This is the first post in our “cost answers” series: where the numbers come from and how to do the math — nothing for sale here.
The short answer: what order of magnitude?
Split the question in two: how much electricity a container farm burns in a year, and what that electricity costs. Based on figures reported in public research, a 20-ft lettuce container farm falls roughly in the range of 4,800–14,200 kWh per year. At commercial tariffs of CNY 0.6–0.9/kWh, that works out to roughly CNY 240–1,070 per month. If you want the answer for your exact box — it depends on three variables, covered below.
Where these two numbers come from
The lower bound comes from a simulation study. The study modeled a full year of operation for a 20-ft container farm in Chongming, Shanghai, validated against a 16-day lettuce growing trial. It reported an optimized floor of about 4.76 kWh per kg of fresh lettuce. At roughly one tonne of annual yield per box, that is 4,760 kWh/year.
The upper bound comes from a review. A 2025 systematic review of artificial-light plant factories aggregated published data and reported a status-quo level of about 17 kWh/kg. Same one-tonne assumption: 17,000 kWh/year.
To be clear: these figures come from different studies with different calibers — one is a “thoroughly optimized simulation floor”, the other is “industry status quo per a review”. Put side by side, they give you a span: your box almost certainly lands somewhere on this line, and where it lands is an operating question.
Three variables that decide where you land
1. The tariff — same electricity, up to 2x the cost
Commercial tariffs are time-of-use. In many regions the peak-to-valley spread exceeds 100%. Lighting is a controllable load — shifting the photoperiod into valley hours is the only zero-investment lever on the list. This is also why several studies converge on early-morning photoperiods (with total daily light integral unchanged; response varies by cultivar).
2. Lighting — the fastest-spinning part of your meter
Lighting is usually the single largest load in a plant factory. Here is a back-of-envelope you can run yourself:
Annual lighting energy (kWh) = area m² × fixture density W/m² × photoperiod h × 365 ÷ 1000
Plug in 15 m² of growing area, 200 W/m², 16 h/day: 17,520 kWh a year — more than the entire box’s total above. That is exactly the point: fixture density and photoperiod deserve a line-by-line check against your configuration sheet. We put this formula into our free energy calculator.
3. Climate control — the bill paid to AC, dehumidification and fresh air
The simulation study above also reported this: by moving from a fixed year-round air-conditioning setpoint to stage-wise optimization, annual AC energy dropped from about 2,287 kWh to about 1,513 kWh — a 33.8% cut (as reported by the study, Shanghai climate). That is roughly 126–191 kWh per month for climate control alone. It is why we keep saying: climate strategy is the most overlooked second bill of a container farm.
So what do you do?
Three steps, in order:
- Keep accounts first. Meter lighting and climate control on separate circuits for a full month. Without this ledger, everything else is guessing.
- Benchmark yourself. Divide the monthly total by monthly yield to get your own kWh/kg, and see where you sit between 4.76 and 17.
- Pick the cheapest cut. Shift photoperiod into valley hours (zero investment) → audit fixture density → then consider climate-strategy optimization (quoted per project).
Sources
① Annual AC energy 2,287→1,513 kWh (−33.8%) and 4.76 kWh/kg: container-farm two-stage energy optimization study published in Applied Energy (Chongming, Shanghai, 2024; 16-day lettuce trial plus full-year simulation).
② Status quo ~17 kWh/kg: review of artificial-light plant factory energy use published in Renewable and Sustainable Energy Reviews (2025; aggregating 104 publications).
③ Electricity at 40–60% of opex: common industry-review caliber. All figures are as reported by each study under its own conditions; cite the original papers when reusing. This article is an estimate, not a promise.