Wednesday, August 23, 2017

More Experiments, AC Circuit On Board LED Downlights

I keep investing in new offerings of LED disk downlights at Amazon. Buy, try, post observations in a Google Photos album. Feel disappointed but not inspired to give public criticism. It is with self interest. I currently have nothing to offer my weatherization customers. I need to find something new, that I love. New offerings favor the common opportunity to replace a crummy incandescent fixture on a tiny and overloaded little ceiling junction box with 2.75" pitch of luminaire attachment screws. These boxes are usually open in many ways to critters in the closed ceiling or attic, that will be irresistibly drawn to any above-revealed light of the luminaire. An LED replacement luminaire that then permits dead bugs to litter the lens, will be cursed. An aware installer of Hamilton Hills lights reported here might tape over keyholes to block light and bugs. Bug-proofing of the GetInLights is impossible except with perfect sealing of ceiling junction boxes. In the matter of bug-litter susceptibility for the unaware, not warned, I am disappointed in these lights. Please read linked photo albums, for details.

On 8/7/2017, I ordered this at Amazon:
GetInLight 6 Inch LED Disk Light 3000°K 
At the linked album, see similarity to 4" GetInLight, reviewed here , in February 2017.

On 8/16/2017, I ordered this at Amazon:
Hamilton Hills 5.5" LED Disk Light 

I may find uses for both of these lights, where I am able to control the bug susceptibility in mounting on new air-tight RACO175 junction boxes. I then don't care about AC direct wiring to the circuit board. I don't know which is more durable, AC conversion in a separate assembly, or the simple-seeming AC circuit board.

I would be happy to again be able to buy improvements of pretty and usable 4" Glimpse and 6" Glimpse lights, packages of about 500 lumens and 750 lumens, preferring always 3000°K. I still love my Glimpse lights .

These Glimpse lights, and many others foolishly discontinued, demanded ever less space for converter blocks within junction boxes, or could instantly replace a bulb in a can light. I miss them. Why won't a new entrant to "manufacturing," pick up some of these at a willing China factory?

Current innovation with circuit on board light engines that can be mounted on any existing light junction box, are important to many home owners not inclined to bear costs of improving old boxes often crammed with wires. But, this shall not come with attachment methods that will surely lead to dead bugs fouling lenses. An LED light should be maintenance-free, forever.

On 9/5/2017, I ordered this at Amazon:
Westinghouse 6322300 Small Led Indoor/Outdoor Dimmable Traditional Surface Mount Wet Location, Brushed Nickel Finish with Frosted Lens 

Only in brushed nickel, at 4000°K color temperature. I couldn't know from the listing whether it might be better than the Hamilton Hills or GetInLight offerings not customer-ready, so took a chance. I have written this up in a Google Photos album . At 9/7/2017, I am ready to ship this back.

One might keep bugs out  by taping over keyway clearances, where the lens need not ever be removed. A buyer is not warned, and that is mean.

Amazon: there is no leadership here. Your customers are being abused and you should be sorry. Who is in charge of what ships from China, anywhere?

Still at his, 9/8/2017, I see that the "Westinghouse" and "Hamilton Hills" lights have the same circuit board, 2D02937A.

They have packaging curiously similar, and different:

The standalone circuit board, 2D02937A, which anyone could safely fire up as a light, is not available except through China factory and government relationships; not recognized by Digi-Key.

Of the two packagings of this board, I think the "Westinghouse" is more USA-consumer-ready. It can more easily be bugproofed with pieces of tape, and has better removability as to paint a ceiling: just pry off.

Thursday, July 6, 2017

The Odd Insulation Math of US Department of Energy, Home Energy Scores

The following is public sharing of one persons' trial of US Department of Energy's Home Energy Scores Tool. The tool is a product of SRA International, Inc., in public ownership through US Government contract.

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
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.

Primary Resources:

Introduction Video

Sim User's Manual
Here be sure to find critical information at Slide 6, not mentioned anywhere else:

"Driving" through a simulated house is not intuitive, and will be happily forgotten, irrelevant to life.

Step-By-Step Guide to Training House #1

Step-By-Step Guide to Training House #2

Home Energy Score Overview (Part II Study Guide)
Beware: This slide show contains the information needed to pass the final step in the assessor training, a twenty-question quiz. Read at Slide 2:
You will need to study this presentation to pass the Assessor written exam.
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.

