Energy & Smart Systems · Project 3 of 12

The Four-Hundred-Rupee Leak

Which appliance is quietly eating the bill

Read your own meter for a fortnight and find the one appliance quietly taking hundreds of rupees a month.

The calendar this needs: Thirty-five measurement days — fourteen consecutive days of twice-daily readings for the baseline, then twenty-one more after the change — so the baseline must start in the first week and cannot be shortened later.

Six weeksNo equipment on the paper route 20 written stepsMarked out of 20Free forever
The question

Which single appliance or habit in your home costs the most rupees per month, measured from your own meter rather than guessed?

A household that cannot say where its units go cannot argue with its bill, and neither can a school, a hospital or a factory. Energy auditing is a trade built on exactly this method — baseline, isolate, convert to money, change one thing, measure again — and it is paid for because the savings pay for it. Grid operators, solar installers and building managers all hire people who can defend a before-and-after number in front of somebody who does not want to believe it.

Two acts. Find, then fix.

Every EAD project runs the same shape. The first act produces a number nobody in the room could previously state. The second act changes exactly one thing and proves whether that number moved.

Act 1 · Find
You read your own meter at the same two times every day for fourteen days to build a baseline with a noise floor in it, then isolate one appliance while a named adult runs it alone for a measured period and you read the meter before and after. You convert units to rupees using the tariff printed on your household's own bill, and you log load-shedding, generator and UPS hours every single day.

A one-page costed problem statement carrying five lines: whose bill, units per month for the one appliance, rupees per month at your household's own rate, rupees per year, and that appliance's share of the whole house. Behind every line sits a dated meter photograph or a circled line on the bill.

Act 2 · Fix
You change exactly one thing that costs nothing — a setting, a timing, a habit, a door seal, or a bulb already in the house — and keep reading the meter at the same two times for three weeks. The isolation test is repeated under the new condition, and load-shedding hours are logged for both periods so the comparison survives them.

Two charts of the baseline fortnight against weeks one, two and three — one in units, one in rupees, never both on one axis — plus the mean after-figure, the week-to-week spread inside the baseline itself, the next printed bill set beside your own arithmetic, a named confounder list, and the bill-payer's recorded answer on whether the change stays.

What actually gets measured

The numberrupees per month for one appliance or one habit, in rupees per month
BeforeFourteen days of twice-daily readings, not seven, so the two baseline weeks can be compared with each other and the ordinary week-to-week wobble is known before anything is changed. Units per hour comes from a timed isolation run against the meter, multiplied by hours actually tallied per week, multiplied by the rupee-per-unit rate calculated from your household's own bill. Load-shedding, generator, solar and UPS hours are recorded for every one of the fourteen days.
AfterThe same isolation test and the same twice-daily meter readings repeated for three weeks after the change, compared with the baseline fortnight — mean and spread — and with the next printed bill, with load-shedding hours stated for both periods. A fall smaller than the gap between the two baseline weeks is not yet a finding.
The honest partA well-measured failure scores higher than an unmeasured success. If the number did not move, say so and explain why.

If your household cannot run this

Run it on the school's own meter. A member of staff reads it with you at two fixed times for fourteen days, and the site electrician or caretaker — the person who already switches the school's boards — does every switching operation for the isolation run while you stand back, read and record. One pump, one geyser, one corridor of lights, one server cupboard. The school's own bill supplies the tariff, and the bursar signs the before-and-after in place of a bill-payer. This is marked exactly as the home version is marked, out of the same twenty. It is not a reduced project, and the school meter is in some ways the better instrument, because the bill behind it is bigger and somebody in the building is already arguing about it.

Every step, written out

Twenty steps in total — ten to find the number, ten to fix it. Pick the route that matches what your school actually has.

The meter is already an instrument and the bill is already printed, so a notebook, a watch and a pen produce exactly the same rupee figure as any spreadsheet.
You need: The printed electricity bill, this month's and last month's · A notebook ruled into six columns with a pen and a ruler: date, time, reading, difference, load-shedding hours, notes · A clock or watch showing minutes, used for the timed isolation run · A torch for reading the meter after dark, held by a named adult who walks out with you and stays within sight for the whole reading — no reading after dark on your own · Squared paper for the day-block and before-and-after charts, drawn to a stated scale · A tally card kept beside the appliance for start and stop times

  1. Find the meter

    40 minutes
    Locate your meter, work out what its display means, and take the first dated reading without touching anything.
    • Stand in front of the meter in daylight and copy every figure on the face into the notebook exactly as it appears, hands at your sides.
    • Copy the meter number printed on the front and check it against the meter number printed on the bill.
    • Identify which figure is the units total in kWh; on a digital meter press nothing and wait for the display to cycle to that screen by itself.
    • Sketch the meter face and label what each figure means, marking the decimal digit if there is one.
    • Rule the log columns: date, time, reading, difference, load-shedding hours, notes.
    Write down: The meter number, the meter type, the labelled sketch, and the first reading with date and time to the minute.
    Finished when: The labelled sketch and the first reading are in the notebook, and the meter number matches the bill.
    Commonest mistake: Pressing buttons on a digital meter to reach the screen you want. Press nothing and wait. If units never appear, copy every screen down and ask the expert which one it is.

