How Bright Is The Energy Star? Part 1

Some problems with calculating energy efficiency benefits: Part 1

You’ve certainly seen the Energy Star logo before – white on sky blue, with “energy” in an electricity-evoking script and the outline of a five-pointed star under a protective parabola, that is affixed to everything from computers to refrigerators to fluorescent lighting to air conditioners. Energy Star describes the logo as “the government-backed symbol for energy efficiency”^[i] (the Environmental Protection Agency established Energy Star in 1992 under the Clean Air Act, and continues to administer the program, with help from the Department of Energy), and it is keen for you to know that it is not a simple marketing ploy. The “ENERGY STAR Impacts” page of its website includes the following.^[ii]

Savings since 1992:

• Electricity: 5 trillion kWh
• Energy Costs: >$500 billion
• Emissions: 4 billion metric tons

2020 savings:

• Electricity: 520 billion kWh
• Energy Costs: $42 billion
• Emissions: 400 million metric tons

These are impressive numbers to be sure, but can we be sure the numbers are this impressive? There are reasons to think we can’t. At least, not entirely.

The position of assuming

First, consider that Energy Star provides certification standards for over 75 product categories and for new homes, and also provides guidance or management assistance for commercial buildings, industrial plants, and improvements to existing homes. That is all to the good, but it does mean that producing numbers like those above involves wrangling massive amounts of data, far too much to proceed at the level of direct measurement. So, it is unsurprising that Energy Star’s overview of its benefits methodology^[iii] includes a number of estimations and assumptions. 

In some cases, these assumptions are conservative, but in some cases not. For instance, the methodology only assumes that Energy Star products meet its minimum standards for energy savings. However, it also assumes that non-Energy Star products only meet minimum federal efficiency standards when present, and in their absence assumes the average energy use of products in the relevant category. It avoids double-counting by subtracting savings from Energy Star products used in Energy Star homes, but it also addresses interactive effects by assuming consumers start with the most cost-effective measure. (This last being questionable given that the most cost-effective measure often carries the highest initial cost – a family may well be ready to invest in new windows before being ready to invest in a new HVAC system.)

To be sure, there is nothing wrong with employing such assumptions. They are, as noted, unavoidable, and it seems clear that Energy Star has not set out to simply stack the deck in its favor.  Nevertheless, each assumption, estimate, or indirect measure introduces some degree of uncertainty into the calculations. Of course, that uncertainty means that it is possible Energy Star is undercounting, rather than inflating its benefits.

Possible, but, for at least a couple of additional reasons, unlikely.

Part II publishing next week.

^[i] About ENERGY STAR.

^[ii] ENERGY STAR Impacts.

^[iii] Technical Notes: EPA ENERGY STAR Benefits Methodology.