DOE Profiles Commercial Building Stock

The U.S. Department of Energy (DOE) has begun releasing results from the 2012 Commercial Buildings Energy Consumption Survey (CBECS).

The CBECS is an estimated profile of the U.S. commercial building stock based on an interviewed sampling. Information includes number of buildings, floorspace, age, building type, region, energy consumption, end-use equipment and more.

DOE defines a commercial building as one in which at least half of the floorspace is used for a purpose that is not residential, industrial or agricultural. It therefore includes schools, hospitals, religious worship and other buildings.

Want to know how many healthcare buildings there are in the Midwest? Or the total floorspace of office buildings? Or adoption of occupancy sensors in buildings built before 1980? The CBECS has an estimate.

What does the 2012 CBECS have to teach us about the commercial building stock and adoption of lighting upgrades and controls?

Taking stock

In 2012, DOE estimates that there were:

• 5.6 million commercial buildings in operation
• 87 billion sq.ft. of commercial building floorspace

This is a 14% increase in the number of buildings and a 21% increase in floorspace over the 2003 CBECS. The number of office, warehouse, food service and public assembly buildings increased, while some markets, such as retail/malls and grocery/convenience stores, decreased.

With its large population, the South (Census region) had the largest population of commercial buildings and floorspace, followed by the Midwest and West regions. The smallest population of buildings, but also the largest, resided in the Northeast.

Looking at size:

• Nearly three out of four buildings were 10,000 sq.ft. or smaller
• About half were 5,000 sq.ft. or smaller
• The average size was 15,700 sq.ft. due to weighting effect of small number of very large buildings
• Largest buildings 2% of building population but about 35% of total floorspace

DOE found that newer buildings continued to trend larger, particularly healthcare, lodging, retail and religious worship buildings. Buildings built in the 2000s average 19,000 sq.ft., 17% larger than those built from 1960 to 1999 and 58% larger than those built before 1960. On average, the largest were in the education, healthcare and lodging markets. About half of commercial buildings built since 2000 are in the South.

Lodging buildings are the largest building type, while food service buildings are the smallest. Source: U.S. Department of Energy.

Looking at age:

• Median age for commercial buildings is 32 years
• About half of commercial buildings were built before 1980

Detailed energy consumption data for commercial buildings, the final phase of the data release, will be published by September.

Lighting and controls

The 2012 CBECS estimated adoption of various lighting sources:

• Standard fluorescent lamps illuminated 92% of all commercial floorspace
• Compact fluorescent lamps, 62%
• Incandescent, 44%
• Halogen, 32%
• HID, 27%
• LED, 25%

I believe the high incandescent and LED numbers are due to exit signs. When interpreting the results of a study like this, one must be careful about conclusions. We simply do not know how the interviewer and respond interpreted each question.

And lighting controls:

• Occupancy sensors controlled lighting in 41% of all commercial floorspace
• Time-based scheduling controls, 35%
• Multilevel and dimmable lighting, 17%
• Daylight harvesting, 7%

Automatic lighting controls have significantly gained in popularity in commercial buildings. Flexible lighting, once reserved for spaces such as conference rooms, has become more popular, driven by energy management and visual needs. Multilevel and dimming control is most popular in retail (35% of floorspace), in-patient healthcare (35%), lodging (24%), office (17%) and education (16%). These lamps are controlled by line- or low-voltage dimmers. Daylight harvesting, while still controlling a small percentage of floorspace, nonetheless is demonstrating remarkable growth in terms of floorspace.

While extensive in terms of floorspace, however, these strategies are prevalent in a relatively smaller percentage of buildings. For example, while daylight harvesting is deployed in an estimated 7 percent of floorspace, it is installed in only 2 percent of buildings. Multilevel and dimmable lighting, 6 percent. Occupancy sensors and time-based scheduling, 15 percent and 17 percent, respectively. This indicates there is still significant room for growth in adoption of automatic lighting controls in existing buildings.

Lighting upgrade potential

The greatest potential for lighting and control upgrades is buildings with older lighting systems, overlighted spaces, long operating hours and high energy rates. Buildings built before 1980, for example, would be a good place to start looking for opportunity. In 2012, this market represented an estimated 2.8 million buildings comprising 38.6 billion sq.ft. About half of all buildings and 44% of all floorspace.

The 2012 CBECS estimates:

• Lighting upgrades have been performed in 25% of these buildings
• Lighting upgrades have been performed in 40% of this floor space
• Lighting upgrades have *not* been completed in nearly 2.1 million buildings, or 75% of buildings built before 1980
• Lighting upgrades have *not* been completed in 23.1 billion sq.ft., or 60% of floorspace built before 1980

This suggests that despite big gains over two decades, the lighting upgrade market is still far from realized.

Got a question?

There’s plenty more in the 2012 CBECS that can be used for business planning oriented around the existing buildings market. The lighting data alone can be parsed by building size, age, type, region and so on, providing rich insights. It’s important to note, however, that the results are estimates based on a sample population. It’s important to view the results with an educated eye. It’s also important to remember that how some data appears depends on how the question was interpreted by both DOE and the respondent.

Click here to check out the 2012 CBECS, available free in a series of tables.