For Facility Managers & Engineers who work with Cooling Towers

Cooling towers have long been the industry standard for heat rejection—but today’s performance and sustainability demands call for a more nuanced approach. As water becomes scarcer and energy prices climb, alternative solutions like dry, hybrid, and adiabatic coolers offer viable, sometimes superior, alternatives.

The right system for your facility hinges on how you balance four key variables: water availability, energy consumption, capital cost, and environmental compliance. This guide breaks down the major cooling methodologies along the water-vs-energy spectrum to help you make informed, future-proof decisions. Use the included diagram to visualize where each option falls and guide stakeholder conversations.

Table of Contents

  • 1. Cooling Methodology Snapshot
  • 2. Dry Coolers — Zero Water, Highest Energy
  • 3. Hybrid Coolers — Minimal Water, Moderate Energy
  • 4. Adiabatic Coolers — Low Water, Low-to-Moderate Energy
  • 5. Evaporative Coolers (Cooling Towers) — High Water, Lowest Energy
  • 6. Comparative Metrics & Selection Checklist
  • 7. Water Treatment & Environmental Compliance
  • 8. Choosing the Best Fit for Your Facility
  • 9. Next Steps & How Chemstar WATER Can Help

1. Cooling Tower Methodology Snapshot

Method Typical Water Use Relative Energy Use Ideal Applications
Dry 0 gal/ton-hr Highest Water-scarce regions, high discharge fees
Hybrid (Dry/Adiabatic) 5–15% of tower water ↓ 20–30% vs. Dry Data centers with plume & water constraints
Adiabatic 30–50% of tower water ↓ 20–40% vs. Dry Light-industrial, commercial HVAC in temperate climates
Evaporative (Tower) 100% baseline Lowest Heavy industrial, humid climates, large chiller loads

Key Insight: As you move from evaporative to dry systems, water consumption drops—but energy use increases. A total cost of ownership (TCO) model should always evaluate both axes.

2. Dry Coolers — Zero Water, Highest Energy

Operation: Finned coils reject heat using ambient air only. No evaporation means no water use or chemical treatment.

  • Pros: Zero water/chemical use, simple compliance, no Legionella risk
  • Cons: High fan energy, large footprint, limited performance above ~85°F

Use when: Water costs or restrictions make other options impractical—and your energy budget can support it.

3. Hybrid Coolers — Minimal Water, Moderate Energy

Operation: Functions dry in mild conditions; uses adiabatic assist when temperatures rise. Smart controls limit water use.

  • Pros: Reduced energy use, minimal plume, automated operation
  • Cons: More maintenance than dry systems, higher upfront cost

Best for: Data centers and urban hospitals needing high uptime, low visibility, and water-efficiency.

4. Adiabatic Coolers — Low Water, Low-to-Moderate Energy

Operation: Mists or wetted pads pre-cool air before it contacts coils—mimicking evaporative performance without soaking the process fluid.

  • Pros: Significant energy savings vs. dry, lower water use vs. towers, closed-loop fluid
  • Cons: Component wear, moderate humidity limitations, maintenance required

Ideal when: You need better energy efficiency than dry systems but can’t justify full evaporative water use.

5. Evaporative Coolers (Cooling Towers) — High Water, Lowest Energy

Operation: Relies on water evaporation to reject heat—making it the most energy-efficient but most water-intensive option.

  • Pros: Lowest kW/ton, compact, time-tested
  • Cons: High water and chemical consumption, Legionella compliance, potential plume

Use when: Water is available and inexpensive, and energy efficiency is critical.

pastedGraphic.png

6. Comparative Metrics & Selection Checklist

  1. Water tariff & discharge fees
  2. Electricity costs & sustainability goals
  3. Local wet-bulb vs. dry-bulb conditions
  4. Noise, plume, and visual constraints
  5. Capital budget vs. operational cost window
  6. In-house maintenance capabilities

Pro tip: A 2% change in water or energy tariff assumptions can change the most cost-effective option in lifecycle models.

7. Water Treatment & Environmental Compliance

Method Water-Treatment Focus Key Regulations
Dry None ASHRAE 90.1, local noise codes
Hybrid Low-TDS control, pad disinfection ASHRAE 188 (if wetted >30 days/year)
Adiabatic Pad/nozzle hygiene, Legionella prevention Local & ASHRAE 188 guidance
Evaporative Scale, corrosion, biofilm, blowdown ASHRAE 188, NPDES/state permits

Key takeaway: If any water is present—even adiabatic pads—a Legionella risk-management plan is essential.

8. Choosing the Best Fit for Your Facility

  1. Model all-dry and all-evaporative systems first; hybrids fall between.
  2. Plan for redundancy—dry/hybrid often require more units for n+1 design.
  3. Factor climate change. Hotter summers penalize dry coolers more.
  4. Get consensus. Sustainability teams prioritize water, finance prioritizes energy.

pastedGraphic_1.png

Best practice: Use ASHRAE design-day data and real utility rates to anchor your comparisons.

9. Next Steps & How Chemstar WATER Can Help

Whether you’re evaluating a new data center in the desert Southwest or designing a new hospital facility in the Midwest, Chemstar WATER’s engineers can help you:

  • Benchmark your existing cooling system performance
  • Simulate alternatives using localized weather and tariff data
  • Design water-treatment systems aligned to your selected system
  • Bundle equipment, treatment chemicals, and compliance into one integrated contract

Our vertical integration ensures agility, quality control, and long-term value—no matter which heat-rejection method you choose.