Energy Management Working Group B. Schoening
Internet-Draft Independent Consultant
Intended status: Informational Mouli Chandramouli
Expires: June 20, 2012 Cisco Systems, Inc.
Bruce Nordman
Lawrence Berkeley National Laboratory
December 20, 2011
Energy Management (EMAN) Applicability Statement
draft-ietf-eman-applicability-statement-00
Abstract
The objective of Energy Management (EMAN) is to provide an
energy management framework for networked devices. This
document presents the applicability of the EMAN framework for a
variety of scenarios. This document lists use cases and target
devices that can potentially implement the EMAN framework and
associated SNMP MIB modules. These use cases are useful for
identifying requirements for the framework. Further, we
describe the relationship of the EMAN framework to relevant
other energy monitoring standards and architectures.
Status of this Memo
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This Internet-Draft will expire on June 20, 2012.
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Table of Contents
1. Introduction .............................................3
1.1. Energy Management Overview ............................4
1.2. EMAN WG Document Overview .............................5
1.3. Energy Measurement....................................5
1.4. Energy Management ...................................6
1.5. EMAN Framework Application ...........................6
2. Scenarios and Target Devices .............................7
2.1. Network Infrastructure Energy Objects ...............7
2.2. Devices Powered by and Connected to a Network Device .8
2.3. Devices Connected to a Network ......................10
2.4. Power Meters ........................................10
2.5. Mid-level Managers ..................................11
2.6. Gateways to Building Systems ........................12
2.7. Home Energy Gateways ................................13
2.8. Data Center Devices .................................13
2.9. Energy Storage Devices ..............................15
2.10. Industrial Automation Networks .....................15
2.11. Printers ...........................................16
2.12. Off-Grid Devices ...................................17
2.13. Demand/Response ....................................18
2.14. Power Capping ......................................18
3. Use Case Patterns .......................................18
3.1. Metering ............................................18
3.2. Metering and Control ................................19
3.3. Power Supply, Metering and Control ..................19
3.4. Multiple Power Sources ..............................19
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4. Relationship of EMAN to other Standards ..................19
4.1. Data Model and Reporting .............................19
4.1.1. IEC - CIM.....................................19
4.1.2. DMTF..........................................20
4.1.3. ODVA..........................................21
4.1.4. Ecma SDC.....................................22
4.1.5. IEEE-ISTO Printer Working Group (PWG).........22
4.1.6. ASHRAE........................................23
4.1.7. ZigBee........................................23
4.2. Measurement ..........................................24
4.2.1. ANSI C12......................................24
4.2.2. IEC62301......................................24
4.3. Other ................................................25
4.3.1. ISO...........................................25
4.3.2. EnergyStar....................................25
4.3.3. SmartGrid.....................................26
5. Limitations ..............................................27
6. Security Considerations ..................................27
7. IANA Considerations ......................................27
8. Acknowledgements .........................................27
9. Open Issues...............................................27
10. References ..............................................28
10.1. Normative References ................................28
10.2. Informative References...............................29
1. Introduction
The focus of the Energy Management (EMAN) framework is energy
monitoring and management of energy objects [EMAN-DEF]. The
scope of devices considered are network equipment and its
components, and devices connected directly or indirectly to
the network. The EMAN framework enables monitoring
(heterogeneous devices to report their energy consumption)
and, if permissible, control. There are multiple scenarios
where this is desirable, particularly considering the
increased importance of limiting consumption of finite energy
resources and reducing operational expenses.
The EMAN framework [EMAN-FRAMEWORK] describes how energy
information can be retrieved from IP-enabled devices using
Simple Network Management Protocol (SNMP), specifically,
Management Information Base (MIBs) for SNMP.
This document describes typical applications of the EMAN
framework, as well as its opportunities and limitations. Other
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standards that are similar to EMAN but address different domains
are described. This document contains references to those other
standards and describes how they relate to the EMAN framework.
The rest of the document is organized as follows. Section 2
contains a list of use cases or network scenarios that EMAN
shall address. Section 3 contains an abstraction of the use case
scenarios to distinct patterns. Section 4 deals with the
standards related to EMAN and applicable to EMAN.
