Which energy efficiency upgrade would you do?

[SE Iowa]

I've got some money budgeted for upgrades/changes for my home. I've made list of pros/con but always want to bounce ideas off others in case I miss something so here goes.

Option 1. Spray insulate my roof or ceiling with foam insulation. Cost I'm told will be about $3-4/ft which includes removal of old cellulose blow-in, so total cost is around $6-7K. This would help with heating and cooling as the roof is a major source of heat gain during the summer. Only major drawback is my concern over my house being too tight leading to moisture problems (live in a icf home).

Option 2. Install GARN in outside building and plumb into existing radiant floor heating system. Cost around $15-20K. I cut wood all winter long clearing land for farming operation so unlimited amounts of wood although I don't need to waste time blocking it up more than I have to. I can place unit in building but will have to pipe water ~135ft. Major benefit is the guilt-free turning up of our thermostats, but this still isn't a totally passive option so will have some maintenance.

Option 3. Install interior storm windows on all windows. Cost is about $3-5K. Major benefits are reduced condensation on windows (we get build up due to moisture issues in icf home esp if we have lots of people over and/or cooking alot on cold days). Would allow window shades to be opened more. Some minor labor required every year and then have to store units during summer etc.

Option 4. Put in a WOOD buring stove/fireplace in the living room on the north side of my house. Cost $5K due to removal of old gas fireplace. I'm not sure how I'd run a chimney since I think it would have to run higher that the second story of the main part of the house. Cons include wood debris inside house and ash removal, plus installation issues.

So what would you do?

 

[Highbeam]

Do option 4, good heat in the winter during power outages and a nice radiant heat source. No reason to dink with your cellulose, it's fine, as said perhaps add more if you feel you are lacking in the insulation department.

 

[SE Iowa]

We have prairie grass completely surrounding our house so we get mice up there in the falls and winter. The spray foam would help deter nesting or at least we wouldn't hear them up there. The improved envelope that sprayfoam insulation provides is also a plus. We also are in a high wind area and do get some blowing around of the cellulose (not much though). Finally, our air conditioner's air handler is in the attic in a small room that would benefit from an air-tight seal.

 

[SE Iowa]

Highbeam, how do I determine how high to put the chimney? Does it have to be above the 2nd story? If it did then I would just have a 12-15ft pipe sticking up in the air which wouldn't look very nice.

 

[mbcijim]

i would add cellulos, not remove it, why remove it?

x2

Are you going to add R- Value by doing so? That might be a reason to do it. But in my experience most of the homes that do have blown-in-cellulose have enough. Just my opinion. You will tighten up the house with the spray foam, but I'd be surprised if it was significant.

So you need to answer these two questions for yourself to decide if that is really an option:
1. Am I going to increase the R-value?
2. Will I make the house tighter?

 

[SE Iowa]

Mothballs for mice? That would be an interesting experiment.

 

[freeburn]

I would agree with option 4. You pay too much extra for the foam insulation and for that price, it will take forever to recoup it. If you are going to do something with insulation, blow it in. If you get free wood and enjoy doing that sort of thing, get that stove in there and make sure it's one that qualifies for the tax credit. As for the mess, well, that's a small price to pay for free heat. Could you save some extra cash in tearing out the old gas fireplace. They are pretty easy to tear out. Good luck with your project, whatever that may be.

 

[DBoon]

Without knowing anything more than what you told us, in general the best payback would probably be in this order:

1) First, make sure you attic hatch is sealed extremely well. Then, get up to 16" of cellulose blown in in the attic floor. I wouldn't take any insulation out.

2) Second, install the wood stove indoors. Shorter payback than boiler. $15-20k must have a long payback period. Wood stove will still keep you plenty warm. Depends on room layout, of course.

3) Unless you have really bad windows with no outdoor storms, then I an extra storm window layer isn't going to make that much of a difference.

4) Garn for $20k seems like an awfully long payback unless you have a really big house.

 

[woodgeek]

Studies show most houses lose more heat through (repairable) air infiltration than passive loss through window glass....

