The green movement is growing, as the government and industry alike are promoting energy efficiency as a way to fight global warming. Researchers believe that using more efficient products will reduce the need to generate more electricity. In turn, this will reduce the emissions produced by this generation that cause climate change.
Design engineers, however, have confronted energy efficiency issues starting with the vacuum tube era and moving on to transistors and microprocessors. Also, energy efficiency has always been a consideration because it impacts virtually every aspect of system design. Now, it is being emphasized because greenhouse gas emissions affect the entire planet.
From an electronic design standpoint, boosting energy efficiency involves establishing maximum power consumption requirements for electronic systems, effective power management for microprocessor-based systems, and minimizing standby power. Fortunately, the side effects of improved energy efficiency offer their own benefits too.
ENERGY MANAGEMENT
The Energy Efficient Digital Networks (EEDN) group at the Lawrence Berkeley National Laboratory has been reviewing distinct consumer electronic products that facilitate audio and/or video content in U.S. households. Their numbers are increasing, and current controls and interfaces focus on function without energy as a consideration.
EEDN suggests amending existing electronic industry standards to allow better power control in consumer electronic devices. Doing this will require background research to fully document the standards and other factors that affect how power control operates, as well as to design a simple and coherent system to organize amendments and future standards.
Also, EEDN is looking at products whose principal function is to provide network connectivity while using an increasing amount of energy. These include switches, routers, firewalls, modems, hubs, wireless access points, and Voice over Internet Protocol (VOIP) phones.
As the number of networked IT products increases and Power over Ethernet (PoE) and related technologies expand, the amount of power flowing into network products—as well as the savings from more efficient power conversion and control—will only increase.
EEDN says there should be energy efficiency specifications for network equipment to help manufacturers and consumers move the market to products that use less energy. The U.S. Environmental Protection Agency (EPA) Energy Star program could adopt these specifications to ensure global reach. With the wide range of network products sold today, these first specifications will only cover a few of the most energy-consuming categories.
The EPA established the Energy Star program in 1992 for energy-efficient computers. It identifies efficient products that will reliably deliver energy savings and environmental benefits. The EPA and the U.S. Department of Energy (DOE) work closely with more than 1000 manufacturers to determine the energy performance levels that must be met for a product to earn the Energy Star. Companies awarded the Energy Star emblem often use it is a marketing tool. We can expect a reduction in emissions (Fig. 1) from 2003 to 2012 because of the Energy Star program and the resultant improvements in energy management.
Many Energy Star requirements include both electronic and non-electronic products. For example, Energy Star 5.0 covers the requirements for computers, which became effective July 1, 2009. Version 5.0 also covers desktop computers, notebook computers, and workstations. It doesn’t cover computer servers, handheld devices, PDAs, or smart phones.
Power-supply efficiency requirements are applicable to all product categories covered by the Energy Star Computer Specification. Computers using an internal power supply must have 85% minimum efficiency at 50% of rated output, 82% minimum efficiency at 20% and 100% of rated output, and a power factor greater than or equal to 0.9 at 100% of rated output.
Power supplies sold with Energy Star computers must be Energy Star qualified or meet the no-load and active mode efficiency levels provided in version 2.0 of the Energy Star program requirements for single-voltage external ac-ac and ac-dc power supplies. This performance requirement also applies to multiple-voltage output external power supplies as tested in accordance with the internal power-supply test method.