1.1. Energy Management Overview
While energy is available in many forms, EMAN addresses only the
electrical energy consumed by devices connected to a network.
First, a brief introduction to the definitions of Energy and
Power are presented.
Energy is the capacity to perform work. Electrical energy is
typically expressed in kilowatt-hour units (kWh) or other
multiples of watt-hours (WH). One kilowatt-hour is the
electrical energy used by a device drawing 1 kilowatt for one
hour. Power is the rate of electrical energy flow. In other
words, power = energy / time. Power is often measured in watts.
A utility bill is usually based on electrical energy use
measured in kWh.
A first step to increase the energy efficiency in networks and
buildings is to enable energy objects to report their energy
usage over time. The EMAN framework addresses this problem with
an information model for some electrical equipment: energy
object identification, energy object context, power measurement
and power characteristics.
The EMAN WG framework defines SNMP MIB modules based on the
information model. By implementing the SNMP MIB modules, any
energy object can report its energy consumption according to the
information model. In that context, it is important to
distinguish energy objects that can only report their own energy
usage from devices that can also collect and aggregate energy
usage of other energy objects.
Target devices and scenarios considered for Energy Management
are presented in Section 2 with detailed examples.
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1.2. EMAN WG Document Overview
The EMAN working group charter called for producing a series of
Internet standard drafts in the area of energy management. The
following drafts were created by the working group.
Applicability Statement [EMAN-AS] this document presents the
use cases and scenarios for energy management. In addition,
other relevant energy standards and architectures are listed.
Requirements [EMAN-REQ] this document presents the
requirements of energy management and the scope of the devices
considered.
Framework [EMAN-FRAMEWORK] This document defines a framework
for providing Energy Management for devices within or
connected to communication networks.
Energy-Aware MIB [EMAN-AWARE-MIB] This document proposes a MIB
module that characterizes a device's identity, context and the
relationship to other entities.
Monitoring MIB [EMAN-MONITORING-MIB] This document defines a
MIB module for monitoring the power and energy consumption of
a device. The MIB module contains an optional module for
metrics associated with power characteristics.
Battery MIB [EMAN-BATTERY-MIB] This document contains a MIB
module for monitoring characteristics of an internal battery.
Energy Management Terminology [EMAN-DEF] This document lists
the definitions for the common terms used in the Energy
Management Working Group.
1.3. Energy Measurement
More and more devices are able to measure and report their own
energy consumption. Smart power strips and some Power over
Ethernet (PoE) switches can meter consumption of connected
devices. However, when managed and reported through proprietary
means, this information is minimally useful at the enterprise
level.
The primary goal of the EMAN MIBs is to enable reporting and
management within a standard framework that is applicable to a
wide variety of end devices, meters, and proxies. This enables a
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management system to know who's consuming what, when, and how at
any time by leveraging existing networks, across various
equipment, in a unified and consistent manner.
Given that an energy object can consume energy and/or provide
energy to other devices, there are three types of energy
measurement: energy input to a device, energy supplied to other
devices, and net (resultant) energy consumed (the difference
between energy input and provided).
1.4. Energy Management
Beyond energy monitoring, the EMAN framework provides mechanisms
for energy control.
There are many cases where reducing energy consumption of
devices is desirable, such as when the device utilization is low
or when the electricity is expensive or in short supply.
In some cases, energy control requires considering the energy
object context. For instance, in a building during non-business
hours: usually not all phones would be turned off to keep some
phones available in case of emergency; office cooling is usually
not turned off totally, but the comfort level is reduced.
Energy object control requires flexibility and support for
different polices and mechanisms: from centralized management
with a network management station, to autonomous management by
individual devices, and alignment with dynamic demand-response
mechanisms.
The EMAN framework can be used as a tool for the demand/response
scenario where in response to time-of-day fluctuation of energy
costs or possible energy shortages, it is possible to respond
and reduce the energy consumption for the network devices,
effectively changing its power state.
