Understand the load
Set the energy and power boundaries before modelling costs.
INTEGRATED PRACTICE · ORIGINAL CASE
Assess a data-centre energy plan.
A developer wants more computing capacity. Can the site supply it, what would the energy cost, and does the backup actually work?
Produce a calculation workbook and a one-page recommendation. This is self-paced practice, not a marked qualification or a real connection proposal.
Start the projectReconcile the exposure
Separate physical imports from financial cover.
Test the alternative
Check operating limits and the consequence of changing a load.
Two boundaries. One recommendation.
You are reviewing a six-hour operating proposal. The three two-hour intervals are consecutive; loads and prices are constant inside each interval. The site's requested demand may exceed its assumed import ceiling. Identify that problem before treating the cost model as an operating plan.
PHYSICAL FLOWGrid import→Facility demand→IT + cooling + auxiliaries
FINANCIAL SETTLEMENTSpot energy cost−Contract receipt=Energy-only net cost
| Interval | IT load MW | Facility / IT power ratio | Financial cover MWh | Spot price AUD/MWh |
|---|---|---|---|---|
| Morning | 24 | 1.25 | 50 | 60 |
| Midday | 30 | 1.30 | 60 | 90 |
| Hot afternoon | 32 | 1.40 | 0 | 240 |
Import ceiling 42 MW · Fixed strike AUD 70/MWh · Usable backup 8 MWh / 12 MW · Critical load 16 MW · Backup target 30 minutes
Model boundaries and what is deliberately excluded
- The facility/IT ratio is an assumed concurrent power multiplier for each steady interval. Measured PUE is an energy ratio over a specified period; an annual PUE must not automatically be used as a peak-power multiplier.
- The financial contract is a simplified fixed-for-floating swap at the same reference price as the physical purchase. The stated MWh volumes are fixed. There is no basis risk in this example; real PPAs may introduce generation-volume, shape, location and contractual differences.
- The two-hour blocks are teaching aggregates, not the actual NEM settlement resolution. No marginal loss factors, network or demand charges, retail margin, tax, premiums or financing are included. This is not a bill or investment valuation.
- Backup MWh are usable AC energy delivered at the critical-load boundary, with no additional losses in this screen. Backup is reserved for critical service; do not count it again for ordinary peak shaving. No on-site generation or battery charging is included.
- The limit and every number are invented teaching inputs. A network connection offer, protection review, operability study and resilience design are outside this exercise.
Find the constraint before the saving.
Physical feasibility
Facility MW = IT MW × power ratio
Energy MWh = facility MW × hours
Energy MWh = facility MW × hours
Each interval lasts 2 hours. Calculate the facility load first, then multiply by time:
- Morning
- 24 MW IT × 1.25 = 30 MW
30 MW × 2 h = 60 MWh - Midday
- 30 MW IT × 1.30 = 39 MW
39 MW × 2 h = 78 MWh - Hot afternoon
- 32 MW IT × 1.40 = 44.8 MW
44.8 MW × 2 h = 89.6 MWh
Total requested energy: 60 + 78 + 89.6 = 227.6 MWh.
The hot interval exceeds 42 MW by 2.8 MW. A positive result on the cost worksheet would not make this load feasible.
Commercial exposure
Receipt = covered MWh × (spot − strike)
Net cost = spot cost − receipt
Net cost = spot cost − receipt
| Interval | Spot cost | Swap receipt | Net cost |
|---|---|---|---|
| Morning | 3,600 | -500 | 4,100 |
| Midday | 7,020 | 1,200 | 5,820 |
| Hot afternoon | 21,504 | 0 | 21,504 |
| Total | 32,124 | 700 | 31,424 |
Requested spot cost is AUD 32,124. The swap receipt is −500 + 1,200 + 0 = AUD 700. Net cost is AUD 31,424.
When spot is below strike, the receipt is negative: the buyer pays. The uncovered hot interval drives much of the exposure.
Cross-check: fixed covered energy costs 110 × 70 = AUD 7,700. Residual energy costs 10 × 60 + 18 × 90 + 89.6 × 240 = AUD 23,724. Sum = AUD 31,424. This equality uses the exact matched-reference assumptions above.
