Results

 

Data centre

 

              With the coolers determined by the heating demand and also the time of free cooling available as the use of lights inside the datacentre is possible to calculate the energy and costs demand during the year. Reminding that this is an estimation of the worst case scenario, where the servers run at full load 100% of the time, giving the maximum value of energy spent. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

As can be seen in Table 1 and Figure 1 the costs majority  for the data centre as expected is due to IT equipment, the second biggest expense is in losses from UPS, distribution lines, transformer and other losses [1], this can bring the PUE from 1,04 to 1,2 meaning that a possible investment to increase the data centre efficiency, would be to reduce the energy losses. Since datacentre cooling comes from free cooling the majority of time (99% of the time), the energy spent for cooling is quite low, because a mechanical cooling isn’t required. 

An important result that allows to measure the efficiency of a data centre is the PUE (power use efficiency), in this work the PUE was calculated as follows [2]: 

 

 

 

 

 

The table below shows the PUE based on the type of cooling used and an average PUE for the entire year:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

As it can be seen the data centre runs very efficiently, a PUE of 1,2 is considered a very efficient data centre [2], but a Google datacentre as reference in energy efficiency has a PUE of 1,13 [3] this could due to investments in the distributions lines decreasing the amount of energy loss, that can be very significant as shown in the Table 2.

 

Office

 

Using the Simulink model for the office, was possible to account the amount of energy required to keep a comfort temperature inside the office, to do that an aircon unit  that pumps outside air to cool it was used (similar to the data centre cooling system) and a heating system that uses hot air from the server room (air at 34°C), the Figure 2 shows the monthly energy and costs spent in the office.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

As expected an increase in the energy consume can be seen during the summer, due to increase use of the aircon system that waste energy by pumping air inside the building. As mentioned before the office heating system uses hot air from the servers, Figure 3 shows how much energy and money was saved by using this system.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

          Comparing the energy spent in the office with the economy made it can be seen that if were required a heating system the energy costs would be more than double, that seems a reasonable value since the heating system in UK can reach 60% of the energy building demand.