Cooling Tower Fan Retrofit

Project Summary

The customer campus covered by this case study is comprised by more than sixty (60) buildings, each having its own purpose and staff. For this project, Lockheed Martin Energy engineers audited three (3) cooling towers. Cooling tower 62 (CT62) serves the large ammonia refrigeration compressors which serves the process systems and space conditioning for one of their buildings. Cooling tower 62A (CT62A) serves a chilled water system for a second building and cooling tower 82 (CT82) serves a chilled water system for a third building.

CT62 is a six cell tower rated at a capacity of 2000 tons and each cell has a fan that Is powered with a two-speed motor. The high speed motor horsepower (HP) is rated at 30 hp and the low speed motor is rated at 7.5 HP. CT62A is a two cell tower with the same capacity as CT62, however it's fan's high speed motor HP is rated at 75 HP and its low speed is rated at 18.8 HP. CT82 is a three cell tower with a capacity of 2880 tons with fan motors that have a same high and low speed HP rating as CT62A.

Energy Engineers audited the three different cooling towers that serve their respective buildings. Individual Variable Speed Drives (VSDs) were installed on each fan's motor. VSDs control the speed of the motor to meet the demand of the cooling tower cell, typically a cooling tower is sized to meet the peak demand which represents approximately 3% of the total hours. During all other times, the air flow is reduced while still meeting the load requirements. Additionally, the outdoor air temperature fluctuates throughout the year which changes the operating requirements of the cooling towers. Energy savings is achieved by installing VSDs to reduce the speed of the fan beyond the high and low speed settings of the motor.

The total project cost was $224,012, however Lockheed Martin Energy paid an incentive of $49,310. Implementation of these upgrades saved the facility 477,486 kWh annually, corresponding to a energy cost savings of $57,298 per year. During peak hours, the facility also had a reduction in energy consumption of 63.37 kW. These savings make the simple payback period only 3 years!

Project Team

PGE Logo
Program Pacific Gas and
Electric Company
Lockheed Martin Logo
Lockheed Martin Energy
Heavy Industry Energy Efficiency


To reduce the energy consumption of this company's refrigeration process


Install a variable speed drive on each cooling tower fans' motor


Total Energy Savings

477,486 kWh annually

Peak Energy Savings

63.37 kW

Equipment Installed

(11) variable speed drives

Financial Analysis:

Total Project Cost


LME Paid Incentive


Energy Cost Savings

$57,298 annually

Simple Payback

3.0 years

It is our objective to assist PG&E heavy industry customers in:

Improve product quality and production rate
Identify process-focused energy efficiency improvements and other opportunities
Facilitate electricity and natural-gas energy efficiency equipment and demand reduction upgrades
Reduce operating costs per unit of product
Reduce waste, pollutants, and Green House Gas emissions

Increased production efficiency = Lower production costs = Increased profits