Metrics and Benchmarks for Energy Efficiency in Laboratories Page: 2 of 11
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Addendum ac, which will be incorporated into the 2007 version of the standard. To the extent
that other elements in the guidelines are not yet part of the standard, it is recommended that they
be followed when modeling laboratory buildings.
Table 1 Issues addressed by the Labs2l Modeling Guidelines
Guideline Area ASHRAE 90.1 sections addressed Intent and rationale for modification
I. Baseline HVAC 6.5.7.2 Fume Hoods Clarify that a baseline building must
system type and Baseline HVAC have either a VAV system OR energy
energy recovery Gyp. a si ioA System recovery, but not both. This provision
Type and Description applies to all laboratory air handling
Table G3.1.1A Baseline HVAC systems, not just systems serving
System Types fumehoods.
G3.1.2.10 Exhaust Air Energy
Recovery
II. Laboratory fan 6.5.3.1 Fan Power Limitation Increase the allowable fan power
power limitation G3.1.2.9 Fan Power limitations. While the standard provides
pressure credits for filtering systems,
heat recovery, etc., laboratory fan
systems typically exceed the fan
limitations even with these credits.
III. Modeling load Table G3.1 No.4 Schedules Ensure that reheat energy use due to
diversity and reheat internal equipment load variations is
energy impacts (new) G3.1.3.16 Supply-Air-to- properly modeled. Labs have large
Room Air Temperature Difference variations of internal equipment loads
from one space to the next - this has a
substantial impact on reheat energy use.
Basis for % reduction: There are two commonly used ways to express % reduction:
1. % reduction relative to total loads (including process loads)
2. % reduction relative to 'regulated loads' (excluding process loads)
Appendix G of the 2004 version specifies the first approach (i.e. based on total loads). Earlier
versions of LEED-NC (prior to 2.2) followed the second approach. This often created confusion
about what was included or excluded in the percentage calculation, and was especially
problematic in laboratory buildings. For example, fumehoods were sometimes included because
they are part of the HVAC system, and other times excluded because they were considered a
process load. Figure 1 compares different options for calculating % reduction for the Science and
Technology Facility at the National Renewable Energy Laboratory, which received a LEED-NC
Platinum rating. The difference between the options underscores the need to clearly define how it
is calculated and compared with other facilities [3].
While % reduction of total load is the primary metric that should be used, it is also useful to track
% reduction of regulated loads, since it provides a measure of the efficiency of features that
designers have significant control over. This is particularly true in laboratories, where process
loads can vary significantly across different projects and design estimates are often grossly
inaccurate.2
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Engineers, Rumsey; Mathew, Paul; Mathew, Paul; Greenberg, Steve; Sartor, Dale; Rumsey, Peter et al. Metrics and Benchmarks for Energy Efficiency in Laboratories, article, April 10, 2008; Berkeley, California. (https://digital.library.unt.edu/ark:/67531/metadc897577/m1/2/: accessed March 28, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.