August 2024 Green Power Page 1
Green Power
Technical Reference
OVERVIEW
The U.S. Environmental Protection Agency (EPA) defines green power as electricity generated from
renewable resources, such as solar, wind, geothermal, low-impact biomass, and low-impact hydro
resources. Whereas energy efficiency measures may be implemented to reduce the overall energy use in
your building, the purchase of green power helps to reduce the environmental impacts associated with
the generation of electricity used in your building. Green power may be obtained from either onsite
sources (i.e., solar photovoltaic panels at your property) or offsite sources (i.e., a wind turbine farm). The
specific requirements for benchmarking and the resulting effect on your metrics depend on where the
electricity is generated:
•
Onsite Green Power. Onsite green power may be generated through solar photovoltaic panels
or wind turbines located at your property. To benchmark, you will enter two meters: one to track
how much onsite renewable electricity you use and export, and a second to track the electricity
that you purchase from the grid. Because onsite renewable electricity generation is part of your
building’s energy requirement, it must be tracked; it is not sufficient to enter only grid-purchased
electricity. When you enter onsite green power, it is important that you indicate whether you own
the Renewable Energy Certificates (RECs) that are associated with the green power you
generate. You must own the RECs to see the benefits of onsite green power in your emissions
metrics. However, you will see a benefit in your Source Energy and Score even if you do not own
the RECs.
•
Offsite Green Power. Offsite green power is generated from projects that are not located at
your facility (e.g., from a nearby wind farm). In some cases, the green power may be generated in
an entirely different part of the country. To benchmark, you will enter “green power” records for
your green power purchases. Currently, Offsite green power only improves your “Avoided
Emissions.” It is the purchase of an emissions benefit, but your electricity still comes from the
traditional grid.
The only onsite green power meter types in Portfolio Manager are solar and wind, the most common forms
of green electricity. You may have other forms of renewable energy at your building, such as geo-thermal
heating and/or solar hot water. Portfolio Manager does not have specific tracking modules for these
energy sources because it is not common or feasible to quantify their heat input. In these cases, you
receive credit to the extent you lower your energy purchases. You also may buy RECs independent of your
actual physical electricity. These purchases are typically made at a corporate level and are often not
traceable to individual buildings. Because Portfolio Manager focuses on building metrics, there is no
specific module for tracking these unbundled RECs at the portfolio level, but you may choose how to apply
your corporate RECs across your building portfolio.
August 2024 Green Power Page 2
Technical Reference
This document explains the benchmarking requirements and metric details in the following sections:
UNDERSTANDING ONSITE GREEN POWER ................................................................................... 2
How to benchmark ................................................................................................................ 2
What onsite green power means for your performance metrics ................................ 5
UNDERSTANDING OFFSITE GREEN POWER .................................................................................. 7
How to benchmark ................................................................................................................ 5
What offsite green power means for your performance metrics ................................ 8
UNDERSTANDING ONSITE GREEN POWER
Onsite green power is electricity generated at your property from a renewable energy source (currently
only solar or wind). There are two important principles followed in tracking onsite green power in Portfolio
Manager:
•
All energy use must be tracked to evaluate energy performance. You must track exactly
how much renewable electricity you use, as well as how much electricity you obtain from the grid.
It is not sufficient to track only the grid-purchased electricity for the property since it does not
accurately reflect the total property energy use.
•
REC Ownership must be tracked to properly evaluate environmental impacts. Your ability
to claim the emissions benefit associated with onsite green power depends on whether you own
the Renewable Energy Certificates (RECs)
1
associated with renewable energy produced by the
system at your property. Your environmental benefit is affected by any transfer of RECs, including
REC arbitrage. In August 2024, Portfolio Manager began accounting for the REC ownership
associated with onsite energy exported to the grid. Any onsite energy exported to the grid where
the RECs are owned will be automatically counted as offsite green power.
How to benchmark
Portfolio Manager lets you to track two types of onsite green power: power generated from solar
photovoltaic panels and power generated from wind turbines. These renewable sources of electricity are
tracked with a unique “meter type.” The special meter type lets us collect additional pieces of information
that are unique to onsite solar and wind systems and are required for accurate performance metrics.