I put self-adhesive plastic v-strip on all my 40 yo double hung, exterior storm, windows--dropped my heating demand by ~15%, for 1 WE of work and <$50.

Also, a blower door test is a lot cheaper than your options...

Get an exterminator in for the mice, if you can't solve it yourself.

 

[begreen]

Agreed. Sealing air infiltration leaks is going to provide the most bang for the dollar. Caulk is cheap. Maybe get an energy audit to map out a plan and locate the leaks?

 

[Gooserider]

Highbeam, how do I determine how high to put the chimney? Does it have to be above the 2nd story? If it did then I would just have a 12-15ft pipe sticking up in the air which wouldn't look very nice.

Not HB, but...

The standard code required minimum rule for chimney height is known as the 3-2-10 rule - you have to be at least 3 feet above the highest point where you came through the roof, and at least 2 feet above any other substantial obstruction within 10 feet of the chimney.

In practice, if you have a high roof close by, or are at the bottom of a steep hill, have lots of tall trees nearby, etc. that minimum may not be enough, especially if the obstructions are frequently upwind, but it can be hard to predict - it's one of those try it, and if you have problems add more pipe situations to some extent. However you generally don't have to go above the obstacle, just get enough additional height to get the needed airflow to make the chimney draft properly.

As to the choices, I'd agree with the idea of airsealing and blowing in more cellulose first, then maybe the wood stove. Unless you think you'll want the heat for more than just the house (or are looking for an excuse to get a cool toy) I don't think the Garn really offers enough of a payback.

Gooserider

 

[eba1225]

I would go with option 4 and look into getting fibergalss insulation at a discount for the attic.

I was able to search CL in my area and found a guy that was selling "like new still packaged" insulation for 1/2 the cost of the big box stores. I installed it myself and saved a bundle. It saves all year long, heat in during the winter, heat out during the summer.

 

[Chain]

I don't mean to high jack this thread, but I assume it's okay to add blown in cellulose on top of fiberglass insulation, correct? Seems as though that shouldn't cause any problems. Anyone?

 

[Gooserider]

I don't mean to high jack this thread, but I assume it's okay to add blown in cellulose on top of fiberglass insulation, correct? Seems as though that shouldn't cause any problems. Anyone?

Shouldn't be a problem at all - however I have heard it suggested that before putting in the cellulose, it can be a good thing to lift the fiberglass and make sure you have done a good job of air-sealing under it - Neither cellulose nor glass stops air infiltration, and the more insulation you have the harder it is to get under it to air seal later.

Gooserider

 

[Chain]

Thanks for the clarification.......Good advice.

 

[Slow1]

I don't mean to high jack this thread, but I assume it's okay to add blown in cellulose on top of fiberglass insulation, correct? Seems as though that shouldn't cause any problems. Anyone?

Shouldn't be a problem at all - however I have heard it suggested that before putting in the cellulose, it can be a good thing to lift the fiberglass and make sure you have done a good job of air-sealing under it - Neither cellulose nor glass stops air infiltration, and the more insulation you have the harder it is to get under it to air seal later.

Gooserider

I had an energy audit done this summer - had the 'pros' look at my attic where I had fiberglass batt 'to code' insulation. In the end the recommendation was to air seal (as Goosrider said - lift, seal, put it back down), then blew in another 4-6" on top of it all. Made an incredible mess up there! heh. I could see every spiderweb stand out after that job was done. The difference this summer when it finally was hot was VERY noticeable - ever since moving in 9 years ago (new house then) we could feel and smell the heat from the attic on hot days. Not this summer after the work was done. The kicker is that with the rebates from the state and utility company and everything the estimate is that we'll re-coup our cost in less than two years. Sweet.

So - yes, you can blow on top of the fiberglass and air-sealing first is recommended. I add to this - research rebates (check with utility company as well as state!) and you may find it is even more cost effective than you think.

