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Plan: Off grid solar with a Model S battery pack at the heart
- Thread starter wk057
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It should be in the few hundred buck range. It's going to depend a lot on your location, and how common this kind of thing is. It's likely a lot cheaper out west where this sort of thing is presumably common. Making it mandatory should only make it cheaper. Presumably most HVAC guys that are doing the work would be the ones doing the test if its now mandatory, I wouldn't think it would add very much to something like a A/C system replacement thats generally in the several thousand range. Forcing the contractor into measuring duct leakage, and presumably fix problems, might even end up forcing those guys into making the duct systems tighter from the start. So many of these older systems are absolute garbage with huge leakage, especially on the return air. It's such a shame, since the cost to slather mastic on the ducts is not significant, and running a bead of caulk on a stud before putting the sheet meal down would go a long way to improve indoor air quality and lower indoor radon levels. This is not difficult stuff, it's just skipped since most homeowners won't notice.
Tedkidd
Member
This is outside my field of expertise, unfortunately.
Anyway, I'm starting to have some more time to start working on this particular aspect while I wait on parts and such for my ground mount array install. So, where should I start?
Don't start with surgery. Start with measurement, diagnostics and planning.
Did you simply start randomly buying and installing solar and batteries?
Don't assume you know where your house is deficient and start "fixing" unless you enjoy wasting your time and being frustrated.
If you were going on a diet, would you step on a scale? When? Before, during, and after, right? You would measure your progress and set a goal. You would keep going until you reached your goal.
If you are going to diy this project, you should probably buy yourself a blower door. Thats the home performance version of a bathroom scale.
Pffft. That's crazy talk! *starts adding layers of insulation to everything*
j/k
Yeah, I've been researching and just trying to get a feel for what would be the easiest place to start. I'm only just now *starting* to have time to really dive into this, and I really won't have a substantial amount of time for another few weeks. But, I don't like being idle...
I called around to a few places within a reasonable distance and didn't really find anyone that seemed competent in the field. So, it's looking more like the DIY route is going to be the way to go.
I looked around a little at blower doors.... commercial setups seem pretty expensive. For a fan, a tarp, and a pressure gauge something like $2k seems a bit much. Seems like something I could probably DIY for a tenth of the cost, but I don't know.
Walking into my attic, common sense is telling me that I need better ventilation up there, and I'm thinking that can't hurt anything but who knows.
In any case, definitely going to be a long term project.
Tedkidd
Member
If you can't find BPI certified professionals in your area, look for HERS raters (resnet).
If you can get a blower door setup for $2k, that's a good price. It probably won't depreciate much when you go to sell it in a year, and you'll likely get $2k of value and knowledge from it in the meantime.
Leave the common sense at the door. It's flat earth thinking.
If you can get a blower door setup for $2k, that's a good price. It probably won't depreciate much when you go to sell it in a year, and you'll likely get $2k of value and knowledge from it in the meantime.
Leave the common sense at the door. It's flat earth thinking.
Been gone most of the day today, so set thermostats to away this morning. Inside temps 72 and 74F on the two bottom zones and ~84F on the attic/loft zone.
Outside temp ~95F. As of 5:45 PM, inside temp is now 83F on the bottom two zones and has been holding 90 in the loft/attic with short runs of that A/C unit. (Heading home, so set it back to home to cool it down by the time I get there).
It was mostly sunny according to my solar output up until about 30 minutes ago.
Seems like the house soaked up a decent amount of heat during the day.
Outside temp ~95F. As of 5:45 PM, inside temp is now 83F on the bottom two zones and has been holding 90 in the loft/attic with short runs of that A/C unit. (Heading home, so set it back to home to cool it down by the time I get there).
It was mostly sunny according to my solar output up until about 30 minutes ago.
Seems like the house soaked up a decent amount of heat during the day.
Tedkidd
Member
Might want to set thermostats to 77 when you are away. You have enough data to calculate if there is measurable energy cost to this approach.
Letting the house get hot and wet is a comfort and control nightmare. Keep mean radiant and latent at a more reasonable place and you won't be dealing with "uncomfortable at any air temperature" situation.