Assessor Calculator
A URL for the calculator download is not offered. The online download is an Excel 2010 file usable only with Microsoft Office 2007 and newer. Such commercial offering is inconsistent with US Government policy. Here then is a free version of the calculator:

Secondary Resources:

Part 1: About This Home

Part 2: Roof, Attic & Foundation

Part 3: Walls

Part 4: Windows & Skylights

Part 5: HVAC & DHW Systems

Remaining content is accessible only to those admitted to the beta web site.

3D Practical Training

House #1

House #2

House #3

3D Practical Test

Multiple Choice Test

User Review
(Submit feedback to SRA.)

Assessing The Assessor Calculator Tool:
The goal for existing home energy efficiency ratings shall be that anyone can find a score by himself if such has value, and with that believingly see how home improvements can move the score. Improvement is the need, not assignment of nonsense scores that do not motivate home improvements. There must not just be instead, an enrichment of cooperating organizations and auditors, in an absurd system. A home owner must find only self interest in the engagement with home-quality scoring mandates. We must not tolerate any involvement of persons not thinking first of the home owner interest.

Please see calculation as I perform it, superimposed on the insulation averaging portion of the HES calculator: 

Applied math is evident in spreadsheet cell definitions:
For each of several parallel paths:
A pathway contribution of U-Value where all pathways add to 100% of path areas: This is simply (Fraction of Total) * (Path U-value). I can readily define as many parallel paths as are needed, typically four or more.

The HES Averaging Calculator imagines at most three parallel paths and poses for each a computed value UA, for example at Cell B30:
UA =B29/IF(B28=0,0.4,B28)

where B29 is a path's percentage of the total of all path areas, and B28 is the R-value of that path and has value not less than 0.4.

For this path in the first column at the Google Sheets link, HES computes 1.250 for a tiny piece of uninsulated drywall, an evil access hatch, and I correctly compute Ui = 0.005*0.333 = 0.00167, and 100*Ui = 0.167.

Average U-value, called "Cavity U-Factor," is simply the sum of values of (Fraction of Total) * (Path U-value). Instead, the tool poses a calculation such as:
B38 =(IF(B30=0,0,B30)+IF(B33=0,0,B33)+IF(B36=0,0,B36))/(IF(B30=0,0,B29)+IF(B33=0,0,B32)+IF(B36=0,0,B35))
computed by HES calculator for this path as U = 0.074, then inverted as R = 13.52. 

For this attic floor with well-placed R19 batts, joist thermal shorts and, a little uninsulated hatch, I correctly compute U = 0.0519, then resolved as inverse minus 3, value R = 16.28.  At the next column, see that if the hatch is fully insulated R19, floor values change very little: U = 0.0504, R = 16.83.

We must counter false statements such as this of 1999, Don’t leave a hole in the ceiling ,  passed along by Habitat for Humanity, as written by It is way past time that the offending web page should be deleted or disconnected. Attic access is necessary, not evil. USDOE and Lawrence Berkeley Lab have not gotten the message. In wanting to demonstrate evil of a hatch if without an absurd stapled batt-on-top, the training considers a hatch 5% of floor area, perhaps of dimension 2 ft by 25 ft with a 1000 sf floor!

I wonder about behavior of complex if-statement HES calculator cell definitions that avoid a divide-by-zero problem. Examine this with study of a 2x4 wall that is well insulated with R16 batts, then with increasing decrepitude of the insulation batts as missing or not in contact with bypass:
Observe linear drop-off of value with decrepitude. Present again the tables at the top of this post:

There is not a razor's edge transition with "no insulation," but there are odd results if input no-insulation R-values in the HES calculator are less than 0.4. There is only an up to times seven error in U-value and energy cost with decrepit insulation (see discussion at top of post).

Now examine a crude provision for decrepit insulation in HES Calculator.
Here is a screen capture of the Excel form of the calculator, with function selectors in four tabs at bottom.

Where the Insulation De-rate Calculator is dysfunctional in the free version of the calculator, look instead for taught methods of USDOE perhaps mandated in Home Energy Scores, at an Insul-calcs tab now visible. 

Here, defy an unfounded and outmoded bias for blown cellulose and against all batt insulation. Want well-placed insulation of highest quality as in filling a 2x4 wall to R15, regardless of insulation form . Completely filling the wall is what matters, then stilling bypass in convective loops.A rater may not be commanded to believe the 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.


