ASHRAE Journal - June 2024 - 37

FEATURE
100, Standard 228 does
not contain any energy
effi ciency targets that must
be achieved independently,
but rather targets net zero
performance of energy or
carbon on an annual basis.
Role of Refrigerant in the
Standard
The role of refrigerant in carbon calculations can
span both embodied and operational scopes. While the
original refrigerant charge for a system is considered
embodied carbon, the leakage of that refrigerant can be
considered either operational carbon or maintenance
of embodied carbon (B2). Refrigerants can cause
signifi cant operational carbon emissions due to leakage,
particularly in systems with high leak rates and/or high
global warming potential (GWP) refrigerants, and are a
component of the GHG calculation in Formula 7.4(2). An
example of the impact of refrigerants is a supermarket
refrigeration system with refrigerant charge of 1800 kg
(3,968 lb) and annual leak rate of 30%; the annual GHG
emissions from R-404A would be 2.7 million kg CO2e,
while a low GWP R-744 (carbon dioxide) system would
be only 540 kg CO2e.
To determine the annual GHG emissions per year
from refrigerant leakage in kg CO2e/year, the amount
of refrigerant lost is multiplied by the refrigerant's
GWP. To determine the annual refrigerant loss, two
methods can be used. For existing buildings, service
records for the equipment can be used to determine
the actual annualized loss, or it can be estimated by
multiplying the refrigerant charge by the equipment's
assumed annual leakage rate. In Standard 228,
reference tables are provided for typical refrigerant
leak rates of various equipment types (Table 9) and
GWPs of commonly used refrigerants (Table 10).
The calculation for the impact of refrigerants as
operational carbon is made in terms of GWP100
CO2e. Like other GHG factors, a set of GWP20 values
for refrigerant operational carbon is provided in
Informative Appendix E.
Once calculated, the impact of refrigerants in the
carbon balance is reported alongside the rest of the
carbon balance terms in the forms in Normative
Appendix A.
FIGURE 3 Building refrigerant impacts over building life cycle.
A1
B2
Product Stage:
Raw Materials
Impacts of refrigerant used in
the initial charge of the HVAC
equipment.
Use Stage:
Maintenance
Annual emissions due to
refrigerant leakage from HVAC
equipment over 75 years.
B4
Use Stage:
Replacement
Impacts from the production
of refrigerant used in the
initial charges of replacement
equipment over 75 years.
C4
End of Life Stage:
Disposal
Leakage of refrigerant during
the disposal at end of life.
New Construction vs. Existing Buildings
The scope of Standard 228 encompasses the design
and construction of new buildings (proposed), as
well as the operation of existing buildings (existing).
Because these sets of provisions at different phases
of a building's life use different sources of data,
buildings must follow Section 4.2.2 if using proposed
data, Section 4.2.3 if using as-built data and Section
4.2.4 if using operational data. It was the intention
of the committee to make the standard applicable
to all three of these phases of a building's life cycle,
and further versions of the standard may attempt
to make more direct connections between net zero
performance measured during the operation,
construction and design phases of a building's life
cycle.
Case Study-Establish Baseline and
Form Decarbonization Plan
When planning decarbonization over time,
Standard 228 can provide a valuable and recognized
methodology of baselining existing operational
emissions and understanding the anticipated
effects of carbon reduction measures that make up a
decarbonization plan of buildings and portfolios. The
baseline energy and emissions balance defi ned by
Standard 228 establishes the current performance and
a transparent breakdown of where those emissions
are coming from. With this knowledge a practitioner
can begin to analyze measures affecting the energy
and/or carbon emissions of each term in the balance
equation, identify how effective targeting each portion
of energy associated with the site is and sequence
them to achieve decarbonization over time. The
methodology then also provides a clear and widely
accepted method of determining the quantity and
quality of off-site renewable energy or carbon offset
credits that may be required at any time during the
decarbonization sequence for the site or portfolio to
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