Page 50 - Green Building Through Integrated Design

THE LEED RATING SYSTEMS 27

water use, waste generation, etc.) and its basic ingredients (materials and systems).
Owners of commercial and institutional buildings have far less knowledge of what is
in the building they just built or bought than you might think, because the construction
process is pretty messy; there are usually thousands of design decisions made, along
with many product and materials substitutions and changes during construction, and
there is seldom money left over to document what really went into the building, so the
construction documents often give an incomplete or even inaccurate picture of what’s
actually there and how all of the building systems are supposed to work together.
To understand a building’s ingredients and its expected performance (including
operating costs for energy and water), an “eco-label” such as the LEED rating is
especially valuable both to building owners and to occupants who may naturally be
more concerned about how healthy the building is, rather than how much water it saves.
Complicating this rather straightforward percentage method (for determining levels
of LEED certification) is the addition of a sixth category with up to five “bonus” points
for “innovation and design process” (see Table 2.2). In addition to securing a certain
number of points, each rating system has “prerequisites” that each project must meet, no
matter what level of attainment it achieves. For example, a LEED-NC–certified building
must reduce energy use at least 14 percent below a comparable building that just meets
the ASHRAE 90.1-2004 standard (or 10 percent below the newer ASHRAE 90.1-2007
standard).
Table 2.5 shows the four major systems that account for the vast majority of LEED
registered and certified projects as of early 2008, not including the LEED for Homes
and LEED for Neighborhood Development pilot programs. From this table, you can
see that the LEED-CS system is the second-most popular, followed by LEED-EB. For
the purposes of this book, we’re only going to focus on LEED-NC and LEED-CS,
which represent about 80 percent of all LEED registered and certified projects to date.
To best understand LEED, it helps to think of it as a self-assessed, third-party verified
rating system. In the case of a LEED certification, a project team estimates the partic-
ular credits for which a project qualifies and submits its documentation to the USGBC,
which assigns the review to an independent third party. The reviewer has three choices
with each point:

1 Agree with you and award the point claimed.
2 Disagree and disallow the point.
3 Ask for further information or clarification.

To resolve differences of opinion, there is a one-step appeal process.

LEED FOR NEW CONSTRUCTION
The most widely known and used LEED system is LEED-NC, which is useful for all new
buildings (except core and shell developments), major renovations and housing of four
stories and above. Table 2.2 captures the essence of the LEED-NC rating system’s major
issues. Through the end of 2007, about 68 percent of LEED projects were registered and
74 percent were certified under the LEED-NC assessment method. LEED-NC can also be