B1: Building Site Energy Use Intensity

Description:

This metric is the sum of the total site energy use per unit of gross building area. This metric is one of the most commonly used whole-building performance metrics, because the data required are usually easy to obtain from utility bills. However, it can be misleading because it does not account for the source energy for each energy stream.

Units: kBTU/ft2 [kWh/m2, MJ/m2]

B1 = ((dE1*3.412 + (dE2 + dE3 + dE4 + dE5 + dE6 + dE7)*1000) dB1
where:
dE1: Annual electrical energy use (kWh)
dE2: Annual natural gas energy use (Million BTU)
dE3: Annual fuel oil energy use (Million BTU)
dE4: Annual other fuel energy use (Million BTU)
dE5: Annual district steam energy use (Million BTU)
dE6: Annual district hot water energy use (Million BTU)
dE7: Annual district chilled water energy use (Million BTU)
dB1: Building gross area (ft2)

See Required Data for more information on the data items.

Benchmarks:

This metric can be benchmarked relative to peer buildings in the Labs21 database. The peer group should be a sub set of buildings in the Labs21 database that have similar characteristics in terms of climate zone, lab type, lab area ratio and occupancy hours. The Labs21 tool provides guidance on selecting a peer group.

Combination bar and line chart illustrating site energy intensity for a subset of buildings in the Labs21 database; X axis: Facilities, Left Y axis: kBTU/gsf-yr, 0-1000, Right Y axis: Lab Area Ratio, 0-100. Bar chart represents kBTU/gsf-yr (site), Line chart represents Lab Area %, the red marker on top of the bar indicates Estimated Values.

Figure. Site energy intensity for a subset of buildings in the Labs21 database, with the following filters applied: located in climate zone 5A (cool humid); lab type: biological, chemical, chemical/biological.

Actions Inferred:

This metric provides a measure of overall efficiency potential, i.e., higher values relative to the peer group suggest higher efficiency potential and vice versa.

Special Considerations:

This metric is not effective for comparing sites with co-generation, because it does not account for source energy of electricity. Therefore this metric should be complemented with source energy use intensity (B2).

The ability of this metric to identify efficiency potential is limited by the degree to which the peer group of buildings has similar characteristics. While the Labs21 benchmarking tool allows for simple data filtering of key characteristics (climate zone, lab area ratio, lab type, occupancy hours), there may be other characteristics (e.g., process loads) that cause energy use to be higher or lower independent of efficiency. Therefore, this metric is only a coarse screen for overall efficiency potential.