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Hi, three courses need your input. What do you want to work on?
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Hi, three courses need your input. What do you want to work on?
I have one edge case for you to review before High Performance Buildings HW1 is ready to post.
Submission 004 writes “inside-film drop” and builds the full resistance stack, then uses the exterior-film term in the final ratio. The first pass put Question 2 at 10/20. That could be a model error or one substituted term, so I want your call.
Edge case · Question 2
1 affected
Treat the wrong film term as a minor execution error or a major conceptual error?
The total resistance is right. The line above the equation says “inside-film drop,” but the numerator uses the exterior-film resistance. That conflict is the edge case.
R_{\mathrm{tot}}=2(0.18)+1.20+0.70+0.20=2.46
T_{s,i}=70-\frac{\color{#8c1515}{0.20}}{2.46}(70-25)=66.3^{\circ}\mathrm{F}
The response labels this step “inside-film drop.” The inside-film term is R_{f,i}=0.70.
The written label and the equation disagree. Read literally, the equation models the inside surface with the wrong film. Read with the written intent, one term was substituted into an otherwise correct setup. I lean 15/20 because the full stack and the named physical drop are both right.
Prompt: A double-glazed opening separates indoor air at 70 °F from outdoor air at 25 °F. Each pane has R_g=0.18; the sealed gap has R_{\mathrm{gap}}=1.20; the inside and outside films are R_{f,i}=0.70 and R_{f,o}=0.20.
All resistances are in \mathrm{h\cdot ft^2\cdot{}^\circ F/Btu}. Assignment weights: Q1(a) 10 · Q1(b) 25 · Q2 20 · Q3(a) 30 · Q3(b) 15.
Find the total resistance and the inside glazing-surface temperature. Show the resistance stack.
R_{\mathrm{tot}}=2R_g+R_{\mathrm{gap}}+R_{f,i}+R_{f,o}
T_{s,i}=T_i-\frac{R_{f,i}}{R_{\mathrm{tot}}}(T_i-T_o)
+20 Determines the total series resistance and the inside surface temperature from the proportional temperature-drop relation.
+15 Determines the total series resistance and the inside surface temperature from the proportional temperature-drop relation, with a minor execution error or not carried to a final number.
+10 Determines the total series resistance and the inside surface temperature from the proportional temperature-drop relation, attempted but with a major conceptual error.
+0 No attempt.
Missing units: −1 once for Question 2, floor 0. Method ladder: 20 points.
004 Writes “inside-film drop” and includes both panes, the gap, and both films.
R_{\mathrm{tot}}=2(0.18)+1.20+0.70+0.20=2.46
T_{s,i}=70-\frac{R_{f,o}}{R_{\mathrm{tot}}}(70-25)
Keep Submission 004 at 10/20, or use the 15/20 execution-error tier?
Grade the displayed equation: it assigns the inside-surface drop to the wrong film.
Credit the written intent: one substituted term conflicts with the otherwise correct setup.
Reply A B or describe a change.
Got it. I recorded a major conceptual error and checked all 12 for the same pattern. Submission 004 stays at 10/20 on Question 2; the other 11 proposals are unchanged.
Done. I recorded a minor execution error and checked all 12 for the same pattern. Submission 004 moves from 10/20 to 15/20 on Question 2; the other 11 proposals are unchanged.
I need your call first: keep Submission 004 at 10/20 for a major conceptual error, or use 15/20 for a minor execution error?
I updated the full draft. Two parts are complete; three have a specific correction. Proposed total: 86/100.
Feedback draft · Submission 004
The envelope heat-flow paths and post-retrofit design load are correct. In Question 1(b), finish the area-weighted conductance and invert it to the whole-window resistance. In Question 2, use the inside-film resistance in the surface-temperature ratio and explain why that film governs the inside surface. In Question 3(b), add the upper bound of the sensitivity range.
I updated the full draft. Two parts are complete; three have a specific correction. Proposed total: 91/100.
Feedback draft · Submission 004
The envelope heat-flow paths and post-retrofit design load are correct. In Question 1(b), finish the area-weighted conductance and invert it to the whole-window resistance. In Question 2, use the inside-film resistance in the surface-temperature ratio and recalculate. In Question 3(b), add the upper bound of the sensitivity range.
Grade review
High Performance Buildings HW1 · 100 points · 3 questions · 5 scored parts · 12 submissions
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Review sequence
12 proposals prepared
1 rubric question held
12/12 compared
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More work from this batch
I checked a regrade request on Question 2. Submission 009 uses the same surface-temperature balance we already accepted for Submission 002, but it was proposed at 15/20 instead of 20/20.
The algebra is arranged differently. The rubric is method-agnostic, so I flagged the mismatch before approval.
Consistency check · Question 2
1 mismatch
Should these equivalent setups receive the same tier?
Both responses use the full series resistance and the inside-film temperature drop. Submission 002 applies the resistance ratio directly; Submission 009 computes heat flux first.
T_{s,i}=T_i-\frac{R_{f,i}}{R_{\mathrm{tot}}}(T_i-T_o)
Applies the inside film’s share of the total temperature drop.
q''=\frac{T_i-T_o}{R_{\mathrm{tot}}},\qquad T_{s,i}=T_i-q''R_{f,i}
Computes heat flux, then the inside-film drop.
Same given values · same governing balance · no additional error in Submission 009
Algebraic order is not a rubric criterion. Both responses demonstrate the full surface-temperature balance, so the applied rubric item should match unless Submission 009 contains a separate execution error. It does not.
