It is widely recognised that large energy savings can be made by fitting Altivar 212 variable speed inverter drives to fan and pump applications particularly where valves or dampers are employed.  Most new build is optimised, but thee are significant opportunities with fast pay-back times for existing buildings.

According to estimates, motors consume 70% of the energy used by European industry. Therefore, using variable speed drives within HVAC systems is a major component of the energy-efficiency and cost-savings game.

How Much Energy Can Be Saved?

Generally, a centrifugal pump or fan delivering 80% of its rated flow requires only 50% of the rated power. Figure 3 demonstrates the relationship between flow and power requirements for a centrifugal pump or fan.

Key to identifying the energy savings opportunities of variable speed drives in HVAC systems is an understanding of the operating cycle of the system versus the heating and cooling needs actually required. Most HVAC systems are designed to keep the building cool on the hottest days and warm on the coldest days. Therefore, the HVAC system needs to work at full capacity only on the 10 or so hottest days and the 10 or so coldest days of the year.

On the other 345 days, the HVAC system can operate at a reduced capacity. This is where a variable air volume system with variable speed drives (also called variable frequency drives, or VFDs) can be used to match air flow to actual heating and cooling demands. The VFD can reduce the motor speed when full flow is not required, thereby reducing the power and the electrical energy used.

If a building uses a constant-volume air handling system with no variable speed drives, the system runs at full speed all the time. Using dampers to mechanically adjust the air flow output into the appropriate rooms does not control the speed of the motor and does not save energy.

HVAC equipment offering opportunities for energy savings for:

• Centrifugal air handler fans

• Centrifugal exhaust fans

• Centrifugal chilled water pumps

• Centrifugal hot water pumps

• Cooling tower pumps

• Cooling tower fans

See our range of HVAC drives and systems here