Modern Building Services

MODERN BUILDING SERVICES MARCH 2023 27 FEATURE PIPED SERVICES, PUMPS ANDWATER Traditionally, throttling is used to regulate flow in a pumping system. While throttling reduces the flow, the motor is still running at full speed and works even harder as it has to work against a restriction. By reducing the speed of the motor, the variable speed drive ensures no more energy than necessary is used to achieve the required flow. A centrifugal pump running at half speed consumes only one-eighth of the energy compared to one running at full speed. Using an electrical VSD is the simplest and most economical way of controlling the pump and matching it to the pump system. When specifying a new pump, ask for a high efficiency motor to be fitted. If you are replacing or rewinding a motor, then evaluate the cost of fitting a high efficiency motor remembering to factor in the running savings which will pay back any increase in cost. Energy Audits Invest in conducting an energy audit. Review your utility bills and understand the energy you are using. Carry out an audit if: • Your energy bills are high • You have continuously operating pumps • You havemany pumps in the system • You have processes with varying flows • You have throttled pumps • You have pumps that are on bypass • You have noisy valves or pipework • You have critical systems which have been subject to breakdowns The purpose of an energy audit is to reduce operating costs by reducing energy consumption and the government has estimated that most companies can reduce their energy consumption by 10% to 20%. Energy audits carried out in accordance with ISO 14414 have shown that savings from 30 to 50% are not unusual. When deciding whether or not to carry out an energy audit a good starting point is to assume that you will save at least 10% of your current energy consumption. By reviewing utility bills, you can get an indication of the savings to be made and the investment that you should be prepared to put into the auditing process. Across most industrial and commercial sites, some two-thirds of the total energy consumption is used to power electric motors. Furthermore, the overall cost associated with operating these essential pieces of equipment throughout their entire life span can be broken down as follows; 5% accounts for the initial purchase/ installation costs, 10% for ongoing maintenance and a massive 85% for the energy used to run them. Clearly, any reduction in the energy consumed by electric motors is important, and with modern designs that reduction can be as much as 30%. It is also evident that many pumps and motors are constantly operated at full power, irrespective of process needs, and so across Europe’s installed base there is the potential for significant energy savings; savings which can in turn drop to the bottom line and increase the profitability of any business. BPMA involvement Given the amount of energy consumed by pumps through their normal operation, and the potential for energy efficiency gains within pump systems, the BPMA has worked to develop a Certified Pump System Auditor Scheme (CPSA). Through the CPSA, pump engineers are being trained to correctly assess the efficiency of pump systems, and to provide appropriate recommendations in order to improve the efficiency of those systems. The CPSA accreditation is achieved by successfully completing a four- day residential course, followed by the satisfactory completion of a pump system audit. Only then can ‘Certified Pump System Auditor’ status be achieved. Within the Energy Saving Opportunities Scheme (ESOS) Guidance document, the ISO/14414- Pump System Energy Assessment standard is referenced as an auditing methodology that can be accepted by “Lead Assessors” approved by the Environment Agency. Accordingly, it is hoped that CPSA accredited persons (who are trained to the IS0 14414 standard) will be recommended by Lead Assessors to undertake the pumping system elements of company-wide energy audits. More information can be found at www.bpma.org.uk