Reducing Life Cycle Costs Through Pump Specification
Gary Wheatley, Technical Manager at Wilo Salmson, considers Life Cycle Costs (LCC) and looks at how variable-speed pumps can cut long-term overheads.
Without the humble pump, the world's buildings and offices would be uncomfortably cool or, alternatively, sweltering in an unbearable heat. Water for radiators, air-conditioning systems and drinking water would cease to flow. Our factories would grind to a halt and basic sanitary services would be unsafe.
Circulating pumps are used everywhere; in domestic, commercial, agricultural and industrial settings. They are an integral part of our lives, but are often neglected and taken for granted. Even worse is the disregard shown by many to their potential for energy conservation.
Research has shown that pumping systems account for nearly 20% of the world's energy demand and, in some industrial operations, up to 50% of its energy costs. Yet, because pumps are incorporated into larger systems, many engineers fail to take advantage of the numerous opportunities presented by pumps to achieve life-long cost savings and improved system performance.
Life Cycle Cost (LCC) analysis is a management tool that can help engineers minimize waste and maximize energy efficiency in a variety of systems, including those utilizing the services of pumping equipment. It has been calculated, for example, that the running costs of an average production system can reach five times that of the original (capital) investment. Careful product selection can therefore be important in reducing the overall costs of a new or even retrofitted system. This is especially true if the product, or pump, delivers energy savings and/or requires minimum levels of maintenance.
Product selection is generally influenced by a number of decision makers, each of whom may expect different benefits from a pump or pumping system. One major benefit of LCC is that it can assist in meeting the needs of all concerned: the building owner, for example, wants a pump to be energy efficient throughout its life to reduce fuel bills; the contractor is primarily concerned with the capital cost while the specifier normally considers both of these elements with equal emphasis. As the LCC equation illustrates, all of these factors are given consideration within the calculation, making Life Cycle Costing relevant and beneficial to all those involved in choosing the pump.
The LCC equation
To determine the actual costs of acquiring and operating a pumping system, a number of elements must be examined. The first and most obvious consideration is the initial purchase cost of the pump, pipe and auxiliary components, which although important are only the initial elements in the often-complex LCC equation. Since LCCs consider the total lifetime costs, expenditure on installation, operation, maintenance and disposal is also included.
Installation costs, for example, include commissioning fees and training, while operating costs incorporate the most costly expenditure for many companies - energy consumption. Additional factors include environmental costs, which comprise contamination from media and auxiliary equipment, decommissioning and the cost of disposal. For high-usage pumps - i.e. those operating for more than 2,000 hours annually - energy consumption will undoubtedly be the largest single cost element.
By comparing the relative LCC statistics of various designs and components, it is possible to identify the most cost-effective solution for a specific application. In this way, resource allocation can be based on a methodical, systematic tendering process, rather than a decision based on initial, or capital, costs.
The main advantage of specifying new equipment in terms of their total LCC is the elimination of waste at the earliest possible opportunity. This requires a commitment to commission with a long-term view and supports the argument that building services engineers can maximise life-long cost savings by specifying state-of-the-art pumps that limit energy consumption through efficient operation.
For example, energy consumption - the most significant element in most LCC calculations - can be significantly reduced if variable-speed pumps are selected over fixed-speed units. By doing so, the engineer will ensure the system's output matches the actual demands of the building. This principle is encapsulated in the Cube or Square law, which states that as the speed of a motor, or pump, is reduced, power consumption falls disproportionately when compared to the associated reduction in output. Therefore, if an air or liquid flow rate is halved, the power needed to operate the system falls to only 12.5% of the power needed to operate the system at a 100% flow rate. The savings can be substantial.
Rather than simply comparing components' price tags, LCC analysis can be an effective way of reducing life-long costs and improving levels of efficiency. Many manufacturers, including Wilo, have embraced long-term specification strategies by introducing products that not only feature competitive shelf prices, but also cut energy consumption and provide greater levels of responsiveness. The latest variable-speed pumps, for example, reduce total life costs, while also improving the efficiency of practically all building services.
Source: WILO SE