Illustrative c5 annual plant example
PUE 1.16 hybrid; 1.20 dry/mechanicalmodeled
| Value kind | modeled — Interpret this value according to its displayed kind, scope, source, and as-of date. |
|---|---|
| Scope | Assume the 400 kW IT design runs all 8,760 hours, with 323 kW liquid duty including the 3.00 kW CDU heat allowance from 5.6. Synthetic bins are 6,000 h at 15/10 °C dry/wet bulb, 2,000 h at 28/20 °C, and 760 h at 35/27 °C; these are not site weather. Supply is 30.0 °C, dry approach 5.0 K, assist effectiveness 0.750. Assume both candidate selections cover normal duty and their own heat in each bin. Hybrid liquid-plant input is 20.0, 25.0, 100 kW, including CDU/pumps/fans; makeup is 0, 0.500, 0 m³/h. A dry/mechanical alternative uses 20.0, 100, 100 kW and no cooling makeup. Both also use 16.0 kW residual-air cooling and 20.0 kW other overhead. No other site-water input is assumed. Surviving hot-day liquid capacity with the required unit unavailable is assumed only 300 kW. These inputs exercise this chapter’s selection method. |
| As of | 2026-09 |
| Source | Guide calculation from expressly assumed teaching inputs. Primary reference supplies method or equipment context, not evidence that this design was built or tested. |
| Derivation | Cold-bin dry supply screen = 15 + 5 = 20 °C: modulate to 30 °C. Middle-bin dry gives 33 °C, while assist gives 28 − 0.750(28 − 20) + 5 = 27 °C: use assist or mechanical cooling. Hot-bin assist gives 35 − 0.750(35 − 27) + 5 = 34 °C: mechanical cooling is required. A temperature screen does not supply a missing capacity curve. Hybrid liquid-plant energy = 6,000 × 20.0 + 2,000 × 25.0 + 760 × 100 = 246 MWh; dry/mechanical = 6,000 × 20.0 + 2,760 × 100 = 396 MWh. IT energy is 3,504 MWh. Common overhead is (16.0 + 20.0) × 8,760 = 315.36 MWh. Facility totals round to 4.07 and 4.22 GWh; PUE is 1.16 and 1.20. Hybrid input water = 2,000 × 0.500 = 1,000 m³, giving 0.285 L/kWh IT on the declared total-input boundary. Input is not all evaporation when discharge exists. Assist saves 150 MWh for 1,000 m³: 150 kWh avoided per m³. Choose assist when water is permitted and its marginal burden is below the value of that electrical saving. Above that crossover, or with no water allocation, choose the dry/mechanical alternative if it meets capacity. No tariff assumption is needed to expose the trade. Both fail the stated outage: 323 − 300 = 23 kW uncovered. Add surviving duty or demonstrate an accepted reduction of at least 23 kW while retaining the air path. Annual efficiency does not release the fault state. ASHRAE heat-rejection guidance supports the method; 15.1 owns metrics, 15.4 water accounting and 13.5 installed acceptance. |
| Review | checking…cadence-derived review 2027-01-03 · standard cadence |
| Recorded changes | none recorded |
| Claim id | p5-c5-annual-plant-example |
Where the guide uses it
Not quoted in a chapter yet; it is kept in the curated register.
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