🧊 Commercial Thermal Ice Storage (TES) & Peak Shaving Sizer

Calmac & BAC TES Engineering
Institutional Thermal Energy Storage (TES) Ice Tank & Stratified Chilled Water Sizer. Models partial vs. full storage load shifting, on-peak electric demand charge reduction ($15–$35/kW), chiller nameplate downsizing (-40% to -55%), nocturnal ice-build derating, utility peak shaving rebates, and 20-year LCOE/NPV economics.
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Operating Archetype Preset:
🏢 Peak Cooling Load & Storage Strategy
Tons
Design coincident building peak cooling load.
Hours/day
e.g., 1:00 PM – 7:00 PM summer peak period.
Hours/night
Available off-peak ice freezing time (e.g. 10 PM - 8 AM).
Ton-Hours / day
Integrated 24-hour design day thermal load integral.
❄️ Ice Storage Tanks (Calmac / BAC) Specs
% Derate
Chiller capacity drop when producing 22°F glycol for ice build.
kW/Ton
kW/Ton
💰 Electric Tariffs, Demand Charges & Rebates
$/kW-month
$/kWh
$/kWh
$/kW shifted
$/Ton-Hour
Turnkey ice tanks, heat exchangers & glycol loop.
$/Ton
Sized Chiller Plant
680 Tons
-43.3% Smaller than 1,200T Baseline
Ice Storage Battery
3,450 Ton-Hrs
14 Calmac Tanks (260 Ton-Hr each)
On-Peak Demand Shaved
385 kW
$113,190/yr Demand Charge Reduction
Total Annual Net OPEX Savings
$148,600/yr
Simple Payback: 2.8 Years
🧊 24-Hour Thermal Load vs. Ice Discharge & Nocturnal Charge Profile
On-Peak Chiller Load Shifting
📑 Engineering Spec & Financial Audit
Plant Component / Metric Conventional Chiller Plant TES Ice Storage Chiller Plant Variance / Net Economic Benefit
Installed Chiller Capacity 1,200 Tons (Full Peak Sizing) 680 Tons (Levelized Load) -$702,000 Chiller CapEx Avoided
Thermal Storage Battery (Ice Tanks) 0 Ton-Hours 3,450 Ton-Hours (14 Modular Tanks) +$327,750 Ice Tank Hardware
On-Peak Electric Power Draw 696 kW (1,200T @ 0.58 kW/T) 311 kW (Partial Chiller + Ice Melt) -385 kW On-Peak Shaved (-55.3%)
Monthly Peak Demand Charges $17,052 / month $7,619 / month -$113,196 / year Saved
Energy Arbitrage Savings (Time-of-Use) $0 (Daytime Flat Grid Exposure) $35,404 / year (Nighttime Ice Freeze) Off-Peak Electric Rate Advantage
Utility Demand Management Rebate $0 -$173,250 ($450/kW Shifted) Immediate Direct Utility Incentive
Net Plant Capital Outlay (First Cost) $1,620,000 (1,200T @ $1,350/T) $1,072,500 (Turnkey Net Outlay) -$547,500 LOWER FIRST COST
20-Year Net Present Value (NPV @ 7%) Baseline Standard +$2,122,000 IRR: Immediate First-Cost Advantage
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💡 Commercial Thermal Energy Storage (TES) Engineering Insights
Why does Thermal Ice Storage result in a LOWER upfront capital cost?
Because cooling demand is shifted to night hours, the chiller plant can be downsized by 40% to 55%. The capital cost savings from purchasing 500 fewer tons of centrifugal chillers, smaller cooling towers, downsized electrical switchgear, and smaller transformers often exceeds the cost of the ice storage tanks themselves—delivering immediate "negative payback" (lower first cost on Day 1) even before factoring in utility peak demand rebates.
What is the difference between Full Storage and Partial Storage?
In Partial Storage, the chiller runs 24 hours a day at a steady, leveled output. During on-peak hours, the chiller provides part of the cooling while the ice tanks melt to satisfy the peak spike. In Full Storage, chillers are completely shut off during the 4-to-8 hour on-peak utility window, and 100% of the building's cooling load is supplied by melting ice. Full storage maximizes demand charge elimination but requires larger ice tank footprints.
How does nocturnal ice-build efficiency affect energy use?
To freeze ice, chillers produce 22°F (-5.5°C) glycol instead of 44°F chilled water, reducing chiller thermodynamic efficiency by ~25%–35% during freezing. However, night ambient temperatures are typically 15°F–25°F cooler (lowering condensing temperatures) and off-peak nocturnal electricity is 60%–75% cheaper than daytime peak tariffs, creating net operating cost reductions of 30% to 50%.