Calculation note
This page says where every amount on the site comes from, and which ones rest on a public source rather than on our own judgement. It is deliberately short: a figure that does not fit in one paragraph has no business on a landing page.
Reference consumption
Annual consumption per square metre, all energy combined, as final energy. Each value sits inside the documented range for its sector.
| Type of premises | Consumption | Avoidable share | Break-even |
|---|---|---|---|
| Offices | 130 kWh/m² | 22 % | 82 m² |
| Retail | 170 kWh/m² | 20 % | 69 m² |
| Food trade | 350 kWh/m² | 15 % | 45 m² |
| Restaurant | 400 kWh/m² | 15 % | 39 m² |
| Hotel | 240 kWh/m² | 18 % | 55 m² |
| Practice, care centre | 200 kWh/m² | 20 % | 59 m² |
| Other | 150 kWh/m² | 18 % | 87 m² |
Sources: CEREN surveys published by the SDES, the French "absolute values" decrees published in the Journal officiel, and ADEME averages. Our categories are finer than most comparators use, because the variance inside a sector often exceeds the variance between sectors: food retail draws two to three times what a clothing shop does.
The avoidable share is our own hypothesis
No public statistic measures the share of a bill that simple actions recover. We looked, we found nothing solid, and we will not manufacture a citation to fill the gap. This percentage is ours, and here is how we build it.
A week has 168 hours; an office occupies about fifty of them. The rest of the time, anything drawing power is suspect. So we cross the share of unoccupied hours with the share of peak load that persists through those hours for no reason.
That reasoning is what explains the differences between sectors. A restaurant has a high night baseline, but a legitimate one: the cold rooms have to run. An office drawing power at night has no such excuse. Hence 15% in catering against 22% in offices.
The price of a kilowatt-hour
We use 0,20 € per kWh, taxes and network charges included. It is an order of magnitude for a small business; your real price is on your bill, and that is the one the diagnostic uses.
The case shown on the home page
A 200 m² office draws roughly 26 000 kWh a year, for a bill of 5 200 €. The 22% avoidable share gives 1 140 € a year: 470 € of night baseline, 420 € of weekends and 250 € of exceeded subscribed capacity. The first two, 890 € together, come back through simple adjustments; the third needs a contract change.
When the subscription is not worth it
Break-even is the floor area above which the estimated waste exceeds the cost of the Premium subscription, 39 € excl. VAT per month per site. Below it, the subscription costs more than it returns — and we will tell you, rather than let you find out.
What this page does not say
Everything above is an estimate made without seeing a single one of your readings. It gives an order of magnitude; it commits nobody. The diagnostic works on your real consumption at the finest interval available: at that point the waste is no longer estimated, it is measured. A night baseline is recorded consumption, and a subscribed-capacity gap is arithmetic on a regulated tariff.