Recent Comments and Answered Questions on Green Building Advisor

  • Michael Chandler | Apr 05,2009 04:42 PM EDT
    The NAHB University of Housing offers a Certified Green Professional designation which won't give you any leverage re: LEED-h but is a good quick overview of the range and intent of green building ...
  • Michael Chandler | Apr 05,2009 02:05 PM EDT
    I've done a few brick roofs that have performed well. Schluter Ditra shows a detail for it in their manual but the system we have used is cheaper and thinner. There is a picture of it here if you ...
  • Michael Chandler | Apr 05,2009 01:42 PM EDT
    The answer hear depends on a number of factors. Are you getting electricity from coal? do you have access to natural gas or are you looking at LP? how is your house laid out? My preference in ...
  • Michael Chandler | Apr 05,2009 12:50 PM EDT
    So long as you truly seal the space and prevent bulk air filled with humidity from the bath from infiltrating into the area between the foam and the sheathing you should be fine. The key is ...
  • Grant Dorris | Apr 04,2009 10:53 PM EDT
    David, You ask the question that I hear second most - the first is "how much is this going to cost"? Trying to figure it out yourself, meaning increasing your knowledge of the subject, is ...
  • Anna Johnson | Apr 03,2009 03:33 PM EDT
    This is not a passive solar house. It is a super-insulated shop with a small temporary apartment. We do intend to try external panels for the hot water for the radiant heat. We are in the ...
  • Martin Holladay | Apr 03,2009 01:33 PM EDT
    John, Good question — Anna, what's your climate? Here's my two cents on insulation: 1. The colder the climate, the thicker the insulation. 2. A slab with radiant heat needs more insulation ...
  • John Brooks | Apr 03,2009 12:11 PM EDT
    Martin, What is Anna's climate? Does your advice apply to all climates and all ground temperatures? What temperature is typical for the radiant floor heat?
  • Martin Holladay | Apr 03,2009 12:09 PM EDT
    Robert, Thanks for contributing; I've learned something. However, I'll try again: is it correct to say that under these circumstances (a passive solar house on a sunny morning), a warm ...
  • | Apr 03,2009 11:26 AM EDT
    What Martin states about the inefficiency of a radiant slab floor for solar gain is correct only in the parts of the slab not in direct sun. To absorb thermal energy by conduction requires that ...
  • Martin Holladay | Apr 03,2009 08:44 AM EDT
    An interesting blog on the same topic: http://www.27east.com/story_detail.cfm?id=199824
  • Martin Holladay | Apr 02,2009 03:43 PM EDT
    William, I think you need to check out the Green Building Certification Institute Web site: http://www.gbci.org/ The Web site notes, "LEED Accredited Professionals (LEED APs) are building ...
  • Martin Holladay | Apr 02,2009 03:08 PM EDT
    Anna, I'll take a stab at responding to your request for "best practice" advice on this topic  "slab floors, thermal mass, vapor retarders and gravel underneath." From the bottom up: Crushed ...
  • | Apr 02,2009 12:32 PM EDT
    Brick is about R-0.2/inch, so you can determine the average thickness and calculate heat loss. To calculate exfiltrative heat loss, you'll have to measure the average passive airflow past the ...
  • | Apr 02,2009 12:18 PM EDT
    Yes, three perpendicular 1" XPS foam layers will flex better without separation at joints. The gravel (or do you mean crushed stone?) should not be between VP/insulation and concrete, as it will ...
  • Anna Johnson | Apr 02,2009 11:30 AM EDT
    the first comment above was meant as answer to the 2nd comment - don't know how it showed up first. I'm the person who asked the question in the first place.
  • Anna Johnson | Apr 02,2009 11:20 AM EDT
    The reason for the gravel under the concrete was to minimize curling of the concrete - a "blotting layer". But all this is a tradeoff. And we are thinking that what you suggest may be a better ...
  • David Quillin | Apr 02,2009 10:59 AM EDT
    I would think you would want the gravel, whose primary job is as a capillary break for any groundwater, to be beneath the insulation. If you did it that way, the grading does not be too precise. ...
  • jim blodgett | Apr 02,2009 10:34 AM EDT
    Tristan asked "Are there any builders reading this who have confronted these issues in their work?" Yes. Regularly. Customers are constantly looking for advice, ideas, reccomendations on ...
  • Martin Holladay | Apr 02,2009 05:14 AM EDT
    James, You wrote, "You should know how flawed R-value tests are. If you do know how flawed the R=value test is, then write about the test." I have written about the R-value test. Read about it ...
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