The backup trap
8 MWh ÷ 16 MW × 60 = 30 minutes on energy alone. But the backup can deliver only 12 MW, below the 16 MW critical load. It cannot serve the full stated critical demand. Do not report “30 minutes of backup” without that qualification.
A staged alternative
Reduce the last interval's IT demand to 30 MW. Facility demand becomes 42 MW, energy becomes 222 MWh and net cost falls to AUD 30,080 with unchanged cover. The AUD 1,344 energy-cost reduction excludes lost computing service and does not fix the backup power shortfall.
A defensible recommendation: do not approve the original load schedule. Investigate staged demand subject to service and control checks; separately resolve the critical-load backup shortfall. Request coincident load measurements, the actual connection conditions, verified flexibility and a resilience design review.
Same method. Different decision inputs.
Use a blank worksheet. Do not copy the worked site's numbers. For the staged alternative, test 27.5 MW of IT demand in the final interval; leave all other inputs unchanged.
| Interval | IT load MW | Facility / IT power ratio | Financial cover MWh | Spot price AUD/MWh |
|---|---|---|---|---|
| Morning | 20 | 1.20 | 40 | 50 |
| Midday | 26 | 1.30 | 50 | 100 |
| Hot afternoon | 30 | 1.45 | 0 | 300 |
Import ceiling 40 MW · Fixed strike AUD 80/MWh · Usable backup 9 MWh / 20 MW · Critical load 18 MW · Backup target 30 minutes
Keep the same model boundaries as the worked example. Calculate the requested energy, the worst exceedance, the net cost and the energy-only backup duration. Then decide whether both backup constraints meet the target.
Compare the independent working
Facility demand: 24, 33.8 and 43.5 MW. Multiplying each by two hours gives 202.6 MWh. The hot interval exceeds the 40 MW ceiling by 3.5 MW.
Requested spot cost is AUD 35,260. The swap receipt is 40 × (50 − 80) + 50 × (100 − 80) = −AUD 200: the buyer pays the net settlement. Subtracting that negative receipt gives AUD 35,460. This is the cost of the unconstrained request, not a feasible dispatch plan.
9 MWh ÷ 18 MW × 60 = 30 minutes, and 20 MW exceeds 18 MW. Both ideal checks pass. State of charge, transfer time, redundancy and auxiliaries still require verification.
Stage the hot-interval IT load to 27.5 MW: facility demand becomes 39.88 MW, within the limit. Requested energy becomes 195.35 MWh and net cost AUD 33,285 with unchanged cover. The energy-cost reduction is AUD 2,175; lost computing service is not valued. 40 ÷ 1.45 is about 27.586 MW: rounding up to 27.59 MW would exceed the ceiling.
Write the decision, not just the answer
Prepare a short decision memo and retain your spreadsheet. A reviewer should be able to reproduce the calculation without seeing the solution first.
Temporary notes stay in this page only. Download before leaving; refresh clears them. No confidential information.
What would a reviewer accept?
Ask a competent reviewer to assess each dimension as not yet demonstrated, with guidance or independently explained. Numerical checks are not a substitute for this review. No tutor review is supplied by the platform.
- Accuracy
- Reconciles MW, MWh, the settlement sign and both backup constraints. A critical physical error requires correction regardless of other strengths.
- Traceability
- Lists the case version, original input rows, formulas and assumptions. Distinguishes synthetic numbers from external guidance.
- Alternatives
- Recalculates staged demand and explains the missing service cost. Does not use reserved backup twice.
- Judgement
- Separates a screening result from permission to connect or operate. Assigns missing checks and a clear condition for proceeding.
Use in a study group
Exchange the workbook and memo, not just the final answer. Have a peer reproduce one row, challenge one assumption and identify one claim that needs stronger evidence. Record the revision. For formal evaluation, an educator would need a separate unseen task and an agreed assessment process: the public solutions here make this an open practice activity.
Read alongside the case
External sources provide context, not validation of these invented inputs. Record the version and boundary of any source used in your memo.
- Australian Government: data-centre energy efficiency — measurement and operational context.
- PPA lesson and source readings — contract structure and residual exposure.
- Storage lesson and source readings — energy, power and operating constraints.
Original teaching scenario by OohEnergy · 17 October 2026 · No actual customer, network offer or university endorsement is represented.