Case Study: Over 10 Million Baht a Year Saved with a Chemical-Free Ozone Cooling Water System

The problem before installation: electricity costs driven by scale and algae in the condenser

Before the ozone cooling water treatment system was installed, algae (biofilm) had accumulated within the cooling tower and scale had formed on the tube surfaces in the condenser, preventing heat transfer from operating at full efficiency. The resulting impacts were:

• The chillers had to run harder than normal, consuming more electricity.
• Chemicals and a softener were required continuously to condition the water, raising costs.
• The condenser had to be taken offline periodically for cleaning, costing time and increasing maintenance expenditure.

These problems were a significant cause of the building’s rising energy costs, as well as requiring downtime and the use of water conditioning chemicals with long-term environmental consequences.

The solution: installing a chemical-free ozone cooling water treatment system

ECONOWATT installed an ozone cooling water treatment system, model OZG 120 S, to control water quality in the system in place of chemicals. The ozone system acts as the oxidant in the cooling water instead of chemical treatment, inhibiting scale formation and eliminating algae and bacteria, while reverting to oxygen and leaving no residual. The system also operates as a closed loop with automatic control, so there is no need to shut down the building’s cooling system.

After the system was running, the building was able to decommission its softener system and reduce the use of water conditioning chemicals by 100%, cutting both chemical costs and the maintenance burden in a single step.

Results after installing the ozone cooling water treatment system

After installation, chiller electricity costs were clearly reduced, arising from two main factors: removing scale from the condenser, which improved heat exchange efficiency, and reducing the number of chillers that had to operate, which lowered overall system energy consumption. From the condenser cleaning effect alone, electricity savings of 512,460 baht per year were achieved.

In addition, where previously three chillers had to run at full load, after installation this was reduced to just two chillers at approximately 60% load, with one chiller shut down entirely, producing electricity savings of 9,562,635 baht per year. In total, actual electricity cost reductions came to 10,075,095 baht per year, not including additional savings on water, labour and other maintenance.

The ESCO and Shared Savings investment model

The installation of the ozone cooling water treatment system to reduce chiller electricity costs in this project was carried out under an ESCO (Energy Service Company) model on a Shared Savings basis, designed so that the customer does not need to use their own capital investment (CAPEX). ECONOWATT funded the entire system installation, and the client paid a share of the actual savings achieved on a monthly basis.

The investment model can be described as follows:

• The customer makes no initial investment → ECONOWATT funds the entire system installation (2.4 million baht)
• Shared savings contract term → 24 months
• Savings achieved = 840,000 baht/month
• ECONOWATT’s share, 2.4 million baht over 24 months = 100,000 baht/month
• The client receives, net and immediately = 740,000 baht/month

On the sharing of benefits: total savings across the two years came to 20.15 million baht, of which ECONOWATT’s share was fixed at 2.40 million baht, leaving the client with 17.75 million baht over the two years. From year three onward, the client receives 100% of the savings (10 million baht per year).

The project produced positive cash flow from the first month, with the client paying its share out of “money actually saved”, without affecting the existing budget. Under this model, ECONOWATT carries the performance risk, because its revenue is tied to actual savings rather than to a one-off equipment sale, reflecting the company’s position of delivering “guaranteed results”.

This is a clear example of how a Shared Savings model allows an organisation to begin an energy saving project immediately, without affecting its capital budget.

Engineering evidence: Condenser Approach Temperature improved by more than 90%

Condenser Approach Temperature is the difference between the temperature of the condensing refrigerant and the temperature of the water leaving the condenser. It is a direct indicator of heat transfer efficiency in a chiller system, the lower the value the better, because it means the heat exchange surface is clean and working at full capability. Measurements before and after installation are summarised below:

The Approach Temperature fell by more than 90%, and the system was able to hold the value below 1°F continuously for as long as 10 months, demonstrating that it had returned to full operating efficiency. This is substantially better than ECONOWATT’s own guarantee criterion, which is that the value will not rise more than 2°F from the starting point.

The following graph shows the Approach Temperature values actually recorded throughout the operating period (under real operating load), demonstrating consistently stable performance at a low level.

Screenshot of the control panel (HMI) confirming the actual measured values before and after installation.

In addition to the two machines still operating, the improved heat rejection efficiency also made it possible to shut down Chiller No.2 entirely after the ozone system was installed — which is the principal source of the 60% electricity cost saving, or approximately 9.56 million baht per year.

Another of the most tangible results is the condition of the cooling tower basin: from a state where algae had accumulated until the water was cloudy and the drain openings were blocked, it returned to being clean and clear after the ozone system began operating.

More than electricity savings: over 1,367 tonnes of carbon reduced per year

The results of this project reflect not only reduced energy costs but also a clear positive environmental impact. From actual operating data, electricity consumption was reduced by 2.88 million kWh per year, as a result of the chiller system operating more efficiently and being able to reduce the number of machines running from three to two on a continuous basis.

Calculated using Thailand’s Grid Emission Factor (Scope 2) of 0.4750 kgCO₂e/kWh, this is equivalent to a greenhouse gas emission reduction of approximately 1,367 tonnes CO₂ per year, and 2,735 tonnes CO₂ across the full 730-day operating period, comparable to taking approximately 297 private cars off the road for a year.

This still does not count the environmental benefit of eliminating chemicals and the softener system, which reduces both chemical residue and the wastewater arising from blowdown.

Conclusions from the case study: installing a chemical-free ozone cooling water treatment system

This case study clearly demonstrates that an ozone cooling water treatment system can genuinely improve cooling tower efficiency and reduce the workload on chillers, resulting in chiller electricity cost reductions of more than 10 million baht per year, payback within 2.86 months, an Approach Temperature improvement of more than 90%, and carbon reductions of more than 1,300 tonnes per year.

Combined with an ESCO Shared Savings model requiring zero investment, monthly payment of a share of the savings actually achieved, and receipt of 100% of savings after the two-year contract term, all of this rests on 730 days of real operating results, with continuous monitoring and guaranteed performance.

For those seeking to manage energy costs efficiently, Econowatt is pleased to provide energy management and water treatment solutions for air conditioning systems, delivered by a team of specialist engineers and committed to delivering “guaranteed results” to customers in industry, commercial buildings, hospitals and organisations seeking to improve cooling system efficiency.

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Frequently asked questions about ozone cooling water treatment systems (FAQs)