Data Center Energy Analysis Tool

Simulation logic in this app: the operating threshold is tied to the selected ASHRAE thermal target instead of a separate approach delta, as requested for this project.

Three Phases:
1. Full Free Cooling: outdoor temperature is at or below the selected target temperature, so compressor operation can be bypassed in the simplified model.
2. Partial Free Cooling: outdoor temperature is above the target but still within the assisted zone, so compressor lift is reduced.
3. Mechanical Cooling: outdoor temperature exceeds the assisted zone and compressors carry the full duty.

Engineering note: real plant design still depends on exchanger geometry, hydronic layout, glycol strategy and factory control logic. This tool is an early-stage comparison simulator.

Official source reference: ASHRAE Handbook—Fundamentals 2025, Chapter 14, together with the ASHRAE Weather Data Center.

0.4% Design Condition: The outdoor temperature is exceeded only 0.4% of annual hours (~35 hours/year). This is the standard design temperature for mechanical cooling systems — sized to handle all but the most extreme conditions.

How this app uses it: city design dry-bulb references are positioned as an official ASHRAE 2025 climate basis. The annual chart and energy logic still use representative monthly averages for fast project-stage simulation; hourly weather files would be the next step for detailed design validation.

A1: 18–27°C, mission critical envelope.
A2: 10–35°C, standard data center envelope.
A3: 5–40°C, less controlled envelope.
A4: 5–45°C, minimal control envelope.

In this interface the thermal class constrains the target cooling temperature slider, and manual mode opens a custom operating envelope when the project needs a non-standard range.

A separate local data file is included in assets/data/daikin-free-cooling-chillers.js.

The file stores model family, compressor type, refrigerant, nominal capacity range, free cooling description and source URL fields so the app can be expanded later without rewriting the calculator logic.

Definition (The Green Grid): PUE = Total Facility Power ÷ IT Equipment Power

Ratings:
• PUE < 1.2 → Platinum (Ultra-Efficient, e.g. hyperscale)
• 1.2–1.4 → Gold (Excellent — target for modern data centers)
• 1.4–1.6 → Silver (Acceptable — typical legacy facility)
• > 1.6 → Bronze (Poor — significant improvement needed)

Free cooling reduces mechanical cooling power by 30–70% in favorable climates, directly reducing PUE. A facility in a cool-climate city like Stockholm or Warsaw may achieve annual average PUE of 1.15–1.25 with a free cooling chiller system.

COP — Coefficient of Performance: Cooling capacity ÷ Power input. Higher = more efficient.
EER — Energy Efficiency Ratio: COP × 3.412 (BTU/h/W). US rating standard.
ESEER — European Seasonal EER: Weighted average at 100/75/50/25% load conditions.
PUE — Power Usage Effectiveness: Total power ÷ IT power.
Free Cooling — Using outdoor cold air (directly or via refrigerant circuit) to cool without compressor.
Thermal Envelope — Allowed operating band selected from ASHRAE A1–A4 or defined manually.
Dry Bulb Temp — Standard air temperature measured in shade with dry thermometer.
ASHRAE — American Society of Heating, Refrigerating and Air-Conditioning Engineers.
Thermosiphon — Natural refrigerant circulation by gravity/buoyancy without pump/compressor.