Page 173 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

LEED Ener gy and Atmospher e 151

that these same chemicals react differently when they enter an atmospheric environment
similar to that found in the stratosphere. There, many of these same chemical compounds
apparently serve as catalysts that destroy the amount of ozone (O ) in the stratosphere,
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converting it into oxygen molecules (O ). In the troposphere, we usually regard O as a
2 2
“good” molecule, since this is the form of oxygen that we use to breathe, and we usually
regard O as a “bad” molecule, as it can cause air pollution problems and adversely
3
impact health. However, in the stratosphere, the O molecule advantageously aids in
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filtering out some of the ultraviolet radiation from the sun that might otherwise reach
the surface of the earth and negatively impact health and property. As is well known,
places in the stratosphere where the concentrations of O have been reduced are
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commonly referred to as “ozone holes.” Therefore, there is an effort to internationally
reduce the use of certain refrigerants and fire suppression chemicals that might have the
greatest negative impact on the amount of ozone in the stratosphere.
EA prerequisite 3 deals with a group of common refrigerants collectively referred to
as chlorofluorocarbons (CFCs). They are organic carbon–based compounds in which
the hydrogen atoms have been replaced by chlorine and fluorine atoms. The chlorine
atoms are thought to be some of the chemicals responsible for problems in ozone
depletion in the stratosphere. There are alternative compounds which can be used.
Many of these are discussed under EA credit 4. Many of the CFCs also go by the DuPont
trademark name Freon. The intent of this prerequisite is to ban or limit the use of CFCs
in new projects and major renovations.

USGBC Rating System
LEED-NC 2.2 lists the Intent, Requirements, and Potential Technologies and Strategies
for EAp3 as follows, and the requirements in LEED 2009 are essentially identical:
Intent
Reduce ozone depletion.
Requirements
Zero use of CFC-based refrigerants in new base building HVAC&R systems. When reusing
existing base building HVAC equipment, complete a comprehensive CFC phase out
conversion prior to project completion. Phase-out plans extending beyond the project
completion date will be considered on their merits. (Small HVAC units (defi ned as
containing less than 0.5 lbs of refrigerant), and other equipment such as standard
refrigerators, small water coolers, and any other cooling equipment that contains less than
0.5 lbs of refrigerant, are not considered part of the “base building” system and are not
subject to the requirements of this credit.)
Potential Technologies and Strategies
When reusing existing HVAC systems, conduct an inventory to identify equipment that uses
CFC refrigerants and provide a replacement schedule for these refrigerants. For new buildings,
specify new HVAC equipment in the base building that uses no CFC refrigerants.

Calculations and Considerations
This prerequisite is quite simple. There will be no CFCs used for heating, ventilating, air
conditioning, and refrigeration (HVAC&R) base building systems in new buildings,
and they must be taken out of existing buildings if economically feasible for which
there must be a detailed phase-out plan. There must be a third-party audit proving that
this is not economically feasible to replace or convert the system based on a 10 year
simple payback if existing systems are to remain.