Look what happens when you go out of town. The world keeps on going, haha. Surf, the simple best bang for the active solar buck is in DHW and even in Chicago two panels can give you 70+% of your annual load (depending on your load). I have 6 panels but that is only because I am feeding heat to an air source heat pump to better the COP (but thats beside the point).

The PV is a no brainer because the grid is your battery and the panels are long lasting (as long as you know what to look for....forget Harbor Freight, etc....get name brand stuff), especially if you are using heat pumps for your heat. You can get as close to net zero as possible this way.

What's a DHW? "something" Hot Water?

You don't have to live in a lightless cave to have a high performance house, but you DO have to consider both their solar gain and thermal losses relative to the site's shading factors and which side of the house they're on. Most certified PassiveHouse have more than the average amount of glazed surface area. What you can't get away with is a whole lot of glazed area at code-max U-factors- expect to spend some money on U0.18-U0.25 windows.

Well most of my glass is on the East and West. But, I'll get shade on these windows in early AM and late afternoon/early evening due to large trees East and West. I plan to do U-0.25 SHGC-0.25 on the West windows and 0.3/0.3 on the East (East has a bit more shading due to no driveway removing trees). The S wall has a house 20 feet away so the only passive solar is upstairs and that is two bedrooms. So that won't work.

Domestic Hot Water.

Chris thanks. Yea I figured it out a little while after. Mike, I see your website. Interesting stuff. Toronto is roughly similar to Chicago's weather.

I go to Toronto all the time (will be there Sept 30-Oct 3) for the CMTS show. I am wondering if you guys have any comment on what my guy is proposing. I would appreciate any advice! --

"I am proposing a modulating boiler that will heat the radiant floors, a hot water coil connected to a variable speed air handler to provide heat, and an indirect hot water tank to provide domestic hot water for your house. The boiler will modulate the gas flow from 10%-100% depending on the load, making sure it is using the minimum Btu's possible at all times. I am checking with our solar supplier to see if this tank will work in conjunction with his system to provide back up hot water if you decide to go with the solar thermal option he quoted. For the air conditioning I am quoting a 19 seer 2 stage air conditioner or a heat pump system, in which case the hot water coil would provide back up heat. I don't think the heat pump option is the best scenario for your system because most heat pumps only work efficiently down to 20 degrees and an electric Btu cost almost 3 times a natural gas Btu. I know you will have the solar system providing electric but I don't feel that in the long run it would be worth using the heat pump over a high efficient air conditioner. I think that the 19 seer 2 stage air conditioner would be the better investment overall. "

Posted By Surfsup on 06 Sep 2013 03:30 PM
Chris thanks. Yea I figured it out a little while after. Mike, I see your website. Interesting stuff. Toronto is roughly similar to Chicago's weather.

I go to Toronto all the time (will be there Sept 30-Oct 3) for the CMTS show. I am wondering if you guys have any comment on what my guy is proposing. I would appreciate any advice! --

"I am proposing a modulating boiler that will heat the radiant floors, a hot water coil connected to a variable speed air handler to provide heat, and an indirect hot water tank to provide domestic hot water for your house. The boiler will modulate the gas flow from 10%-100% depending on the load, making sure it is using the minimum Btu's possible at all times. I am checking with our solar supplier to see if this tank will work in conjunction with his system to provide back up hot water if you decide to go with the solar thermal option he quoted. For the air conditioning I am quoting a 19 seer 2 stage air conditioner or a heat pump system, in which case the hot water coil would provide back up heat. I don't think the heat pump option is the best scenario for your system because most heat pumps only work efficiently down to 20 degrees and an electric Btu cost almost 3 times a natural gas Btu. I know you will have the solar system providing electric but I don't feel that in the long run it would be worth using the heat pump over a high efficient air conditioner. I think that the 19 seer 2 stage air conditioner would be the better investment overall. "

He's trading on decades-old data regarding the performance of heat pumps (5 years ago I would have agreed with him, and I would have been wrong then, but even more so circa 2013.) It matters the type of heat pump you're talking about!

