The impact of underperformance

It is well known that no matter how well designed and installed systems are, their performance will be disappointing if in practice the products do not meet the manufacturer’s promised specifications. This is a serious problem because poorly performing products can:

• Not complying with legal requirements and regulations in force
• Consume more energy than necessary
• To contribute to the increase in carbon footprint
• Generate high operating costs
• Not meeting the needs of the end user
• Be more prone to malfunctions and breakdowns
• Negatively affect the operation of other system components
• Lead to penalties, litigation and reputational damage

Even a slight deviation from optimal performance can significantly influence the entire life cycle of a product. In this regard, a case study by Eurovent & BAC highlights how a poorly performing cooling tower can negatively affect the operation of the entire HVAC system.

Project

A new one was needed cooling tower in an industrial HVAC application, operating year-round, with a load variation from 100% in summer to 80% in winter. The cooling tower for this application was chosen for the summer season to cool 52 L/s of water from 32°C to 27°C at an inlet temperature of 21°C.

Cooling tower

The customer had to choose between two cooling towers. Model A is a certified cooling tower, with independently verified performance data. Model B is uncertified. Its data has not been verified with an actual performance of only 80% of the required load when used under the specified conditions. Therefore, Model B generates a water temperature 1.2°C higher than desired.

The apparent difference is small, but the impact on the HVAC system is major.

Performance under design conditions

Model A will operate within design conditions, delivering the expected performance. In contrast, Model B will have to operate slightly outside of design parameters to achieve the 1.090 kW cooling capacity. This underperformance of Model B will impact the entire system because:

• The chiller will not be able to stop completely, due to the high pressure generated by the 1.2°C higher water temperature.
• Although it will not fail, the cooler will reduce its cooling capacity and will discharge more frequently.
• In industrial applications, this can lead to a slight slowdown in the production process.

At first glance, the impact of underperformance may seem insignificant. In some summers, the design water temperature conditions may never be exceeded, making the differences appear minor. However, the real problem becomes apparent when we look at the annual economic impact. Comparing the two models—model A and model B—we see that the fan energy requirement is 27.770 kWh for model A and only 25.400 kWh for model B, due to the use of a smaller fan motor. However, if we look at the energy consumption of the chiller, model A requires 1.114.360 kWh, while model B consumes 1.178.700 kWh, almost 6% more. Thus, adding the fan and chiller consumption, model B ends up using about 5% more electricity annually.

It is important to note that energy prices have fluctuated significantly over the past two years. For example, in early 2023, the cost of electricity peaked at €0.50/kWh, which in our case would have meant an additional cost of +€30.985 per year.

But the impact of underperformance doesn't stop there. In addition to higher electricity costs, Model B also involves additional water consumption, as the chiller will work harder to dissipate the residual energy, leading to greater evaporation. In the scenario analyzed, Model B would consume annually 500 m³ of extra waterEven at a relatively low cost for water, sewage and chemical treatments, estimated at 3.61 EUR/m³, this additional consumption would generate an additional cost of EUR 1.805 per year.

Conclusion: total costs

The additional annual operating cost for water and electricity for the system equipped with Model B amounts to 14.199 EURThis amount represents approximately half of the investment required for a new cooling tower and demonstrates that the apparent price advantage at installation is, in fact, a deceptive economy. In the long run, Model A proves to be the more energy-efficient, reliable and cost-effective choice, offering consistent operating benefits.

Thermal Performance Testing Certification guarantees that the equipment is operating according to specifications, thus eliminating the risks and uncertainties related to achieving the estimated system savings. Basically, the assumptions are removed, and the performance becomes certain and verifiable.

Eurovent certification provides permanent, free access to transparent, accurate and standardized information about product performance, through Online directory of certified productsWhether you are analyzing a new product on the market, a brand you have not used before, or you want to check the performance of a selected piece of equipment, you can objectively compare products, relying on certified data, to make correct and well-founded decisions.

You can search for HVAC and refrigeration products by category, type, brand, model or certificate number. If a product does not appear in the directory, it means it is not certified.

Performance is essential, and at InterCooling, as official BAC partners and distributors in Romania, we are fully aware of this. Choose certified equipment which guarantees you long-term savings and reliable operation.