My son is planning on building an ICF story and a half home. The home is near Waterloo, IA and 1,672 square feet. The question was how to optimize the HVAC system. I downloaded BEopt and listened to all the training videos. I input the pertinent information associated with the proposed home and ran three design scenario’s varying only the HVAC system; a boiler (the base system) with central air, ductless air source heat pump and a ground source heat pump. The BEopt results showed the air source heat pump had the lowest initial investment ($5,188 less than the boil) while the ground source heat pump was $7,136 more than the boiler. It also calculated the cost saving on the utility bill to be 11.3% on the ASHP vs. 12.0% for the GSHP. I’m not sure how the program “ginned up” those numbers but I think the overall relationship between the HVAC systems is correct. Does anyone have any insights on BEopt to share? How much confidence should one have in BEopt? I also looked at double pane vs. triple pane windows. BEopt showed a $23 yearly utility bill difference between the two and a two hundred year simple payback for the triple pane! My take is that windows just are not a good wall component or investment choice. Thus one should not get sucked up in to the window game. I understand BEopt does a Manual J. It came up with 25 MMBtu for the heating season. Again, what is the confidence level on that calculation? I have run the numbers on the home design using 2 different spreadsheets and an on-line tool and have all have been in the same ballpark.

I'm not familiar with the program, or the exact cost savings you mention, but I am familiar with super insulated houses of that size, and they are very easily and inexpensively heated with mini splits, or ASHPs. There are lots of details about these houses and mini splits at buildingscienceadvisor.com.
The real advantage of a good quality triple pane window (U.20 or better) is comfort, not dollar savings: the inside pane of a triple glazed window is much closer to room temperature than the identical double pane, so the body loses much less heat to the window and is more comfortable.

Profess that I am not familiar with BEopt, wish I had known about it 4+ years ago when I planned our new house.

I did use a couple different off the shelf HVAC load programs, two PEs ran the numbers for our house, and I even bought a copy of Manual J and did the calculations by hand myself using an ASHRAE spreadsheet as a template. Couldn't justify the added expense of triple pane windows. In addition our Marvin rep said that he had never sold any, and it was expensive enough changing to LOe-180 on the south facing glass.

However, with the benefit of hindsight, I think I might reconsider triple panes today.

Certainly triple panes seem to have become more mainstream now, even advertised on TV by the local "windowworldama" guy. My gut also says that with triple panes, and a few more changes like upping to graphite impregnated SIPs (that I also couldn't make the $ numbers work on), we just might have been able to certify as a Passive House.

Food for thought.

Even the best window is significantly worse than the worst wall assembly. So we always recommend reducing the quantity and size of windows before purchasing the most expensive windows. Typically the heat loss analysis will show that infiltration is where the majority of heat loss occurs for a given size building and reducing infiltration can be accomplished relatively cheaply. Don’t forget that house size significantly affects heat loss… Triple pane windows are a wonderful finishing touch, but be sure you consider and address the other things too.

Heat pump based HVAC systems always win the efficiency/performance game...no matter what program one uses to assess the performance. However, what HVAC system wins the ROI game largely depends on the cost of fuel. Expensive fuel tends to offset the higher acquisition cost of the more expensive heat pump based HVAC systems. Having a free onsite renewable fuel source negates the importance of efficiency/performance, so that should be considered when looking for property.

Posted By sailawayrb on 28 Jan 2015 08:07 AM
...

Heat pump based HVAC systems always win the efficiency/performance game...no matter what program one uses to assess the performance. However, what HVAC system wins the ROI game largely depends on the cost of fuel. Expensive fuel tends to offset the higher acquisition cost of the more expensive heat pump based HVAC systems. Having a free onsite renewable fuel source negates the importance of efficiency/performance, so that should be considered when looking for property.

Agreed, this is definitely a YMMV calculation where all variables are important.

My reply neglected to mention that we have 40 acres of hardwood forest as feedstock for our masonry heater, and that we had a dud 500' deep water well that we re-purposed for our geothermal system.  We also have relatively reasonable electric rates.  

In essence we spent our triple pane window premium money on our masonry heater.  It's a balancing act.

Great thoughts!