1.5. EMAN Framework Application
A Network Management System (NMS) is the entity that requests
information from compatible devices using SNMP protocol. An NMS
implements many network management functions, e.g. security
management, or identity management. An NMS that deals
exclusively with energy is called EnMS,Energy Management System.
It may be limited to monitoring energy use, or it may also
implement control functions. In a typical application of the
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EMAN framework, management software collects energy information
for devices in the network.
Energy management can be implemented by extending existing SNMP
support to the EMAN specific MIBs. SNMP provides an industry
proven and well-known mechanism to discover, secure, measure,
and control SNMP-enabled end devices. The EMAN framework
provides an information and data model to unify access to a
large range of devices.
The scope of the target devices and the network scenarios
considered for energy management are listed in Section 2.
2. Scenarios and Target Devices
In this section a selection of scenarios for energy management
are presented. The fundamental objective of the use cases is to
list important network scenarios that the EMAN framework should
solve. These use cases then drive the requirements for the EMAN
framework.
Each scenario lists target devices for which the energy
management framework can be applied, how the reported-on devices
are powered, and how the reporting is accomplished. While there
is some overlap between some of the use cases, the use cases
serve as illustrative network scenarios EMAN framework supports.
2.1. Network Infrastructure Energy Objects
This scenario covers network devices and their components. Power
management of energy objects is considered as a fundamental
requirement of energy management of networks.
It can be important to monitor the energy consumption and
possibly manage the power state of these devices at a
granularity level finer than just the entire device. For these
devices, the chassis draws power from one or more sources and
feeds all its internal components. It is highly desirable to
have monitoring available for individual components, such as
line cards, processors, and hard drives as well as peripherals
like USB devices.
As an illustrative example, consider a switch with the following
grouping of sub-entities for which energy management could be
useful.
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. physical view: chassis (or stack), line cards, service
modules of the switch.
. component view: CPU, ASICs, fans, power supply, ports
(single port and port groups), storage and memory.
The ENTITY-MIB provides the containment tree framework, for
uniquely identifying the physical sub-components of network
devices. A component can be an Energy Object and the ENTITY-MIB
containment tree shall express if that Energy Object belongs to
another Energy Object (e.g. line-card Energy Object contained in
a chassis Energy Object. The table entPhysicalContainsTable
which has the index of entPhysicalChildIndex and the MIB object
entPhysicalContainedIn which points to the containing entity.
The essential properties of this use case are:
. Target devices: network devices such as routers, switches
and their components.
. How powered: typically by a PDU on a rack or from a wall
outlet. The components of a device are powered by the
device chassis.
. Reporting: direct power measurement can be performed at a
device level. Components can report their power consumption
directly or the chassis/device that can report on behalf of
some components.
2.2. Devices Powered by and Connected to a Network Device
This scenario covers Power over Ethernet (PoE) devices. A PoE
Power Sourcing Equipment (PSE) device [RFC3621] (e.g. a PoE
switch) provides power to a Powered Device (PD) (e.g. a desktop
phone). For each port, the PSE can control the power supply
(switching it on and off) and meter actual power provided. PDs
obtain network connectivity as well as power over a single
connection so the PSE can determine which device is associated
with each port.
PoE ports on a switch are commonly connected to devices such as
IP phones, wireless access points, and IP cameras. The switch
needs power for its internal use and to supply power to PoE
ports. Monitoring the power consumption of the switch (supplying
device) and the power consumption of the PoE end-points
(consuming devices) is a simple use case of this scenario.
It is also possible to illustrate the relationships between
entities. The PoE IP phone is powered by the switch. If there
are many IP phones connected to the same switch and the power
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consumption of all the IP phones can be aggregated by the
switch. In that case, the switch performs the aggregation
function for other entities.
The essential properties of this use case are:
. Target devices: power over Ethernet devices such as IP
phones, wireless access points, and IP cameras.
. How powered: PoE devices are connected to the switch port
which supplies power to those devices.
. Reporting: PoE device power consumption is measured and
reported by the switch (PSE) which supplies power. In
addition, some devices can have support for the EMAN
framework.
