ABB guide to VSDs in retail environments.

According to the Carbon Trust, the retail sector accounts for about seven percent of the UK’s carbon emissions, with the biggest energy users being refrigeration and heating, ventilation and air conditioning (HVAC). Refrigeration accounts for about 40 percent of energy consumption, but for certain retailers this can be as high as 90 percent. HVAC costs average about 40 percent.

Variable-speed drives

All retailers, including department stores, supermarkets and convenience outlets can potentially reduce their energy bill by an average of 50 percent by installing variable-speed drives (VSDs). A drive is a device that can be used to regulate the speed or torque of an electric motor. These devices control pumps, fans and compressors, eliminating energy waste.  The ACH550 is a VSD designed specifically for HVAC applications

Energy savings are achievable through affinity laws. The affinity laws explain the relationship between variables involved in pump or fan performance; including capacity, head and power consumption. The power required to run a pump or fan is proportional to the cube of the speed. This means that if 100 percent flow requires full power, 75 percent requires (0.75)³ or 42 percent of full power and 50 percent flow requires 12.5 percent of full power.

The affinity laws show that flow is proportional to motor speed, pressure is proportional to motor speed squared and power required is proportional to motor speed cubed. If the specified output is only required some of the time and output can be varied by motor speed, a VSD might be able to provide rapid payback for a number of HVAC and refrigeration applications across the retail sector.

Energy appraisal

To discover the energy saving potential in any store, retailers should consider bringing someone in to undertake an energy appraisal.  email 999 inverters for more information

Several problems are often found with the HVAC controls, specifically economisers that are not working, air handling units (AHUs) running without control, variable air volume controls that are not working properly, and uncontrolled chilled water valves. Often when the motor of a fan is started across the line at full power, the belts can stretch, requiring frequent tightening. The fan may run at maximum speed, creating a high noise level and resulting in excessive airflow in the store. This can cause a drafty and low-humidity environment during winter. During summer, high humidity can make the store uncomfortable, even if the temperature is maintained within the recommended limits.

A large number of these issues can be overcome by installing VSDs. An appraisal will aim to identify issues throughout the retail environment and identify applications that can benefit from VSD control.

When a VSD is installed into a motor-application, energy spend is reduced and in many instances, maintenance on AHUs decreases as it is no longer necessary to replace any of the motor belts. The units run quieter and also maintain comfortable temperatures and humidity levels within the store.

Payback on VSD investment is often less than 12 months for these typical applications.

For ABB VSDs for retails building contact us here or go to 999 Inverters.com