Why You Can't Just Google "Average Energy Use"
GOOGLE...It's everyone's go-to for finding answers to any questions we may ponder. And I admit, I'm guilty of relying on Google as the ultimate authority. This reliance has even impacted our memories to the extent that psychologists have coined it the Google Effect. But as a building energy enthusiast, how many times have you searched for a simple "average energy use" number only to find outdated case studies or appliance-specific averages? In a world where we expect simple and immediate answers, why is it so difficult to Google the "average energy use" for a building? Today we help answer what Google can't.
Different Energy Sources
The most obvious difference here is between buildings that are heated with electricity versus gas or oil. Although electrically fueled baseboards and heat pumps both operate with at least 100% efficiency (heat pumps average 250% efficiency due to their utilization of the refrigeration cycle), the energy lost in the electricity production process is still significant. Inefficiencies in the generation and transmission process mean that only around 35% of the energy that goes into a power plant makes it to the end user, and almost two-thirds is lost when we generate electricity.
Alternatively, directly consuming gas as a heat source is between 60% and 98% efficient. Even at the lowest levels, gas is much more efficient than electric baseboard heat. Therefore, if you look at the source energy, it’s often more energy-intensive to heat a space with electricity instead of gas. Because building owners often don't have a choice as to what type of fuel they can use, it's important to recognize "average energy use" fuel type variances during benchmarking.
Different Climate Zones
If you're trying to benchmark average energy use for a building in Maine, it doesn't make sense to think about how buildings in Southern California are performing. Because location has a significant influence on variances in annual temperatures, humidity, and overall weather patterns, you need to incorporate climate zone into your energy benchmarking. For example, to produce median energy use numbers for our clients, our methodology incorporates eight possible climate zones when defining a "similar building":
Figure 1. WegoWise Climate Zones
Different Building Types
With so many different building types trying to measure energy use, we must recognize that there isn't a set usage based solely on square footage. For example, WegoWise has two different platforms to split up the differences between multifamily residential buildings and commercial or industrial buildings. And even within the commercial grouping, an office space is going to use energy in completely different ways than a restaurant, for example.
Another important factor in comparing average energy use is building construction type. The specific heat capacity of brick is much higher than lighter materials like wood, so although its construction cost is higher, brick is generally much more energy-efficient over time. Additionally, some buildings in the eastern half of the U.S. were built over a century ago. Building age can greatly affect average energy use, and should thus be taken into account when looking at average benchmarks. Finally, databases like WegoWise also include options to compare your building to the top performers in your peer group, such as LEED-certified ones.
Figure 2. WegoWise LEED-certified Electric Use (kWh per square foot)
So the next time you resort to googling "average energy use" figures, consider looking into a database with more specific benchmarks. Not only will you be accessing more accurate data, but you might also be surprised to find out where you can save the most with retrofits or other energy efficiency efforts. For more information, check out our utility benchmarking FAQs (and how we answer them).