Chillers are among the most energy-intensive components in HVAC systems—often accounting for over 40% of total cooling energy use in large commercial buildings.Improving chiller performance isn’t just about energy savings—it directly impacts system reliability, occupant comfort, and lifecycle cost. In this blog, we’ll walk through 10 actionable tips based on ASHRAE guidelines and real-world field experience to help HVAC professionals optimize chiller efficiency.
Why Chiller Performance Matters
Chillers can represent up to 50% of a building’s HVAC energy consumption. Sub-optimal performance leads to:
Increased operating costs
Poor comfort levels
Reduced equipment lifespan
ASHRAE Standard 90.1 emphasizes the importance of chiller efficiency through performance metrics such as Integrated Part Load Value (IPLV) and Full Load kW/ton.
Top 10 Tips to Improve Chiller Performance
1. Maintain Optimal Condenser Water Temperature
Reducing condenser water temperature improves chiller performance, especially in water-cooled systems.
ASHRAE Guideline 22 recommends minimizing condenser water temperature while avoiding low-pressure trips.
Energy impact: ~1–2% savings per 1°F drop in condenser water temperature.
2. Clean Heat Exchangers Regularly
Fouling increases heat transfer resistance and reduces efficiency. Perform annual tube cleaning using rotary brushes
or chemical descaling. Monitor condenser approach temperature (trigger alerts if >5–7°F).
3. Use Variable Frequency Drives (VFDs)
Install VFDs on chilled water pumps, condenser water pumps, cooling tower fans, and compressors (if compatible).
VFDs enable part-load modulation and save energy during non-peak hours.
4. Implement Chiller Plant Optimization Controls
Modern BAS or energy management platforms help sequence multiple chillers based on COP, optimize pump/tower speeds,
and adjust flow rates based on real-time demand. Use adaptive logic and real-time analytics.
5. Maintain Proper Refrigerant Charge
Incorrect refrigerant charge leads to reduced capacity and efficiency. Monitor superheat and subcooling levels.
Match refrigerant levels with manufacturer specs. Use refrigerant analyzers for leak detection and charge diagnostics.
6. Upgrade to High-Efficiency Chillers
Consider replacing outdated equipment with oil-free magnetic-bearing chillers or high IPLV-rated screw/centrifugal units.
Refer to ASHRAE 90.1 Table 6.8.1 for minimum acceptable efficiencies.
7. Use Free Cooling Where Applicable
In moderate climates, waterside economizers (free cooling) can reduce chiller runtime by using ambient air.
Ideal for process cooling or shoulder seasons. Integrate economizer loop into control sequencing.
8. Monitor and Trend Performance Data
Continuous data collection allows for predictive maintenance. Track kW/ton, COP, ΔT, and equipment runtime.
Use cloud-based platforms or integrated building analytics.
9. Perform Annual Eddy Current Testing
Detects internal tube degradation in shell-and-tube heat exchangers. Prevents tube rupture and loss of capacity.
Recommended annually per OEM and ASHRAE guidance.
10. Ensure Proper Water Treatment
Scale, corrosion, and biofouling reduce heat transfer efficiency. Use side-stream filtration, automated chemical dosing systems,
and monitor pH, TDS, conductivity, and biological load.
Case Study: Chiller Plant Optimization in a Commercial Building
Location: Mumbai, India Challenge: 25% higher-than-expected energy bills from the HVAC system
Actions Taken:
Tube cleaning increased heat transfer efficiency by 15%
BAS-integrated sequencing logic reduced energy consumption by 20%
Adding VFDs to condenser pumps saved ₹6.2 lakh/year in electricity costs
Result: Achieved 0.65 kW/ton average efficiency across the year.
Summary
Conduct regular preventive maintenance
Clean heat exchangers and maintain refrigerant levels
Use VFDs and BAS for optimized control
Retrofit old components with energy-efficient upgrades
Follow ASHRAE guidelines for performance monitoring
Q1: How often should I perform chiller maintenance? Monthly visual checks and annual deep maintenance per OEM and ASHRAE recommendations.
Q2: What is a good efficiency rating for a chiller? High-performance chillers operate below 0.65 kW/ton at full load and below 0.45 kW/ton at part-load.
Q3: How does water treatment affect chiller performance? Poor water quality leads to scale, reducing heat transfer and increasing energy use by 10–15%.
Q4: Are VFDs suitable for all chillers? VFDs are ideal for centrifugal or screw chillers with varying load profiles.
Q5: Can BAS alone improve performance? BAS improves control but must be combined with physical system enhancements and maintenance.
Karthikeyan
Hi, I’m Karthikeyan Balamurugesan, a content creator and HVACR professional passionate about simplifying complex concepts in heating, ventilation, air conditioning, and refrigeration. With years of industry experience, I specialize in sharing practical insights on energy-efficient systems, data center cooling, and sustainable technologies.
Through TheHVACLab, my goal is to empower engineers, consultants, and business owners with clear, actionable knowledge to make informed decisions and stay ahead in the industry.
Let’s connect and explore the future of HVACR together!