To OP: I would recommend go with the stove for heating, if you need more insulation in attic air-seal and blow more in (I too have my HVAC up there and considered the foam for roof, but no matter how I did the calculations the payback just isn't there!). Your description of window issues may not be so much with your windows but may be more an issue with moisture in your home - consider investing in some sort of humidity control in the way of a ventilation system with heat exchanger. Monitor the humidity level in your house - you may simply have too much moisture in the air. Also - given that ICF homes tend to VERY tight homes to begin with I would think an OAK may well be something to consider in your stove install - again, depends on the whole picture.

 

[Highbeam]

You folks mention airsealing before blowing in more insulation. What do you mean? Simply sealing up the various penetrations for wiring, light fixtures, and plumbing or do you mean rolling out a poly barrier beneath the batts?

 

[Slow1]

Air sealing the attic means sealing up penetrations as you say - where the plumbing etc come through and the tops of walls, etc. Basically everywhere that air will push up into the attic. It also in a sense means putting a dome over (and cinching it down) or otherwise sealing up around whatever hatch etc access the attic.

Part of the deal with my project included a blower-door test before and after the air-seal job. It was impressive the amount of air infiltration that reduced simply through these measures (the blower sucks air out of the house). Thus, in theory at least, now I'll have less air headed up into the attic this winter which is good from both the heat loss in the house and the humidity gain in the attic points of view.

 

[Gooserider]

You folks mention airsealing before blowing in more insulation. What do you mean? Simply sealing up the various penetrations for wiring, light fixtures, and plumbing or do you mean rolling out a poly barrier beneath the batts?

It means sealing all the leaks as you mentioned, plus any cracks between wall panels, the tops of plates, and any other place where you could get a passage of air, aka "drafts". It does NOT mean putting down a vapor barrier, as you still want the same potential for vapor diffusion / drying as you did before. The big difference is that vapor diffusion doesn't carry a significant amount of heat with it, while air leaks do. The ideal in essence is "air tight" but not "vapor proof" - there is a difference...

Gooserider

 

[precaud]

Spray insulation on the outside of your roof only makes sense if you plan to do the same on the outside of all the walls to make a continuous exterior insulation barrier for the whole structure. I'm with Ghettontheball, add more cellulose to what you now have in the ceiling, and use the balance of the money for something else. Cellulose does stop air infiltration much better than fibreglass, but seal those leaks before you put more material in. I've got R-60 cellulose and love it.

Something to consider... if you are circulating hot air to adjacent rooms, it happens at the ceiling level. So better to insulate the ceiling than the outside of the roof.

 

[SE Iowa]

DBoon - About the windows, they are <5 years old and are of a mid-level quality. The biggest issue is that they stand out as the weekest link compared to the icf walls. And as stated by others, humidity is a problem which compounds the problem.

Gooserider - Thanks for the info. We should be fine then. The fireplace would be on one end of our living room which is on the far north end of our house. It is a 2 story colonial brick house with single story wings on the north (family) and south (garage) ends of the main house. Each "wing" is 24' long so that would be ~2.4 times your 10 ft rule.

Slow1 - We do have 2 HRV's that we turn on periodically. We turn then on for at least 20 minutes when we shower and then very periodically during the day when we are there. Problem is during the day when we are not there or at nightswhen the temps drop and condensation occurs. I'm thinking about biting the bullet and running the dehumidifier upstairs this winter to see if it will help. Other big issues is that the house in not an open floorplan and with radiant floor heat there is not much circulation of air from the heating system.
You mentioned and OAK. What is an OAK system?

 

[Slow1]

An OAK is an "Outside Air Kit" - basically it is a way to pull outside air directly to your stove for combustion. In a very tight home (as it sounds like you may have) it can help improve your draft and thus insure your stove gets enough combustion air. There is a tremendous amount of controversy about the value of them - there are articles from reliable sites both for and against them. However, there does appear to be a consensus that in a "very tight" house they would have value. Standard US construction methods (2x4 covered by whatever) is very hard to tighten up, but as you know your home is tighter than 'normal' construction.

