CEA energy and economics — separate load and cost ledgers

Do not collapse electricity into one efficiency number

Measure LEDs, heating and cooling or dehumidification, pumps, fans, controls and auxiliary equipment by circuit or meter. Keep production-zone kWh separate from shared building loads, with period, runtime, meter and missing-data fields. Do not attribute a yield or temperature change to electricity alone.

A minimum load ledger can use one row per meter and operating phase:

If a meter reports power rather than energy, integrate it over the interval: E=\sum P_i\Delta t_i. Keep the interval and unit beside the result; a 1.2 kW reading is not itself a monthly energy value.

Keep cost ledgers separate

Record CAPEX (equipment, installation and meters), fixed OPEX (rent and service contracts), variable OPEX (electricity, water, substrate and starts) and labor on separate rows. Preserve quote versus actual, depreciation period, currency and tax or freight assumptions; do not mix assumptions with invoices.

For a simple monthly operating view, calculate each category separately:

This table is an accounting example, not a local price assumption. Put tariff, tax, delivery and labor assumptions in separate fields so a later comparison can change one assumption without rewriting the measurements.

Show resource-to-yield ratios with boundaries

A synthetic example of 1,200 kWh per month and 100 kg shipped gives 12 kWh/kg. This ratio is bounded by its measurement period and shipment definition; it is not a performance guarantee for another crop or season. Keep waste, reuse and unharvested zones visible in the denominator definition.

For cost, the same boundary gives ¥920/kg when ¥92,000 of monthly OPEX produces 100 kg shipped. Report the numerator and denominator together: production-zone electricity, shared loads, shipped mass, rejected mass, and the dates covered. A ratio that silently changes from shipped mass to harvested mass cannot be compared across months.

The US Department of Energy guide to controlled-environment agriculture is a useful starting point for separating lighting, climate control and crop production assumptions. Actual tariffs, labor rules and crop yields must be measured for the local facility.

Scope

This guide defines load and cost records. It excludes future tariff forecasts, yield or profit guarantees, LCA, investment advice, measured equipment performance and local tax or legal decisions.