This use case can be subdivided into two sub cases:
a) The end device supports the EMAN framework, in which case
this device is an EMAN Energy Object by itself, with its own
UUID, like in scenario "Devices Connected to a Network"
below. The device is responsible for its own power reporting
and control.
b) The end device does not have EMAN capabilities, and the
power measurement may not be able to be performed
independently, and so is only performed by the supplying
device. This scenario is similar to the "Mid-level Manager"
below.
In the sub case (a) note that two power usage reporting for the
same device are available: one performed by the PD itself and
one performed by the PSE. Device specific implementations will
dictate which one if the most accurate.
It is also possible to illustrate the relationships between
entities. The PoE IP phone is powered by the switch. If there
are many IP phones connected to the same switch and the power
consumption of all the IP phones can be aggregated by the
switch. In that case, the switch performs the aggregation
function for other entities.
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2.3. Devices Connected to a Network
The use case covers the metering relationship between an energy
object and the parent energy object it is connected to, while
receiving power from an external source such as a power brick.
An example is a PC which has a network connection to a switch,
but draws power from a wall outlet. In this case, the PC can
report power usage by itself, ideally through the EMAN
framework.
The wall outlet the PC is plugged in can be metered for example
by a Smart PDU, or unmetered.
a) If metered, the PC has a powered-by relationship to the Smart
PDU, and the Smart PDU will act as a "Mid-Level Manager"
b) If unmetered - or running on batteries - the PC will report
its own energy usage as any other Energy Object to the switch,
and the switch can possibly provide aggregation.
Note that a) and b) are not mutually exclusive.
In terms of relationships between entities, the PC has a powered
by relationship to the PDU and if the power consumption of the
PC is metered by the PDU then there is a metered by relation
between the PC and the PDU.
The essential properties of this use case are:
. Target devices: Energy objects that have a network
connection, but receive power supply from another source.
. How powered: Children (e.g.: PCs)receive power supply from
the wall outlet (unmetered), or a PDU (metered). That can
also be powered autonomously (batteries).
. Reporting: Devices can measure and report the power
consumption directly via the EMAN framework, or,
communicate it to the network device (switch) and the
switch can report the device's power consumption via the
EMAN framework.
2.4. Power Meters
Some electrical devices are not equipped with instrumentation to
measure their own power and accumulated energy consumption.
External meters can be used to measure the power consumption of
such electrical devices as well as collections of devices.
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This use case covers the proxy relationship of energy objects
able to measure or report the power consumption of external
electrical devices, not natively connected to the network.
Examples of such metering devices are smart PDUs and smart
meters.
Three types of external metering are relevant to EMAN: PDUs,
standalone meters, and utility meters. External meters can
measure consumption of a single device or a set of devices.
Power Distribution Unit (PDUs) have inbuilt meters for each
socket and so can measure the power supplied to each device in
an equipment rack. The PDUs have remote management functionality
which can measure and possibly control the power supply of each
outlet.
Standalone meters can be placed anywhere in a power distribution
tree are allocated to specific devices.
Utility meters monitor and report accumulated power consumption
of the entire building. There can be sub-meters to measure the
power consumption of a portion of the building.
The essential properties of this use case are:
. Target devices: PDUs and meters.
. How powered: From traditional mains power but as passed
through a PDU or meter.
. Reporting: The PDUs reports power consumption of downstream
devices, usually a single device per outlet.
The meters can have a metering relationship and possibly
aggregation relationship between the meters and the devices for
which power consumption is accumulated and reported by the
meter.
2.5. Mid-level Managers
This use case covers aggregation of energy management data at
"mid-level managers" that can provide energy management
functions for themselves as well as associated devices.
A switch can provide energy management functions for all devices
connected to its ports, whether or not these devices are powered
by the switch or whether the switch provides immediate network
connectivity to the devices; such a switch is a mid-level
manager, offering aggregation of power consumption data for
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other devices. Devices report their EMAN data to the switch and
the switch aggregates the data for further reporting.
The essential properties of this use case:
. Target devices: Devices which can perform aggregation;
commonly a switch or a proxy
. How powered: Mid-level managers can be are commonly
powered by a PDU or from a wall outlet and can be powered
by any method.
