Freecool® Cooling Energy Performance
Like traditional Air Conditioning systems Freecool® technology will deliver constant equipment inlet temperatures at the agreed set point.
The energy performance of Freecool® technology is dependent upon the temperature of the air and its relative humidity. Higher temperatures give greater cooling. Low relative humidity also gives greater cooling.
There are two operating modes of the Freecool® system:
- Ventilation Mode – Fan Assisted Airflow Only
- Cooling Mode – Evaporative Cooling plus Fan Assisted Airflow
When the ambient air temperature is under 21°C there is no requirement to deploy the evaporative cooling process. During these periods which in the UK are in excess of 80% of running time the energy consumption equates to the sum of the low energy axial fans. Only when the ambient air temperature exceeds 21°C is there any need to engage the evaporative cooling circuit.
Supply Air Temperature Achieved By Freecool® Systems
In the UK during a typical hot period the ambient temperature approaches 30°C. This coincides with a Relative Humidity of under 50%. As the air passes over the pads it will typically cool down to about 22°C. There is less evaporative cooling in the night as the temperatures reduce and the humidity rises.
The graph above shows the performance of a cooling unit in the UK. As can be seen due to higher temperatures and low relative humidity both giving greater cooling the result is an even pattern to cooling.
In cool conditions Freecool® operates in ventilation mode and in hot conditions in cooling mode. The Freecool® control system will automatically balance the fan speeds to ensure constant computer equipment inlet temperatures relative to the external ambient.
Freecool® Impact on Data Centre Efficiency
Traditional cooling technology is a major contributor to data centre infrastructure power overhead. The chart below shows typical examples, very often even with energy efficient technology PUE figures of only 2.0 (DCiE 50%) can be achieved.
The deployment of Freecool® technology makes it possible for data centre efficiency figures to achieve PDU ratings >1.25 (DCiE 80%) when combined with additional energy saving technology e.g. passive aisle containment and airflow management technology.
Table 1 – Comparison of Energy Running Costs for typical Data Centre’s with different efficiency ratings (10p per KW/hr)
Table 2 – Comparison of CO2 with different efficiency ratings
* Data Centre Infrastructure Efficiency / Power Usage Effectiveness are industry recognized standards for data centre room efficiency measurement introduced by the Green Grid.