Better ductless heat pumps will have a COP of about 2 at Chicago's 0F design temp, 1.8 at -13F.  At part load at Chicago's ~25F AVERAGE mid-winter temp they'll do about 2.8-3.  Your average performance will be in the high-2s, maybe even the low 3s, if ductless.  At a COP of ~3 they're about dead even on heating cost, but the very high air conditioning efficiency is also built into the same unit.  Any ducted system has potential system-loss efficiency issues dependent on best-in-class duct design & installation to really get the performance out of them, but there are at least a couple of options for continuously-variable ducted systems:

Ducted variable speed heat pumps like the Carrier GreenSpeed or Bryant Evolution Extreme don't have a lot of third-party independent testing over a range of system configurations & climates the way NEEA did for ductless, but the output curves of the Greenspeed look promising for delivering design-day heat in Chicago.  (See their interactive graphic tool -tap on the "Heating Capacity" tab, and play around with the compressor & air handler unit options, as well as the maximum heat load number.)

I suspect your annual COP with one of those would fall somewhere between 2-2.5, maybe a bit better, depending on the duct design & implementation and sizing/load matching, but from a comfort point of view on par with the variable-speed hydro-air solution the guy is proposing. And either of those systems would ROCK on both comfort & efficiency over any 2-stage 19 SEER AC unit. 

A boiler and hydro-air approach would work, but could be substantially oversized for the heating load if you really pay attention to the envelope design to bring your peak & average loads down. A condensing hot water heater + hydro-air with a plate-type isolating heat exchanger would be cheaper, and still more than enough for low-temp radiant + hydro-air heating, if that's really important to you.

During the shoulder seasons the ducted heat pumps would beat the operating costs of the gas hydro-air with some margin, since the rated HSPF of 13 implies a COP of 3.8 @ 45F, and that rating includes air-handler power (and air handler + pumping  costs aren't estimated in the operating cost of  in the hydro-air/boiler combination efficiency numbers.)  If you've been drinking the frackwater Kool-Aid and believe gas will always be this cheap (with spot prices lower that the costs of producing said gas) you're looking at rough parity in operating cost, with best in class air source heat pumps somewhat more expensive to heat with than condensing gas. But gas price will (and actually MUST) rise.  If you believe electricity price inflation is imminent, there are reasons to believe it's actually going to be fairly steady or falling as more midwestern wind comes on line, given the price-flattening effect that massive wind development in Iowa and Texas has had on the price of electricity in those markets.

The marginal cost per kwh of wind is effective zero, and wind operaters are $0 bidders in the day-ahead market.  Wind that blows during peak load periods kills the traditionally high spot-market and day-ahead peak, lowering the overall average wholesale price of electricity, savings that show up in the residential retail rate.  (Wind at $0 bid is what killed the economics of the Kewaunee nuke more than anything else.) An increase in wholesale gas prices would cause electricity to rise, but at a lower rate than the cost of retail residential gas, which is even MORE volatile & sensitive to natural gas prices. The levelized cost of wind is already getting down near the cost of combined-cycle gas, and isn't subject to fuel prices- the more wind that gets built, the more it'll eat into even CC gas capacity factors, and as grid storage gets built out (and it doesn't take much to make a difference) the grid-share of wind & PV will soar.

Ok this is all great information thanks Dana. I will approach my contractor with this. For me, I understand what you are saying but I don't understand what this means relative to the load on the house I intend to build. I realize the lower the load the better but we all have budgets. The main loss of heat seems to be the walls so I will be focusing there, perhaps doing the 1.375" of polyiso on the wall exterior to kick up the values to reduce this. I will repost my BTU load HVAC-Calc results now:

Total Home Heat Gain: 41k BTUs
Total Home Heat Loss: 56k BTUs

You commented earlier thinking this was primarily solar-heated and that was not the intention. Do you think the system as you describe with the heat pump would serve me well with a reduced load of approximately 45k-50k?