Fair and Poor installations may in fact have large areas without insulation contact, hidden from view and having no value. Regardless, the visually-interpreted table penalties are too small.

Tuesday, June 27, 2017

Flawed Measurement Of R-Value With A Certainteed InsulSafe4 Gage

I want to at last dispose a gage saved from a job in which I concluded the following:
The Builders Statement of found insulation states that for intended R38, one bag covers 44 sq ft. 37 bags were applied, sufficient for 1628 sq ft. The installer was unaware of actual area  2315 sq ft, then with 30% under-fill,  R26 before discount for overwhelming consequences of missing insulation.

General fill of insulation was 10", not a goal of about 15".  A greater depth of insulation did not exist at time of construction, then lost by settling. A failure of inspection occurred, on top of a perhaps-conscious failure of math. Was compensation for the job not proportional to cost of materials?

Adjacent to the found access hole where inspection would be expected, the gage is revealed at 10" depth. By human nature, depth is less at a majority of area not accessible for inspection.

Here is a cropped photo of the gage, with marking of depths at values of common interest, a black line and arrow under-lining each named value.  For example, named value R60 is at depth 22.0".The gage corresponds to a table in PDF document InsulSafe® SP Installation Guide - CertainTeed .

Having insulation generally R26 where R38 was wanted, is mean. Call the weighted average of loose fill R24.  The overall effective R value of the attic floor is diminished by areas bare of insulation and by thermal equalization of interior walls through assorted floor openings often large. Bare areas are mainly at edges of the attic, and are typically 5% of floor area.

Do the Insulation Math , of found effective R-value:

Allow for thermal shorts of 2x8@24" framing.

1/(Reff + 3) = fjoists/(Rjoists +3) + finsulation in contact/(Rinsulation +3) + fbare/3
For 2x8 framing, Rjoists is  6.8.
1/(Reff + 3) = 0.06/9.8 + .89/27 + .05/3

Reff = 15

The work of sealing the attic floor is an insulation cost, and I think the expenditure should be encouraged by allowing its result is that of finding another 5% floor bare area:

1/(Reff + 3) = fjoists/(Rjoists +3) + finsulation in contact/(Rinsulation +3) + fbare/3

1/(Reff + 3) = 0.06/9.8 + .84/27 + .10/3

Found attic floor insulation:
Reff = 11

The now-accessible attic has a large decked area 18.6" up from ceiling drywall, and much additional area accessible with movable flooring upon raised floor supports. HVAC ducts are more efficient and are buried under floor insulation where allowed. Conditioned space below the attic floor is 2315 sq ft.

A section of hallway ceiling ruined by step-though during electronics wiring is now occupied by a wonderful European attic ladder.

Ladder installation at a 45° diagonal across 2x8 floor joists is supported by 2x18 box beams, a first-ever feat of cleverness.

I imagine a 150 sq ft work room 8' tall from the new flooring level, at the attic space with greatest headroom. The space might be a wood shop or music room, conditioned or not. An attic has congenial temperature a portion of most days of the year.

With dispersed insulation,  fbare is zero. One bag of R21 insulation, 89 sq ft, 89/2315 = 4% of the floor, is placed over the master bedroom loft ceiling. 5% of the floor at eaves is insulated to R30 with pushed loose fill. The remaining loose fill is 3" to 4" deep everywhere else, called R11.

1/(Reff + 3) = 0.06/9.8 + .04/24 + .05/33 + 0.85/14

In the now-accessible attic:
Reff = 11.

This is the same as-found, not diminished. Where this condition must exist for some time, my churn of insulation beyond just creating safe attic access, has not hurt my customer. This finding is very important to me. I hope you agree with my math. Distributing insulation to eliminate bare areas is smart, even where found unstable loose fill insulation is collapsed in the churning.

Find then:
Perfect, fullest placement of insulation is absolutely required in weatherization. Perfect full-filling coverage is far more important than insulation depth or available thickness. Where insulation has been placed carelessly, do not hesitate to trample insulation if necessary, to perfect the installation. Never delegate placement of insulation to be done without caring, in haste. The value of insulation placement is proportional to time spent.

Back to that now-disposed gage then. Don't believe it, even where it reads correctly in perhaps revealing fraud. Diligent work is harder to gage.