Your humidity issue needs to be solved stove or not. It is unhealthy to live in a home with excessive humidity levels for so many different reasons. Fresh air exchange is likely the most cost effective way to improve this but I've not really studied the subject enough to know for sure. Running the dehumidifier will remove the moisture, but you also need to generally exchange air too - the humidity may just be one symptom of the general problem of insufficient air exchange. As good as it may be to tighten up a home, you shouldn't live in an airtight bottle either.

Why don't you run your HRV's more often or longer? What is the average humidity level in your home?

 

[SE Iowa]

We try to run them (HRV's) more often but mostly just with our morning showers. When we built our house the recommendation for HRV's was to not have them run on automatic timers. the expert I consulted stated that testing had shown that they actually were at best energy neutral in automatic mode and sometimes actually wasted energy. He therefore told us to just run them in an as needed mode. We had the main intake vents located in the bathrooms above the showers and a few others stragetically placed other areas in the house. I work great in the bathroom. even with back to back showers in the winter, our bathroom window does not have more moisture issues than anywhere else, plus our mirror never fogs up. the problem is that we sleep ~8 hrs per day and work ~8 hrs per day leaving only 8 hours that we occupy the house. During that time, I only think about it once and a while.

 

[Slow1]

Well.... perhaps a re-evaluation of the advice is in order. HRV's should be more than just fancy bathroom vent fans. I can make the same claim as you do with my bathroom fans that we use the same way - don't get much energy benefit though.

Purpose of HRVs is not really a net energy efficiency gain. The purpose of an HRV system is to improve air quality by increasing the fresh/stale air exchange in the home while minimizing the energy loss. Even in the best case you are likely losing 15% or more of your heating/cooling energy while running them - but this is far better than opening a window. If you run them on a regular basis and the air vents are reasonably placed then you should be able to swap out the air in your home several times a day.

Why do this? Well, there are a lot of things that make up "indoor pollution" such as the chemicals released by the construction materials (paints etc), toys (including electronics), etc. Bodily gases etc, cooking puts out all sorts of things into the air, the list is rather endless. Humidity control is of course one of the big benefits that started this conversation. If you fail to control the humidity in your home you risk having issues such as mold (if it is condensing on your windows then it may well be condensing elsewhere that you can't see and keeping some area damp enough to grow who knows what eh?), also there are a lot of pathogens that generally thrive in damp environments so you risk creating a nice home for them putting your health at risk.

I'm not there - I don't know what your average humidity level is, nor do I actually know how tight your home really is (get a blower door test done and you can have objective numbers). However, based on the symptoms you have reported and what you have shared about the construction of your home it does sound reasonable to me that you may well have less ventilation in your home than is generally considered healthy.

As to the expert advice you received - A second opinion is always available. If you pursue this, be sure you are asking the right questions and you have someone qualified to answer what you are asking. My experience is that often times folks walk away from talking to 'experts' feeling that they have received a more comprehensive consultation than what has really been given to them. This is either because the 'expert' is unqualified to answer more fully or because only a narrow question has been asked and that is all that is being answered.

 

[DBoon]

I echo everything Slow1 said about your humidity and your HRVs. Your shower is probably not the largest source of indoor humidity. You would be surprised how much moisture a single person can exhaust into a house in a day, and if your house is sealed that tightly, it will just build up inside. The following is from here (broken link removed to http://www.ag.ndsu.edu/disaster/winterstorm/wintermoisture.html)

"Moisture is added to air in a house from many sources. Each person contributes about 3 pints per day while breathing. Each shower, and air drying towels afterward, contributes about a pint of moisture. Houseplants also contribute moisture to the air."

It sounds like you've already done the hardest work - you have really good wall insulation. I wouldn't get too crazy about the windows. If your windows are of "medium" quality and you already have an outside storm, I'm guessing the R-value is already ~R-3. Adding another storm or storm equivalent inside will only increase the R-value to R-4. Seriously, this will not make a really big difference for you, and if the reason for thinking of doing this upgrade is to stop condensation on your windows, then you should really solve the moisture problem instead.