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Tool 20: Plant Energy Efficiency & Payback

Chiller Plant Lifecycle Operating Cost & Payback Estimator

Evaluates operational expenditure (OpEx) savings and simple capital payback for premium high-efficiency chillers (VFD magnetic bearing vs standard screw) using AHRI 550/590 4-bin part-load operating profiles.

✔ 1. Formula Verified → ⚡ 2. Engineering Screening → 📐 3. Standards Referenced (AHRI 550/590 / ASHRAE 90.1) → ⚖ 4. Engineer Review Required
⚙ Chiller Efficiency & Economic Inputs
TR
Total installed chiller plant refrigeration tonnage.
kW / TR
Standard fixed-speed water-cooled chiller (typically 0.65–0.75 kW/TR).
kW / TR
VFD magnetic bearing oil-free centrifugal chiller (typically 0.50–0.54 kW/TR).
Hours / Year
Annual run hours (e.g. 10 hrs/day × 350 days = 3,500 hrs; 24x7 pharma = 8,000+ hrs).
₹ / kWh
Blended commercial/industrial tariff rate per unit (typically ₹7.50 to ₹9.50/kWh in India).
₹ (INR)
Incremental capital cost for VFD / magnetic bearing package over baseline unit.
📊 Lifecycle Payback Sizing Sheet
Preliminary Screening
Simple Capital Payback Period
7.73 Years (~92.8 Mos)
Annual Electricity Bill Savings: ₹ 15,52,950 / Year
Annual Energy Saved
182,700 kWh/yr
10-Year Net Financial Savings
₹ 35.30 Lakhs
Baseline Chiller Energy
710,500 kWh/yr
Proposed Chiller Energy
527,800 kWh/yr
Annual Part-Load Operating Profile (Screening)
100% (35h) | 75% (1,470h) | 50% (1,575h) | 25% (420h)
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Governing Engineering Standards & Calculation Model

Governing Standards & References

  • AHRI Standard 550/590: Performance Rating of Water-Chilling and Heat Pump Water-Heating Packages.
  • ASHRAE Standard 90.1: Energy Standard for Buildings (Mandatory minimum chiller full-load and part-load IPLV).
  • BEE Energy Conservation Code: Bureau of Energy Efficiency star labeling guidelines for water-cooled chillers.

User-Defined Annual Part-Load Operating Profile (Screening Model)

Operating Profile (Screening):
Bin 1 (100% Load): 35 h (1.0% Operating Hours)
Bin 2 (75% Load): 1,470 h (42.0% Operating Hours)
Bin 3 (50% Load): 1,575 h (45.0% Operating Hours)
Bin 4 (25% Load): 420 h (12.0% Operating Hours)
Total Operating Hours = 3,500 h/year
EFLH = (35 × 1.0) + (1470 × 0.75) + (1575 × 0.50) + (420 × 0.25) = 2,030 h

Annual_Savings (₹) = (kWh_base - kWh_prop) × Tariff
Payback_Years = Capex_Premium / Annual_Savings
10-Year_Net = (Annual_Savings × 10) - Capex_Premium
⚖ Statutory Notice & Engineering Disclaimer (Tier D Integration)

This calculator employs a user-defined annual part-load operating profile used for screening (35h @ 100%, 1,470h @ 75%, 1,575h @ 50%, 420h @ 25%; Total = 3,500h; EFLH = 2,030h), which is an engineering screening profile rather than a normative AHRI 550/590 multi-bin profile. Actual building thermal load curves depend on climate zone, occupancy schedules, internal sensible equipment heat, and cooling tower entering condenser water temperature relief (ECWT relief). Financial calculations represent simple undiscounted payback; detailed life cycle cost analysis (LCCA) including net present value (NPV), escalation, and maintenance contracts should be conducted before major central plant capital investments.