The Bill Predictor's Printable Sheets

The Quest Map

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Eleven stations, one a chapter. Tick each box when its number is in your Bill Predictor; the Build is the last stop, when the bill arrives.

Template A — The Meter Reading Log

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A clean printable copy of this log is on the companion site:

Chapters 1 and 2 run on two meter reads a day apart and one outdoor temperature. Read both meters at the same time each morning, and the min/max thermometer outside; write the numbers down before you work anything out. The book's house is printed as a worked example, worked out on paper from published figures, not measured by us: read your own meters and log your own month. Reading is yours; opening is not. Never open a meter, its cover or the consumer unit (US: the panel): if a meter looks damaged, or you smell gas, leave it alone and call the supplier or the gas emergency line.

The four-week reads (Chapter 1)

Copy the calorific value (CV) and, in the US, the therm factor from your own bill: they change a little from bill to bill.

The daily log (Chapters 1 and 2)

Degrees below 15.5 °C = 15.5 − the day's mean outdoor temperature (0 if the day was warmer). Mean = (min + max) ÷ 2. Add a day's "degrees below" up over the month and you have its degree-days (Chapter 6).

The first three rows are the book's; the last row is its whole month. Print two copies for a 28-day log. The book's month: 298.5 degree-days (537 °F-days).

The bill, line by line (Chapter 1)

The tariff is illustrative, shaped like the GB price cap of October to December 2026, written without a currency sign. Copy your own unit rates and standing charges from your bill. Is each read on your bill marked A (actual) or E (estimated)? Your read: The bill's:

Template B — The Plug-Meter Audit

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A clean printable copy of this sheet is on the companion site:

Chapter 3 finds where the day's kilowatt-hours go: the meter's flashing light for the watts right now, a plug-in meter for each appliance's kWh over a week, and the remainder nobody has explained yet. The book's house is a worked example, worked out on paper from published figures, not measured by us.

Safety first. Use a plug-in meter rated above the appliance it measures (the rating is printed on both). Never run a space heater through a plug meter or an extension lead unless its maker allows it, and never chain extension leads for a high-power load. US plug-in meters are for 120 V devices only, not 240 V dryers, central air or water heaters (DOE). Count the meter's flashes through its window; never open the meter or the consumer unit (US: the panel).

Watts right now, from the meter's light (Chapter 3)

Every flash is one thousandth of a kWh on a meter marked 1,000 imp/kWh (read the number printed on yours). Watts = flashes × 3,600,000 ÷ (imp/kWh × seconds counted).

The audit: kWh a day, appliance by appliance (Chapter 3)

Leave the plug meter on for a week and divide its kWh by 7; or work it out as watts × hours ÷ 1,000; or cycles a week × kWh a cycle ÷ 7.

What is left over (Chapter 3)

If the two base loads agree, the audit has found the house's all-night load. If they do not, the difference is still switched on somewhere: walk round at night with the plug meter.

Template C — The Overnight Cooling Log

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A clean printable copy of this log is on the companion site:

Chapters 4, 5 and 7 run on one night's readings: switch the heating off at bedtime, then read an indoor thermometer and an outdoor one every hour until morning. The book's night is a worked example, worked out on paper from published figures, not measured by us: log your own.

Safety first: cold has costs. Do this test only on a night when nobody who needs warmth is at home (a baby, an older person, someone with a health condition), when no pipe can freeze, and not in a home with damp or mold: follow your public-health service's guidance on indoor warmth. If a gas boiler or furnace is involved, have a working carbon-monoxide alarm. Never open the boiler, the tank or the meter.

The log, hour by hour

Gap = indoor − outdoor (the book uses the night's steady 4 °C outdoor). Slope = this hour's indoor − the last hour's, in °C an hour. ln(gap) is the calculator's ln key, for Chapter 7.

What the night tells you (Chapters 4, 5 and 7)

The last two rows are the same heat counted two ways; the book's agree within 2 %. A 0.1 °C error in the last reading moves the book's τ from 35.3 to 37.7 h, which is why a good thermometer read at the same height each hour matters more than a clever formula.

Template D — The Bill Audit Sheet

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A clean printable copy of this sheet is on the companion site:

Chapters 10 and 11: reproduce every line on the bill from your own reads and your own tariff. Most bills are right, and a line that matches is good news. The book's bill is a worked example, worked out on paper, at an illustrative tariff written without a currency sign.

The checks before the sums

Every line, reproduced (Chapter 10)

The book's gas line used an estimated closing read: 2,980 − 2,698 = 282 kWh too high, 282 × 0.08 = 22.56. Send the supplier your read (a dated photo of the meter is best) and ask for a corrected bill.

Your bill

When a line is wrong

1. Send a read. An estimate that is too high is corrected by an actual read; the supplier sends a new bill.
2. Ask in writing, with the bill's date, the line, your read and a photo of the meter. Keep every message and reply.
3. Keep paying the part that is not in dispute, and ask about ways to pay if you cannot pay in full.
4. If it is not settled: UK: after 8 weeks, or sooner with a deadlock letter, the Energy Ombudsman (free). Ofgem's back-billing rule: in most cases you do not have to pay for energy used more than 12 months ago that you were never correctly billed for. US: the utility first, in writing; then your state's public utility commission.

Rules and tariffs change and differ by country and state: check the regulator's own page before you rely on one.

Template E — The Decision Ledger

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A clean printable copy of this ledger is on the companion site:

One line a decision, each in your own household's numbers (Chapters 8, 10 and 12). Money a year = kWh saved a year × the price of a kWh; payback = cost ÷ money a year. The book's rows are worked examples at an illustrative tariff, written without a currency sign. Nothing here is a promised saving: your house, your habits and your tariff decide it.

The book's house

A kWh of heat from gas costs 0.08 ÷ 0.9 = 0.0889 (the boiler is 90 % efficient). The setback is 5.8 % of the month's heating gas; the standby is 8.75 % of the house's electricity. The fridge pays back in 10.9 years: replace it when it fails, unless it is failing now.

Yours

Do not add the rows up. Decisions overlap: a thicker loft makes the setback save less, because the house cools more slowly. Put each decision into the model (Chapter 10) and run it again; the new prediction is the honest total. A published figure (a government program's "up to 10 %") is the source's, with its conditions: write it beside your own, never in place of it.

Before any work. Insulation near recessed lights, flues or vents, and anything electrical, is an installer's or an electrician's job. Heat pumps, solar panels, batteries and EV chargers are fitted by certified installers (UK: MCS); you do the arithmetic, they do the installing.

Template F — The Call It Log

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One line a chapter. Write the call before you measure, in pen. Gap = (measured − call) ÷ measured, ignoring the sign. Within 5 % scores 3 points, within 10 % scores 2, within 20 % scores 1; beyond that 0, and find out why, because that is the chapter. Some numbers can only be measured later in the month: those lines are checked in Chapter 11.

Each chapter's own Call It box says exactly what to call and how to check it; where it and this line differ, follow the chapter. The book's own calls are printed in the chapters, never in the "Your call" column: the game only works if the prediction is yours. Family variant: everyone in the house writes a call; nearest wins.

The miss that taught you the most. Chapter: What you had assumed:

What you found out:

The Trophy Page

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Called, measured, audited. Write it down.

The Bill Score

Gold within 5%; Silver within 10%; Bronze within 20% with the audit sheet complete. The Audit level every line on the bill reproduced from your own reads and tariff. The book's bill as sent, 343.11, was 10% from its call (Silver); the audit found 282 kWh (22.56) on an estimated read.

The season scoreboard

The miss that taught you the most

Signed   Date