Key Energy Efficiency Standards Every Design Engineer Must Know
Energy efficiency is a focus for most power system designs, and engineers should need no encouragement to strive for ever-better efficiency. To support more responsible and efficient power usage, international regulations exist to certify products based on efficiency, as well as voluntary labelling schemes that encourage energy-efficient products.
Three of the most important initiatives that relate to energy efficiency are:
- The ErP Directive – a European Union (EU) eco-design directive for energy-related products
- Energy Star – a US-based program that identifies and labels energy-efficient products
- 80 Plus – a certification program for measuring the efficiency of power supplies in computers and servers
This article introduces each initiative and explains what you, as a design engineer, need to know.
The Standards
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In the 1990s, most power supplies used linear conversion techniques, and efficiency could be as low as 50 per cent. This meant that phone chargers, TVs, and other devices drew significant power when left plugged in, which could account for up to 30 per cent of electricity usage in the home.
Something had to be done to increase efficiency. One of the major contributors to the dramatic reduction in wasted power over the last few decades has been the emergence of international standards for energy efficiency. This shift is still taking place, with many OEMs now more aware of the need for power efficiency.
ErP Directive
The Energy-related Products Directive (ErP) was introduced in 2009 to replace the existing Eco-Design Directive (EuP). It aims to motivate manufacturers and importers to make their products more energy and resource-efficient[1] by reducing energy consumption across the entire supply chain and throughout the full product lifecycle.
ErP covers consumer products such as dishwashers, air conditioners, and boilers. These products can only be sold in the EU if they comply with the ErP directive and consume energy and resources below the defined limits.
When a product has demonstrated its compliance, typically through documented results of suitable tests, it can be labelled with a ‘CE mark’, which allows it to be sold in the EU. The UK has an equivalent scheme, the UK Conformity Assessed (UKCA) marking.
Energy Star
Energy Star is the US government-backed symbol for energy efficiency. It is administered by the US Environmental Protection Agency (EPA), in partnership with thousands of private companies and other organisations. Since its launch in 1992, Energy Star has become hugely successful, in part driven by tax rebates encouraging consumers to buy compliant products. It has helped save more than $500 billion in energy costs and prevent 4 billion metric tons of greenhouse gas emissions.
Energy Star is a voluntary labelling program. The EPA is responsible for setting the energy efficiency specifications, and products that comply can display the Energy Star logo. Consumers and business customers can look for the Energy Star logo to help them choose efficient products.
The program is wide-ranging. It includes energy-saving programs for new and existing homes, industrial plants, and commercial buildings. It also includes white goods such as washing machines and tumble dryers, refrigerators and cookers, and products for heating, air conditioning, and water heating.
80 Plus
The 80 Plus rating system was launched in 2004. It shows the efficiency achieved by a power supply unit (PSU) in converting AC main power to the DC power required by a computer. While not compulsory, 80 Plus is recognised by Energy Star and the EU for being substantially more efficient than standard computer PSUs.
The objective of 80 Plus was to make PSUs deliver high efficiency over a larger proportion of their load curve. In particular, data centres often operate with redundant systems and current sharing, which means their PSUs are operating at relatively low loads most of the time. Therefore, the maximum efficiency point for 80 Plus was centred on 50 per cent capacity.
As the name suggests, the 80 Plus specification requires power supplies in computers and servers to achieve 80 per cent or better energy efficiency at 0 %, 25 %, 50 %, and 100 % of the rated load. The highest level, 80 Plus Ruby, was introduced in 2025 and specifies an efficiency of at least 90 %.
Figure 1 shows the different efficiencies required for each of the 80 Plus levels. This information is for a 230 V internal PSU; similar information is available for 115 V PSUs.
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SEE OVERVIEWFigure 1: 80 PLUS Certification ratings for a 230 V internal PSU (Source https://www.clearesult.com/80plus/program-details) Over the years, these programs have motivated companies to shift to more energy-efficient designs and prioritise efficiency in their work. For example, Energy Star encouraged washing machines in the US to switch from using permanent split capacitor motors, which are about 60 % efficient, to permanent magnet brushless DC (BLDC) motors, which are about 80 % efficient[2]. These newer motors also enable variable-speed operation, which saves a significant amount of power in applications such as HVAC fans. BLDC motors require inverters to drive them, which creates challenges for design engineers who must work with semiconductors and power system design in unfamiliar ways. This places the onus on semiconductor vendors and their partners to step in and provide assistance. Many manufacturers want to be able to sell the same product in different countries, without an expensive redesign. This means that it often makes sense to design a power supply, or an entire product, that meets the strictest international regulations applicable to any of the target markets. Of course, energy efficiency is a major benefit to customers, irrespective of whether legislation exists to enforce it. By complying with regulations in one country, manufacturers can achieve a competitive advantage in other markets due to better power efficiency. Beyond the three standards examined in this article, there are multiple other similar standards and industry initiatives. In some cases, these are focused within particular industries or sectors, setting the requirements for a specific niche, such as the Green Grid for data centres[3], while others have been more wide-ranging in their scope. For design engineers, this means being aware of the relevant energy efficiency initiatives, standards, and regulations that may affect them, which will likely include those from multiple countries. This can be complex, but semiconductor vendors provide extensive documentation and support to help engineers using their devices. Working with the right vendors and an expert partner, such as Avnet Silica, ensures that design engineers can create efficient and reliable power systems and products that comply with all necessary standards.
80 PLUS Certification
230V EU Internal Non-Redundant
230V Internal Redundant
% of Rated Load
10%
20%
50%
100%
5%
10%
20%
50%
100%
80 PLUS
-
82%
85% PFC ≥ 0.90
82%
-
-
-
-
-
80 PLUS Bronze
-
85%
88% PFC ≥ 0.90
85%
-
-
81%
85% PFC ≥ 0.90
81%
80 PLUS Silver
-
87%
90% PFC ≥ 0.90
87%
-
-
85%
89% PFC ≥ 0.90
85%
80 PLUS Gold
-
90%
92% PFC ≥ 0.90
89%
-
-
88%
92% PFC ≥ 0.90
88%
80 PLUS Platinum
-
92%
94% PFC ≥ 0.95
90%
-
-
90%
94% PFC ≥ 0.95
91%
80 PLUS Titanium
90%
94% PFC ≥ 0.90
96%
91%
-
90%
94% PFC ≥ 0.95
96%
91%
80 PLUS Ruby
-
-
-
-
90% PFC ≥ 0.90
91% PFC ≥ 0.90
95% PFC ≥ 0.96
96.5% PFC ≥ 0.96
92% PFC ≥ 0.96
The Impact on Design Engineers
References
Other safety and regulatory articles
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