What heating loads are required by other homes, build 10-20 years ago? I have no idea if my envelope is horrible, decent, good, great...? I know it is not great but it is better than 2013 code for my area which <1% of homes are built to, so it must be pretty good, yea?

Well I just went through the HVAC-Calc software and upgraded all my exterior wall definitions to R27 from R19 and I still get a 53k load. It did not affect too much. The main loads are as follows:

Windows - 17k
Infiltration - 11k
Walls - 10k
Glass Doors - 7k
Fireplace - 3.5k
Ceilings - 3.3k
Floors - 3.2k

So unless I really decide to reduce the windows, the main areas of change I can make are infiltration and skipping the fireplace entirely to save another 3.5k. Increasing wall R value up from R27 based on cost is kinda pointless...so I'm going to be at 50k BTU load.

What heating loads are required by other homes, build 10-20 years ago?

Can I ask why you would want to compare your new build to homes built 10 or 20 years ago? Mine was designed three years ago and built over the last two and there are still things I'd want to change.

Here is a comparison for you. For reference, my build was "grandfathered" in under previous code, by permit application date, so it doesn't quite comply with all aspects of 2009, but it is right in there. My heat loss was calculated at about 32k, and early indications show that it might come in more like 24k - 28k. That is for a design temp in the 'teens.

ETA: It's 7,000 sf and has a larger than normal volume, even for its footage.

Why does your fireplace have a 3.5k heat loss?  It is a sealed unit with outdoor air combustion supply, isn't it?

Interesting, the Hvac-calc software i d/l from a recommendation at hvac-talk.com was set for chicago to default at -4 degrees for winter. At 15deg, my heat load is only 43k.

The software seems to default to 3500 for any fireplace. I felT it was high as well, but didn't have any factual basis for that. It will be a +90 direct vent closed system as you state.

Perhaps the Hvac-Calc software is not as great as some think at that other forum...?

7000SF and a heat loss in the upper 20s? I'd like to know more, please share!

7000SF and a heat loss in the upper 20s? I'd like to know more, please share!

It seems to be about air sealing as the volume of the house is huge. I know it's sealed because I did it myself, but when I circulate to other homes, I don't see any sealing going on despite code requirements. For example, on one I just visited, I asked about air sealing and was told that was what the Tyvek housewrap was for and even though the workers wanted the light and ventilation, they weren't going to cut out any more than two of the windows and doors until the units arrived for installation. Whatever that means.

Other than that I have 12" TJI roof joists with 2" of spray foam up on the sheathing and blown-in fiberglass to fill. ICF first floor and 2X6 second floor with 2" of spray foam against the sheathing and filled with blown-in fiberglass. I think everything hovers right around code requirements.

Windows are U.26 to about 0.34, which is right about code, too , I think. Windows maximized on South, restricted on North and moderate on East and West. Big overhangs control insolation

I don't know what a "+90 direct vent closed system" is. When I Google it I get a bunch of gas fireplaces.

Well, the ACCA Manual J puts Chicago, O'Hare AP heating 99% dry bulb temp at -1F which is closer to -4F then +15F:

ACCA Manual J Outdoor Design Conditions

You need to use the proper design conditions for the building location. It is NOT the software that makes for a great heat loss analysis as much as having a competent person doing the analysis.

ICFHybrid. The gas fireplace technical jargon is what it is. How it relates to a 3k5 loss is simply what that software uses. I have no idea if that is high or what it should be. It is high enough to make me question having it, but I want the fireplace so it wiill likely stay.

I plan to seal the home myself. I'll probably tack up visqueen on the entire interior as we did on my dad's home years ago. He did standard 2x6 with batts and his A/C and heating bills for a 4k SF home were very low.

sailawayrb, I consider myself competent. As an aerospace engineer having studied thermal dynamics, etc, I can probably handle filling in some fields in a software package. What is the point of your last statement? My using a 15deg was simply a comparison to ICFHybrid to see how he was achieving low heat loss for 7000SF.

