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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>In the same post you are discussing cost but also talking about net zero as a goal. I think that illustrates the dilemma – how do you establish a ‘rational’ system that covers 2 paradigms (jane Jacobs has an excellent book ‘systems of survival’ that explores this problem). Jane argues you can’t – and when you try you compromise both objectives by bending over backwards it goes sideways (my experiences)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>That said I think passivehaus is a good attempt at a standard and it raises challenges that get us thinking. For example 9” of foam is no longer just a thermal insulating material but is a structural material – at that point its thickness is related less to insulation value than structural value. 4 and 6” lends itself easily to eliminating concrete slabs from buildings. Greater thickness and/or density can easily allow us to eliminate concrete footings and retaining walls and we have the technical data and infield applications (geofoam) to support this usage – eliminating concrete is a huge achievement in reducing energy costs from a building. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Can I do this for a client? I don’t know – my relationship with a client is in the realm of commerce and the concept and designwork required for such initiatives is in the realm of the environment – two different worlds, two different areas of faith, understanding and codes of conduct.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>changing to 2" of foam increases the SSHD to 5.90 Btus/SF/year, requiring about 20 additional therms of natural gas to make up the difference. Local cost for the first 45 therms per month runs $0.3853/therm.<br><br>doubling down to 4" of foam drops the SSHD to 5.28 Btus/SF/year, saving about 10 therms. <br><br>in summary, PHPP tends to validate Norbert's vivid example.<br><br>the bigger question is of course, does this exercise in itself invalidate the PH requirement to hit the magic 4.75 target? It's worth noting, and perhaps no surprise that the cooling load is higher with the thicker subslab insulation. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>This all goes back to my original point, which seems to have gotten lost under some slab, that rules of thumb-- such as, that two, or four, or however many inches of subslab foam is "enough"--only gets us so far, and that if we are to achieve a performance standard, or a means of achieving net zero, or carbon neutral, or whatever measure--some rational system of putting this all in a greater context is necessary.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>AA<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><br><br>AA<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div></div><div><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><div><p class=MsoNormal>On Sat, Aug 24, 2013 at 7:42 AM, Norbert Senf <<a href="mailto:mheat@mha-net.org" target="_blank">mheat@mha-net.org</a>> wrote:<o:p></o:p></p><p class=MsoNormal>Or, you could invest that $1350 in a US 30 yr bond @3.8% instead of styrofoam and get $51.00 per year instead of $4.00.<br><br>-------------previous message-------------------------<o:p></o:p></p><div><p class=MsoNormal><br><br>A 5 lb piece of wood burned at 70% efficiency gives about 32,000 BTU. That would cover the slab heat loss for 7 days. For a 5 month heating season, it would need 100 lbs of wood. Doubling the foam thickness to R20 would save about 50 lbs of wood per year. At $240 per cord, that's a saving of about $4.00 per year.<br><br>At $1.50/sq ft for the extra foam (not counting labour), 900 sq ft would cost $1350, for a simple payback of 337 years..........N<br><br><br>At 05:44 AM 8/24/2013 -0400, you wrote:<o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm'><div><p class=MsoNormal style='margin-bottom:12.0pt'>RT <<a href="mailto:archilogic@yahoo.ca" target="_blank">archilogic@yahoo.ca</a>> writes:<o:p></o:p></p><p class=MsoNormal>... In putting our pants back on frontwards, someone noticed that we had all received tattoos onto our backsides:<br><br>? ? ? ? ? "? q? =? A [ dT ( K/s + hc ) +? ( ? * T^4 ) ]? "<o:p></o:p></p></div><p class=MsoNormal>(snip)<o:p></o:p></p></blockquote><div><div><p class=MsoNormal style='margin-bottom:12.0pt'><br>-------------------------------------------<br>Norbert Senf---------- mheat(at)<a href="http://heatkit.com" target="_blank">heatkit.com</a><br>Masonry Stove Builders<br>25 Brouse Rd.<br>RR 5, Shawville------- <a href="http://www.heatkit.com" target="_blank">www.heatkit.com</a><br>Québec J0X 2Y0-------- fax:-----819.647.6082<br>---------------------- voice:---819.647.5092<br><br><br><br><br><br><br>_______________________________________________<br>Greenbuilding mailing list<br>to Send a Message to the list, use the email address<br><a href="mailto:Greenbuilding@bioenergylists.org" target="_blank">Greenbuilding@bioenergylists.org</a><br><br>to UNSUBSCRIBE or Change your List Settings use the web page<br><a href="http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org" target="_blank">http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org</a><o:p></o:p></p></div></div></div><p class=MsoNormal><br><br clear=all><o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal>-- <br><span style='color:#660000'>Alan Abrams<b><br></b></span><i><span style='color:#666666'>certified professional building designer, AIBD<br>certified passive house consultant, PHIUS</span></i><o:p></o:p></p><div><p class=MsoNormal><i><span style='color:#666666'>certified passive house builder, PHIUS<br></span></i><span style='color:#660000'>Abrams Design Build LLC</span><span style='font-size:13.5pt;color:#660000'><br><i>sustainable design for intentional living</i></span><span style='font-size:7.5pt;color:#666666'><br>cell 202-437-8583<br><a href="mailto:alan@abramsdesignbuild.com" target="_blank"><span style='color:#666666'>alan@abramsdesignbuild.com</span></a><br><a href="http://www.abramsdesignbuild.com/" target="_blank"><span style='color:#666666'>www.abramsdesignbuild.com</span></a></span><o:p></o:p></p></div></div></div></body></html>