I applied the prior treatment and rechecked all 12 Question 2 proposals. Submission 009 moves to 20/20; the other 11 are unchanged.
Consistency recheck
Five of 12 submissions reduced annual energy after the envelope retrofit but kept the original peak load when sizing the heat pump.
I kept the grades as proposed. Want the examples or a short note for the next lab?
Class pattern · Question 3(a)
5 of 12
Want to see what they did, or a teaching note for the next lab?
The common miss is using a yearly energy result to choose equipment for the coldest design hour.
Reduced annual energy, then reused the original 18.0 kW peak load.
Submission 003 “Annual heating falls 22%, so keep the original 18.0 kW unit.”
Submission 008 “The retrofit saves energy; design heat loss remains 18.0 kW.”
Coverage: 12/12 precomputed Question 3(a) rubric notes · 5 shared the same specific error
I’d revisit one distinction before the next lab: annual energy tells you how much heat the building needs over a year; design load tells you the equipment capacity at the cold hour. Five of 12 mixed those up.
Next lab · teaching note
I kept the proposed scores unchanged. Five feedback drafts point to the post-retrofit design-load step; the other seven Question 3(a) drafts are unchanged.
Feedback impact
I’m grading the Engineering Economy Midterm and need your input on the Midterm rubric. I’m through Question 2 on all 24 midterms; the decision affects six responses before I keep going.
Midterm: Q1 time-value equivalence 25 · Q2 annual-cost uncertainty 30 · Q3 present-worth comparison 25 · Q4 rate of return and breakeven 20.
Question 2 · Mobile LiDAR unit: Purchase price $72,000; resale value $18,000 after 5 years; annual service $4,800; energy and maintenance $0.38/km; interest rate 8%. Annual use is 12,000 km optimistic, 24,000 km most likely, and 36,000 km pessimistic. Use (A/P,8\%,5)=0.25046 and (A/F,8\%,5)=0.17046.
Part (a) · 15 points: Compute equivalent annual cost for all three distance cases and show the cash-flow expression.
Part (b) · 15 points: Using 1–4–1 weights, report one equivalent annual cost for planning and show your method.
EAC(m)=72{,}000(A/P)+4{,}800+0.38m-18{,}000(A/F)
+15 Weights the three annual-distance inputs 1–4–1, then recalculates equivalent annual cost.
+11 Weights the three equivalent-annual-cost results directly.
+7 Uses the wrong weights, drops a case, or does not reach an estimate.
+4 Sets up a three-point estimate but does not complete it.
+0 No attempt.
Option B merges the +11 response type into +15 for this item only.
Submission 006 · Weights the three equivalent-annual-cost results.
\overline{EAC}=\frac{24{,}324.84+4(28{,}884.84)+33{,}444.84}{6}=\$28{,}884.84/\mathrm{yr}
Submission 011 · Weights annual distance first, then recalculates equivalent annual cost.
\bar{m}=\frac{12{,}000+4(24{,}000)+36{,}000}{6}=24{,}000\ \mathrm{km/yr}
EAC(\bar{m})=19{,}764.84+0.38(24{,}000)=\$28{,}884.84/\mathrm{yr}
Should the six affected responses stay at +11 for method, or receive +15 on this question?
Reply A B or describe a change.
I recommend B. The course method weights the uncertain input first, but this prompt only asks for a 1–4–1 annual-cost estimate. With these data and the linear cost model, both calculations are exact and give the same result. I’d make the input-first instruction explicit next time.
Got it. I kept the input-first distinction and rechecked all 24. Six responses stay at 11/15; the other 18 are unchanged. I’ll apply that rubric as grading continues.
Got it. I accepted either route for this item and rechecked all 24. Six responses move from 11/15 to 15/15; the other 18 are unchanged. I’ll apply that rubric as grading continues.
I need your decision on the Midterm rubric first: keep the six responses at 11/15, or accept them at 15/15 for this item?
Rubric review
Three-point estimate · 15 points · 24 responses checked
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not a grading run
Review sequence
24 responses checked
6 boundary cases
24/24 compared
Midterm in progress · 0 posted
Grading continues
No grades are available for approval or posting in this preview.
I found an integrity signal in two final pro formas. 847 of 917 compared cells match. Every computed cell matches; only the written descriptions differ. Scores are unchanged.
Faculty review recommended · not a finding
Illustrative comparison · scores unchanged · students not contacted
Stanford’s Honor Code prohibits submitting another person’s work as your own and accepting unpermitted aid on graded work. This match is a reason for faculty review, not a verdict.
Why Leaf flagged it
I prepared the faculty review. No score changed and no student message was created.
Confidential faculty review
Team A ↔ Team B · integrity signal
Demo preview
signal, not proof
Faculty review recommended
Leaf records the match. Faculty decides what it means.
In this preview, I can show the High Performance Buildings edge case, the Engineering Economy Midterm rubric review, or the Real Estate Development integrity signal.
I can explain why Leaf flagged the match or prepare the faculty review.
That’s outside this rubric review. I can explain the distinction or record Option A or B.
That’s outside this guided preview. I can show the submission or explain why I flagged it.
That’s outside this preview. I can compare the two methods or explain why their rubric treatment should match.
That’s outside this preview. I can show the class pattern or the teaching note.
The receipt is already ready below. The batch is still proposed.