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Measuring energy use

This page explains how to measure energy use in a church or other premises, with a view to saving energy and carbon emissions.

See Churches and people; and also Energy and carbon, global warming and climate change and Climate Action Plans.


We need to cut our energy use as far as we can – for reasons of energy scarcity and climate change. Not just cost; whether fuel costs are on an upward trend long-term is debated, and there is great political pressure to keep costs down, but so far this has proved ineffectual.

We have to be more frugal in straitened times. Climate change itself will add to economic pressures.

Accurate recording is essential, if one is to know whether any savings have been made.

In the Diocese of London, church energy use is reported via Parish Annual Returns. See also Entering annual returns.

But how does the long-suffering churchwarden read the figures to put on their church’s returns?


We measure oil in litres; by checking the level in the tank, or adding deliveries up during the year.

Otherwise we use kWh for everything. That’s easy for electricity. The kWh is the standard unit, on most meters and on the bill.

Gas units are confusing, and they’re not labelled on the meter. The word ‘unit’ used to mean heat units (therms or BTUs), now it means volume. It can be imperial (100s of cubic feet) or metric (cubic metres, ie 1000s of litres). Then that has to be converted to kWh. Your bills should tell you how to multiply units to kWh.

Meter readings

It’s best to take the number of units from meters if possible, not rely on bills unless you can’t avoid it. Bills may be estimated, but you shouldn’t let this go on too long anyway. Nowadays suppliers are asking for customer readings when they can’t get access – they know they need some check on their estimated figures. Returning a customer reading means you pay the right amount and can keep tabs as you go along.

Finding your meter can be tricky, and working out what it covers – the whole site or part? Are any areas sub-metered? Or separately metered, with an independent intake?

For annual returns, you need to report the difference between the end of last year and the end of the year before that. Therefore it makes sense to take your own readings as close as possible to the turn of the year.


If you can’t avoid taking readings from your bills, quarter dates will probably not correspond to year ends. You can apportion the amount which straddles each year end, between the numbers of days in the old year and the new year. Then add the two reduced amounts at the beginning and end of the year to the other three complete quarters between.

An estimated bill is better than nothing! For the whole Diocese, the errors tend to cancel out, so this is useful for purposes of Annual Returns.


As explained above, electricity meter readings will be in kWh. The total for the year can be entered straight in Parish Annual Returns.

Electricity supply companies

Your incoming cable, and the electricity flowing through it, are the responsibility of your District Network Operator (DNO), which is the regional branch of the National Grid. In London the DNO is UK Power Networks (UKPN). They used to own and install the old-style meters.

The DNO is responsible for network repairs and emergencies. If you suffer a power cut, the DNO is supposed to fix it.


Once it has been established whether your meter measures imperial or metric units, take the annual total and multiply from units to calorific value, then again from calorific value to kWh, using conversion factors stated on bills.

Your bills should tell you the conversion factors. Alternatively, call your utility company and request conversion factors.

‘Gross calorific values’ (‘gross CV’) should be used, not ‘net CV’.

Smart metering

Smart metering should help with accurate and easy reporting, and with improving efficiency.

Smart metering is now being rolled out for electricity supplies, beginning with some larger premises including churches.

See Smart metering.

Energy-saving Benchmarking

Accurate energy readings are also an essential first step in taking part in the Diocese’s Energy-saving Benchmarking scheme.

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