All just food for thought,
Eric Anderson

Check with your local codes first because they will determine whether or not you can install such a fireplace and what code ventilation is needed if you do. Wood burning fireplaces are illegal in a few cities and counties. In Phoenix/Maricopa County all wood burning fireplaces are illegal in any homes built after 1998. The reason was simple, the EPA determined that wood burning fireplaces cause air pollution by releasing particulate matter, carcinogens and carbon monoxide into the air. This causes repository disease and other health problems.

If your local code allows for wood burning fireplaces, the next step is to do a Manual J on your home. Depending on the location of the fireplace, that will play a role in the load calculation. Overheating is very common with open wood burning fireplaces. An open hearth wood burning fireplace will run at around 8% efficiency while burning.

As far as my criticism goes. This is a Green Building Forum and you asked on how to install a very inefficient fuel source that contributes to the local air pollution problem. Trying to dissuade you from making a bad environmental and energy decision that will last the lifetime of the home is not out of line.

If you, or anyone else, can offer any workable advice, I would appreciate it.

Lbear is right. An open fireplace is an abomination. Just get a sealed fireplace with provision for outside combustion air. You can get one that has the ability to move the heat via ducts to far flung corners of the house and cut down on the tendency to overheat the immediate area. Of course, you will want to get one that doesn't put out too much heat for your home in the first place. That would just be a waste of wood.

nearly everyone on this forum is making decisions that aren't green, but the criticisms are unequal.  someone recently posted that they built a 9,000 sq ft ICF home, and almost everyone congratulated that individual on having a great home, but the reality is that the OP having a 3400 sq ft home and an open fireplace will use way less resources than the owner of the 9,000 sq ft home.

some people have posted that they have redundant heating systems which is also a waste of resources.

some people live in a desert and pump in tons of water which is a great waste of resources.

the OP was asking for suggestions.

that the OP having a 3400 sq ft home and an open fireplace will use way less resources than the owner of the 9,000 sq ft home.

People are different and have different needs. The notion that you can do something inefficient or wasteful because your house is smaller than someone else's is the first step down the road to foolishness.

Posted By ICFHybrid on 23 Jul 2014 08:36 PM

that the OP having a 3400 sq ft home and an open fireplace will use way less resources than the owner of the 9,000 sq ft home.

People are different and have different needs. The notion that you can do something inefficient or wasteful because your house is smaller than someone else's is the first step down the road to foolishness.

People are different and have different needs.  The notion that you can build something huge because your house uses less energy than a comparable mcmansion is the first step down the road to foolishness.

Jon,
Do some research about " masonry heaters ". If one is designed and fired correctly for your space, it should not back draft, nor overheat the space. It depends a lot on where you will be locating this home geographically, but one generic size masonry heater typically will not heat the entire 3400 square feet, even though it is an ICF structure ! You could pull the makeup air from a crawl space or basement, and in the summer months this cooler air could also help cool the thermal mass of the masonry heater, adding a bit of passive cooling to the space around it.

I did a house in Los Gatos California in '05, had 3 fireplaces, more for the ambiance then anything.

Not sure of today's rules there, I did inquire as to how the fireplaces got approved...answer was no natural gas on the street, wood burning was approved

Also did a house in Shasta in '08/'09, They had propane and a wood burning stove

HRV/ERV if it is not mandatory, should be

We fully concur with Yellowcat and we love masonry heaters too.

http://www.borstengineeringconstruction.com/Masonry_Heater_Performance_Calculator.html

The software instructions for the associated masonry heater performance software highlight the advantages of using masonry heaters in energy efficient buildings. We even have a yellow cat who enjoys sleeping on our heated bench...  The downside is that masonry heaters can be very expensive if you hire out the entire job.

One has to ask what the purpose of the fireplace is- is it for space heating? Ambiance? Incinerating the evidence when the cops are banging at the door and the place is surrounded? :-)

As nice as they are, masonry heaters come at a significant up-charge over an open hearth fireplaces. If the purpose of the wood-burner is space heating, that upcharge is worth it (though a soapstone wood stove might be both cheaper, and easier to manage, if not quite the same look.)

Wood burners always come with a localized air-pollution down side, but open hearth wood burners have truly INSANE particulate emissions, an order magnitude higher than an EPA qualified wood stove. A typical open hearth fireplace emits on the order of 50 grams/hour of particulates while heating at (if you're lucky) 10% thermal efficiency, compared to a pretty-good non-catalytic EPA qualified woodstove at less than 5 grams/hr at something like 80% thermal efficiency. The wood stove is delivering an order of magnitude MORE heat at an order of magnitude LESS pollution. From a heating-BTUs delivered point of view it's really about 2 orders of magnitude less particulate emissions (less than 1% of what a fireplace emits for the same amount of space heating.). Masonry heaters tend to be somewhere in-between (since they aren't usually designed with secondary burners the way all EPA qualified wood stoves are), but they're pretty good if fired in short, hot intermittent burns, which is how they are designed to be used.

And that's just the particulate emissions, not even getting into the dramatically higher volatile organic emissions from open hearth wood burning. (It's not surprising that some urban areas ban the use of open hearth fireplaces.)

Achieving IRC 2012 code-max or tighter building tightness can sometimes be difficult with a masonry fireplace, which could easily become THE single largest air leak in the house, even with the dampers closed. And without ducted proximity make-up air (another big air leak) they're prone to backdrafting on start up in a tight house. Masonry heaters & wood stoves can (and should, in a tight house) have ducted combustion air directly into the appliance, with no uncontrolled leakage paths between conditioned space, the combustion air duct, firebox, or flue. Most wood stoves have combustion air kits available (some are only proximity-air ducts though), and some standard masonry heaters do too. With the combustion air duct pressure-isolated from the conditioned space air, even in the event of backdrafting from wind gusts, etc, none of the combustion products enter the house.

Masonry heaters typically burn much cleaner than EPA certified wood stoves and also operate at higher conversion efficiencies too. They don’t need or have secondary burners like EPA approved wood stoves require because the entire combustion chamber of a masonry heater operates at about 1,700F.

Posted By sailawayrb on 24 Jul 2014 04:22 PM
Masonry heaters typically burn much cleaner than EPA certified wood stoves and also operate at higher conversion efficiencies too. They don’t need or have secondary burners like EPA approved wood stoves require because the entire combustion chamber of a masonry heater operates at about 1,700F.

Theoretically maybe, but third party testing of a Tulikivi indicates that they're more like ~80% efficiency, like better class wood stoves:

"The stove was found to be 79.5% efficient.

6. CONCLUSIONS

The initial hypothesis that the masonry heater would operate at 90% efficiency proved incorrect. The heater in fact operated at 79.5% efficiency."

Dana, the resident Building Science expert has clearly stated that an open hearth wood burning fireplace is a really bad energy efficiency idea and devastating to the environment. There are other options out there and it's best to pursue those as an open hearth wood burning fireplace will not get recommended on a green building forum.

Lbear, Can you just stop.  people are trying to find a workable solution and are offering some suggestions.  All you do is spout nothingness.  If you want to be talk about being truly green, you wouldn't choose to build a home in the desert.

Actually, wood stove efficiency is 80% at best and masonry heater efficiency is commonly 90%:

http://energy.gov/energysaver/articles/wood-and-pellet-heating

Our Envirotech masonry heater efficiency is 92%.