Solar panel question...

Discussion in 'Environmental Discussion' started by Celtic Blue, May 23, 2009.

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  1. SageBrush

    SageBrush Senior Member

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    I solved the 'what about solar collection' problem by deciding to place my collectors off the roof. If you have that option it opens up many more solutions. I am lucky to have a hill I can site mine on, but I have seen panels on easels that looks quite nice. They remind me of sunflowers :)
     
    #21 SageBrush, May 25, 2009
  2. SageBrush

    SageBrush Senior Member

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    Shawn, I was surprised by you calling a 70F average temp day a 'cooling day'. Are you not able to cool off your house at night ? This graph is similar to what is true at my house, although the maximums are lower by about 5F. Humidity is 20 - 30%. I'm guessing that I will be able to modulate the ambient temps in the house to within 5F of the daily mean. I ventilate at night, and shade during the day with interior blinds on the more western and eastern and windows, but exterior and interior shades on the more southern windows . I have a polyurethane foam flat roof. Am I wrong ?
     

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    #22 SageBrush, May 25, 2009
  3. Celtic Blue

    Celtic Blue New Member

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    Official cooling degree days are typically based on 65 F using hourly averages rather than daily if memory serves. Bodies in the home, plus appliances, and radiant heating from the Sun produce enough heat that the ambient needs to be considerably lower than the thermostat. I typically set the thermostat around 80F in summer, but I've let it hit 84 and even 85 inside a few times recently without ever turning on the AC.

    The problem is not the averages, but the extremes. When it hit 86 two days ago with full sun I was lucky to keep the house at 85 by the early evening. Cooling off at night helps, but it's not easy to manage in town. Out in the sticks I would leave windows open all night and only hear typical night sounds, to be awakened by cows chewing on grass in the morning, but in town it's not quite the same atmosphere and the windows can only be slightly open while asleep. Plus it is much windier where I am now, so open windows with a rain shower can be a real problem. This reduces how much cooling I can do for the next day.

    What I've seen is that when the temp hits 80 F by 10-11 AM it is pretty toasty inside by 4 PM and won't really be cooling down inside until after 8 PM even with the windows open.

    Humidity here is running about 50% this time of the year on the days I was describing (about 75% right now, but it rained earlier today.) 20-30% humidity would be mid-winter.
     
    #23 Celtic Blue, May 25, 2009
  4. SageBrush

    SageBrush Senior Member

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    Another idea (joking): if your shingles are wood, how about spraying them with a water mist and enjoying evaporative cooling ?

    As I mentioned above, my climate is ideal for passive heating and cooling. Today was very temperate and wet (and humid for my locale), so there wasn't any real heat challenge. The house started out at 68F in the morning, peaked at 72F, and is now 70F at 8pm after cooking dinner. Outside temperature will nadir tonight at 50F. I'd like to see the house cool down to 65F. And if it cools down to 70F in the summer peak that would be brilliant.
     
    #24 SageBrush, May 25, 2009
  5. Celtic Blue

    Celtic Blue New Member

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    Yep, never was crazy about them myself, so it isn't what I would have built, but I do like the house. The high ceiling creates operational and efficiency problems. We've got ceiling fans and use them to combat the stratification in summer. I can work on them from my very large step ladder, but to reach the ceiling to hang/rehang them takes scaffolding or a true 16 foot stepladder.

    Winter has not been a problem with that surprisingly. I pinched back the floor registers through much of the upper level(s) so that the registers in the lower level(s) were getting the bulk of the heating. The upper split levels get enough buoyant hot air from below that they are fine--except one corner with a lot of glass that really needs another register.

    Summer has been when I've needed the ceiling fans, and when I've been forced to use the blower to move the too cold air from downstairs up to where it is needed. I nearly close the outlet registers in the lower levels since the AC needs to be pulling from there and expelling up top.

    The upper level returns are located at normal full wall height, with upper level registers mostly in the floor. Lower level returns are near the floor, with registers in the ceiling.

    About 5,000+ heating degree days/year. Not severe like the Upper Plains, but a good honest winter.
     