. Reporting: The middle-manager aggregates the energy data
and reports that data to a NMS or higher mid-level manager.
2.6. Gateways to Building Systems
This use case describes energy management of buildings. Building
Management Systems (BMS) have been in place for many years using
legacy protocols not based on IP. In these buildings, a gateway
can provide a proxy relationship between IP and legacy building
automation protocols. The gateway can provide an interface
between the EMAN framework and relevant building management
protocols.
Due to the potential energy savings, energy management of
buildings has received significant attention. There are gateway
network elements to manage the multiple components of a building
energy management system such as Heating, Ventilation, and Air
Conditioning (HVAC), lighting, electrical, fire and emergency
systems, elevators, etc. The gateway device uses legacy building
protocols to communicate with those devices, collects their
energy usage, and reports the results.
The gateway performs protocol conversion and communicates via
RS-232/RS-485 interfaces, Ethernet interfaces, and protocols
specific to building management such as BACNET [ASHRAE], MODBUS
[MODBUS], or Zigbee [ZIGBEE].
The essential properties of this use case are:
. Target devices: Building energy management devices - HVAC
systems, lighting, electrical, fire and emergency systems.
. How powered: Any method.
. Reporting: The gateway collects energy consumption of non-
IP systems and communicates the data via the EMAN
framework.
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2.7. Home Energy Gateways
This use case describes the scenario of energy management of a
home. The home energy gateway is another example of a proxy that
interfaces to the electrical appliances and other devices in a
home. This gateway can monitor and manage electrical equipment
(refrigerator, heating/cooling, washing machine etc.) using one
of the many protocols that are being developed for the home area
network products.
In its simplest form, metering can be performed at home. Beyond
the metering, it is also possible to implement energy saving
policies based on energy pricing from the utility grid. The EMAN
information model can be applied to the protocols under
consideration for energy management of a home.
The essential properties of this use case are:
. Target devices: Home energy gateway and smart meters in a
home.
. How powered: Any method.
. Reporting: Home energy gateway can collect power
consumption of device in a home and possibly report the
metering reading to the utility.
Beyond the canonical setting of a home drawing power from the
utility, it is also possible to envision an energy neutral
situation wherein the buildings/homes that can produce and
consume energy with reduced or zero net importing energy from
the utility grid. There are many energy production technologies
such as solar panels, wind turbines, or micro generators. This
use case illustrates the concept of covers self-contained energy
generation and consumption and possibly the aggregation of the
energy use of homes.
2.8. Data Center Devices
This use case describes energy management of a data center.
Energy efficiency of data centers has become a fundamental
challenge of data center operation, as datacenters are big
energy consumers and have expensive infrastructure. The
equipment generates heat, and heat needs to be evacuated though
a HVAC system.
A typical data center network consists of a hierarchy of
electrical energy objects. At the bottom of the network
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hierarchy are servers mounted on a rack; these are connected to
top-of-the-rack switches, which in turn are connected to
aggregation switches, and then to core switches. Power
consumption of all network elements, servers, and network
storage devices in the data center should be measured. Energy
management can be implemented on different aggregation levels,
at the network level, Power Distribution Unit (PDU) level, and
server level.
Beyond the network devices, storage devices and servers, data
centers contain UPSs to provide back-up power for the network,
storage devices in the event in the event of a power outage. A
UPS can provide backup power for many devices in a data center
for a finite period of time. Energy monitoring of such energy
storage devices is vital from a data center network operations
point of view. Presently, the UPS MIB can be useful in
monitoring the battery capacity, the input load to the UPS and
the output load from the UPS. Currently, there is no link
between the UPS MIB and the ENTITY MIB.
Thus from a Data center energy management point of view, in
addition, to monitoring the energy usage of network devices, it
is also important to monitor the remaining capacity of the UPS.
In addition to monitoring the power consumption of a data
center, additional power characteristic metrics should be
monitored. Some of these are dynamic variations in the input
power supply from the grid referred to as power characteristics
is one metric. Secondly, how the devices utilize the power in
terms of efficiency can be useful to monitor these metrics.
