The Energy Star Guide: How to Calculate Savings with Energy Star

The Energy Star Guide: How to Calculate Savings with Energy Star
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About the Rating System

The Energy Star initiative rates home appliances, computers and electronic goods, heating and cooling systems, lighting equipment and fans, and certain building products, based on the energy consumption of the specific product class. It measures and verifies the energy consumption of products meeting the energy efficiency requirements set forth in the product specifications, and issue visible labels to certified products, to help users differentiate products based on their power efficiency and purchase energy efficient products.

Energy Star ratings aim at reducing the inefficient use of energy, and thereby reduce emissions of greenhouse gasses and other pollutants. It also help people reduce their energy bills without sacrificing product performance, features, or comfort. It is guided by principles of the products generating significant energy savings, while still delivering the features and performance available in conventional counterparts, and allowing recovery of any additional purchase costs compared to a lesser energy-efficient conventional counterpart through utility bill savings within a reasonable period.

Savings Calculator

There are many device-specific calculators to compare and calculate the energy efficiency of different rated products and conventional non-rated devices. Use the link in the references section for a comprehensive list of Energy Star rated products and their energy consumption figures. Ascertain energy consumption figures for a conventional unrated product using a tong tester or through some other method. Effect a comparison to determine savings.

Also in the reference section, use the Energy Star savings calculator link for various devices including computers and computer monitors. These calculators allow users to:

  • calculate energy savings and determine amounts saved on utility bills.
  • predict product life-cycle energy and cost savings when replacing conventional non-rated products with rated products.
  • compare operating costs of various equipments.
  • calculate the payback on the additional investment to purchase a rated product.

Commercial users find the Summary Calculator, an add-on to the simple savings calculator useful. This calculator estimates the annual and lifetime energy, costs, and emissions savings resulting from the purchase of multiple products, when the user inputs the number of products for each product type.


An illustration of how the Energy Star simple calculator works to calculate savings follows:

  1. Multiply the units of energy consumed by the product per year with the cost of energy.
  2. Multiply the resultant figure with the estimated product life cycle. The product life cycle varies from appliance to appliance, with an average of ten years.
  3. Add the resultant figure to the appliance cost to get the gross holding cost of the device.

Repeat the calculation for unrated products.

The difference between the gross holding costs of the unrated product and the rated product is the lifetime savings. Divide this lifetime savings with the product life cycle to get annual savings. For instance, a conventional monitor consumes around 462 units of electricity, which costs about $48, whereas an LCD monitor consumes just 36 units of energy, costing just $4, a whopping savings of 426 units and $44 savings every year.

Making the home and office more energy efficient by using Energy Star rated products not only reduces high-energy bills, but also improves comfort and helps protect the environment. Such calculations are necessary in this age of increased concern for environment and over-exploitation of natural resources.


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