Tag Archives: Savings

Fan of Energy Savings?

Grey Green has investigated the fans at numerous factories, including at several large grain mills. Often dampers are used to control flow rates and pressures. If so, removing the dampers or changing the fan speed produces good savings.

Case 1

A mineral processing works has six identical, belt driven fans. All operate against dampers which are approximately half closed.

Example of a Fan with Inefficient Control

Grey Green calculated that a simple change to the belt drive ratio with fully open dampers would:

  • Cost approximately R 7 500 to implement (equipment only – installation could be done by the factory’s own maintenance staff).
  • Produce annual savings of R 173 400 (No typos here the payback period is really only 0.04 years – i.e. less than 1 month).

Case 2

Another local grain mill has approximately 30 significant sized fans. None have damper control; whenever the mill is operating the fans run continuously at fixed speed.

Grey Green assessed 18 of the biggest fans. Our measurements and calculations showed that many of the fans were far from their optimum (maximum efficiency) operating points – i.e. when plotted on a fan curve like the typical one in the following diagram, their combination of flow rate and pressure rise was far from the best efficiency point.

Typical Fan Curve
Typical Fan Curve

Due to the age of the fans and their motors we recommended replacement of the worst performers.

  • For five fans replacement gave payback periods less than 1 year and total annual electricity savings of >R 2 million.
  • Six more fans could be replaced to produce payback periods between 1 and 2 years, with combined annual electricity savings of R 634 000.

What is an ESCo?

ESCo Framework

This slide (Source: Jan W. Bleyl, 2009) summarizes what an Energy Service Company (ESCo) is by explaining what it does for its clients. The ESCo integrates the various Technology vendors and contractors offerings using its professional Know-How and design expertise to provide suitable energy Supply (Mega-Watt Hours) or Savings (Nega-Watt Hours) solutions for its clients based on their particular needs and contexts. These solutions are also based on available Energy Sources / Carriers, the current Legislative and regulatory frameworks in place and finally incorporating the best Finance options available, including incentives. The client need only be concerned about the energy Supply or Savings provided by the ESCo which comes with Functional, Performance and Price guarantees. The risk of dealing with the various other stakeholders and managing the energy solutions themselves are largely taken over by the ESCo being the specialists in this field.

Grey Green 24-Hour Tariff Clock

Grey Green 24 Hour Tariff Clock

We have developed our very own tariff clock based on ESKOM tariff structure for our time-of-use clients. This clock uses a 24-hour clock mechanism and simply shows people when they are in or close to peak, standard or off-peak zones during the day.  One is now able to schedule or avoid using high powered machinery and equipment by just timing these activities appropriately and thereby making substantial savings in electricity bills. The concentric rings also show the differences on weekdays, Saturdays and Sundays. Last but not least, it  can also help tell the time.

Distell Energy Audits

We have completed three intensive energy audits at three large distilleries in the Western Cape. This included a month of energy data collection through sub-metering at the departmental as well as the equipment levels to get a highly accurate energy demand breakdown.

The assessment included an analysis of the steam system, including an analysis of the boiler stack flue gases and condensate return. A number of detailed business cases were developed to present energy saving opportunities. It also included an analysis of the existing metering systems and recommendations were made to increase the effectiveness of the existing measurement systems. Finally, a number of behaviour change initiatives were recommended.

Energy Efficiency Savings Realized

Energy & Cost Saving Examples

• Identified R300 000 annual electricity and R500 000 annual coal savings at no/low cost for a large brandy distillery
• Achieved R 800 000 annual savings at a shock absorber manufacturing plant which can be achieved at NO cost.
• Energy management program at two large hotels where we identified 20% savings (amounting to R206 000 per year) using no cost interventions
• Diagnostic audit at a concrete factory where we identified a 5% saving at no cost and a further 21% using interventions with a one year payback. This excludes the additional benefits from reduced demand charges
• Achieved a 10% no cost savings at an office block and identified a further 5% low cost saving
• Identified a 30% saving at manufacturing facility using a medium cost intervention with 2 year payback period


Payment Models & Results Achieved

EE Case Study -Payment Models

• The above 3 Year Total Savings are guaranteed & verified by Eskom’s independent M&V team
• Upfront payment means the client paid for the equipment and collected the rebates
• Financed payment means Grey Green financed the equipment & charged a monthly fee
• Shared savings payment means Grey Green paid for the equipment & took a % of the savings


Feasibility Study & Intervention Examples

• Boiler efficiency studies including flue gas analysis and combustion efficiency where we also assessed feasibility for supplementing coal with biomass
• Simpler interventions such as heat pumps, low-flow shower heads and energy efficient lighting


Diagnostic Audit Results Examples


Caledon Hotel Energy Audit

Grey Green audited the Caledon Hotel & Spa on behalf of Heritage South Africa. An intensive energy audited was conducted over a few months. The hotel is a large complex consisting of the hotel, restaurants, casino, spa and conference facilities. A number of interventions were identified and included in a report to the client highlighting how energy is currently being consumed and outlining possible ways to reduce energy consumption.

Haven Night Shelters Energy Audit

We conducted a detailed energy audit of a homeless shelter for the Haven. This included metering of the incoming supply as well as a detailed assessment of the energy needs for water heating and cooking. Many recommendations were made to reduce the use of electricity through upgrading of old inefficient refrigeration and AV equipment, as well as using heat pumps for heating water and low flow shower heads.