Green Building and LEED Core Concepts Guide First Edition

The study concluded that the federal
government's green buildings outperform
national averages inall measured
performance areas-energy,
operating costs, water use, occupant
satisfaction, and carbon emissionsand
that buildings achieving LEED
Gold certification achieve the best
overall performance. The agency attributed
this performance to a fully
integrated approach to sustainable
design that addressed environmental,
financial, and occupant satisfaction
issues.
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ENERGY USE INTENSITY
(kBlu/sf/yrl
Figure 3. Energy Use IntenSlt>es for Sustain abl y DeSIgned U.S. Government Buildmgs
(Soulce: GSA 2008)
The led b ~ r In dIcates the national a'ffllage energy use Inlenslty.
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Making buildings more comfortable and productive for
their occupants has special significance in light of studies
conducted by the U.S. Environmental Protection Agency
(EPA), which fou nd that people in the United States spend,
on average, 90% of their time indoors, where they may be
exposed to pollutant concentrations two to 100 times higher
than outdoor levels. Occupants of green buildings typically
have significantly greater satisfaction with air quality and
lighting than occupants of conventional buildings. Case
studies show that these benefits can translate into a 2% to
16% increase in workers' and students' productivity. And
even small increases in productivity dramatically Increase
the value of the building.
What is the cost of these benefits lfwe view sustainability as an added feature of a building, we
would consider efforts to reduce energy costs or improve indoor environmental quality comparable
to specifying a better grade of countertop or a more impressive front door: any improvement beyond
a minimally code-compliant baseline is an added cost. This perspective often leads to conclusions
that green buildings cost slightly more than conventional buildings, with estimates ranging
from 2.% to marc than 5%. If, however, we consider energy improvements as pall of an integrative
design, the added costs are often balanced by new savings. Forinsrance, specification of more costly,
high-performance windows may allow for the use of a smaller, lower-cost heating, ventilation, and
air-conditioning (HVAC) system. More fundamentally, if we view sustainable design as part of the
Green Bui ld ing 11