<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">I would just pick the R-value for insulation (21, 25?) that best matches the R-value of 4 inches of polyurethane spray foam. The depth of the cavity doesn’t make much difference to the end result. If the R-value you’re aiming for isn’t 21, or 25, just interpolate using the numbers in the table. Note that small differences in the R-value don’t make much difference to the effective R-value as thermal bridging has such a strong effect. <div class=""><br class=""></div><div class=""><div class="">
<div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">—<br class="">Daniel Knapp PhD, P Phys, LEED AP<br class=""><a href="mailto:danielk@arborus.ca" class="">danielk@arborus.ca</a><br class=""><br class="">Energy Efficiency Expert<br class="">Arborus Consulting<br class="">2-43 Eccles Street<br class="">Ottawa ON K1R 6S3<br class="">(613) 234-7178</div></div>
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<br class=""><div><blockquote type="cite" class=""><div class="">On Jul 19, 2017, at 10:16 AM, Morteza Kasmai via Equest-users <<a href="mailto:equest-users@lists.onebuilding.org" class="">equest-users@lists.onebuilding.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="gmail_default" style="font-family:tahoma,sans-serif;color:rgb(39,78,19)"><p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span style="font-size:10pt;font-family:Arial,sans-serif" class="">There is a wall
section in this project with 4” thick interior polyurethane spray foam inside
the metal studs.<span class=""></span></span></p>
<span style="font-size:10pt;line-height:115%;font-family:Arial,sans-serif" class="">Since Table A9.2B of ASHRAE
90.1 does not provide the effective insulation/framing layer R-Value for this
type of insulation, how can one calculate this value?<br class=""><br class="">
Your thoughts and suggestions would be highly appreciated,<br class="">Morteza
</span></div><div class="gmail_default" style="font-family:tahoma,sans-serif;color:rgb(39,78,19)"><br class=""></div><div class=""><div class="gmail_signature"><div dir="ltr" class=""><img src="https://lh6.googleusercontent.com/Uuukta80GuFfvKouzA0mdSvUXqml7MtSwSiw-evuGMU=w147-h43-p-no" class=""><br class=""><div class=""><br class=""></div></div></div></div>
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