If you have an onsite system, chances are you also get some electricity from the grid. For example, you
may use electricity at night or at other times when there is not adequate supply from an onsite solar
system. Therefore, you need to enter two meters: an onsite renewable electric meter and a grid electric
meter. The colored arrows in
Figure 1
show the electricity flows that are captured in each of these two
1
Renewable Energy Certificates (RECs) are tradable certificates that are widely used to establish environmental claims associated with buying
or using green power. They represent the environmental, social, and other non-power qualities associated with the generation of one
megawatt-hour of electricity from a renewable resource.
August 2024 Green Power Page 3
Technical Reference
meters. The green arrows correspond to information about your onsite system (your onsite renewable
meter); the black arrow corresponds to information about energy from the grid (your grid electric meter).
1. Onsite Solar or Wind Meter (Labeled as Flow R). This meter is used to track both the
electricity that you use onsite and any electricity that is exported back to the grid.
•
Electricity generated by your system and used at your building (Labeled as Flow
R
u
). The energy you generate and use onsite is an important energy need that must be
included in your energy performance metrics. This amount is not always metered, but
most buildings do meter the total amount of electricity generated, and if you do not export
any energy to the grid, then this is the amount you need. If you do export electricity to the
grid, and you do not have a physical meter tracking the amount of electricity you use you
will need to compute this value by measuring your total system generation (R) and
subtracting any exports to the grid (R
ex
). You may want to consult with the energy service
provider or utility that assisted with your system installation to determine where you can
find this amount (energy that is generated by your system and used at your property).
•
Electricity generated by your system and exported to the electric grid (Flow R
ex
).
Many onsite systems export electricity to the grid. For example, a small school may have
periods during which the generation of the onsite system exceeds the building’s demand
and therefore the excess electricity is exported to the grid. In contrast a large office
building may never generate more electricity than it needs and therefore will not export
any electricity. If you export electricity, you must quantify your exports. This information
might be obtained from a bi-directional digital electric utility meter installed at your
property that measures flow to the grid. Some buildings may not be able to read this value
from a physical meter on their site, but rather will find it on the utility bill. You may want to
consult with the energy service provider or utility that assisted with your system
installation to determine where you can find this export amount.
2. Grid Electricity Meter (Flow G). This Portfolio Manager meter is used to track all electricity that
is sourced from the grid, meaning all electricity (kWh) that flows from the grid to your building. If
you do not export green power, then your utility bill is your total grid electricity. If you do export
green power, then you need to be very careful to include
all
energy that flows from the grid to
your property; this is typically tracked via a bi-directional meter and may be reported on your
utility bill. It is not sufficient to enter a “net” meter, which only shows you the difference between
the energy you import from the grid and the energy you export (i.e., G – R
ex
). Although your utility
may give you financial credit for exports (R
ex
), the total flow of energy from the grid into your
building (G) is required for a complete assessment of your performance. It is common for utility
bills to separately report the “net” value (G – R
ex
) and the export value (R
ex
). In this situation, you
will need to compute G by adding these two values together. You may want to consult with your
energy service provider or utility to determine how you can quantify G from your utility bill.
August 2024 Green Power Page 4
Technical Reference
Figure 1 – Configuration of an Onsite Renewable System
The Electric (Onsite) Solar or Wind Meters are unique meter types in Portfolio Manager.
Figure 2a
illustrates an onsite green power meter example. There are columns to track both the energy generated
and
used onsite
, and the energy generated and
exported offsite
(i.e., back to the grid).
Figure 2b
shows
the information tracked at the meter level, which includes the REC ownership of both the solar energy you
use onsite and the solar energy you export. There are three options for REC Ownership: Owned, Sold/Not
Owned, and REC Arbitrage. You can change your REC ownership over time. It is possible that you will sell
your RECs in one year but retain them in the following year. Information on your REC ownership over time
is critical to accurately calculate of your GHG emissions benefit.
It’s important to make sure you actually “own” the RECs. This can be confusing, especially if you have a
Power Purchase Agreement. Please review your contractual agreement to double check ownership of the
RECs. You may have purchased the energy with the RECs (bundled) or just the energy (unbundled). In
some cases, RECs associated with onsite green power installations are sold to help finance the
installation/operation of the onsite system or in a power purchase agreement to reduce the price of the
energy you are purchasing. Once the RECs are sold, the onsite system’s electricity generation is no longer
considered green power and you may not claim any emissions benefits for power generated from the
onsite system. You will still see a benefit in your Source Energy and Score.