Lastly, the nameplate power consumption (the worst case possible
power draw) of all devices will make it possible to know an
aggregate of the potential worst-case power usage and compare it
to the budgeted power in the data center.
The essential properties of this use case are:
. Target devices: All IT devices in a data center, such as
network equipment, servers, and storage devices, as well as
power and cooling infrastructure.
. How powered: Any method but commonly by one or more PDUs.
. Reporting: Devices may report on their own behalf, or for
other connected devices as described in other use cases.
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2.9. Energy Storage Devices
There are two types of devices with energy storage: those whose
primary function is to provide power to another device (e.g. a
UPS), and those with a different primary function, but have an
energy storage as a component as an alternate internal power
source (e.g. a notebook). This use case covers both types of
products.
The energy storage can be a conventional battery, or any other
means to store electricity such as a hydrogen cell.
An internal battery can be a back-up or an alternative source of
power to mains power. As batteries have a finite capacity and
lifetime, means for reporting the actual charge, age, and state
of a battery are required. An internal battery can be viewed as
a component of a device and thus could have the containment
relationship from an ENTITY-MIB perspective to the device that
contains the battery
Battery systems are used in mobile telecom towers including for
use in remote locations. It is important to monitor the
remaining battery life and raise an alarm when the battery life
is below a threshold.
The essential properties of this use case are:
. Target devices: Devices that have an internal battery
. How powered: From internal batteries or mains power
. Reporting: The device reports on its internal battery
2.10. Industrial Automation Networks
Energy consumption statistics in the industrial sector are
staggering. The industrial sector alone consumes about half of
the world's total delivered energy, and a significant user of
electricity. Thus, the need for optimization of energy usage in
this sector is natural.
Industrial facilities consume energy in process loads, and in
non-process loads.
The essential properties of this use case are:
. Target devices: Devices used in industrial automation
. How powered: Any method.
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. Reporting: Currently, CIP protocol is currently used for
reporting energy for these devices
2.11. Printers
This use case describes the scenario of energy monitoring and
management of printers.
Printers in this use case stand in for all imaging equipment,
also including multi-function devices (MFDs), copiers, scanners,
fax machines, and mailing machines.
Energy use of printers has been an industry concern for several
decades, and they usually have sophisticated power management
with a variety of low-power modes, particularly for managing
energy-intensive thermo-mechanical components. Printers also
have long made extensive use of SNMP for end-user system
interaction and for management generally, and cross-vendor
management systems manage fleets of printers in enterprises.
Power consumption during active modes can vary widely, with high
peak levels.
Printers can expose detailed power state information, distinct
from operational state information, with some printers reporting
transition states between stable long-term states. Many also
support active setting of power states, and setting of policies
such as delay times when no activity will cause automatic
transition to a lower power mode. Other features include
reporting on components, counters for state transitions, typical
power levels by state, scheduling, and events/alarms.
Some large printers also have a "Digital Front End" which is a
computer that performs functions on behalf of the physical
imaging system. These typically have their own presence on the
network and are sometimes separately powered.
There are some unique characteristics of printers from the point
of view energy management. While the printer is not in use,
there are timer based low power states, which consume very
little power. On the other hand, while the printer is printing
or copying the cylinder needs to be heated so that power
consumption is quite high but only for a short period of time
(duration of the print job). Given this work load, periodic
polling of power levels alone would not suffice.
The essential properties of this use case are:
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. Target devices: All imaging equipment.
. How powered: Typically AC from a wall outlet.
. Reporting: Devices report for themselves by implementing
[EMAN-MONITORING-MIB].
2.12. Off-Grid Devices
This use case concerns self-contained devices that use energy
but are not connected to an infrastructure power delivery grid.
