Heat Pump Running Cost Log

Who this is for

What the heat pump uses and what it costs. Write down its electricity meter reading, and the heat meter if you have one, and the log works out the kWh between readings, the ratio of heat out to electricity in, and the running cost per day at the unit rate you enter.

Homes with an air or ground source heat pump that want to see what it costs to run through a season, whether it has its own electricity meter or a heat meter, or only a reading from its controller.

What this helps you track

• Electricity used by the heat pump between readings
• Heat delivered, where a heat meter is fitted
• The ratio of heat delivered to electricity used, from your own readings
• Running cost per day at your own unit rate
• Outside temperature on the day, to read the figures against

How to use it

1. Write the make and model, its rated output from the paperwork, whether it has a dedicated meter, and your electricity unit rate from your own bill.
2. Take a first reading of the heat pump meter, and the heat meter if fitted, and write them on the first row with the date. Put that date in the header as the first reading date.
3. Read both again at regular intervals and add a row each time, with the outside temperature if you know it.
4. The kWh, ratio, days and cost per day are worked out in the browser and the workbook; on paper, subtract each reading from the one above and divide by the days between.
5. Compare runs of similar weather rather than single readings, and note defrosts, settings changes and faults in the notes.

Formats

• Printable PDF (A4 and US Letter)
• Fillable PDF with form fields
• Fill in online, saved in your browser
• Excel / Google Sheets workbook

The printable is laid out inside a box that fits both A4 and US Letter, so the two files are identical and neither one is scaled. The fillable PDF has real form fields. The workbook uses plain formulas only — SUM, IF, COUNTIF and the like — so it opens in Excel, LibreOffice and Google Sheets without anything breaking, and every calculated cell is grey so you can see which figures it worked out.

How to print

Download the A4 or US Letter file to match the paper in your printer, open it in a PDF reader and print at 100% — not "fit to page", which shrinks the writing space. Both files leave a 14 mm margin, which clears the unprintable edge on home printers. To print the online version with your entries in it, use the Print this sheet button, which prints only the sheet and none of the page around it. More on printing.

Questions

What ratio should my heat pump achieve?

The log does not say. The ratio column simply divides the heat meter figure by the electricity figure for each period. What is reasonable depends on the system, the house and the weather, so ask your installer.

I have no heat meter. Is the log still useful?

Yes. Leave the heat columns blank and the log still gives electricity used and cost per day. The ratio column stays empty without a heat meter reading.

My heat pump shares a meter with the house. What then?

Use the heat pump's own controller or app reading if it gives one, and say so in the header. Without a separate figure the log would be costing the whole house.

What if my unit rate changes?

Start a new sheet from the date the rate changes. The cost columns use the single rate in the header, so one sheet per tariff keeps the costs honest.