My son has 18 acres of woods so there is a plentiful supply of firewood. I have heated our home for 30 years with wood only so he is familiar with the process and knows how to cut and split wood. However, he is a very busy engineer and doesn't have the time nor a wife that want s put up with the mess. They do wish to have a wood burning fireplace for the ambiance. The calculated MMBtu for the heating season is 25, so he will only need minimal backup heat for the heat pump. So what is a ballpark cost of a masonry fireplace? How about a wood stove from Rika?

switchgrassfarmer, would you share your calculated heat loss numbers and the one you feel after living in your home is most accurate?

Burning wood is dirty, ha!   You are certainly right about that, I have been doing it in our temporary location 24/7 for the last five winters.  

One of the nice things about the masonry heater is that you burn less wood more efficiently.  Have enjoyed the largely "set it and forget it" nature of ours as I started using it for the first time this month.  Still do need to methodically close the various dampers one by one in order to retain the warmth in the core.

As to masonry heater cost, I think you can plan on anything from $10k up depending on what core you use, how you face it, chimney, what you need to do for a foundation etc.  I bet spending $20 - $25k might not be unusual.  (I am not familiar with the Rika.)

We used about 5334 KWH during heating months in 2014, and that is pretty much heat only since there was only construction going on with the house. T-stat set near 70 at the start of the year to drive out moisture, and 62 - 64 this past fall.   We run a 3 ton geo unit, house is about 2800 square feet.

Am looking for my calcs from 2011, only finding the generic ones that showed a 5 ton unit size.   Think the more detailed hand calcs that illustrated that we could go down to a 3 ton unit are on a file server backup.

I think he can get an air source heat pump installed for $5,000 give or take. Maybe the smart thing to do is install the ASHP and harvest firewood to offset any substantial increase in electrical rates. Does that make sense? Or does a PV system fit in to the equation?

The loads on a PV system are prohibitive. ASHP with wood backup is what we do, oh yes, the hydronic radiant with electric boiler when is gets cold and the wood-work is too much.

We have a DIY built masonry heater that hubby keeps supplied with wood from our property. The masonry heater is backup to our passive solar heating and hydronic radiant floor heating which is supplied by an electric boiler that uses onsite hydro power. However, the masonry heater is more than just a backup heat source. The masonry heater is really the focal point of the great room interior design and has heated benches and an oven on the kitchen side. PV is likely still too expensive to supply heating load, but perhaps the day isn’t too far off that this will no longer be the case. So perhaps designing with electric in mind would be a wise "be prepared" choice.

Burning wood in fireplaces while cheap and easy is bad for the planet and for peoples health. In Phoenix, AZ they have made wood fireplaces illegal and they cannot be installed in a new home because they caused the pollution levels in the valley during winter to skyrocket and cause serious health problems.

Even in places like Alaska it is becoming a problem. The air quality readings in places like Fairbanks, Alaska during winter is actually TWO TIMES worse than air readings in Beijing, China. At times, China's air is cleaner than Fairbanks Alaska thanks to fireplaces:

 NPR report on Poor Air Quality in Alaska Due to Fireplaces


I don't know why people think wood fireplaces is a clean source of heat, it's not. Just because it comes from a "tree" doesn't make it "green".

Doesn't the ban in Phoenix also have to do with fire risk in the arid climate?

Just to be clear, a masonry heater is NOT a fireplace. The average masonry heater generates about 50% less emissions than an EPA certified woodstove. Burning wood is "green" in the sense that wood is a currently living renewable fuel resource that has recently removed an equal amount of carbon from the atmosphere that it will add to atmosphere when it is burned. So only burning recently harvested wood would result in a net zero impact to the current atmospheric carbon level...if we were NOT burning fossil fuels... Burning fossil fuels like coal, oil and gas adds carbon to the atmosphere that was originally removed from the atmosphere millions of years ago. The earth was a lot hotter place millions of years ago when this carbon was in the atmosphere! It is certainly true that given the current state of the planet, even burning wood is harmful.

Posted By Jelly on 29 Jan 2015 02:12 PM
Doesn't the ban in Phoenix also have to do with fire risk in the arid climate?

