ASHRAE Journal - January 2014 - 28

TECHNICAL FEATURE
Metrics and Measurements
BY STEVEN BAUMGARTNER, P.E., MEMBER ASHRAE
Traditionally, measures of energy efficiency are
designed to compare usable energy outputs such as
electricity, heat, etc., to units of fuel consumed. The
current prevailing energy metric for buildings, energy
use intensity (EUI), is fundamentally not a measure of
energy efficiency; as the name suggests, EUI reflects
annual energy consumed on a square-foot basis, never
accounting for the ratio of any outputs to inputs.
Instead, EUI has always been intended as a metric
to compare a building to itself over time. Energy Star
comes closer in its efforts to approximate building
efficiency by normalizing EUI by occupant density,
schedules, and computer count, but the resulting metric,
a 1 to 100 score, still reflects intensity of energy use,
and cannot be used interchangeably with efficiency.
New benchmarking laws-including New York's Local
Law 84 (LL84) and similar legislation forthcoming in
Washington, Boston, and Chicago-have given way to
new databases of publicly available building energy
data. In these, we have already seen a huge range of
EUI for commercial buildings. In an effort to understand
these large ranges, some analysts in the New
York region have been developing additional normalizers
based on physical and behavioral characteristics
for building energy intensity. Normalizing for glazing
ratio, orientation, and floor depth can help when considering
physical planning. On the behavioral side,
tenancy is a key factor-particularly in determining
the energy intensity described in LL84 EUI and Energy
Star data-but currently there are no methods for connecting
commercial tenant types and their economic
three to five years. Start today. That being in place and
a realistic idea of plug loads allow engineers to design
electrical and HVAC systems to meet this load.
Next, attack the lighting loads. On a national aver-
age, 80% of the area of commercial buildings is within
15 ft (4.6 m) of an exterior surface, which means a
huge potential for daylighting.3 Lighting a building
should be primarily from daylighting augmented
with electrical lighting. This will lead to proper sizing
of glass: first for daylighting and then providing an
appropriate amount and type of glass for views. All of
this results in a substantial reduction in cooling loads
and sometimes can help the heating loads.
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contributions to the energy use of the buildings those
tenants occupy.
In developing a measure for building efficiency, the
inputs-electricity and other energy consumed-are
fairly clear once utility data is in hand; the challenge is
establishing the best outputs against which to measure.
A recent study completed by Buro Happold has defined
a commercial building's output as the combined economic
contributions of a building's tenants. The resulting
metric is intended to represent a new definition of
commercial building efficiency: the relative economic
contribution of a building's tenants per unit of energy
consumed. This novel metric, called the Building
Economic Energy Coefficient (or BEEC) has been
presented at Greenbuild and will be presented at the
2014 ASHRAE Winter Conference and other national
conferences, initiating discussions about building
performance metrics and opportunities to link energy
benchmarking data to other economic and even social
datasets to more fully understand the role of buildings
in our communities.
A white paper on this topic analyzes nearly 1,000
buildings in Manhattan by building height, year built,
and LEED ratings (if applicable) to begin to reveal
trends in commercial building's energy use and their
tenant's economic contribution. As several conclusions
were highlighted from the data, this paper (www.
tinyurl.com/khntvgc) discusses the broader implications
of these metrics and that future studies have the
potential to inform infrastructure, policy and market
trends in New York and cities throughout the world.
Steven Baumgartner, P.E., is an associate at Buro Happold, New York. He is an ASHRAE certified HighPerformance
Building Design Professional. His Twitter handle is @SBaumgartnerNY (#BEEC).
Finally, design the HVAC system to match these
loads. I have seen reductions in HVAC systems of
more than 75% when integrated design concepts are
used. Moreover, it leads to innovative systems that
further increase efficiency. One final note, keep the
complexity down. Otherwise the setup and O&M
practices become a dominant factor in operational
success.
Take it on as a personal goal to design buildings to the
50% savings benchmark. Anyone who makes a decision
related to buildings plays a part, and together we can
all make a difference on "what is next" for the performance
of the built environment.

ASHRAE Journal - January 2014

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