Once we fix a home our goal is to never adjust the thermostat. If we see the homeowner make adjustments, it's a sign of discomfort. Discomfort is sign of design or implementation failure.
We want people to say: "Holy Cow, we're saving 29% and our home has never been so comfortable!"
We DON'T want people to say: "We're saving 30% but our house still kinda sucks..."
What people think EE is and what it really is are two different things. EE is sigmoidal. It is WAY better to go a little bit too far than to go a little bit too short: How Has Poisoned Energy Efficiency : Greentech Media
- - - Updated - - -
Want the red house or the green one?...
This is a before and after of a house my friend Mike MacFarland fixed.
Letting the house get hot and wet is a comfort and control nightmare. Keep mean radiant and latent at a more reasonable place and you won't be dealing with "uncomfortable at any air temperature" situation.
Once we fix a home our goal is to never adjust the thermostat. If we see the homeowner make adjustments, it's a sign of discomfort. Discomfort is sign of design or implementation failure.
We want people to say: "Holy Cow, we're saving 29% and our home has never been so comfortable!"
We DON'T want people to say: "We're saving 30% but our house still kinda sucks..."
What people think EE is and what it really is are two different things. EE is sigmoidal. It is WAY better to go a little bit too far than to go a little bit too short: How Has Poisoned Energy Efficiency : Greentech Media
- - - Updated - - -
Want the red house or the green one?...
This is a before and after of a house my friend Mike MacFarland fixed.
Since everyone likes graphs.. Heres the load from a shower with DWER.
Looks like the temp was adjusted within the first minute, and remained unchanged for the duration. About two minutes in, the sharp drop off with a slight overshoot is probably the tankless unit freaking out when the incoming water temp rises a bit unexpectedly, then it slowly drops off and maintains from there.
Financially the returns are not terribly overwhelming for most, but it is nice when its this obvious. Normally the consumption would be a horizontal line from that first initial temp adjustment. About a 35-40% savings after 4 minutes.
Looks like the temp was adjusted within the first minute, and remained unchanged for the duration. About two minutes in, the sharp drop off with a slight overshoot is probably the tankless unit freaking out when the incoming water temp rises a bit unexpectedly, then it slowly drops off and maintains from there.
Financially the returns are not terribly overwhelming for most, but it is nice when its this obvious. Normally the consumption would be a horizontal line from that first initial temp adjustment. About a 35-40% savings after 4 minutes.
nwdiver
Well-Known Member
With SunPower 435w panels that's ~26kW :love:
I'm surprised that more people don't build solar into new homes; It's A LOT easier to run conduit before walls are up AND you're basically cash flow positive from day 1. If you can get it installed for $2/w have average solar insolation and good net metering laws a 26kW system would cost ~$52k and generate 42MWh/yr. Your mortgage would go up by $250/mo and your electric bill would go down by $350/mo.
Setting at 77 and both systems still run quite a bit. (I tend to ignore the attic/loft system since it is unoccupied, and I can condition it for a couple of days before it gets used by guests.) I have the upstairs/zone 2 system set at 77 during the day normally, since most activity happens downstairs during the day. The downstairs system is around 74 during the day and runs pretty much continuously.
@TedKidd - Looks like I need to find the Hickory, NC equivalent to Mike MacFarland
Tedkidd
Member
You could try connecting with Mike - he might work with you. There are probably 5 people in the country that are within eyesight of his rear end, I doubt any are near you. None I'm aware of.
Nate might be going to Tennessee this summer, I could get him to go to NC too.
Vetting is tough, there are so few that are any good. Try these - lemme know what you find out:
Centennial Energy Solutions LLC
Cornelius, NC
Morris Jenkins Company
Charlotte, NC
These guys may have some envelope skills:
Blue Ridge Community Action
Morganton, NC
Find a BPI GoldStar Contractor and Companies with BPI Certified Professionals on Staff Near You
28602
Find a Contractor, Auditor or Builder | RESNET
You can spend some time here: HVAC-Talk: Heating, Air & Refrigeration Discussion - most contractors who spend time there know infinitely more than the average tin knocker
Energy Smart Home Performance :: Energy Smart Home Insulation Contractor Attic Walls Basement
Nate might be going to Tennessee this summer, I could get him to go to NC too.
