Johannesburg Supreme Court is in the centre of Johannesburg and is often on the TV News. Normally only the entrance to the old building is shown, which is the original section in the front that was built in 1910. The tower block of 12 floors at the back, built in 1987 is seldom seen. This section includes offices and 24 court rooms.
The building has central air conditioning with four large air handling units and two chillers. The old building has unitary air conditioning units.
SEM Solutions was awarded a contract for energy management on this building that falls under the Department of Public Works. We started our investigation in the beginning of 2000 with implementation from June 2000 onwards.
The original power consumption profile is shown in Graph 1 for the period 4 June to 18 July 2000. The night load was ±1100 kVA. A typical day profile is shown in Graph 2 for 04 June 2000.
The first step to reduce power consumption was to switch off the air conditioning during after-hours. This was a major break through because for a quite a number of years the occupants were used to air conditioning at all times. The immediate reduction in power consumption was in the order of 250 000 kWhr per month. The night load reduced to 550 kVA as can be seen on Graph 3 for 17 July 2000.
The second step was the installation and commissioning of power factor correction to improve on the ± 0.78 factor of the building. An average of 150 kVA was achieved with a small potential remaining. The building has four transformers each supplying a certain section of the building. A step control unit was fitted on each of the four supplies. See the photo of two of the units. Towards the end of the year the building was performing as shown in Graph 4 for 01 Dec.2000.
The third step towards the end of the year was to implement time clock control on the lights in the building. The night load was reduced by a further ± 200 kVA or ± 90 000 kWhr per month. The building was now running on a power consumption profile as shown in Graph 5 for 29 Jan.2001.
An upgrade on the air conditioning installation caused a marginal increase in power consumption. But in general the building is performing well with a relative constant power consumption profile as can be seen from Graph 6 for April 2005. Continuous monitoring of the power consumption by Shared Energy Management assures that the savings are maintained.