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Air Systems Energy Optimisation

At CFW, we offer consultation on air system energy efficiency from some of the most experienced specialists in Southern Africa. Our decades of wide-ranging work in air technology engineering mean that we can provide solutions for virtually any system making use of fans, including:

  • Commercial and industrial kitchen ventilation
  • Mining ventilation
  • Domestic and commercial HVAC and evaporative cooling systems
  • Industrial process air systems (e.g. convection furnaces)
  • Pneumatic conveying systems

Higher energy prices and ever more stringent legal requirements mean that opportunities for increasing energy efficiency are an important cost-cutting measure for a wide variety of industries. Optimising HVAC and industrial process air systems is part of this drive to improve savings. While they have often been overlooked in the past, air systems are known to make up a large part of total energy consumption. While energy consumption can differ widely, research suggests that the proportion of total energy use accounted for by ventilation is about 28% for commercial kitchens and 50% for mines (up to a third is of power use in mines is accounted for by the fans alone).

Air systems energy optimisation is a complex field that calls for dedicated solutions. Usually, a holistic solution or “systems approach” is needed – merely replacing parts will not produce good results.

To minimise energy use while ensuring that the system continues to perform adequately, we will consider the fans, fan accessories, ducting, vents, and airflow patterns in the building or other space and make the appropriate recommendations. We also provide the necessary equipment and installation services should they be required.

Whether you are installing a new system, upgrading an existing one or only making adjustments, CFW will work with you to ensure optimum performance for your system at the lowest operating and maintenance costs.

It is important to remember that energy optimisation does not mean the minimum energy use apart from all other considerations. If an air system cannot provide enough air when and where it is needed, or if it becomes inordinately difficult and costly to maintain, the price of lower energy use will outweigh the benefits. Fortunately, energy-saving improvements often go hand in hand with longer equipment life and lower noise.

The particular optimisation strategies recommended may vary. However, they might include:

  • Controlling fan speeds. Eliminating excess is the most fundamental principle of efficiency. Various ways of controlling fan operation are available. In many cases the higher capital cost of variable-frequency drives on fans is justified by the savings in operating costs. When ventilation or process loads are lower, fan speeds can often be reduced accordingly. Because the fan affinity laws state that horsepower is proportional to the cube of speed, a relatively small reduction in fan speeds can result in a large reduction in fan power consumption. For example, in the ideal situation, a 10% reduction in fan speed will lead to a reduction of 27% in power use.
  • Optimising ducting diameters. This results in reduced friction and pressure drops, reducing the energy consumption of fans.
  • Implementing IGV control on large centrifugal fans.
  • Improving system layout. More duct turns and turns at greater angles have higher pressure losses. The location of fans and vents is also important to ensure that air is properly distributed.
  • Selecting the right ancillary equipment. Fan accessories such as guards, louvers and cones all have advantages, but tend to increase the power demand of the system.
  • Implementing advanced computer control systems. This reduces the effort and possibility of human error inherent in manual control of the air system.
  • Reconfiguring according to the loads that are actually placed on the system at various times. This will involve carefully ascertaining how the air system is used in practice. For example, long experience has led many agricultural users of fans (e.g. for livestock barns and greenhouses) to install multiple fans that are sized and selected according to the needs of a certain time of year.
  • Recommending a maintenance programme. Dust and debris in the air system will reduce the total system efficiency considerably. Fan components need to be properly lubricated, leaks repaired and louvers, impeller blades and filters cleaned or replaced as necessary.