In many industries, energy use in manufacturing processes far outweighs its use in powering offices and factory buildings. In others, real estate is a major portion of the energy use total. In still other industries, the separation between “process” and “building” energy may be artificial if interior conditions are critical to production. Regardless, in my experience, the efficiency opportunity presented by buildings in North America is vastly underestimated and the effort to capture the opportunity grossly overestimated.
As in all energy productivity opportunities, the place to start is with some simple benchmarking. For any given type of building, there is at least a 2-to-1 energy intensity difference between the U.S. average and the systematic global best practice, once variables around climate and regional practices are accounted for. When we benchmark commercial and industrial buildings, a 3:1 ratio is not uncommon.
In contrast, the spread of energy intensity of manufacturing processes is much tighter around the world – often within plus or minus 20% per unit of production. With this in mind, on a proportional basis, the energy use in a company’s buildings has roughly twice the impact of that of manufacturing. Depending on location, they may also attract higher energy tariffs.
Where buildings are individually metered, the next obvious step is to get a simple index of energy use per square foot per hour of full operation. When metering isn’t available, as is often the case in complex industrial or commercial sites, simple energy demand modeling will give a reasonably good estimate of energy use.
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The energy intensity can be compared with data for comparable buildings, available from the growing number of databases from government and industry sources. Consider benchmarking against data for recognized global leaders such as Germany, too.
As an example, in a recent college project I was involved in, the campus energy-use average placed the school in the poorest-performing quartile of comparable institutions in the state. Energy use was nearly 50% higher than the levels specified by the region’s new construction code and 100% higher than a fully compliant LEED Gold level facility. The game-changer for the owner was the realization that it was three times the level of German A-rated buildings.
This local and global benchmarking set the stage for this organization to establish performance goals for both renovation and any new construction. In this case, the school decided on renovation targets of 50% from today’s level and new construction targets of at least 50% better than local code, along with clear minimum investment return targets.
With targets established, the next step is to assess the combination of measures that will create the most cost-effective way to get there. The easiest way is to make detailed energy models of at least the major buildings. This costs a small amount up front but provides the simulation object to try out efficiency measures in terms of investment, operating cost, efficiency. and emissions impacts.
Every building is different, but some common themes emerge. Efficiency gained from metering, control, and activity management more than rewards often-modest upgrades in control systems and changes in management practices.
Investing in the envelope with insulation, windows, weather-stripping, and closure management yields high returns in terms of economy and comfort. The impact of these measures is frequently underestimated because of initial disturbances and upfront costs. But they open a pathway to using less energy-intensive lighting.
Buildings with efficient envelopes and flexible controls require smaller, simpler mechanical systems to manage temperature and air quality. They also are prepared to make better use of local clean or renewable supply, including solar PV, solar thermal, or on-site combined heat and power.
Taking this holistic view of building efficiency built on data, models and benchmarks put a 50% to 60% primary energy reduction with high internal rates of return well within reach. In most cases, the risk of disturbing manufacturing is low and can be fairly easily managed. New construction can be specified to even higher levels of efficiency with attractive economics.
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