    #25 Celtic Blue, May 25, 2009
  6. Celtic Blue

    Celtic Blue New Member

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    The thing is that numerous studies have shown a relatively small impact on peak shingle temps from this. http://www.fpl.fs.fed.us/documnts/pdf1999/tenwo99a.pdf This summary gives some examples and shows that the effect on heat gain through the ceiling. One showed only a net 3% change in cooling load, another showed a 25% increase in ceiling heat gain (but this neglects to factor in total cooling load from windows, walls, air changes, etc., so the basis is completely different.) The 25% change in just the ceiling heat transfer makes sense since the decking will be cooler on average throughout the day. It's right in the ballpark of what one would predict based on temps and fixed resistance.

    Yep, ours does not have ridge vents and instead has static vents. The soffits are not blocked (I checked this last year in the attic section with blown insulation.) I have considered the guides and baffles to use in a section of flat attic that I might add some more feet of blown insulation to.

    I might have the roof converted to ridge vents whenever it needs to be reshingled. It's a fairly new roof so the last couple of hellacious windstorms that blew down two local restaurants and resulted in a lot of new roofs for my neighbors didn't seem to phase it.
     
    #26 Celtic Blue, May 26, 2009
  7. jayman

    jayman Senior Member

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    A co-worker has a house with a "cabover" bedroom. An example of a "cabover"

    http://www.ahdesign.mb.ca/Drawings/04-010P.pdf

    In winter, the bedroom floor was ice cold, as they didn't have the garage insulated. By code, the garage ceiling must have fire-rated gyproc, as a bedroom is directly above

    I gave them a hand pulling the gyproc off the garage ceiling. Had a spray-foam guy swing by and spray the entire i-joist area with iso foam, along with the garage walls

    Hung new gyproc and that made a huge difference in winter. However, that house faces SE on their lot. In summer, they could have the lower area ice cold, but the bedroom was still boiling hot

    The HVAC contractor who put in their furnace and A/C claimed they would have to live with the temperature problem. I told them about Mr Slim

    Mitsubishi Electric - Product Information for MS-A09WA

    They found a contractor locally who carries them, and put the smallest unit in the master bedroom. As a result of being able to leave the main A/C set much higher, their power bill in summer went from $120 to $74

    Not sure if this is an option for you, but if you have problems with excess heat, a small purpose-built evaporator coil mounted at ceiling height is much more efficient than floor registers
     
    #27 jayman, May 26, 2009
  8. jayman

    jayman Senior Member

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    Shawn

    A large contributor to this problem is how the building envelope is sealed. Even if vapor barrier is used, as is almost universally mandatory, is tuck tape used to actually seal the seams?

    Insulation values up here haven't changed too much over the past 20 years, although now more communities are mandating 2x6 walls. What has changed up here is the requirement for much better building envelope sealing

    As an example, older homes typically have drafty baseboard areas on exterior walls. Newer homes don't have that problem. Acoustic sealant - a flexible thick caulk - is applied to the interior junction of the bottom plate and floor. Then the vapor barrier is stapled up

    The acoustic sealent provides for an airtight seal at the bottom plate, eliminating drafts.

    As the vapor barrier is put up, tuck tape is used to seal the overlap. At one time, the overlap was just assumed to stop airflow, until tests were done that determined the vapor barrier overlap allowed significant airflow. So now tuck tape is used to ensure an air tight seal

    The cabin I sold around 10 years ago, if I heated it in winter I had significant ice dams and condensation. It had cathedral ceilings, which I will never again have. It needed a roofing job around a year after I bought it

    I pretty much dismantled the entire roof, built up extensions to allow 16 inches of space between the ceiling and roof, and used the Owens Corning rafter product to ensure proper airspace above the insulation.

    When I put the ceiling together, I used both acoustic sealant and tuck tape on the vapor barrier. After all that work, no more ice dams, no more condensation, and NO more boiling hot ceiling in summer

    Insulation and air tight construction is essential. But you have to accept that a cathedral ceiling is not very good for insulation anyway

    You can also browse the Canadian Housing and Mortgage Corporation website to learn more about building envelope sealing in cold climates

    Canada Mortgage and Housing Corporation

    Hope this helps

    jay
     
    #28 jayman, May 26, 2009
  9. hill

    hill High Fiber Member

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    The U.L. rating means the tempered glass (in order to pass muster) is subjected to walnut sized ice being fired at 125mph toward it. That'll cover 99% of the hits. But not basket ball sized ... or RPG's, other crazy sized / crazy fast objetcs
     
    #29 hill, May 26, 2009
  10. Celtic Blue

    Celtic Blue New Member

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    That's the general nature of ours although the garage/MBR don't stick out in front of the home. Ours is a 3-2 split or "California split." I call the MBR with its stair balcony "The Keep" (fitting since it is also the armory.) The garage doors are reasonably tight and insulated. I haven't poked a hole to check for insulation in the floor of the MBR, but I've not had trouble with stratification in the room itself, more with the upper great hall/dining space that extends to it.