Under specific type of sale known as REC arbitrage, system financing can be facilitated by selling the
RECs that are associated with your onsite system and purchasing other RECs as replacements. This can
be done to take advantage of price differentials of RECs produced elsewhere. In this case, you have sold
the RECs associated with your onsite system and therefore you cannot claim that your
onsite
system
August 2024 Green Power Page 5
Technical Reference
electricity generation is green. You will, however, get credit for
offsite
green power associated with the
replacement RECs you purchased.
Figure 2a – Example Data Entry Table for Onsite Renewable System – Energy Information
Figure 2b – Example Data Entry Table for Onsite Renewable System – REC Information
What onsite green power means for your performance metrics
A building that uses electricity from onsite green power, as opposed to electricity sourced from the grid,
will have a higher ENERGY STAR score. The score is a measure of the thermodynamic performance of
your building, which is a function of the amount and type of fuel your building consumes. Each fuel is
assigned a national site-to-source factor in order to measure the efficiency of the building, not the
efficiency of the utility supplying energy to the building. Since electricity generated from onsite green
power (located either on the building or property) is effectively “behind” the utility meter, it is not subject
to the generation, distribution, and transmissions losses of traditional grid-sourced electricity. It therefore
is assigned a lower site-to-source conversion factor, resulting in a higher score. This is true even if the
RECs are sold or arbitraged.
The environmental implications (total emissions and avoided emissions) of onsite green power depend on
whether you own the RECs associated with your onsite renewable electric generation. If you own the
RECs, then you will see the benefit of your green power in lower Total GHG emissions. If you sell the RECs
associated with your onsite system (or never owned them in the case of power purchasing agreements)
then the power generated by your onsite system is no longer considered green. This means your Total
GHG emissions are computed as though you had purchased grid electricity. If you arbitrage the RECs, then
you no longer have onsite green power (that has no emissions associated with it), but you have offsite
August 2024 Green Power Page 6
Technical Reference
green power (which is the equivalent of buying RECs bundled with grid electricity). The effect on these
metrics is summarized in
Figure 3.
Figure 3 – Performance Metrics Associated with Your Onsite System
Metric
Own
RECs
Sell
RECs
Arbitrage
RECs
Explanation
Site Energy No Effect No Effect No Effect
Renewable electricity is still a real energy
requirement for the operation of your building.
Source Energy
Improves
Improves
Improves
Onsite renewable energy is not subject to the same
generation, transmission, and distribution losses as
the grid.
Score
Improves
Improves
Improves
The score is based on your source energy and will
also improve.
Total
(Location-Based)
Emissions
Improves No Effect No Effect
If you own the RECs, there are no emissions
associated with onsite green power.
If you sell or arbitrage the RECs, this electricity is
treated as if it came from the grid.
Total
(Market-Based)
Emissions
(Coming in late
2024)
Improves No Effect
Improves
If you own or Arbitrage the RECs, there are no
emissions associated with this onsite green power.
If you sell the RECs, this electricity is treated as if it
came from the grid.
Avoided
Emissions
Improves No Effect
Improves
If you own the RECs, you get credit for the avoided
emissions from your onsite system.
If you sell the RECs, you do not get any avoided
emissions credit.
If you arbitrage the RECs, you get avoided
emissions based on the new RECs you received in
the trade.
August 2024 Green Power Page 7
Technical Reference
UNDERSTANDING OFFSITE GREEN POWER
Offsite green power is a product you purchase from your local utility or third-party supplier. Often the
supplier will bundle RECs with the underlying physical electricity into a single product. In this case, the
actual electricity may be generated at a fossil fuel power plant in your area, while the RECs may be the
environmental attributes of green power generated in another part of the country. Although the RECs were
generated elsewhere, they are bundled to your electricity purchase, and therefore, you own the rights and
can count the avoided emissions in your GHG reporting. The emissions benefit in Avoided Emissions is
based on the location where your RECs were generated, not the location of your property.