Good question. The answer is that the ban has nothing to do with the fire risk. Ban when into effect in 1995 due to pollution  and health concerns.
Maricopa County Fireplace Ban
No Burn Days

Maricopa County/Phx, Arizona has banned all wood burning fireplaces in new homes and even outdoor firewood burning during winter. The ban was 100% environmental because the toxins from firewood caused the air quality to plummet to very dangerous levels. All valley areas that are surrounded by mountains experience "inversion" during winter. That means any and all emissions from cars, factories, etc. begins to pool and settle in the area and the winds become stagnate. The air quality begins to deteriorate fast if you start pumping out pollutants. There even have been cases of inversion in the USA that caused the rapid deaths of 100's of people back in the early 1900's.

That is why even areas like Fairbanks, Alaska which has a lot of trees, forests, etc has the air quality of Bejing, China thanks to people burning their fireplaces during winter. It's a serious problem that is often overlooked by people because they believe that burning trees/firewood is "green" because it comes from trees and is "natural" but the toxins in wood when burnt will kill you and destroy your health faster than a new coal factory being built next door.

Burning wood in fireplaces during winter is not green and not a wise choice to use as the main heating source for a home. During no burn days my lungs begin to have issues and I know the air quality is horrible just from how I feel in the AM when I breathe the polluted Phoenix air during winter.

New EPA wood stoves fairly low particulate emissions , under 4.5 grams per hour but many are less. There is a big difference between open fireplace and wood stove as the chart shows.

Posted By agagent3 on 26 Jan 2015 08:19 PM
My son is planning on building an ICF story and a half home. The home is near Waterloo, IA and 1,672 square feet. The question was how to optimize the HVAC system. I downloaded BEopt and listened to all the training videos. I input the pertinent information associated with the proposed home and ran three design scenario’s varying only the HVAC system; a boiler (the base system) with central air, ductless air source heat pump and a ground source heat pump. The BEopt results showed the air source heat pump had the lowest initial investment ($5,188 less than the boil) while the ground source heat pump was $7,136 more than the boiler. It also calculated the cost saving on the utility bill to be 11.3% on the ASHP vs. 12.0% for the GSHP. I’m not sure how the program “ginned up” those numbers but I think the overall relationship between the HVAC systems is correct. Does anyone have any insights on BEopt to share? How much confidence should one have in BEopt? I also looked at double pane vs. triple pane windows. BEopt showed a $23 yearly utility bill difference between the two and a two hundred year simple payback for the triple pane! My take is that windows just are not a good wall component or investment choice. Thus one should not get sucked up in to the window game. I understand BEopt does a Manual J. It came up with 25 MMBtu for the heating season. Again, what is the confidence level on that calculation? I have run the numbers on the home design using 2 different spreadsheets and an on-line tool and have all have been in the same ballpark.

ASHP seems like a good bet based on very low heating load.

$5000 installed is the same price I have around here for Mitsu FE18 or FH15, which to me seems expensive compared to the cost of the unit. 

The general consensus seems to be that Manual J has a little fluff built in.  That is, if you put accurate numbers in, it'll give you a heat loss that would be slightly higher than actual.

If you ran the same numbers and came up with similar results on multiple different programs, I would bet you are in the right range.

Again, great thoughts. If I have an abundance of wood I would be more "green" if one turned the wood into lumber or furniture. If fireplaces are so horrible in terms of particulate matter, is there an EPA rated fireplace that is more similar to EPA rated wood stoves?

You can get an EPA rated wood fireplace insert that should be burn similarly to a wood stove.

On a new construction, I think just a stand alone wood stove would be more effective, easier and cheaper but I could be wrong.

Yes, perhaps the wood stove would be best. I found a stove the burns either wood or pellets from Rika. They rate it as heating 266 cubic meters and an output of 9 Kw. The conversion from Kw puts it at about 30,000 Btu. I think that would be enough for those 30 below zero days. Or am I wrong? The conversion from the cubic meters is about 800 cubic feet, but that seems awful small? An I missing anything?

Yes, perhaps the wood stove would be best. I found a stove the burns either wood or pellets from Rika. They rate it as heating 266 cubic meters and an output of 9 Kw. The conversion from Kw puts it at about 30,000 Btu. I think that would be enough for those 30 below zero days. Or am I wrong? The conversion from the cubic meters is about 800 cubic feet, but that seems awful small? Am I missing anything?