Case Studies

Clothing Manufacturer

The Background

The audit was carried out on a medium-sized clothing manufacturer which designs and manufactures high quality ladies clothing. The factory is located in a single facility in Cape Town and occupies an area of approximately 2800m2.

Given the recent and the anticipated future tariff increases, the company has embarked on an energy efficiency initiative in order to reduce operating costs whilst also reducing its impact on the environment.

The Objectives

The objectives of this project were to:

  • Improve the current energy systems at the facility;
  • Reduce the overall energy consumption of the facility, thereby reducing the overall carbon footprint and energy bills.

The Process

The following methodology was used in compiling this energy efficiency audit:

  • A detailed energy efficiency audit of all energy-consuming devices in the building which included the following areas:
    • Lighting
    • Heating, Ventilation and Cooling (HVAC)
    • IT & Office Equipment
    • Water Heating (Geyser)
    • Factory Equipment (Boilers, Air Compressor, sewing machines etc)
  • Analysis of historical consumption to establish a building performance baseline;
  • Logging and analysis of the main incoming feeder for one week;
  • Analysis of the data gathered during the energy efficiency audit and identification of energy management opportunities;
  • Evaluation and financial analysis of proposed interventions;
  • Development of an energy management action plan for the facility.

In addition, a pre-feasibility study was conducted on the installation of a rooftop solar photovoltaic (PV) system.

The Results

The audited data, including a full inventory of energy-consuming devices in the facility was analysed with the following results:

Lighting was found to be the largest energy consumer in the facility followed by factory equipment and then the HVAC system (ventilation fans and individual ‘window rattler’ office units).

The Opportunities

The following energy management opportunities were identified and are summarised in the table below:

Lighting:

Most savings can be achieved through technology changes as follows:

  • Change of ballast from magnetic to electronic in fluorescent fittings;
  • Change of lighting layout on factory floor to achieve 500 lux throughout the manufacturing area using only 2 x 1.5m ECG fittings;
  • Incandescent and halogen lights to be replaced by CFLs

As the lights are all turned off at night, savings from the installation of a control intervention such as motion sensors would be relatively low, and are therefore not recommended.

HVAC:

The ‘window rattler’ units are notoriously energy-inefficient and should therefore be replaced with inverter-type split units, which not only save energy but also have more effective cooling and heating capabilities.

Office/IT Equipment:

Most office equipment consists of PCs with energy-inefficient cathode ray tubes. These could be replaced with LCD monitors or laptops.

Water Heating:

Although the single geyser is not a large energy consumer, savings can be achieved through the installation of a heat pump, by lowering the geyser temperature and a by using a geyser blanket.

Factory Equipment:

The following interventions were identified as areas of potential energy savings:

  • Insulation of the fusing machine which will prevent heat loss and increase safety (already underway);
  • Insulation of the boiler’s condensate return tank which will prevent significant heat loss in the facility;
  • Continual upgrading of the sewing machines to newer technology where the electric motor turns off when not in use;
  • Repair of steam leaks and insulation around the irons to prevent heat loss;
  • Upgrading the efficiency of the vacuum pump when the current pump is replaced. This will save a large amount of energy and can be done through Eskom’s DSM program which will cover the cost difference between a standard- and a higher-efficiency motor.

The following conclusions were drawn from the audit:

  • The tariff analysis shows that the facility is on the correct electricity tariff.
  • Should the company’s tariff change to a demand-based tariff, power factor correction should be installed as the facility’s power factor is poor.
  • The company has excellent shut-down procedures as the facility showed zero demand during the night and over weekends.
  • The company uses a total of 270,640 kWh per annum.
  • A saving of 18.7% can be achieved should all the energy management opportunities identified be implemented. This however, has financial implications.
  • This percentage will increase as the company continues to replace old sewing machines with new, electronically controlled models.
  • Some of these interventions are general maintenance/housekeeping interventions which can be implemented by employees. Management has already been proactive in certain areas, such as the insulation of the fusing machines, and such initiatives should be continued.
  • A total of 189,960kWh can be produced annually through a 140kW rooftop PV system. However, with a cost of approximately R7 million and an internal rate of return of 2%, this project is not yet feasible due to the high installation cost and lack of feed-in tariff for this size system.

The graph below illustrates the annual savings with the recommended investment and shows a payback of 3.4 years.

The Future

An energy management action plan would incorporate the abovementioned recommendations and will initiate the company’s climate change response strategy, thereby placing the company amongst the leaders in combating climate change.

Not only will this lead to significant and ongoing cost savings, but it will also provide a sound basis for reducing the company’s environmental impact.