Illustrative c5 heat reuse balance
320 kW delivered = 240 kW source + 80.0 kW unit input; 83.0 kW fallback during offtakemodeled
| Value kind | modeled — Interpret this value according to its displayed kind, scope, source, and as-of date. |
|---|---|
| Scope | Assume 323 kW source heat including 3.00 kW CDU heat. A rounded independent recovery selection uses 40.0→30.0 °C source water, density 1.00 kg/L and specific heat 4.18 kJ/(kg·K). The customer accepts 320 kW at 65.0/45.0 °C for exactly 2,000 h, then zero for 6,760 h. Assume unit heating COP 4.00, recovery/network auxiliaries 10.0 kW, electrical allowance 90.0 kW and negligible delivery loss. The 10.0 kW losses reject separately outside IT/FWS and are not credited as delivered heat. The source point approximates 5.6’s 40 °C return; all values are design assumptions, not measurements. |
| 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 | Unit input = 320/4.00 = 80.0 kW; recovered heat = 320 − 80.0 = 240 kW; source flow = 240 × 60/(4.18 × 10.0) = 344 L/min. Source balance: 240 recovered + 83.0 rejected = 323 kW. Delivery balance: 240 source + 80.0 electrical = 320 kW. The separate 80.0 kW IT air duty remains on room cooling. Annual source recovery is 480 MWh, delivery 640 MWh, unit electricity 160 MWh and auxiliary electricity 20.0 MWh. System COP = 640/(160 + 20.0) = 3.56. Available annual source heat is 323 × 8,760 = 2,829.48 MWh; normal rejection receives 2,349.48 MWh, about 2.35 GWh. At zero offtake the full 323 kW returns to the independent sink; an 83.0 kW sink fails by 240 kW. Select the branch with the 90.0 kW electrical allowance and full fallback. Crossover unit COP = 320/(90.0 − 10.0) = 4.00. At COP 3.00, total input is about 117 kW, exceeding the allowance by 27 kW: reduce delivered duty or change the selection. ASHRAE/NEMA/PNNL framework provides system-boundary context; this chapter owns the balance, 15.5 values offtake and 13.5 accepts fallback. |
| Review | checking…cadence-derived review 2027-01-03 · standard cadence |
| Recorded changes | none recorded |
| Claim id | p5-c5-heat-reuse-balance |
Where the guide uses it
Not quoted in a chapter yet; it is kept in the curated register.
← Full numbers register — every date-stamped figure in the guide, with revision history.