Today's HVAC systems are intended to meet the stricter indoor air quality, environmental, and user requirements. Most of the improvements in the efficiency of the HVAC systems have resulted from the advancements in the operating efficiency of system components. Other advancements are the result of using newer technologies.
Even though there are several individual developments that have been a catalyst in improving the operating efficiency of HVAC systems, much of the overall improvement can be credited to the factors mentioned below:
Chiller design changes
Higher energy efficiency is not the only advantage of the new generation of chillers. They also provide better refrigerant containment. While standard chillers lose ten to fifteen percent of the refrigerant charge routinely per year, newer chillers can keep the losses to 0.5 percent. Better purge systems and lower leak rates decrease the amount of non-condensable gases that are found in the new chiller system – an important factor in maintaining better performance of the system over time.
Another important development is in the operation of the boiler system: the replacement of manual and pneumatic controls with microprocessor systems. This has helped the systems to achieve 5% to 7% energy savings over traditional pneumatic-based boiler systems.
The HVAC systems today use energy-efficient motors. These motors provide a moderate but substantial increase in the operating efficiency over traditional motor designs. For instance, a ten horse power energy-efficient motor functions at about 90% efficiency; a traditional motor of a similar size is rated at 85%.
Chillers inside the HVAC are sized for highest cooling loads. Standard control systems close vanes on the chiller inlet, dropping the efficiency of the system at the time of part-load operation. When VFD or variable frequency drives are applied, chillers regulate the operation by decreasing the compressor speed. The end result is full-load operating efficiency over an extensive array of cooling loads.
Conservation of energy is not the only benefit of VFD variable frequency drives. The electric motor along with the mechanical system is strained every time a fan, a pump or chiller is initiated at full-line voltage: Belts slip, high-pressure is developed and drive chains stretch. VFD helps in decreasing these stresses by starting systems at low frequencies and voltages in a soft start, leading to increased equipment and motor life.
At last, the most significant element in a modern HVAC system is the way it’s used. No matter how energy efficient or sophisticated the system is, its performance depends on the way it's maintained and operated. It is important to be properly trained before using the features of the system. Also, it is advised to get the system maintained by professional contractors. The personnel should be equipped and trained with the proper knowledge and tools to keep the HVAC operating in the way it was intended. Maintenance should never be taken lightly.