  2. Fourteen days of readings

    10 minutes twice a day for fourteen days
    Build the baseline by reading the meter at the same two clock times every day for a fortnight, so you know how much a week wobbles on its own.
    • Choose two fixed times, for example 07:00 and 22:00, and agree with the household that somebody reminds you at each. Any reading taken after dark is taken with a named adult beside you.
    • At each time copy the reading into the log with the actual clock time, in ink, without correcting earlier entries.
    • Write load-shedding start and end times every day, and any hours run on a generator, a UPS or solar.
    • Subtract longhand in the difference column to get day-block units and night-block units.
    • Add one word for the weather and a note on whether the house was fuller or emptier than usual.
    • At the end, total each of the two baseline weeks separately and write the gap between them. That gap is your noise floor: nothing smaller than it counts as a change later.
    Write down: Twenty-eight readings, fourteen day-block totals, fourteen night-block totals, both weekly totals with the gap between them, and a load-shedding line for every day including the zeros.
    Finished when: Fourteen complete days with no missing reading, every day carries a load-shedding note even when it is zero, and the difference between baseline week one and baseline week two is written down as a number.
    Commonest mistake: Reading at 'about ten'. A reading an hour late wrecks the block comparison — write the real clock time and subtract from that.

  3. Read the bill properly

    45 minutes
    Turn your household's own printed bill into a rupee-per-unit rate you can defend.
    • Lay this month's and last month's bills side by side and circle in pen: units billed, the slab breakdown, fixed charges, every tax line, and the total payable.
    • Copy twelve months of billed units from the consumption history box printed on the bill itself into your notebook.
    • Divide total payable by units billed, longhand, to get the average rate, and copy the slab rate your next unit falls into from the tariff table printed on the bill.
    • Write one sentence naming which rate you will use for the appliance costing and why.
    Write down: Twelve months of billed units, both rupee-per-unit rates with the working shown, and the reason for the rate you chose.
    Finished when: You can say what one extra unit costs your household tonight and put your finger on the printed line that proves it.
    Commonest mistake: Using the headline slab rate and ignoring taxes and fixed charges. Show both rates: the marginal rate is what a saved unit is worth, the average rate is what the bill feels like.

  4. Isolate one appliance

    30 minutes of setting up, plus two runs long enough to move the meter ten steps — an hour each for a heavy load, several hours for a light one
    Measure what one appliance draws while a named adult runs it alone against the meter. You read and record. You switch nothing.
    • Agree one appliance with the household — an air conditioner, a fridge, a water pump, a geyser, an iron, a heater, or the lights on one floor — and write in the log the name of the adult who will do every switching operation.
    • Copy the wattage and voltage printed on the appliance's own label, without moving it, opening it or removing any cover.
    • Find the meter's least count first: the smallest step its last digit can move, commonly 0.1 units on a domestic meter. Write it down before you time anything.
    • The named adult agrees a quiet window and switches off every other load at the wall switches the household already uses, leaving only the one appliance running, and switches that appliance on and off. Your hands stay at your sides throughout.
    • Copy the meter reading and the clock time, let the run go on until the reading has moved by at least ten least counts — with a 0.1-unit meter that means one whole unit, which a small load will not reach in half an hour — then copy the reading and the time again.
    • Divide units used by hours run longhand to get units per hour, then repeat the whole test on a second day, with the same named adult present from the first switch-off to the last reading.
    Write down: The meter's least count, the name of the adult who switched, start reading, end reading, minutes run, how many least counts the reading moved, units per hour with the working shown, the label wattage, and the gap between the two test days.
    Finished when: Each run moved the meter by at least ten least counts, and the two independent tests agree within the tolerance you calculated from that least count and wrote down before you compared them — or you have written down exactly why they do not. A tolerance set without knowing the least count is a guess: on a 0.1-unit meter a short run on a small load can be wrong by more than a tenth of a unit from rounding alone.
    Commonest mistake: Forgetting the fridge, the router and the standby lights. Anything left on lands inside your appliance's figure — list what could not be switched off and subtract its measured share.

