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HeatVentors server cooling using CrodaTherm™

HeatVentors design and install advanced thermal energy storage (TES) systems using our CrodaTherm™ bio-based phase change materials (PCMs). 

In this case study, we review a TES HeatTank system, which was installed to improve the efficiency of an existing telecommunications server room. 

After one year, operational costs were reduced by 51% and is forecast to return on the initial investment after 4 years.

Rita Andrássyné Farkas, CEO of HeatVentors said, 

“Trust is very important in the energy efficiency sector. We are looking for long-term cooperation with our customers, so it is crucial to calculate the real ROI for them. 

For this, we have to sell high and constant quality products, which means that we have to use high and constant quality PCMs in our storage. 

We investigated and tested many different PCM from many different suppliers and we chose CrodaTherm, because the properties of their materials are totally the same as indicated on the Data Sheet and they provide - high and constant quality.”

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The need: improve HVAC efficiency

HeatVentors received a client request to reduce the operating cost associated with cooling the telecommunications base station installation.

The client had servers in the telecommunications base station that produced between 2.5 and 3.5 kW of heat. Two 6 kW air conditioning systems were used to achieve a server room temperature of 26 °C (78.8 °F).  

Due to the large expenditure on electricity for cooling equipment, with the risk of equipment failure if temperatures were not properly managed, there was an opportunity to significantly reduce operational costs and improve overall energy efficiency.  

The solution: a HeatTank TES system 

HeatVentors proposed the installation of a HeatTank TES structure, using CrodaTherm PCMs, in a room separate from the servers. It included two heat exchange surfaces, refrigerant pumps, and expansion tanks.

This design allowed the cooling potential of the mountainous air outside of the building to be stored and utilised for server cooling.

Even in hot summer weather, the design allowed excess cooling potential to be stored from the air conditioning system, so that peak thermal demand could be met during temperature peaks on a hot summer day.

Figure 1: HeatTank design proposed by HeatVentors for their client for cooling their servers in a telecommunications base station

Published by

  • Kyle Thompson Marketing Coordinator
base station

The result: improved efficiency and reduced operational costs

HeatVentors implemented a TES system using CrodaTherm to improve the efficiency of an existing telecommunications installation, reducing operational costs by 51% after one year with an estimated ROI of 4 years.

The HeatTank system was compared to the existing air conditioning (AC) only HVAC system, comparing 3-day periods with similar weather conditions. 

Full results: efficiency under different operating conditions

Operation without HeatTank

The cooling needs of the server room were well below the cooling capacity of the installed HVAC system. As such, the air conditioning units turned on and off about 10-12 times per hour as they were not needed constantly. However, when idle the AC systems continued to consume energy to circulate air.

During hot summer months, especially during the day, AC demand was higher, and more energy was used. 

Operation with HeatTank using free cooling throughout the day

Cooling demand was primarily met by free cooling when temperatures outside were below 26°C. This meant the cooling potential of the outside air met the server cooling needs with minimal energy investment from the newly installed HeatTank system.

In this instance, the air conditioner operated with almost the same performance, but with almost 6 times the energy consumption, whereas the HeatTank storage solution, operational from the 30th May, was able to take advantage outside temperatures for cooling, resulting in lower energy consumption, even in summer months. 

This represented an 82.4% energy saving. 

Date Temperature/ °C Electricity consumption /KWH
Average Max Min
17th May 10.9 16.7 7.3 28.9
30th May 10.0 15.1 4.4 5.1

Operation with HeatTank using free cooling overnight 

When outside temperatures increased during the day, it eliminated the possibility of free cooling over the 24-hour period. However, with the HeatTank system, cold energy could be stored overnight. During the day, the cold energy store was used to cool the server room with minimal energy input.

This represented an 85.7% energy saving.

Date Temperature/ °C Electricity consumption / KWH
Average Max Min
2nd April 17.7 21.4 13.3 38.0
5th April 17.4 23.5 11.4 5.4

Operation with HeatTank without free cooling

During these conditions, maximising efficiency of the AC units was the aim. To do this, cold energy was stored by AC units over night, to reduce demand during daytime operation when cooling demand was at its peak, which is usually when AC units are least efficient. 
The cooling capacity was provided by the air conditioners and the heat tank

This represented a 20.1% energy saving. 

Date Temperature/ °C Electricity consumption / KWH
Average Max Min
4th July 22.8 30.0 47.9
7th June 22.8 30.5 38.3

 Result after 1 year of operation

 The total electricity saving after one year was 51.3%, with an estimated ROI time of 4 years. 
 energy consumption


Figure: 2  Daily energy consumption over 1 year
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