Panelhead
New Member
Posts:12
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| 17 Feb 2009 10:51 PM |
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OK, I have been doing the research on radiant heat and radiant heating systems. I've worked on several project that have used radiant heating systems. Now I'm working on a small house plan that I want to be able to be a Net-Zero home someday. First I'm starting with the basic must haves.
Super Insulated shell: I sell SIP panels so I have the shell structure figured out.
Highly efficent windows and doors: I need to research and price check more on the windows and doors. I'm familar with the windows to a piont I know for a fact that I would place the building to take advantage of some passive solar. (open to suggestions)
heating and cooling system: This is where things get out of my comfort zone. I want to use solar for hot water for sure to start. where I'm at it works out well for pay back. Now if I were to utilize a product like Warmboard for my floor systems and run the heat loss calcs. on the shell could I size the solar hot water system to provide sufficient hot water to HEAT the house in say Minnesota/Wisconsin. (What would that system look like?)
As far as cooling goes a tigh shell needs fresh air from an HRV so i would incorperate a humidifier/ dehumidifier to my fresh air system (ie NO AC!)
Oh did I mention that this house would be sized and geared towards young families and will need to be affordable. Say under $225k
Am I crazy?
Andy in Wisconsin
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BadgerBoilerMN
Veteran Member
Posts:2010
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| 18 Feb 2009 08:10 AM |
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Not crazy just a little short on the math. You will have partial DHW supply and will need a backup. You could have heat enough for sunny days when it's not too cold, but would need storage and a backup when cloudy or too cold. ROI is going to be decades.
This scenerio will change with time, but I'm not holding my breath for solar in cold climates.
Not what you want to hear but I'm sure this will provoke the commited. |
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craigsward
New Member
Posts:13
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| 18 Feb 2009 09:27 PM |
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I'm doing the same thing panelhead. Starting with enough collectors and a sized storage tank that would be big enough to support my radiant floor and DHW.
First and foremost for me is picking the boiler and installing the radiant in the downstairs.
My solar engineering uncle was over today and did some calcs to figure out the size boiler and to think about future retrofit of integrating solar. Payback will be a bit quicker for me seeing my panels are only $200 a piece for 4x8's and i'm (we) doing the install, but i can see how if you had standard pricing on a solar system and installation expenses, payback would be an issue.
Good luck with your project.
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Brawler
Basic Member
Posts:229
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| 19 Feb 2009 07:39 AM |
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I am in the process of building what i hope to be a solar assisted radiant system for the house i am constructing. You can view my project "Lucky Cove Cottage" to see what we have done. We have lots of clear cold days here in southern North carolina. I am now on the second floor, floor system and need some expert advise. Morgan, what do you think is the best medium for pex in my situation? The thread i started a couple days ago gives alot more detail. I know you arnt a huge proponent of solar water house heating but you know this radiant stuff back and forth so any help would be great. thanks |
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Panelhead
New Member
Posts:12
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| 19 Feb 2009 09:47 AM |
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Thanks for the repilies. I have another idea i guess. I have thrown around the idea of creating a giant heat sink under my garage. The 8" sip foundation that I would use would be roughly 8' deep. i would use xps foam (thickness to be determined) on the bottom as well as between the heat sink and the slab. I would then fill the hole thing with sand while every so often run pex from the solar collectors as well as pex running to the house to draw out the heat. The idea would be that the solar collectors would store all the heat in the summer mounths as well as provide all the hot water. Then in the winter when the solar wouldn't be able to keep up with the heating demand it would pull from the heat sink. I've heard of a few systems like this but have not be able to get ahold of the owners to talk about them. Any thoughts. |
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Jesse Thompson
New Member
Posts:89
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BadgerBoilerMN
Veteran Member
Posts:2010
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| 19 Feb 2009 11:25 AM |
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I love solar! but unfortunately get a lot of calls from people who are disappointed with their systems (both DIY and to a lesser degree, professional). This makes me cautious and conservative in colder climates.
This is a complicated subject, but you will soon find "packaged" solar heating systems making it somewhat easier. In the mean time: "Solar Hot Water Systems" lessons learned by Tom Lane.
Sand is a poor storage medium. |
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Panelhead
New Member
Posts:12
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| 20 Feb 2009 06:06 PM |
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Yes, I have talked with the good people from conservation technologies. I attended and exhibited at the duluth energy and design conference two years ago. My collegue Curt Stendel will be presenting at this years conference. I've talked to several designers about a large heat sinks and the storage medium is always the hitch. I know sand isn't the best medium but its cheap and plentiful. We've looked into using the tailings from the iron ore mines in northern MN. I don't like the idea of water. what else would be an option? Thanks, Andy in wisconsin |
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dmaceld
Veteran Member
Posts:1465
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| 21 Feb 2009 11:15 PM |
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I considered solar assist for space heating when I started designing my ICF house. Fairly quickly came to the conclusion it wasn't practical for me. Main reason? Solar supply is minimum when heat load is maximum. Solar supply and space heating needs are 180° out of phase, both daily and seasonally. Makes for very difficult design options with regard to panel size and heat storage capacity.
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| Even a retired engineer can build a house successfully w/ GBT help! |
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BadgerBoilerMN
Veteran Member
Posts:2010
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| 22 Feb 2009 04:17 PM |
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You are correct. As much as I would like to use solar in my space heating designs (still works in mild climates with lots of sun) I just can't get a reasonable amount of panels to provide a reasonable amount of output. The answer is really super-insulated, high-mass, passive solar. All of the "successful" solar heating systems in cold climates seem to have 100% fossil fuel “backup”. I am not apposed to this; I just don't see the evidence that it is a panacea. |
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