  5. Count the hours

    40 minutes of arithmetic, plus 5 minutes a day marking the tally card for seven days, plus two seated hours watching the appliance cycle
    Tally how many hours the appliance actually runs and turn that into rupees per month.
    • Keep a tally card beside the appliance and mark every start and stop time for seven days.
    • For a fridge or a pump that cycles on its own, sit with it for a full hour with the watch and count the minutes it actually runs, twice at different times of day. That is two hours of sitting still, and it is the only way to get the duty cycle honestly.
    • Multiply units per hour by hours per week, then by the weeks in a month — 4.33, not four — then by your chosen rate, showing every multiplication on the page.
    • Set the figure against the whole-house units from step two and write what percentage of the house this one appliance is. Round that percentage to the nearest whole point and no finer, because it is built on a meter that moves in steps.
    Write down: Hours per week, units per month, rupees per month for this one appliance, and its share of the whole house.
    Finished when: The appliance figure exists in rupees per month and it is smaller than the whole-house bill.
    Commonest mistake: An appliance that appears to cost more than the entire bill. The isolation test or the hours are wrong — redo the test before writing another line.

  6. Name the leak

    50 minutes
    Finish the costed problem statement on one page and choose the single change you will make.
    • Write five lines: whose problem this is, units per month, rupees per month, rupees per year at today's tariff, and share of the whole house. Beside the yearly figure write the caveat in the same line: it assumes twelve months like this one, and a geyser in winter or a cooler in summer runs nothing like the month you measured.
    • Draw the fourteen day-blocks and fourteen night-blocks as paired bars on squared paper, scale stated, titled with the finding.
    • List three candidate changes that cost nothing: a thermostat or fan setting, a timing shift, a door seal pressed back, a bulb already owned, or one habit.
    • Choose one and write: 'I will change X for three weeks and expect this appliance to fall from A units per week to B.'
    • Read the page aloud to whoever pays the bill and have them sign and date it if they agree to the change.
    Write down: The one-page costed problem statement, the three candidate changes, and the chosen change as one testable sentence.
    Finished when: Somebody who was not there reads the page once and repeats your rupee figure back correctly.
    Commonest mistake: Choosing a change that needs something bought. Use what is already in the house, or the result measures money spent rather than a habit changed.

  7. Set the after rules

    40 minutes
    Write the protocol that makes the after-measurement comparable with the before.
    • Write what stays fixed: the same two clock times, the same meter, the same rupee rate, the same appliance, the same tally card.
    • Write what is allowed to move: only the one thing you named in step six.
    • Rule twenty-one blank dated rows in the notebook before any data exists.
    • Write the confounders you already expect: weather, guests, load-shedding hours, a different person using the appliance.
    • Write your prediction of the after figure, date it, and have one person witness it with a signature.
    Write down: The numbered protocol, the twenty-one blank dated rows, the confounder list, and the witnessed, dated prediction.
    Finished when: The notebook holds empty dated rows for three weeks and a signed prediction that predates the data.
    Commonest mistake: Changing two things at once because both looked easy. Two changes give one number you cannot attribute to either — change one and keep the second for the stretch.

  8. Measure week one

    10 minutes twice a day for seven days
    Run the change for seven days and read the meter exactly as you read it before.
    • Take both daily readings at the same two clock times and write them in ink with the real time.
    • Keep the tally card running exactly as it ran in Act 1.
    • Repeat the isolation test once under the new setting and record units per hour again.
    • Write load-shedding and generator hours daily, and mark the week as disturbed if those hours moved sharply against the baseline fortnight.
    • Write down every slip: a missed reading, a night the change was forgotten, a guest who reversed it.
    Write down: Seven days of readings, one repeated isolation test, the hours tally, and a dated failure entry.
    Finished when: Week one is complete with no blank rows and the failure log holds at least one honest entry.
    Commonest mistake: Being unusually careful with electricity all week because you are watching yourself. Name that effect in the log — it is the reason you measure for three weeks and not one.

