What’s the big deal about energy efficient computers?

In the United States, computers use over $2 billion in energy costs and create greenhouse gas emissions equivalent to emissions created by nearly 3 million vehicles.  The average computer is on for more hours today than in previous years, which makes energy efficiency more important than ever.

Computer manufacturers have made huge strides in creating energy efficient units in recent years.  Still, for many buyers it’s challenging to find the most efficient models available.  To help you make the best choice for your family and the earth, TopTen took an in-depth look at the market for computers.  The most relevant information is located here, including our criteria for selecting the ten most efficient products.

Where do we get our info?

Energy Star, the Efficient Products website, and various professional reports provided valuable information about the computers listed at TopTen.  For a complete bibliography, read How We Evaluate.  Resources are listed at the end of that page.

How do we decide which computer monitors to include?

The ENERGY STAR database lists more than 3,000 desktop, laptop and integrated computers.  We separated these into three lists:

  • Expandable desktop computers
  • Non-expandable desktop computers
  • Laptops

To date, we have published rankings for non-expandable desktops and for laptops.

TopTen’s database includes information about computers with the highest energy efficiency in each category based on typical electricity consumed annually while in normal operation.

How do we calculate cost savings? 

A computer’s Total Energy Consumption (TEC) is measured in kilowatt hours per year (kWh/yr).

We compare the TopTen product’s TEC to the average TEC of all ENERGY STAR products in the same performance category.  To calculate energy savings, we subtract the TEC of the TopTen computer from the TEC of the group’s average computer.

Do I have to go to a specialty store to find computer monitors listed on TopTen?

Many TopTen computers are available at national chain stores such as Sears and Best Buy, along with local and regional independent stores.  They are all available online.

What makes a computer energy efficient?

Factors contributing to a computer’s energy efficiency include the power supply, the layout of the motherboard, the design of the hard drive, and the CPU.

  • A computer’s power supply converts the high voltage AC input from your electrical outlet to a lower DC voltage for use by the internal electronic circuits.  The quality of the power supply makes a huge impact on the computer’s energy efficiency.  Many power supplies waste 60%-80% of the energy that passes through them.  Whether external or internal, the best power supplies efficiently use 90% of the energy that passes through them.
  • Manufacturers have found that mounting components of the motherboard as close together as possible reduces energy consumption.
  • Old school hard drives operated with magnets and moving parts.  Today, some hard drives have no moving parts at all.  The most energy efficient hard drives use 5-6 watts less power than standard hard drives.