Vetting is tough, there are so few that are any good. Try these - lemme know what you find out:
Centennial Energy Solutions LLC
Cornelius, NC
Morris Jenkins Company
Charlotte, NC
These guys may have some envelope skills:
Blue Ridge Community Action
Morganton, NC
Find a BPI GoldStar Contractor and Companies with BPI Certified Professionals on Staff Near You
28602
Find a Contractor, Auditor or Builder | RESNET
You can spend some time here: HVAC-Talk: Heating, Air & Refrigeration Discussion - most contractors who spend time there know infinitely more than the average tin knocker
Energy Smart Home Performance :: Energy Smart Home Insulation Contractor Attic Walls Basement
If you can get someone as experienced as Mike, you should have no option but fantastic results that presumably would give reasonable payback periods. I think these savings go even a bit further living off grid, even with your huge system.
One thing I find interesting, is how high my VOC's went the past few days. Normally if they go up a bit in the day, they go back down at night. Presumably from leakage. However, that does not appear to be the case the past few days. My VOC meter slowly crept up, sitting in the 40-50's. The only thing that changed was I turned the HVAC into away mode downstairs for about a week since I was away a few days and it peaked at 73ºF, so I figured I would keep it off and see where it goes. Normally the VOC's indicated on my Honeywell IAQpoint2 stays in the single digits, unless theres people over. It might go up to 20 from cooking something, but go down in a few hours. So 40 something from just setting the HVAC to 76, or effectively off, is a little odd. While I was away it was hot, but the past few days it was more along the high 70's, cracking into the 80's. So my thinking is the similar indoor to outdoor temps is almost eliminating my usual leakage from stack effect. It would be nice if there was a reasonable way to measure leakage all day without a permanent blower door install. I would like to get some data with a fast manometer precise enough to measure the small changes in indoor pressure over the course of the day. I'd like to see the indoor and outdoor pressures correlated to things like wind speed and temps. Presumably its a breeze thats making my damper on the bathroom fan flap around, but it could be useful to measure at what pressure differential this occurs, and I could then optimize leakage and measure its impact on this pressure differential required to move the flapper audibly. Presumably this would be some practical indictor of leakage. It sure moves a lot less now than it used to.
Having the home maintain a comfortable temp without any equipment running is nicer than I thought. This time of year it looks like I can get away with just switching the system off, it holds 68-73º indoors with it being 58-84 outdoors. I still prefer 68º and 45% RH, so ill flick it back on, but its making me want a full out passive house even more. An off grid passive house that heats and cools itself with its own energy is really the business.
Although I should note, my upstairs still kinda sucks and gets hot. Cooling it is no big deal with a 28 SEER mini split, but heating when its holding -10ºF for days is brutal. It probably has a lot to do with the fact that its just a larger bed/bath and loft area, so its effectively one large room with 4 exterior walls and a roof with no shading.
One thing I find interesting, is how high my VOC's went the past few days. Normally if they go up a bit in the day, they go back down at night. Presumably from leakage. However, that does not appear to be the case the past few days. My VOC meter slowly crept up, sitting in the 40-50's. The only thing that changed was I turned the HVAC into away mode downstairs for about a week since I was away a few days and it peaked at 73ºF, so I figured I would keep it off and see where it goes. Normally the VOC's indicated on my Honeywell IAQpoint2 stays in the single digits, unless theres people over. It might go up to 20 from cooking something, but go down in a few hours. So 40 something from just setting the HVAC to 76, or effectively off, is a little odd. While I was away it was hot, but the past few days it was more along the high 70's, cracking into the 80's. So my thinking is the similar indoor to outdoor temps is almost eliminating my usual leakage from stack effect. It would be nice if there was a reasonable way to measure leakage all day without a permanent blower door install. I would like to get some data with a fast manometer precise enough to measure the small changes in indoor pressure over the course of the day. I'd like to see the indoor and outdoor pressures correlated to things like wind speed and temps. Presumably its a breeze thats making my damper on the bathroom fan flap around, but it could be useful to measure at what pressure differential this occurs, and I could then optimize leakage and measure its impact on this pressure differential required to move the flapper audibly. Presumably this would be some practical indictor of leakage. It sure moves a lot less now than it used to.