    The bedroom should have been zoned separately with the room that far removed from the rest of the structure.

    In ours the problem is that the walkout basement level and sub basement are the cold zones in summer while the upper bedroom, MBR, dining, kitchen, den level get warm and together they set the cooling duty. The central stairs serve as a huge duct for rising warm air and sinking cold air.

    A smarter HVAC design for ours would have recognized this and placed a large return near the floor of the sub-basement to pull the cold air for heating in winter, or redistribution in summer. Doing the design with two zones might have worked, instead of the single one we have, but it would still need to directly redistribute air from the bottom zone to the top. At present I manually zone it for heating and cooling each season by throttling to reduce stratification. It effectively feels like two levels.

    Part of the problem is lack of insulation in the walkout basement area. I've been working on that for the stud cavities next to concrete that have a vertical foot or more of above ground exposure. I insulated one wall this Fall. I'm finishing one now, and have one more full wall to do. I believe that the exterior walkout frame walls are actually insulated (since this area was finished from the start) although I have found empty cavities where the sewer lines run through them. I haven't poked holes elsewhere yet to see if if there is insulation in the exterior frame down there, but based on the feel of the walls in the winter/summer I believe there is.

    The other issue with cold floors downstairs is in areas where concrete external walls/slab meet and are covered only by simple vinyl inside. The carpeted areas of the floor are comfortable, but the vinyl stretches in a bath and lower entrance are not. I'm trying to find a thin insulating product to replace the vinyl, then put a thin tile on top of that since they need to be able to handle water on them. Easymat is one possibility... If I can get around R2 it would make a world of difference in the bath during winter.

    My wife grew up with basements and was keen on them. I grew up mostly without them and wanted nothing to do with them. From what I've seen of the dearth of intelligent & tested insulating schemes for basements that keep them both warm and dry, I was right to have concerns. Ours is dry at least with the sump only running once in the past year from what I can tell, but keeping it dry while actually insulated is the current challenge.
     
    #30 Celtic Blue, May 26, 2009
  11. jayman

    jayman Senior Member

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    You've probably already answered this question elsewhere: how cold does it get in winter, where you live? Probably not -40 like where I live, but poor or no insulation is very apparent even at +10 F

    With my co-worker, for whatever reason the HVAC contractor refused to address it "you have to live with it." Another contractor put in the Mr Slim, and that cured all the problems

    That could have easily been done during construction, with the use of dampers. A modern home control system, such as Bryant Evolution, can handle 8 zones. Remote sensors are placed strategically throughout the house, and the zoning dampers direct airflow to where its needed

    Zoning is fairly pricey, but a simple system like yours, with airflow either all on, or all off, obviously does not work.

    The proper way to do that is with thermal breaks on the OUTSIDE. Eg, these products from Beaver Plastics

    Beaver Plastics Logix insulated concrete form blocks

    Beaver Plastics Terrafoam inert closed cell expanded polystyrene

    My artsy-fartsy skills are zero, so I'll have to keep searching for a diagram that lays it all out. With the proper thermal break for the slab at my hobby farm, and now at my home, the floor feels warm, not cold

    Here we go, much better diagrams

    http://www.buildingscience.com/documents/information-sheets/5-thermal-control/slab-edge-insulation/


    I'm not sure if a thin underlay, like cork, will be enough to make that big a difference. One engineered subfloor product, DriCore, is popular up here for basement finishing

    Dricore Subfloor Systems is the essential air gap subfloor system with a moisture barrier

    The *proper* way to fix the bathroom problem involves completely gutting the bathroom, laying down 1/2 to 1 inch closed cell styrofoam, T&G treated ply on top, then the flooring of your choice. The foam will be the thermal break

    You will need to use longer adapters for the toilet. Putting on 2-3 wax rings to make up the difference NEVER works, a leak is all but guaranteed

