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Well after many hours of research i have determined it is not cost efficient for this active solar home due to the replacement of the entire system. I have definitely learned a lot about new battery Tech. and the way a system should be setup. I cant thank you guys enough this is probably the most informative forum i have read.my estimate is around 70 to replace the system and that is not going to work. I have come across another solar active home with a much better setup. I have not had the opportunity to visit this property yet but the setup is definitely an improvement. Good news is Grid power is at the end of the drive, bad news is my guess is about $10.00 a foot for overhead and even more for underground for a grid tie if needed. It is only me and the wife no furnace or AC.Heat is radiant floor and pellet and wood, with 10 k backup generac. I believe it also has some wind power also but i have not been impressed with the wind numbers yet. still lookin in colorado.
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Good we can keep one person from jumping off the cliff
. Unfortunately some other person wont even think about asking questions and end up with expensive education. Optimistic at best wind might work in 1 out a 100 sites. Most folks don't want to live where the wind is blowing enough consistently for wind turbine to make sense.
It always bugs me that many utilities charge a big premium for underground. In my area we have a lot of trees and inevitably the trees grow up near the service and at some point a tree comes down on a wire and takes out the service which means an emergency call. My utility doesn't encourage it but if I dug the trench and installed the conduit they would pull a direct burial feeder through if for the same price as overhead. In an adjacent town they wont issue a electrical permit unless the line is buried.Comment
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I wonder how they heat up the place, seriously. I'm not buying BS about 'thermal mass' keeping them warm through the winter, all that concrete would lose heat in a matter of hours, not months. I also don't know if there were any people in the building- supposedly they were warming up the place with their bodies but that process has a lot of byproducts which are released into the air even if we ignore mismatch between # of ppl required to warm up the place this way. How did they go about filtering all that stale air or was it their internal garden taking care of that? One thing I found living in the moderately cold climate is you still need air exchange with outside if you want to make it through the winter and not be constantly sick with one respiratory infection or the other.Comment
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I realize its thread drift but a properly designed Passivhaus or even the home brew Green Building Advisor Pretty Good House can have very little external heating need even in very cold climates like northern NH and VT. I remember a person boasting of the minimal heat required in a Pasivhause project a couple of years ago, they had an air to air heat exchanger system that used forced draft fans and had small heaters on the indoor vents to temper the outside air after it had gone through a heat exchanger, turns out they excluded the electric heaters in the ducts when they calculated the heating load as the heaters were contributing most of the heat to the house. It was all fed from a net metered solar power but could have just of well been fed by a robust offgrid battery based system (with a standby generator conveniently hidden away in shed. The key with thermal mass is having it inside the insulation envelope. Most folks forget that and regret it. Most of these high efficiency homes get away with a very small woodstove or a minisplit for supplemental heat and they usually only use them after a sustained cold snap. Unfortunately unless the designer has their act together that same thermal mass can make the house a very unpleasant place to live in the summer.Comment
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Even though bastardized for B.S. reasons in the Lovins design, the idea behind the building is one that's been around for several thousand years. It's largely passive solar energy, or suntempered design.
Buy the idea of thermal mass. It is not B.S. Making it cost effective may not be possible in every application, but it, or various iterations of the concept, do have their place, with most all of the residential applications being a lot shorter than seasonal.
On your educational journey, take a stroll through the concepts of thermal mass and insulation and how they can compliment one another, as well as a good measure of building sealing while keeping indoor air quality in mind, and how those things can be used in ways to help produce a very energy efficient building.
Think of the building as something of a thermal capacitor with a lot of Farad capacity and a goal of a low leakage rate.
Aside from Amory Lovins being one of the con men I rail about and the building he came up with (with a lot of free help/labor from his disciples) as an environmental and engineering joke - the idea of growing bananas in the Rockies was actually an original design goal in when conceived in the early '80's - the idea of a suntempered, VERY well insulated and thermally massive building done in a regionally and environmentally appropriate combination of those features, if done correctly, can be produce a very comfortable design. Cost effectiveness is the bigger challenge.
Basically, the idea is to have a design with a very large thermal time constant, or a large ratio of thermal mass to overall heat loss. Once the building heats up, it'll take a long time to cool down, and vice versa. If the heat loss is low enough and the climate is sunny, it's possible to supply a significant portion of the building heat load with fenestration, with the thermal mass helping to avoid interior overheating and also allowing the solar gain to reduce aux. heat addition requirements long after the sun sets.
The idea of seasonal storage is similar, but for the most part much less practical. The reasonable and practical limit for a residential building time constant these days is probable about 50 hrs. or so. My solar magnum opus in the desert had a design time constant of ~ 170 hrs., but that was pushing the envelope. That design would have all code required HVAC, but not use it very often, and probably be mostly/entirely self sufficient for winter heating without daytime overheating.
With respect to existing dwellings, I took the thermal time constant for an existing residence built in 1928 in Buffalo from about 6 hrs. up to about 16 hrs. by lowering the heat loss and adding a sunspace with pretty good moveable insulation that contained about 6,000 BTU/deg. F. of thermal mass coupled to the rest of the building through the HVAC system.
As for body heat, depending on a lot of stuff, ASHRAE will tell you a body might kick off ~ 150-300 BTU/hr., depending on activity level, between sensible and latent (vapor) loading. Most of the time, unless the application is a theatre/auditorium/classroom, etc. that load is mostly ignored for residential heating/cooling applications.
Indoor air quality however, needs additional consideration. Until fairly recently, maybe 10 years or so, it was close to impossible to get a building envelope so tight it would suffocate those inside. Today, it's possible, using newer techniques like Tyvek wrapping, very careful attention to sealing details, not to mention insulated concrete forms, to come up with a design that will reduce infiltration/exfiltration to levels low enough to require controlled air exchange. Unfortunately, most products made for that purpose are usually less than adequate to the task with more than a few products worse than nothing in that, besides being thermally inefficient, they quickly foul up and become breeding areas for stuff that gets transferred to the incoming air, but that's a side bar conversation.Comment
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