  9. Weeks two and three

    60 minutes of arithmetic and drawing, plus 10 minutes twice a day for fourteen days
    Repeat two more weeks, then check your finding against the next printed bill.
    • Take the same two readings daily for a further fourteen days without altering anything else.
    • Add the three after-weeks and divide by three, longhand, then set the mean against the mean of the two baseline weeks — and against the gap between those two weeks, which tells you how big a fall has to be before it means anything.
    • When the next bill arrives, compare its billed units with your own arithmetic and write out any gap and the reason for it.
    • Draw two charts on squared paper, each to one stated scale and each with one unit only: five bars in units — baseline week one, baseline week two, then weeks one, two and three — and the same five bars again in rupees. Never both units on one axis.
    • Write the confounder paragraph: temperature, load-shedding hours, people in the house, and anything else that moved.
    Write down: The two five-bar charts — one in units, one in rupees — the mean after-figure, the gap between the two baseline weeks, the bill comparison with its explanation, and the confounder paragraph.
    Finished when: You can state the before figure, the after figure, and at least two reasons the difference might not be your doing.
    Commonest mistake: Blaming the bill when it disagrees with your notebook. Check the billing dates first — a bill rarely covers the same days you measured.

  10. Share and reflect

    60 minutes
    Publish the finding, defend it to real people, and record what the household will keep.
    • Deliver the defence live, ten to twelve minutes of unseen questions, in front of two witnesses who sign and date the page. On this route there is no recording.
    • Read the one-page explainer to three neighbouring households on the same tariff and write down what each of them said.
    • Hand or post the chart to the expert your teacher wrote to, with one question: what would you have measured that I did not.
    • Ask whoever pays the bill, in front of a witness, whether the change stays and why, and write the answer word for word.
    • Complete the relations ledger with ten codes, roles, dates and replies.
    Write down: The defence, signed and dated by its two witnesses, the one-page explainer, and the relations ledger holding ten coded relationships.
    Finished when: Ten coded relationships are logged with dates and replies, and the bill-payer has said on record whether the change stays.
    Commonest mistake: Presenting the rupee saving without the load-shedding note. Everyone on your street will ask about it — answer it before they do.

What the student hands in

Nine pieces. Together they are the folder a parent can sit down and read.

1. Question cardOne card naming the household, the meter number and the appliance under test, and the question: what does this one appliance cost per month, measured from the meter rather than guessed.
2. Expert interview packFive written questions for an energy auditor or maintenance engineer, sent by your teacher from a school address with your isolation figures attached as one page, the date and channel of the request, and the reply recorded word for word. If no reply comes, the questions as sent, the dated attempts and one named published source stand in their place.
3. Evidence logEvery meter reading with its clock time and photograph or ink entry, the meter's least count written down before any timing, both isolation tests with start and end readings and the name of the adult who did the switching, the circled tariff lines, and a load-shedding note for every single one of the thirty-five days.
4. Failure logThe readings missed, the night the change was forgotten, the isolation test spoiled by a load you could not switch off, and what each of them did to the comparison, all dated.
5. The buildThe measurement rig itself — the log, the tally card, the two fixed alarm times, the isolation procedure written as steps, naming who switches and who reads — plus the two before-and-after charts, one in units and one in rupees, each carrying a single unit.
6. One-page explainerOne page a neighbour reads in ninety seconds: the appliance, the rupees per month, the change made, the three-week result, the load-shedding caveat, and what the figure cannot prove.
7. Identity cardA name and a one-line promise for the measurement, so the household refers to it by name, plus the single sentence you want repeated to the neighbour who asks about their own bill.
8. Relations ledgerTen coded entries, each with a role, a date and what was said: E1 the energy auditor or engineer, A1 to A3 the people affected who pay or share this bill, P1 to P3 the peers who checked your arithmetic, R1 to R3 the people who were sent the chart and replied. No names appear in the ledger. The single sheet matching codes to names is held by the school and destroyed after moderation, and no health, financial-hardship or literacy information about any named person is recorded anywhere in it.
9. The defenceTen to twelve minutes of unseen questions, answered live in front of two witnesses who sign and date the page: the meter, the isolation method, the rupee figure, the one change, the three-week result against the baseline fortnight, the bill comparison, and the limits you accept without argument. A recording is optional evidence and never the requirement; on the No-Tech route there is no recording at all.

The expert they have to find

Ten logged relationships are required before this project can be marked. One of them is an expert, and this is who.

An energy auditor, or the maintenance engineer or technician who manages the electricity bill for a school, hospital, hotel, mill or small factory. A solar installer who sizes loads for a living works just as well.

How to find one

Go by institution and role, not by person. Every school, hospital, hotel, mill and small factory has somebody who signs off the electricity bill — a maintenance engineer, an estate or facilities manager, or the site electrician. Your distribution company runs an energy-conservation desk at its customer services office. Solar installation companies employ engineers who size loads all day. Municipal and university estates departments employ the same role. You name the institution and the role; your teacher makes the approach from a school address, and the reply comes back to the school. You do not ring, message or search for a named individual yourself.

