Siemens Cuts Energy Consumption of Air Conditioners in Half

Siemens has developed a frequency converter that reduces the energy consumption of pumps and fans in building automation systems by up to 50 percent. Instead of reducing the air flow using a choke valve, the SED2 inverter regulates the motor speed to reduce the power. Those thinking of adopting the new solution can get help with their decision by utilizing specially programmed software that calculates how long it will take before the system’s savings amortize the investment. In most cases, the amortization period is just a few months.

Around two-thirds of all electrical power in industrialized countries is used for drive systems — and so-called fluid-flow engines for cooling systems account for half of that figure. This is mainly because air flows are choked off primarily through mechanical means, while the drive continues to operate at maximum power. That’s why an air conditioner motor runs at top speed even when the unit is set to low. This drives up costs over time and poses a particular problem in the light of the currently high prices for energy. In addition, pumps and fans are generally operated for many hours per year, and energy costs account for the lion’s share of the lifecycle costs for such equipment. The new frequency inverter cuts costs in half.

Instead of reducing the air flow mechanically, the SED2 from Siemens Building Technologies controls throughput using the motor speed. In automated building systems in particular, this leads to a very high potential for savings, because heating, ventilation, and air conditioning units seldom need to operate at full power. In addition, a built-in energy-saving mode in the system recognizes when the motor is simply "idling" and brings it to a stop until its output is actually needed again.

Siemens experts have used specially programmed software known as SED2 EasySave to calculate the system’s amortization period, and have found that it only takes a few months for the system to pay for itself. The software calculates the difference between the power of a fixed-speed drive and one equipped with a speed control system, and then multiplies the result by the current energy price.