Metrics and Benchmarks for Energy Efficiency in Laboratories Page: 2 of 11
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2
2 Whole-Building Metrics
2.1 Metrics based on ASHRAE 90.1
ASHRAE Standard 90.1 is increasingly being used to
assess the energy efficiency of laboratories during the
design phase-especially those projects seeking a LEED
rating. Typically, this involves setting goals relative to the
performance of a baseline building, as defined in the stan-
dard. In practice, however, simply specifying a goal of
"x% better than ASHRAE 90.1" is inadequate because it
leaves several key factors open to interpretation, which in
turn will affect the meaning of the percentage reduction
goals. Therefore, it is recommended that owners and
designers further qualify this metric by specifically
addressing and clarifying the following factors:
Appendix G vs. Section 11: An important consider-
ation with regard to the use of ASHRAE 90.1-2004 is
whether to use Appendix G rather than Section 11 for cal-
culating savings. While both are performance-based, there
are some variations in how the baseline performance is
determined. The advantages to using Appendix G include:
" It is specifically designed for quantifying improve-
ments beyond the standard. (In contrast, Section 11
is designed for checking minimum compliance.)
" The baseline does not change with different pro-
posed system selections.
" It is required by LEED-NC 2.2 for any project seek-
ing to achieve energy-efficiency credits.On the other hand, some of the disadvantages are
that:
" At the time of this writing, it is not officially a part
of the ASHRAE standard-it is an informative
appendix. As a result, meeting the requirements of
appendix G does not equate to compliance with the
standard. However, it is anticipated that it will be
approved as a normative appendix shortly.
" It requires more modeling work than Section 11.
On balance, it is recommended that Appendix G be
used as the basis for performance evaluation goal setting.
Labs21 Modeling Guidelines: These guidelines 3 were
developed to clarify or modify selected sections of the
ASHRAE 90.1 standard in order to make them more
applicable to systems serving laboratory spaces. Table 1
summarizes the modifications in the Labs21 guidelines.
While the Labs21 guidelines are designed to be used
in conjunction with Appendix G of the standard, they
were developed by Labs21 and are not officially a part of
the standard. However, it is anticipated that most of the
key provisions will be incorporated into the standard
through "continuous maintenance" proposals. As of this
writing, the fan power limitation has been addressed
through 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 Labs21 Modeling Guidelines
Guideline Area ASHRAE 90.1 sections being modified Intent and rationale for modification
I. Baseline HVAC 6.5.7.2 Fume Hoods Clarify that a baseline building must have either
system type and a VAV system OR energy recovery, but not
energy recovery G3.1.1 Baseline HVAC System Type and both. This provision applies to all laboratory air
Description handling systems, not just systems serving fume
Table G3.1.1A Baseline HVAC System Types hoods.
G3.1.2.10 Exhaust Air Energy Recovery
II. Laboratory fan power 6.5.3.1 Fan Power Limitation Increase the allowable fan power limitations.
limitation While the standard provides pressure credits for
G3.1.2.9 Fan Power 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 internal
diversity and reheat equipment load variations is properly modeled.
energy impacts (new) G3.1.3.16 Supply-Air-to-Room Air Labs have large variations of internal equipment
Temperature Difference loads from one space to the next-this has a
substantial impact on reheat energy use.
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Mathew, Paul. Metrics and Benchmarks for Energy Efficiency in Laboratories, report, October 26, 2007; Berkeley, California. (https://digital.library.unt.edu/ark:/67531/metadc884237/m1/2/: accessed March 29, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.