Having the home maintain a comfortable temp without any equipment running is nicer than I thought. This time of year it looks like I can get away with just switching the system off, it holds 68-73º indoors with it being 58-84 outdoors. I still prefer 68º and 45% RH, so ill flick it back on, but its making me want a full out passive house even more. An off grid passive house that heats and cools itself with its own energy is really the business.
Although I should note, my upstairs still kinda sucks and gets hot. Cooling it is no big deal with a 28 SEER mini split, but heating when its holding -10ºF for days is brutal. It probably has a lot to do with the fact that its just a larger bed/bath and loft area, so its effectively one large room with 4 exterior walls and a roof with no shading.
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Tedkidd
Member
Probably high 50's, not more than 60. It takes a bit more than I'd like to hold 45%RH, and my thermostat is kinda jumpy in dehumidification. On a rainy day, my TED data is all over the place with dehumidification calls of various durations and spacing between them. I put it on a 10 minute delay, and might turn the fan speed up. It could just be how things are, but my house requires effort to hold RH whereas it holds temp OK.
The VOC's are sitting at 1 right now with the HVAC back on. I could switch it off and see if it goes up again. I have UV+PCO, but its only on when VOC's go above the setpoint, and it didn't run in a while.
The VOC's are sitting at 1 right now with the HVAC back on. I could switch it off and see if it goes up again. I have UV+PCO, but its only on when VOC's go above the setpoint, and it didn't run in a while.
Tedkidd
Member
I never tried to get the RH that low. My dehumidification is nowhere near as powerful as I'd like, it would probably have to run half the time to maintain 40. And it just about never gets that hot in here. Heating season is low 60's cooling is high 60's. Although its cold and raining outside, so I might goose the stat and see what happens. It's been sitting at between 1 and 0 VOC lately, so its making me think its likely simply the lack of natural leakage over those days. I have no ventilation setup right now. It's never really an issue until something causes the VOC's to shoot up, then it could take days for that to go away unless I run a bath fan for a long while. I'm thinking of making the VOC meter open a damper from outside to the return air, pressurizing the house slightly. I'm not sure if I would need to filter it before it hits the media filter though. The house allready has a fresh air intake in the basement for some reason, with one of those barometric damper's on it. I don't see why thats required, so I could just plum that into the return air.
Tedkidd
Member
Be careful. Do you have natural draft water heater or furnace? That scuttle could prevent back drafting when you run the dryer or kitchen fan.
Nope. I would replace an atmospheric gas tank right away. I have meter melting electric tankless and a sealed high efficiency gas furnace. That vent has been taped over for a while now. It used to provide a tiny trickle of air all the time, and didn't appear to change much with dryer use oddly enough. I've been meaning to find a good way to seal the basement a bit better. Presumably theres considerable leakage through the sill. Looks like theres fiberglass between the foundation and sill. I could throw ~2000 CFM upstairs by opening the lower door on the furnace, so that ought to make leakage clear. I'm not sure if caulk is the best product to seal that area.
Trying something a little different for a few days to see how it goes. I have a portable 12,000 BTU 120V A/C unit (~1.3kW power usage) that I'm going to try and use to condition the basement and electrical room space and close the rest of the vents down here.
Then each other zone just has one floor to deal with, which should be pretty easy I would think.
*shrugs*
A couple of days ago it hit almost 100F outside and my first floor/basement unit was struggling to hold 77F (didn't shut off until the sun went down). The 2nd floor unit was holding 77F with about a 75% duty cycle.
I have some more travel coming up, and then finally will have more time to actually dive into the balance of this whole project (getting the ground mount array installed, efficiency improvements, etc)
Then each other zone just has one floor to deal with, which should be pretty easy I would think.
*shrugs*
A couple of days ago it hit almost 100F outside and my first floor/basement unit was struggling to hold 77F (didn't shut off until the sun went down). The 2nd floor unit was holding 77F with about a 75% duty cycle.
I have some more travel coming up, and then finally will have more time to actually dive into the balance of this whole project (getting the ground mount array installed, efficiency improvements, etc)
