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  1. #1

    Energy effeciency of new home

    WE are building a 3500 sq foot home in Ohio. Front door faces east Back door faces West and sits on a hill.

    I have been talking to reps from Low-E to find ways to lower our utility bills when this project is complete.

    We are going with a 6ton WF geothermal.

    I wanted to know what you thought of these fairly new products:

    1.) Slabshield- polyethylene foam with aluminum: placed under the basement before cement is poured. This provides an R value of R3
    Simple to install and replaces the mil vapor barrier. Cost is mid 40cents per foot.

    2) Low E- House wrap. Aluminum coated W/ closed cell polyethylene. Blocks 97% radiant energy. Provides Rvalue of R4. Cost is about double that of Tyvek house wrap.

    3) Micro E- for attics/roof: Aluminum facing 1/8" thick. Placed between joists, easy to install stapled with tabs. Rep. claims this will reduce the temperature of the attic between 30- 40 degrees! Cost is close to the house wrap.


    If these work, they sound like they could be very beneficial in the long run. The initial cost (I am guessing) may be around 4-5,000 to install all of these. Which seems low to me for improvement on effeciency. They may produce good returns by lower heating/cooling costs over the next many years.

    Have any of you used/installed these products? Does is seem to be worth the initial expense?

    thanks

  2. #2
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,288
    Has a load calculation been performed for this home? With the possible inclusion of the products you've described above...was the six ton figure arrived at with those materials in mind? Offhand six tons seems a bit much for 3,500 square feet, but I can't see the house plan or architecture from here.

    How about your window choices? Have you considered radiant barrier roof decking vs. the other product mentioned above? Easier to apply...the radiant barrier is already part of the deck. Once the rafters are sheathed with decking, the radiant barrier is in place and goes to work immediately.

    If the length of the house runs north/south (broadest wall areas of the house facing east and west), I could see some benefit from the low E house wrap if both facades will receive considerable solar exposure in summer. If either facade is deeply shaded, maybe not. Hard to give east and west facades enough shade from dawn to mid-morning, and from mid-afternoon to sunset without very broad overhangs, patio covers, trellises, shade trees, etc.

    The caveat for any of these products you are considering to work at maximum benefit is correct installation techniques applied. Same goes for your HVAC system and ductwork. You can have the highest end, most highly lauded energy saving technologies in place, but if they were not selected and installed with care, full benefit will be diminished.

  3. #3
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,260
    Any concerns about IAQ-fresh ventilation and house tightness? Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  4. #4
    Join Date
    Jul 2008
    Posts
    551
    Those are nice but it is all going to depend on the quality of the whole house. Those nice upgrades will still be meaningless if your builder doesn't seal the windows properly or you have cheap windows to begin with. The color of the house, color of the roof (and material), and properly tinted west side windows would also be great additions.

  5. #5
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,137
    3) Micro E- for attics/roof: Aluminum facing 1/8" thick. Placed between joists, easy to install stapled with tabs. Rep. claims this will reduce the temperature of the attic between 30- 40 degrees! Cost is close to the house wrap.

    A better choice would be a radiant barrier plywood or osb
    techshiels or solarply.
    this is a roof decking with rb already applied.
    in adding a rb under the decking you are paying for one area to be worked two times.
    rb decking includes both steps in one application.

    low e windows are a good investment.

    best of luck with your build.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  6. #6
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,137
    3) Micro E- for attics/roof: Aluminum facing 1/8" thick. Placed between joists, easy to install stapled with tabs. Rep. claims this will reduce the temperature of the attic between 30- 40 degrees! Cost is close to the house wrap.

    A better choice would be a radiant barrier plywood or osb
    techshiels or solarply.
    this is a roof decking with rb already applied.
    in adding a rb under the decking you are paying for one area to be worked two times.
    rb decking includes both steps in one application.

    low e windows are a good investment.

    best of luck with your build.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  7. #7
    Join Date
    Jan 2007
    Location
    Minneapolis, MN
    Posts
    415
    If the back of the house faces west you are off to a bad start, minimum west exposure is best. Solar exposure of the windows adds the most heat gain. Shading of the windows works best. Insulate attic to R 50+. Infiltration is a huge energy robber. Have the house built to Energy Star standards or better, it requires actual testing to document performance. House wrap is generally for a water resistive barrier that will breath and let moisture out. The aluminum coating on the low e house wrap may trap moisture and cause damage like the EIFS systems did, do some more research. Building it tight and ventilate right. Go to http://www.natresnet.org/ find a rater in your area and discuss you needs, you will get an unbiased opinion and not a salesman's pitch. The are many considerations when building a energy efficient home so take your time to do it correctly and you will enjoy the added comfort and energy efficiency you desire. R value is how slow heat is transmitted through a material, I doubt house wrap has any R value. Don't go by "effective R value" thats just a sales line. R 3 is the slab is minimal, go R 10+. Make sure to do the walls also.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,721
    Check into open cell insulation.

