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kavade
New Member
Posts:51
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| 17 Dec 2011 07:46 PM |
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Heaven knows, I'd like to be a zero net energy person. But you know the screens only cover half the window - the part that opens-
and some of the windows have no screens because they don't open.
However, as you say, every wee bit helps, so I will remove the screens in the winter, and I will add a solar air heater. But so far I can't see any way to do away altogether with a propane wall furnace. Yet. I'm working on it. |
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jonr
Senior Member
Posts:5341
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| 17 Dec 2011 10:10 PM |
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Electric baseboard may be about the same cost to operate and much cheaper to install. |
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Lee Dodge
Advanced Member
Posts:714
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| 18 Dec 2011 10:08 AM |
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Kavade-
I stand corrected concerning my estimates for energy savings by removiing screens. I was thinking of my own situation with full-length screens on double-hung windows. The energy increase would be much less in your case, but at least the price is right!
Concerning your propane wall heater that gets blown out by high winds, is there no way to add some baffling on the air inlet to fix the problem? Perhaps add onto the inlet air ducting something so that the inlet faces opposite to the prevailing wind direction. You might need to check the flame color if visible to make sure that you don't cause it to run rich. Then you could also add a carbon monoxide monitor inside for the same reason, and they are good to have anyway. The price for this approach would be very modest. |
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Lee Dodge,
<a href="http://www.ResidentialEnergyLaboratory.com">Residential Energy Laboratory,</a>
in a net-zero source energy modified production house
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jonr
Senior Member
Posts:5341
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| 18 Dec 2011 12:08 PM |
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You may be able to optimize the well pump/generator setup. Most (but not all) well pumps have a high starting current (requires an oversized generator) and then much lower operating current (engine runs far below maximum efficiency). |
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Dana1
Senior Member
Posts:6991
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| 20 Dec 2011 03:26 PM |
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Posted By jonr on 17 Dec 2011 10:10 PM
Electric baseboard may be about the same cost to operate and much cheaper to install.
How does electric baseboard make ANY sense for an off-grid installation ? Propane/gas fired generators run at ~20% efficiency vs. 80% + for fossil-fired heaters. The upfront costs of the PV, inverter & battery required to run any signficant baseboard is excessive too, and would have to be compared to what it would take to run a mini-split, trading off the higher costs of the heat pump against that of the 3x larger PV, etc. Electric baseboards only make sense on-grid in low priced electricity markets (preferably with off-peak power rates factored in.) |
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jonr
Senior Member
Posts:5341
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| 20 Dec 2011 03:50 PM |
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Of course one would recover heat from the generator - but I lost track of the context.
With the grid, electric often beats propane, even with normal prices and especially if you factor in install costs. |
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dbollermann
New Member
Posts:20
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| 01 Feb 2012 11:22 PM |
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What kind of well pump do you have? If you don't already have one, you may consider going to a more efficient pump or a pump with no start surge. |
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kavade
New Member
Posts:51
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| 03 Feb 2012 08:14 AM |
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What kind of pump would have no start surge?
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dbollermann
New Member
Posts:20
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| 03 Feb 2012 10:06 PM |
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Grundfos SQ has built in soft start, so there is no starting surge. The Grundfos SQE has soft start and a bunch of other features including variable speed drive but I do not recommend it for off grid if every watt counts because there is an efficiency penalty in running a centrifugal at reduced speeds. The Grundfos SQF series is specifically designed for off grid, very efficient, and the helical rotor models (through 11 SQF sizes) will have superb efficiency at part loads as well. SQF models will run on AC or DC as well. They are a little bit pricey but if you just want to eliminate the start surge the SQ series is reasonably priced and will do the job. Which of these may work best is determined by the specifics of your system. |
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kavade
New Member
Posts:51
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| 04 Mar 2012 04:59 PM |
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I'm thinking about building a small SIPs cottage on my property.And I am very interested in solar air collectors. I'm also interested in the way Koreans traditionally heated their floors by
passing hot air under the floor - an ancient kind of radiant heat I guess. In new construction, would it possible to design a system that was like the Korean system, using hot air from a solar collector? I've tried to imagine how this might work. If the floor is 10" SIP panels, then one could not have channels there, but perhaps if a kind of false floor (large furring channels?) were put on top of the SIP floor, then hot air could be directed under that? |
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Alton
Veteran Member
Posts:2157
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| 04 Mar 2012 07:10 PM |
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Have you considered prestress hollow core planks? If a factory is not too far away, hollow core planks can be reasonable in price. If the span is short then the planks can be fairly thin. I admit it makes more sense to use hollow core planks over a basement than it does for a floor in a cabin but the open cores could be used for air passages. The planks would need to be insulated on the bottom side to make the top side nice and warm. The concrete in the planks would soak up the heat and pass it on to the cottage. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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kavade
New Member
Posts:51
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| 05 Mar 2012 04:06 AM |
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So you're thinking of using the planks for the cottage floor, instead of SIP panels? I'm not familiar with the planks, but I'll check them out. Could be an idea. Thanks. |
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Alton
Veteran Member
Posts:2157
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| 05 Mar 2012 09:52 AM |
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Some motels use prestressed hollow core planks for floors and ceilings. When you look up and see a V-groove every 4' in the ceiling, then more than likely, the grooves are from the joining of two 4' wide hollow core planks. Back when earth sheltered homes were in style, some homes had ceilings/roof made with hollow core planks. The cores were used for utility chases.
Not only are hollow core planks used for flat ceilings/roofs but they can also be installed for pitched roofs. Each precast manufacturer should have an idea of the maximum pitch the roof can be for their planks.
Non-void sandwich (concrete/insulation/concrete) precast panels are primarily used in projects larger than residences. (See Altus Precast Carboncast.) Hollow core planks are regularly used in all size of projects. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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