What to say

Dear [name or role], I teach at [school]. One of my learners has read a household meter twice a day for fourteen days and timed one appliance running alone against that meter to cost it in rupees. Could you spare fifteen minutes — on a call with me present, or by written reply, whichever suits you? Their five questions are below.

What to ask

  • When you audit a building, what do you measure first, and why that before anything else?
  • My isolation test ran for [number] minutes with everything else switched off. What is still drawing current in a house at that moment?
  • Would you cost a saved unit at the marginal slab rate or at the average rate, and why?
  • How do you separate a real saving from a change in the weather or in load-shedding hours?
  • What is the commonest appliance you find people are wrong about, and how wrong are they?

If no reply comes, nobody is chased. You submit the questions exactly as your teacher sent them, the dated record of the attempts, and one named published source — the NEPRA tariff schedule or a published audit guide — in place of the answers. That route scores. The gate is passed by asking properly, never by getting somebody to reply.

The defence

Eight of the twenty marks. A student who cannot answer these has not finished, however good the artefact is.

  • Would the bill have fallen anyway without your change, and how do you know?
  • Your isolation test ran once on one day. What else was drawing current at that moment, how many units did it add, and how far could your meter's least count alone have moved your answer?
  • The tariff has slabs. If your household crossed a slab boundary during the three weeks, what happens to your rupees-per-month figure?
  • Somebody says your saving is just cooler weather and lighter load-shedding. Answer them using only your own data.

How far a student can take it

starterYou take twenty-eight meter readings at two fixed times across a fortnight, isolate one appliance with a timed run an adult switches for you, convert units to rupees from your own bill, and put your questions to one professional.
practitionerYou choose the appliance and defend the choice, cite the exact tariff line you used, and make one chart a stranger reads correctly without you standing there explaining the axes.
researcherYou state the protocol before measuring, justify a fourteen-day baseline and three after-weeks rather than one week against one, and quantify how the meter's least count, load-shedding hours, weather and the loads you could not switch off limit your figure.
contributorYou report the figure you measured and set the appliance's rated wattage and the published tariff schedule beside it rather than in place of it, defend the isolation method to an energy auditor, and publish every reading through your school, where your school agrees it may be published, so the arithmetic can be recomputed.

If you want to go further

Isolate a second appliance and rank every measured load in the house by rupees per month, so the household can see which one to attack next.

When it goes wrong

  • If nobody replies to the messages your teacher sent - then take the next institution off your teacher's brokered contact list, ask for a written reply instead of a call, and if that also goes quiet submit the questions as sent with the dated attempts and one named published source. You do not walk into an office to ask in person.
  • If the household or the site says no - then run it on the school's own meter with a member of staff and the site electrician, exactly as set out above, and be marked out of the same twenty. Nothing about the mark changes.
  • If your before and after look the same - then compare load-shedding hours across both periods first, check the fall against the gap between your two baseline weeks, then report the null result with the numbers, because an honest zero is a finding.
  • If you cannot isolate the appliance because nothing else can be switched off - then have the named adult agree a window when only that appliance runs, measure the whole house across it, and write down the residual load you could not remove.
  • If the meter barely moves in the time you have - then lengthen the run rather than reporting the difference, because a reading that shifts by one or two least counts is mostly rounding.
  • If you run out of time - then shorten the after-period to two weeks, keep the twice-daily readings and the full fourteen-day baseline intact, and state the shortened period on the chart rather than filling the gaps in.

Before you start

Safety and consent.
  • Never open, unscrew or remove the cover of anything: an appliance, a socket, a switch plate, a distribution board, a fuse box or the meter itself. If a test needs a cover to come off, the test is out of scope — choose a different appliance.
  • Never touch wiring, terminals, exposed metal or the face of the meter. Every reading is taken by looking only, from normal standing distance, with dry hands and dry feet, and never in the rain or with wet floors underfoot.
  • You do not switch anything. Every switching operation in this project — every wall switch, every plug, the appliance under test and every load turned off around it — is done by a named adult who has agreed to it in advance, and that adult stays present for the whole isolation run, from the first switch-off to the last reading. Your job is to read the meter, watch the clock and write. Switching is only ever done at the plug or the wall switch the household already uses every day, never at the main board.
  • Never climb or stand on anything to reach a meter mounted high — the named adult reads it out to you instead. Any reading after dark, or any walk to a meter outside the house, happens with that adult beside you and within sight the whole time.
  • Record load-shedding, generator, solar and UPS hours every day of both periods. Power that did not come through the meter breaks the comparison, and a before-and-after made without that note is worth nothing.

Run this with a class

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The other eleven

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