Electricity and Water: Everyone Budgets the Lights, and the Lights Were 3 Percent

Every microgreen cost model in this category budgets the grow lights. In the one published room with a metered breakdown, the lights were the smallest line on the bill.

The one room anyone has broken down

A 2024 study reported 188.4 kWh over 15 days for 12 square meters of microgreen production, and it published where the power went.

The three components sum to 188.4 exactly, which is worth noting because a published breakdown that does not reconcile with its own total is not usable, and this one does.

Cooling drew twenty-eight times what the lighting did. That is the finding, and it inverts how this cost is normally modelled.

Read the limits before carrying it anywhere. This is a warm-climate, air-conditioned room in Sonora, and the study's own authors describe the consumption as an estimate rather than a meter reading of a commercial operation. It does not establish that cooling beats lighting everywhere. It establishes that a lighting-only calculation can be wrong by a factor of thirty, and that is enough to change how a plan is built.

A second source points the same way independently. A 2022 research paper identifies LED heat and moisture from plant transpiration as major reasons plant factories need extensive air conditioning. The lights are not just a load. They are a heat source that a second load then has to remove.

A national average will not price your bill

US residential electricity in May 2026 ran from 12.35 cents per kilowatt-hour to 52.00 cents, depending on the state. That is a 4.2-fold spread, and it means the national figure is a poor basis for anybody's plan.

This site publishes a national average, so here is what that costs. The fans review prices continuous running at the EIA May 2026 US residential average of 18.44 cents. Re-priced across the real state range:

The same fan costs $41 or $173 a year depending on where you plug it in. The figure this site publishes is correct as a national average and it is not your number.

Use your own bill. Not a national average, not a state average, the rate on your last statement including whatever fixed monthly charge sits under it.

Where energy actually lands in a full cost model

One published model breaks out utilities against everything else. A 2021 Welsh cost model for a 48 square meter, four-level controlled-environment operation assigns:

• Electricity: £7,123 a year from 59,357.76 kWh, which is 6 percent of direct costs
• Water and CO₂ together: £55, under 1 percent
• Consumables: 36 percent
• Labor: 24 percent
• Packaging and packing: 15 percent

So in that model energy is a real but modest line and water is a rounding error. That is a cost model rather than surveyed accounts, and it is one operation in one climate at one tariff.

Two cautions on reading it against the rest of this site. Its 24 percent labor share is a share of a whole operation's direct costs, which is not the same denominator as the labor guide's finding that labor is 49 to 69 percent of a single tray's cash inputs. Those two numbers are not in conflict; they are answers to different questions and should not be averaged. And a second published model reports a 34.7 percent operating margin without publishing a comparable utilities share at all.

Water is the cheap one, and the bill is not just the water

Nothing in the opened sources makes water a significant microgreen cost. The Welsh model puts water and CO₂ together under 1 percent.

But the volumetric charge is not the whole bill. Water and sewer are frequently billed together, and fixed service charges vary materially between utilities. A grower on a metered commercial connection and one on a domestic supply are not paying the same structure even at the same nominal rate.

Which is the same instruction as the electricity. Take it off your bill.

What to actually do

• Budget the climate control, not just the lights. In the one metered breakdown available, cooling was 79.6 percent and lighting was 2.9.
• Treat your lights as a heat source as well as a load, because the second load exists to remove the heat the first one makes.
• Price everything off your own bill, including the fixed charges. A 4.2-fold spread across states makes any average a placeholder.
• Measure the fixture at the wall, not on the box. A lighting cost is calculable only from measured wall kilowatt-hours, actual lit hours and your own tariff.
• Do not budget a rack from lights alone. That is the specific error the 188.4 kWh room demonstrates.
• Do not spend long on water. Under 1 percent in the one model that broke it out, and the effort is better spent on the three lines above it.
• If you are in a warm climate, the cooling line is your energy budget, and the room in that study is the closest published analogue to it.

What nobody has measured

• A metered breakdown of a real commercial microgreen operation, anywhere. The 188.4 kWh figure is a study's estimate for a 12 square meter room.
• A climate map or a crossover point at which cooling overtakes lighting.
• Energy per tray or per pound of crop, from any source, which is the unit a grower actually needs.
• A utilities share of total operating costs from surveyed financial statements rather than a cost model.
• Water use per tray, separately from the irrigation guidance this site already publishes.
• Whether a home grower's marginal energy cost differs from a commercial one in any measured way.

Sources

Opened 2026-08-12. The re-pricing of the fans review across the state rate range is arithmetic performed for this page on this site's own published wattages and the published rate range below. The percentage shares of the 188.4 kWh room are computed from the study's own component figures, which sum to its stated total.

• Energy and economic assessment of microgreen production, 2024 (SciELO Mexico) - the 188.4 kWh over 15 days for 12 square meters, broken into 150 kWh for a 12,000 BTU/h air conditioner, 33 kWh for a floor fan and 5.4 kWh for two 20 W LED lamps, the 2021 Sonora household tariff total of MXN 215.01 including VAT, the 34.7 percent operating margin, and the authors' own description of the consumption as an estimate.
• Business Wales, controlled environment agriculture report, 2021 (PDF) - the 48 square meter, four-level model assigning £7,123 a year of electricity from 59,357.76 kWh at 6 percent of direct costs, water and CO₂ at £55 and under 1 percent, consumables 36 percent, labor 24 percent and packaging 15 percent.
• Frontiers in Plant Science, plant factory environmental control, 2022 - that LED heat and moisture from plant transpiration are major reasons plant factories require extensive air conditioning, which is the independent support for the finding that lights are a heat source as well as a load.
• US Energy Information Administration, average price of electricity by state - the May 2026 US residential range of 12.35 to 52.00 cents per kilowatt-hour by state, and the 18.44 cent national average this site publishes elsewhere.