Posted By Surfsup on 06 Sep 2013 03:30 PM
Chris thanks. Yea I figured it out a little while after. Mike, I see your website. Interesting stuff. Toronto is roughly similar to Chicago's weather.

I go to Toronto all the time (will be there Sept 30-Oct 3) for the CMTS show. I am wondering if you guys have any comment on what my guy is proposing. I would appreciate any advice! --

Hi surf, I try to make it to the show as well. Not sure if I will make it this year. Let me know when you are there and perhaps we can meet.

I know there was some mention of using a ductless for AC. I know that some manufacturers are only going to be offering product in heat pump only (I guess to save part numbers), Fujitsu is one of them, I believe so the design could take this into account.

Surf, my comment was just a factual statement and not directed at you. There are many HVAC design software packages that provide ease of use and impressive looking outputs. There are even more HVAC pros that are totally clueless about thermodynamics/heat transfer principals and just plain sloppy when using these flashy software packages. One can accomplish a proper heat loss analysis with just a couple sheets of paper and a pencil if one actually knows what one is doing. ICFHybrid can tell you first-hand about the less than competent heat loss analysis he received while designing his building. Yes, if you are an Aerospace engineer, with a small amount of research you should be more than competent to accomplish this relatively trivial heat transfer analysis given your capability. I was an Aerospace engineer for many years myself (designed flight controls for cruise missiles, ICBMs, helicopters and airplanes) before going into Aerospace management.

I'll probably tack up visqueen on the entire interior as we did on my dad's home years ago

Sounds like you are planning a vapor barrier in there.

the less than competent heat loss analysis

Classic old-school GIGO. Employed to fool the prospective HVAC client into thinking everything is under control and sell a particular slate of products and services without argument. The software package is simply a tool that can be used for good or evil....

Precisely ICF, and some of us call this catalog engineering. Unfortunately, it is a commonly used approach in the HVAC industry. Since there is no shortage of fools to be fooled, it also a very successful approach.

I will be at CMTS all through the show (I have a booth there doing CAD/CAM software) as an OEM. ESPRIT by DP Technology my name is "V"...tall and blonde hair (I'm a guy sorry to get your hopes up!) Ok so my bad. I am trying to keep tabs on 1000 things building my own home as I work a 10 hr average day as it is so I'm getting a little rough under the edges I admit it...I am depending on others as I cannot justify the time to properly and fully educate myself on the many subjects I should. Heat loss and permeable shell I understand but the products to combat these compared to price and labor are killing me. Everyone is so secretive or outright lying... Example, one concrete guy said an ICF basement will be $79,000. I mean, come on. I get three roof quotes for $20k and one guy said it is $61k. HVAC is another animal with all the products. then marrying this to a PV and possible solar thermal system and increasing the complexity? I have a meeting with my solar guy tomorrow to go over cost per BTU and ROI. Should be interesting.

Posted By Surfsup on 07 Sep 2013 12:35 PM
Well I just went through the HVAC-Calc software and upgraded all my exterior wall definitions to R27 from R19 and I still get a 53k load. It did not affect too much. The main loads are as follows:

Windows - 17k
Infiltration - 11k
Walls - 10k
Glass Doors - 7k
Fireplace - 3.5k
Ceilings - 3.3k
Floors - 3.2k

So unless I really decide to reduce the windows, the main areas of change I can make are infiltration and skipping the fireplace entirely to save another 3.5k. Increasing wall R value up from R27 based on cost is kinda pointless...so I'm going to be at 50k BTU load.

R19 batts in a studwall is actually an R13-14 wall after thermal bridging. I'm not sure what R27 means in the context of HVAC-Calc unless it lets you describe a stackup with continuous insulation plus insulated studs or something, which is not anybody's standard code-min type of wall. R30 batts in a 2x10 studwall might be described by some as R30, but after thermal bridging it's only about R22.  The difference in a true whole-wall R27 vs an ~R20-21 whole all (center-cavity R27) is 25% lower heat loss.  The difference between an R19 studwall (R13-14 whole wall) and an R27 whole-wall is 50% lower heat loss from the walls. Comparing what the tool spit out for R19 walls to it's R27 number might tell you what it's really doing.  If the tool is calulating based on center-cavity-R studwall the R27 heat load for walls would only be ~30-35% lower than the R19 (it went from ~15K to ~10K), but if it's calculating R19 cavity+ R13 continuous insulation. it should be about half (dropping from say 19-20K to that 10K number).

