Agriculture & Future Food Systems · Article

Electricity, Cooling and Commercial Boundaries

Turn a room’s electricity readings into a bounded product comparison, while keeping cooling, usable output, costs and market assumptions visible.

Preparation and related reading

Shared Foundations

This article helps you

Include lighting and climate services in one electricity account.
Calculate electricity per kilogram of a defined acceptable product.
Separate operating electricity, full costs and whole-system impacts.

Begin with a meter and a product

Two indoor lettuce rooms advertise different efficiencies. One reports lamp electricity; the other reports the whole room. Before ranking them, ask whether the readings include the same services and whether the kilograms refer to the same product. A smaller reported number may simply have a smaller accounting boundary.

Specify location, period, crop, fresh or dry mass, acceptable quality and meter coverage. Nursery lighting, pumps, fans, cooling, humidity removal and packing or storage may sit on different circuits. Decide which are included and retain the excluded terms.

Follow heat and water

Electricity powers lamps, while plants store some supplied energy in chemical compounds. Other energy becomes heat through lamps, absorption, equipment and biological processes. A room must balance incoming energy with heat leaving, stored energy and other outputs; efficient lighting does not make thermal management disappear.

Transpiration moves water from roots to room air. Humidity management may remove that vapour through air exchange or condensation, depending on the system and outside conditions. Condensing water and moving heat require equipment and energy. Cooling and humidity removal interact, so do not add overlapping meter categories twice.

Calculate a bounded intensity

Suppose one hypothetical month records 600 kWh for lighting,300 kWh for climate management and 100 kWh for other room services. These categories are distinct and exhaustive within the stated meter boundary. The sum is 1,000 kWh. If 100 kg of acceptable fresh lettuce leaves that boundary, the electricity intensity is 10 kWh/kg.

This is an operating-electricity comparison, not total energy or a life-cycle footprint. Building manufacture, supplied nutrients, packaging, external transport and any excluded services require additional evidence. State the actual source and reliability of electricity when examining climate impact and practical resilience.

Add services before dividing by product

The same electricity divided by 80 kg gives 12.5 kWh/kg. Quantities are teaching assumptions; widths and node sizes are not scales. Excluded upstream and downstream processes prevent a full-footprint or profitability conclusion.

Read the diagram as text

Three disjoint hypothetical monthly meter categories total 1,000 kWh. Dividing by 100 kg acceptable fresh lettuce gives 10 kWh/kg within the stated room boundary.

Parts

Lighting: 600 kWh: Hypothetical monthly meter category
Climate: 300 kWh: Cooling and humidity management are included once
Other room services: 100 kWh: Stated categories are disjoint and exhaustive
Total: 1,000 kWh: 600 + 300 + 100 over the same month
100 kg → 10 kWh/kg: Acceptable fresh product; divide 1,000 by 100

Connections

Lighting: 600 kWh → Total: 1,000 kWh: add
Climate: 300 kWh → Total: 1,000 kWh: add
Other room services: 100 kWh → Total: 1,000 kWh: add
Total: 1,000 kWh → 100 kg → 10 kWh/kg: divide by 100 kg

Keep utilisation and rejects visible

If the same 1,000 kWh produces only 80 kg acceptable output, the intensity becomes 12.5 kWh/kg. Fewer usable kilograms can raise the ratio even without a larger meter reading. Empty shelves, interrupted batches and rejected produce therefore affect performance.

Some loads change with production and others remain while the room is partly empty. Do not assume every service scales proportionally with shelf count. Record which changes were observed, and compare equivalent periods rather than a productive week with a whole month containing downtime.

Separate electricity cost from profit

At an assumed flat tariff of€0.20/kWh,1,000 kWh costs€200:€2 per kilogram for 100 kg acceptable output, or€2.50 for 80 kg. These invented numbers illustrate arithmetic only. Real contracts may include time-dependent tariffs and other charges.

Electricity is one cost. Labour, maintenance, crop inputs, rent, equipment replacement, finance, packaging, rejected batches and delivery also matter. Sales depend on actual buyers, product specification and quantity sold. A revenue above the electricity bill alone does not establish profitability.

Compare appropriate options

Compare indoor production with a greenhouse or field crop at a common useful product and delivery boundary. Seasonal sunlight, climate, storage, transport and losses can change the result. Local delivery may be useful, but avoided distance is not automatically a larger saving than added production inputs.

Use a recorded production trial and a realistic range of utilisation, tariffs and acceptable yield before expansion. Adjusting light to electricity prices may help in some cases, but must preserve crop requirements and climate capacity. Treat a demonstrated cultivation result, a modelled scenario and a commercial forecast as different evidence.

Worked examples

One month, two output cases

The stated meters record 600,300 and 100 kWh. What intensity follows for 100 kg or 80 kg acceptable fresh output?

Add the disjoint categories:600+300+100=1,000 kWh.
For 100 kg:1,000/100=10 kWh/kg.
For 80 kg:1,000/80=12.5 kWh/kg.

10 or 12.5 kWh/kg within the same stated operating boundary; the lower output increases the ratio without changing electricity.

Only the electricity component

At the assumed€0.20/kWh tariff, what electricity cost per kilogram follows for 100 kg acceptable output?

Calculate 1,000×€0.20=€200.
Divide€200 by 100 kg to obtain€2/kg.
Keep all other costs and actual sales outside this limited calculation.

€2/kg for electricity alone. This is not a complete production cost, sale-price recommendation or profit estimate.

Check your understanding

Can lamp-only electricity be ranked directly against another room’s total electricity?
Show answer and reasoning
No.
The service boundaries differ; reconcile them before comparing ratios.
Does a high-efficiency LED remove the need to manage room heat and humidity?
Show answer and reasoning
No.
Plant and equipment exchanges remain; their loads depend on the system and conditions.
If sales exceed the electricity bill, is the business necessarily profitable?
Show answer and reasoning
No.
Other operating, capital and distribution costs, losses and actual sales must be included.

Key ideas

Name the product, period, location and meter boundary.
Heat and humidity management belong in the operating account.
Utilisation and acceptable output change per-kilogram results.
Electricity cost and full commercial feasibility are different questions.

References

Sources supporting the explanations and examples in this article.