Technology Corridor

How effective are federal energy efficiency regulations?

 

New buildings must meet federal energy efficiency guidelines, which have historically used site-energy measurements as the metric for building energy consumption. Using site-energy measurements, though, ends up favoring the use of electricity from the grid, rather than using electricity produced on site.

This issue is significant because Congress, in the pending energy bill, is considering a provision that would give incentives to builders and developers based on reductions in the site-energy consumption of their buildings. These incentives-unless limited specifically to reductions resulting from improvements in the building envelope, such as construction materials, insulation, glazing, and shading-would be nothing less than federally funded disincentives to on-site generation. And they would come at a time when the federal government is ostensibly promoting combined heat and power and district energy systems because of their high total energy efficiency and potential to reduce environmental emissions.

The site-energy measurement metric creates a bias toward using electricity from the grid because most losses from producing and delivering electricity placed on the grid occur upstream of the building meter, and therefore do not show up in the site-energy measurement efficiency calculation. In essence, all the inefficiencies of producing electricity happen off-camera. When electricity is produced and delivered on site, the site-energy "camera" captures losses inherent in making electricity, and so in comparison to electricity from the grid, appears inefficient. But a look at all the numbers, not just the ones on site, tell a different story.

Energy process inefficiencies experienced upstream of the customer's meter total approximately 73 percent for grid electricity, but only 10 percent or less for natural gas, propane, and fuel oil. By focusing solely on site-energy measurement, the legislation being considered would encourage building design approaches that result both in higher total energy consumption and in the emission of greater quantities of pollutants associated with building energy consumption. While site-energy measurement may be simple and straightforward, it violates Einstein's recommendation that "solutions to problems should be as simple as possible, but no simpler." In this case, the pursuit of excessive simplicity results in significant error.

How the Numbers Work

The site-energy measurement metric divides the sum of the various forms of energy consumed in the building (in Btus) by the gross floor area of the building (in square feet) to represent the average energy efficiency of the building.

The argument often used to justify the site-energy measurement approach is that it is simple and straightforward. True, it is simple to read the energy utility meters or energy supplier invoices and convert the measured energy consumption into common units. True, it is straightforward to merely sum all of the energy inputs and divide by the gross floor area of the building to obtain the site-energy metric. Although simple and straightforward, this method is wrong as an energy consumption metric. It ignores all of the losses that occur in the production, processing, conversion, transportation, and distribution of the energy to the building site, and the significant differences in the magnitude of these losses among various energy sources.