But look at the windows and infiltration numbers as well as the glass doors- they're an insane fraction of the total, (35K out of 55K) all of which that can be better controlled by both design & implementation.  The total window area can be reduced & higher performance windows can be used, and an infiltration loss of 11K is a high-wind over-estimate that can be made near-zero in reality. 

So, starting at a presumed 55K heat load...

Get religon about air seaing and that infiltration number is no more than 3K (and probably less than 1K), that brings the total down to 47K...

I've yet to see a fireplace worth installing in a new house- skipping it entirely isn't insane, peel off the 3.5K an you're at 43.5K...

Reduce the total amount of window area by 25% (not a huge sacrifice in most instances) and that 17K number is now 13K, bump from U0.30 down to U0.25 (higher peformance double-panes rather than triples. to keep costs bounded) and you're at 10-11K, bringing the total down to the 37K range.

Cut the glass-door area by half and you're at 33-34K.

I'm betting that 10K wall loss is really 7K, not 10K, if the tool did what I think it did, now you're knocking on 30K.

With typical plug loads and other 24/7 internal gains you're probably going to be able to knock another 2K off that too, 250 BTU/hr per sleeping human, 150 BTU/hr per refrigerator etc.etc. unless that too was plugged into the tool.

You can either embrace what it means to have a truly high performance building envelope and the comfort that it impies, or you can keep shrugging and saying it's impossible, pointless, costs too much, etc. and end up with a 50K heat load (probably a 15-25% overestimate anyway if it's a Manual-J type tool) and just forget about it. 

But at a sub-35K heat load or less your comfort goes way up compared to the same house with a 50-55K heat load,  and you're in getting into the range of better class high efficiency air source heat pumps.  Even a ducted  variable speed Carrier Greenspeed would deliver a seasonal COP better than 2.3 in your climate, given that it delivered an HSPF of 8.2, which is a COP of 2.8 at an average outdoor temp of 37F in one third-party tested house. See p24 of this document.  A 3 ton GreenSpeed won't handle a 30K load @ 0F without some help, (play around with the setting on the capacity tab on this web-tool)  but it can handle more than 20K, and could (but I'm not suggesting it should) be the backbone of your HVAC system once you've controlled the peak loads to something more reasonable.  At the same loads 2-2.5tons of ductless CAN carry the whole load, if the floor plan layout is set up for it.

When I swapped the R19 to R27 I saw only ~3k difference in the wall load. So this is why I feel throwing $1000's at the wall for another layer of polyiso is pointless. It delivers very little savings in heat load per HVAC-Calc. But, I don't know if that software is accurate. There seem to be a lot of people that think it is at HVAC-Talk and it has been under development for many years. There have been some comments taht it is a big "high" so that helps my cause.

I can reduce windows and plan to. 25%? I don't know. It is a modern design and windows/doors "make" the design. Here, I will have to sacrifice. But I can reduce.

Good to know infiltration is high. As I said I plan to use visqueen on the whole interior side of exterior walls. My dad did this, it worked great. We will be religious about infiltration. trust me. He is even more anal and a perfectionist than me. The property is 6 blocks from where I live now I will be there everynight and weekend working on something. Insulation will be a HUGE priority. No drywall until we are both satisfied.

I can cut the glass doors to about half. but I will have to add windows to compensate so it will be interesting. Ok I know what I need to do. Now I just need to decide on this solar thermal system.

Alerted my HCVAC guy to Carrier Greenspeed and he loves it. FYI

Wife really wants the fireplace. My dad's home had an old leaky crappy one so this will likely stay.