- Account for energy, labor, losses and replacement.
- Calculate energy cost with local inputs.
- Scale from complete-cycle evidence.
Energy cost calculator
kWh = watts × hours/day × days ÷ 1,000. Cost = kWh × your tariff.
One device at constant power. Add other devices, duty cycles and fixed charges separately. Price is an illustrative input, not a market quote.
01 / Count the whole operating system
Separate one-time equipment from recurring inputs: electricity, water, nutrients or fish feed, seed/stock, testing, cleaning, replacement parts, packaging, labor and losses. Include heating, cooling and ventilation; they can exceed pump consumption.
Use your own local prices and measured consumption. This chapter supplies accounting equations and editable examples rather than current price quotes or yield promises. A home food project and a commercial operation can assign labor differently, but the assumption should be explicit.
| Cost group | Record | Common omission |
|---|---|---|
| Capital | Equipment, installation, structures, backup | Replacement reserve and service access. |
| Energy | Measured watts × runtime | Climate control and standby loads. |
| Water / inputs | Purchased quantity and actual use | Wastewater, purge and rejected batches. |
| Labor | Minutes by task | Cleaning, propagation and records. |
| Production | Usable mass and rejects | Mortality, spoilage and unsold output. |
02 / Calculate energy correctly
Energy in kWh = watts × hours per day × days ÷ 1,000. A measured 60 W continuous load uses 43.2 kWh over 30 days. At an example rate of 0.15 currency units/kWh, that is 6.48 currency units. Enter your own tariff; this is not a quote.
Thermostatically controlled heaters and variable-speed devices do not necessarily run at nameplate power all day. Measure accumulated kWh or estimate duty cycle explicitly. Sum devices only after their different schedules are included.
- List each device and measure consumption safely with suitable equipment.
- Record hours or duty cycle over a representative interval.
- Multiply kWh by the actual applicable tariff, including fixed charges separately.
- Repeat for seasonal heating/cooling rather than extrapolating one mild week.
- Compare total energy with usable crop output over the same interval.
03 / Use output that can actually be used
Cost per usable kilogram = total attributed cost ÷ usable kilograms. Include rejected produce and unsuccessful batches in the cost numerator rather than counting them as yield. For repeated harvest crops, account for the full occupied time and area.
For aquaponics, track fish and plants separately before allocating shared costs. Feed is a fish input and a nutrient source, but counting its entire cost against both products double-counts it. Choose and disclose an allocation method.
FIELD QUESTIONIf a trial yields 20 kg but only 15 kg is usable, which mass belongs in cost per usable kg?
15 kg. The inputs consumed by the unusable portion remain costs of the production cycle.
04 / Expand the measured bottleneck
Run more than one complete crop cycle and include a maintenance and outage rehearsal before expanding. Identify whether light, labor, water quality, root space, market demand or equipment reliability actually limits useful output.
Budget the next increment with required support, drainage, backup and access. A larger installation magnifies an unresolved propagation or recordkeeping problem. Keep a modest trial zone for new varieties or nutrient programs so learning does not disrupt the entire production area.
- Review usable output, quality, losses and task minutes from complete cycles.
- Identify the limiting function and collect evidence for it.
- Cost the smallest change likely to relieve that limit.
- Check the new hydraulic, structural and electrical requirements.
- Commission the change and compare its result against the baseline.
Parts & buying criteria
Showing drip / dutch buckets. Quantities describe the teaching model. Specify real working volume, support, fittings and instruments for your installation.
01Nutrient reservoir1 · illustrated quantity+
Stores the measured nutrient solution beneath or beside the growing area.
Inspect: Compare the surface with the pump intake or lower roots; freeboard is deliberate.
Maintain: Record level before refilling, keep light out and verify temperature, EC and pH.
Opaque, cleanable, intended-use container with volume marks and service access.
Supplier links can be added by the publisher. The criteria stand independently.02Pump & supply1 · illustrated quantity+
Moves nutrient solution from the reservoir to the growing area.
Inspect: Trace installed lift and branching; the pump label does not prove delivered flow.
Maintain: Measure output after service and inspect intake, filter and minimum water level.
Pump curve matched to installed head, required pressure and service needs.
Supplier links can be added by the publisher. The criteria stand independently.03Dutch buckets3 illustrated · illustrated quantity+
Contain a large root-zone medium with a defined drainage outlet.
Inspect: Inspect the flood level, pot bases and accessible drain position.
Maintain: Verify full drainage and inspect moisture in representative pots.
Rigid cleanable tray with independent overflow and adequate support.
Supplier links can be added by the publisher. The criteria stand independently.04Root-zone mediumFor illustrated containers · illustrated quantity+
Stores moisture and air around the roots in the illustrated containers.
Inspect: Compare the medium surface with irrigation and drainage.
Maintain: Inspect wetting at several depths; prevent fines from reaching drains and emitters.
Prepared, stable grade matched to the irrigation method and crop.
Supplier links can be added by the publisher. The criteria stand independently.05Drip emitters3 illustrated · illustrated quantity+
Distribute solution separately to each container.
Inspect: Trace the manifold and the small outlet above each plant position.
Maintain: Collect equal-time samples and compare output; flush the main line before installing emitters.
Emitter pressure requirements matched to pump and filter; flushable connections.
Supplier links can be added by the publisher. The criteria stand independently.06Drain & overflow1 · illustrated quantity+
Returns drainage to the reservoir and provides a controlled high-water route.
Inspect: Follow the full slope and look for the separate high-level opening.
Maintain: Test pump-off drain-back and keep roots and medium out of the outlet.
Accessible fittings and verified capacity under normal and fault conditions.
Supplier links can be added by the publisher. The criteria stand independently.Evidence beside the lesson.
Source checks: September 2026. The geometry, inspection exercises and worksheets are original teaching material. The named organizations have not endorsed or reviewed this site.
Published recipe rates and planning ranges retain their source context. Calculator equations are accounting tools; they do not predict uptake, yield, toxicity or safe stocking. Model dimensions, water speeds, roots and fish counts are illustrative. Verify species, crop, source water and product labels for a real system.
The next useful connections.
Light, temperature and humidity
Measure the growing environment at the canopy and root zone, then adjust one limiting condition at a time.
Interactive tool · 6 min + guided practice →Build, operate & troubleshootCommissioning and daily care
Turn assembled equipment into a repeatable operating system, with a first-crop checklist and a useful log.
6 min + guided practice →