    Doesn't sound like a very energy efficient home, if you need a 6 ton WF.
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  9. #9
    Quote Originally Posted by mbarson View Post
    If the back of the house faces west you are off to a bad start, minimum west exposure is best. Solar exposure of the windows adds the most heat gain.


    The Back of the house will face the west however there is a large mature woods directly behind the house.

    Insulate attic to R 50+. HOw would you reccommend this?


    Infiltration is a huge energy robber. Have the house built to Energy Star standards or better, it requires actual testing to document performance. House wrap is generally for a water resistive barrier that will breath and let moisture out. The aluminum coating on the low e house wrap may trap moisture and cause damage like the EIFS systems did, do some more research. Building it tight and ventilate right. Go to http://www.natresnet.org/ find a rater in your area and discuss you needs, you will get an unbiased opinion and not a salesman's pitch. The are many considerations when building a energy efficient home so take your time to do it correctly and you will enjoy the added comfort and energy efficiency you desire. R value is how slow heat is transmitted through a material, I doubt house wrap has any R value. Don't go by "effective R value" thats just


    a sales line. R 3 is the slab is minimal, go R 10+. Make sure to do the walls also.
    How would you recommend R10 in the basement? What material for the walls?


    I will look at the natresnet.org site and talk with someone there.
    Thank you for your reply.

  10. #10
    Quote Originally Posted by teddy bear View Post
    Any concerns about IAQ-fresh ventilation and house tightness? Regards TB

    No, we have spent over a year checking out builders and found one who is highly praised. I have seen a number of his new construction houses and I dont have any concerns with the tighness of the house. Especially around the windows.

  11. #11
    Quote Originally Posted by badtlc View Post
    Those are nice but it is all going to depend on the quality of the whole house. Those nice upgrades will still be meaningless if your builder doesn't seal the windows properly or you have cheap windows to begin with. The color of the house, color of the roof (and material), and properly tinted west side windows would also be great additions.


    I agree. I believe that the construction will be very well done. The builder has an excellent reputation.

    We are deciding on Jeld-Wen vinyl low e windows or Anderson 200's. Do you have a preference? The back of the house faces west but there is a large woods just behind the house

  12. #12
    Quote Originally Posted by shophound View Post
    Has a load calculation been performed for this home? With the possible inclusion of the products you've described above...was the six ton figure arrived at with those materials in mind? Offhand six tons seems a bit much for 3,500 square feet, but I can't see the house plan or architecture from here.

    I have found a separate company who specializes in Geothermal. They sized the house with my blueprints and said that a 5 ton would work however if we finish the basement (2100 sq foot) later, or add a pool, the 6 ton would not have any problems. I have also worked this out with the builder that the same company that will install the field loops and install the WF will also do all duct work. This made sense to me since I didnt want the builder blaming any future problems on the duct work or vice versa. This company will be fully responsible for both. They also have an excellent reputation and do things correctly.


    How about your window choices? This is either Jeld-Wen low e or Anderson 200's. Do you have any advice on each one. Andersons are 2600 more expensive.

    Have you considered radiant barrier roof decking vs. the other product mentioned above? Easier to apply...the radiant barrier is already part of the deck. Once the rafters are sheathed with decking, the radiant barrier is in place and goes to work immediately.

    This, no. I will look into this. I am very interested in this.


    If the length of the house runs north/south (broadest wall areas of the house facing east and west), I could see some benefit from the low E house wrap if both facades will receive considerable solar exposure in summer. If either facade is deeply shaded, maybe not. Hard to give east and west facades enough shade from dawn to mid-morning, and from mid-afternoon to sunset without very broad overhangs, patio covers, trellises, shade trees, etc.

    The caveat for any of these products you are considering to work at maximum benefit is correct installation techniques applied. Same goes for your HVAC system and ductwork. You can have the highest end, most highly lauded energy saving technologies in place, but if they were not selected and installed with care, full benefit will be diminished.
    Excellent point. I have spent a great deal of time researching and checking on both our builder and the company installing the geothermal. I do not have concerns with the quality of their work. I know they will be done correctly. I am now looking for ways to improve on effeciency.thank you for your help

  13. #13
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,721
    If your house is going to be energy efficient. You shouldn't need more then 4 tons for that 3500 sq ft.

    Sizing for the pool makes the 6 ton more of an energy hog when its not also heating the pool.
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