In some cases, you may purchase RECs separate from your electricity. This may occur if your organization
makes a corporate purchase of RECs to cover electricity use across an entire portfolio of properties.
Although these RECs are not bundled with electricity at the time of purchase, you can effectively “bundle”
them in Portfolio Manager.
How to benchmark
Offsite green power is entered at the property or meter level. If you are purchasing a percentage of your
electricity as green power then you must designate the meter(s) to which the green power applies,
otherwise offsite green power is attributed to the property as a whole. From the Energy tab, you can enter
a Green Power record (Figure 4) from the left navigation bar: “Manage Green Power.”
Figure 4 – Example Data Entry Table for Offsite Green Power
Technical Reference
Agency program helping businesses and individuals fight
climate change through superior energy efficiency.
program helping businesses and individuals fight climate
change through superior energy efficiency.
The quantity of RECs is necessary to compute the benefit of your green power:
• Quantity of Green Power. You may have an agreement that specifies either a certain amount
(kWh) or a certain percentage of your power as green. For accurate characterization of your
emissions benefit, this amount is required.
• Generation Location. You will be asked for the location where your renewable energy was
generated for the calculation of Avoided Emissions. If you know it, you can select the postal code
or eGRID subregion where the energy was generated. The benefits of green power depend on
where it is generated because this is where traditional electric generation is being replaced. That
is, green power reduces the need for conventional methods of electric generation in the region
where it was produced, which may differ from the location of your building. If you do not know
where your green power was generated, you can select “I don’t know.” In this case, your property
will be assigned the emissions factor from the cleanest region of the grid (the one with the
smallest non-baseload emissions factor), yielding the most conservative values for your Avoided
Emissions.
• Fuel Source (optional). If it is helpful for your GHG accounting, you can also enter the fuel
source to provide greater specificity about your green power purchase. If you do not know the
fuel source, you can leave this question blank or select “Unknown.” The fuel source does not
impact any metrics.
What offsite green power means for your performance metrics
The purchase of offsite green power is a GHG reduction strategy. When you purchase offsite green
power, you purchase the rights to a zero-emissions energy supply. These purchases can be an important
part of your overall GHG reductions strategy. With offsite green power you still purchase and receive your
electricity from the local utility and your electricity is sourced from the national grid. Like any other
building that receives its energy from the grid, you are assigned the national source energy factor. For this
reason, the computation of your site energy and source energy are unchanged. These metrics quantify the
real energy requirements of your building. The purchase of the RECs does not change the thermodynamic
energy requirements of your building.
Standard GHG accounting protocols recommend using two complementary methods to estimate GHG
emissions; a location-based approach and a market-based approach.
• Location-based method (which Portfolio Manager uses) uses the regional grid-average emissions
factors. In this method onsite green power (solar or wind on your property) improves (lowers) your
Total Emissions if you own the RECs, but offsite green power (purchasing RECs with grid
electricity) has no effect on Total Emissions. Offsite Green Power is represented in Avoided
Emissions.
Technical Reference
Agency program helping businesses and individuals fight
climate change through superior energy efficiency.
program helping businesses and individuals fight climate
change through superior energy efficiency.
• Market-based method uses energy supplier-specific emissions factors and both onsite and
offsite green power will improve (lower) your Total Emissions because they both are assigned a
zero emissions rate. Market-based emissions metrics will be added to Portfolio Manager by the
end of 2024.
The metrics are summarized in
Figure
6
.
Figure 6 – Offsite Green Power and Your Performance Metrics
Metric Effect Explanation
Site Energy No Effect
Renewable electricity is still a real energy
requirement for the operation of your building.
Source Energy No Effect
Although you have purchased green power, the
actual electrons delivered to your building come
from the main electric grid. Therefore, your source
energy does not change.
Score No Effect
The score is based on source energy. Because
source energy is not affected by the purchase of
green power, neither is your score.
Total (Location-Based)
Emissions
No Effect
Offsite green power is not reflected in your Total
(Location-Based) GHG Emissions.
Total (Market-Based)
Emissions
(Coming in late 2024)
Improves
Offsite green power is reflected in your Total
(Market-Based) GHG Emissions.
Avoided Emissions
Improves
Offsite green power is counted towards the
avoided emissions associated with your building.