PARTNER FOCUS Case study:
The hidden cost of underperformance
Even slight underperformance can signifi cantly impact a product’s lifecycle. This case study by Eurovent-certifi ed manufacturer, BAC, illustrates the eff ects of an underperforming cooling tower on an HVAC system.
In addition to electrical costs, there is more water consumption for Model B because the chiller has to work harder, hence more waste energy has to be dissipated and more water will evaporate.
E
ven the best designed and installed systems will underperform if real life product performance does not match manufacturer claims. This serious issue can lead to:
■Non-compliance with regulations ■Higher energy usage ■Increased carbon footprint ■High running costs ■Failure to meet end-user requirements ■Greater risk of faults and breakdowns ■Negative eff ects on other system parts ■Penalties, litigation, and reputational damage.
The project A new cooling tower is required for use 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 would be selected for a summer condition to cool 52 l/s of water from 32°C to 27°C at an entering wet bulb temperature of 21°C. The cooling capacity to be rejected would be 1,090 kW.
The cooling towers
The decision maker has the choice between two cooling towers. Model A, is a certifi ed cooling tower, with performance data independently verifi ed. Model B is uncertifi ed. Its data has not been verifi ed and unbeknown to the specifi er, its
actual performance is 80% of the required duty if using the specifi ed conditions. Therefore, Model B has supply water 1.2°C warmer than designed and the installation will be penalized the entire year by the higher supply water temperature. It will for example, take a wet bulb of 19.3°C to supply the required 32°C / 27°C water temperatures.
Model B is available at a slightly lower price (approximately 10-15% cheaper). Note that the customer cannot tell that Model B will underperform based on the dimensional data and face values for fan power and sound.
Performance at design conditions Model A will perform to the specifi ed design conditions as
expected. Model B will have to operate slightly outside the design conditions to reach the 1,090kW cooling capacity. The impact of Model B’s underperformance will aff ect the whole system, because:
Example of additional operating costs for a non-certifi ed cooling tower + Chiller = +€12,394/annum at a modest €0.20/kWh: Cooling tower + chiller (kWh)
Model A Certifi ed
Model B Non certifi ed
Fan kWh = 27770 kWh + Chiller power = 1,114,360 kWh
Total (kWh & €)
1,142130 kWh €228,426
Fan kWh = 25400 kWh + Chiller power = 1,178,700 kWh 1,204100 kWh €240,820
16 September 2024 •
www.acr-news.com Diff erence (kWh & €)
0 0
+ 61970 kWh €12,394
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