In a first post, I address access to the HES tool, and then finding of odd math of USDOE in dealing with a divide-by-zero problem in conversion of R-value to U-value, done stupidly as simply a number inversion of the insulation-only R-value. Energy is transmitted through resistances in addition to those of conduction through insulation and framing. The additional "surface" resistances are substantial and well known, though variable in every path. Where the savings achievable in any bid of weatherization must not be over-estimated, a highest value of surface resistance generally applicable, is wanted. In a derivation of Insulation Math , I offer that the wanted round number as a resistance value in USA units, is 3.
Google search "u-value of an empty wood-frame wall " finds this number affirmed by Colorado Energy and by Build It Solar .
USDOE sets a wildly low surface resistances number, 0.4 without explanation. Perhaps such is possible for a shed with very-perforated walls. This might be in an odd very mild climate, else not habitable.
As insulation varies in effectiveness from full to worthless, energy waste changes in linear fashion in proportion to a Transmission Coefficient, U. A realistic particular situation must be considered to understand consequences of the USDOE error. Let that situation be a 2x4 @16 framed wall with at best R15 full filling of insulation .
With best insulation and correct usage of value 3 surface resistance, computed U-values are reasonably close, 0.063 my number vs. 0.087 by USDOE. With worst insulation, none,
my U-value is 0.316, just a bit less than if a wispy wall had no framing thickness, U=1/3. At this condition the USDOE U-value is 2.28, over-estimating energy transmission and heating cost by a multiple of 7.2, roughly 3/0.4 = 7.5. Aside from other allowance by a Insulation Derate Tool, the wrong USDOE math will lead to excessive shaming of found conditions and to large over-estimate of weatherization benefits. The whole USDOE process will fail to discover and report that perfect, fullest placement of insulation is absolutely required in weatherization. Perfect full-filling coverage is far more important than insulation depth or available thickness. The USDOE hire-an-interest-conflicted-auditor process will often lead to hiring of the auditor to pile more crummy insulation on top of a bad situation not repaired, doing more harm than good.
Content at this post will grow as I critically examine and try tools and the scoring process. Large errors found, will justify this examination.
Content for Home Energy Assessor Candidates is at beta.homeenergyscore3dtraining.com.
As I work in this online as a candidate, I am forced to employ a laptop computer with 64-bit OS and with unbearable difficulty of scrolling on the small screen. Offline I transfer lessons learned to my capable desktop computer running 32-bit but with large screen and other needed advantages. I must choose a 32-bit OS and hence 32-bit browsers with the desktop setup. I employ 32-bit to not give up important old software. HES training resources behave better on this full size desktop computer, employing the links that follow.
"Driving" through a simulated house is not intuitive, and will be happily forgotten, irrelevant to life.
Print its 26 pages, and consult them as you sift through the multiple choices for each question. It isn't a "Part II Study Guide". It is the Multiple Choice Test answer key that you would surely have in hand if you have paid for assessor training.
Now examine a crude provision for decrepit insulation in HES Calculator.
Assessment must allow there is never instruction to give allowance for joist thermal shorts or for any decrepitude, as one might then do, shown here. In fact a subsequent step of derating insulation forbids direct allowances.