Discover which class of refrigerants, including CFCs, HCFCs, HFCs, and Ammonia, contributes the most to ozone depletion potential (ODP) according to the USGBC LEED Green Associate certification exam.
Table of Contents
Question
Which class of refrigerants contributes the most to ozone depletion potential (ODP)?
A. Ammonia (NH3)
B. Hydrofluorocarbons (HFCs)
C. Chlorofluorocarbons (CFCs)
D. Hydrochlorofluorocarbons {HCFCs}
Answer
The class of refrigerants that contributes the most to ozone depletion potential (ODP) is:
C. Chlorofluorocarbons (CFCs)
Explanation
Chlorofluorocarbons (CFCs) are the class of refrigerants that contribute the most to ozone depletion potential (ODP). Ozone depletion potential is a measure of how much a substance can damage the ozone layer in the stratosphere, which protects life on Earth from harmful ultraviolet radiation.
CFCs are synthetic chemicals that contain chlorine, fluorine, and carbon atoms. They were widely used as refrigerants, aerosol propellants, solvents, and foam blowing agents until they were phased out by the Montreal Protocol due to their high ODP.
The LEED Green Associate Candidate Handbook states that one of the strategies for achieving energy and atmosphere efficiency is to “eliminate chlorofluorocarbons (CFCs) in new building HVAC&R systems”.
Chlorofluorocarbons (CFCs) have the highest ozone depletion potential among the refrigerant classes listed. CFCs contain chlorine, which is highly effective at destroying ozone molecules in the stratosphere. When CFCs are released into the atmosphere, UV radiation breaks down the molecules, releasing chlorine atoms that react with and break down ozone (O3) into oxygen (O2).
The Montreal Protocol, an international treaty signed in 1987, aimed to phase out the production and consumption of CFCs and other ozone-depleting substances (ODS). As a result, CFCs have been largely replaced by hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), which have lower ODP.
HCFCs still contain chlorine but have a lower ODP compared to CFCs. HFCs do not contain chlorine and have an ODP of zero, but they have a high global warming potential (GWP).
Ammonia (NH3) is a natural refrigerant with zero ODP and negligible GWP, making it an environmentally friendly alternative to synthetic refrigerants.
In summary, chlorofluorocarbons (CFCs) have the highest ozone depletion potential among the refrigerant classes mentioned in the question, due to their chlorine content and the ability of chlorine to destroy ozone molecules in the stratosphere.
USGBC LEED Green Associate certification exam practice question and answer (Q&A) dump with detail explanation and reference available free, helpful to pass the USGBC LEED Green Associate exam and earn USGBC LEED Green Associate certification.