    Well, if worse comes to worse, just blame the wife
     
    #31 jayman, May 26, 2009
  12. Celtic Blue

    Celtic Blue New Member

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    Typical annual low here is in the -5 F range. Cold spells dip down to around 0 F with high winds. Records indicate about 3 months of the year at 30F average daily temp for the month. When I lived about 150 miles farther south we had warmer average temps, but also recorded the all time low for the region of -26 F (when the oil stuck to the dipstick of my car like molasses.) I was wrapping up my interviews at that time and after working two summers in the Bering Sea to pay for school this was the proverbial straw that broke the camel's back. I wiped 6" of snow from my car at the airport and decided I was ready to move someplace warm and not see winter for a long, long time. I remembered only to well the winters of milking cows at 6 AM with ice club tails taking a shot at me from time to time, and my wet hands (from wiping the ice off the teats) flash freezing to the kickers if I didn't sufficiently dry them. So I Xed off any plant that had a real winter and moved to Texas. This was the "Future's so bright I gotta wear shades" era. :cool: After going through my first real winter in nearly two decades I can honestly say it wasn't as bad as I remembered. Of course my percent body fat is no longer that of an endurance runner... :eek:

    Yes, if proper consideration is given to initial construction. My neighbor has a quote for doing an external foamboard application when he has new siding installed. His basement situation is worse than mine.

    I looked at that. It would be a great starting point in most rooms. Unfortunately for my existing rooms it is too thick and probably the wrong material for the substrate in a bath.

    The Easymat will do R1.5 at 5 mm thickness, and R3.75 at 12 mm. http://www.custombuildingproducts.com/docs/data_sheets/EasyMat DS 5_08.pdf?user=diy&lang=en I wish they had a 7 or 8 mm as I think I could make that work for both applications with only minor modification of existing trim pieces and door base. 12 mm doesn't leave me anything to play with while 5 mm doesn't give me enough kick.

    Oh no, the key to a long marriage is not blaming it on the wife. ;) (This works both ways...call it insurance or "you scratch my back, I'll scratch yours.") Besides we both love the house...just not its energy appetite.
     
    #32 Celtic Blue, May 27, 2009
  13. jayman

    jayman Senior Member

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    More than cold enough to notice you do NOT have any thermal break


    I just hate it when teats ice up.

    The cow probably isn't too thrilled about it either

    That's the only way I can see it working properly, it would be a fairly involved job. If you're a handy DIY, eg have done your own renovations in the past, this may be a project to consider

    It's really important to have the thermal break down to the footings. With slab-on-grade homes up here, not only does a 2 inch closed cell styro board go down to the footings, but the slab is poured on Frost Cushion.

    For slab-on-grade, radiant heat is a popular choice. The slab is done in two pours, with the Insulworks pex support inbetween

    Beaver Plastics insulworks hydronic heating insulation

    Insulworks is a neat product. The pex tubing is put into preformed channels, with correct bend radius. The second pour is put on top. That way, you're not heating up the ground underneath the slab, which in this climate would cause pretty severe frost heaving/frost jacking

    You could use it as a thermal break, but a proper substrate is like this stuff

    Waterproofing, Uncoupling and Drainage Membranes - Schluter-Systems

    By the time you get done with the subfloor, you've probably raised the floor height a good inch, probably 1.5 inches

    I'm not sure if you can count on Easymat to be a thermal break. It appears engineered to be an underlay and sound break

    Huh, didn't know that. Oh well, I'm happily single, what could I possibly know about married life?

    Now that I think about it, every time I have told a married guy to "blame the wife" they end up divorced shortly afterwards
     
    #33 jayman, May 27, 2009
  14. EZW1

    EZW1 Active Member

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    Years ago I put an electric fan in the attic with a thermostat control that switched the fan on when the attic temp rose above 120F. The intent was to draw 110F air from the outside into the attic to 'cool' it when solar radiation raised it sufficiently. This in turn would reduce the amount of heat that is migrated into the house through the ceiling drywall. The system seemed to reduce the cyclic effect of the AC (it would cycle on/off less often), but I never put any numbers together. The fan was inexpensive ($20) and the thermostat was another $30 so I figured my $50 investment likely paid for itself the first year I used it.

    Now what I find really attractive is a small solar panel to power the fan! I think I'll work on that installation next.
     
    #34 EZW1, May 27, 2009
  15. icarus

    icarus Senior Member

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    #35 icarus, May 27, 2009
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