These devices typically scavenge energy from environmental
sources such as solar energy or wind power. The device generally
contains a closely coupled combination of
. power scavenging or generation component(s)
. power storage component(s) (e.g., battery)
. power consuming component(s)
With scavenged power, the energy input is often dependent on the
random variations of the weather. These devices therefore
require energy management both for internal control and remote
reporting of their state. In order to optimize the performance
of these devices and minimize the costs of the generation and
storage components, it is desirable to vary the activity level,
and, hopefully, the energy requirements of the consuming
components in order to make best use of the available stored and
instantaneously generated energy. With appropriate energy
management, the overall device can be optimized to deliver an
appropriate level of service without over provisioning the
generation and storage components.
In many cases these devices are expected to operate
autonomously, as continuous communications for the purposes of
remote control is either impossible or would result in excessive
power consumption. Non continuous polling requires the ability
to store and access later the information collected while the
communication was not possible.
The essential properties of this use case are:
Target Devices: Remote network devices (mobile network) that
consume and produce energy
How Powered: Can be battery powered or using natural energy
sources
Reporting: Devices report their power usage but only
occasionally.
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2.13. Demand/Response
Demand/Response from the utility or grid is a common theme that
spans across some of the use cases. In some situations, in
response to time-of-day fluctuation of energy costs or sudden
energy shortages due power outages, it may be important to
respond and reduce the energy consumption of the network.
From EMAN use case perspective, the demand/response scenario can
apply to a Data Center or a Building or a residential home. As a
first step, it may be important to monitor the energy
consumption in real-time of a Data center, building or home
which is already discussed in the previous use cases. Then based
on the potential energy shortfall, the Energy Management System
(EMS) could formulate a suitable response, i.e., the EMS could
shut down some selected devices that may be considered
discretionary or uniformly reduce the power supplied to all
devices. For multi-site data centers it may be possible to
formulate policies such as follow-the-moon type of approach, by
scheduling the mobility of VMs across Data centers in different
geographical locations.
2.14. Power Capping
Power capping is a technique to limit the total power
consumption of a server. This technique can be useful for power
limited data centers. Based on workload measurements, the server
can choose the optimal power state of the server in terms of
performance and power consumption. When the server operates at
less than the power supply capacity, it runs at full speed. When
the server power would be greater than the power supply
capacity, it runs at a slower speed so that its power
consumption matches the available power supply capacity. This
gives vendors the option to use smaller, cost-effective power
supplies that allow real world workloads to run at nominal
themselves.
3. Use Case Patterns
The use cases presented above can be abstracted to the following
broad patterns.
3.1. Metering
-energy objects which have capability for internal metering
- energy objects which are metered by an external device
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3.2. Metering and Control
- energy objects that do not supply power, but can perform only
power metering for other devices
- energy objects that do not supply power, but can perform both
metering and control for other devices
3.3. Power Supply, Metering and Control
- energy objects that supply power for other devices but do not
perform power metering for those devices
- energy objects that supply power for other devices and also
perform power metering
- energy objects supply power for other devices and also perform
power metering and control for other devices
3.4. Multiple Power Sources
- energy objects that have multiple power sources and metering
and control is performed by one source
- energy objects that have multiple power sources and metering
is performed by one source and control another source
4. Relationship of EMAN to other Standards
EMAN as a framework is tied to other standards and efforts that
deal with energy. Existing standards are leveraged when
possible. EMAN helps enable adjacent technologies such as Smart
Grid.
The standards most relevant and applicable to EMAN are listed
below with a brief description of their objectives, the current
state and how that standard relates to EMAN.
4.1. Data Model and Reporting
4.1.1. IEC - CIM
The International Electro-technical Commission (IEC) has
developed a broad set of standards for power management. Among
these, the most applicable to EMAN is IEC 61850, a standard for
the design of electric utility automation. The abstract data
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model defined in 61850 is built upon and extends the Common
Information Model (CIM). The complete 61850 CIM model includes
over a hundred object classes and is widely used by utilities
worldwide.
This set of standards was originally conceived to automate
control of a substation (facilities which transfer electricity
from the transmission to the distribution system). While the
original domain of 61850 is substation automation, the extensive
data model has been widely used in other domains, including
Energy Management Systems (EMS).
IEC TC57 WG19 is an ongoing working group to harmonize the CIM
data model and 61850 standards.
Concepts from IEC Standards have been reused in the EMAN WG
drafts. In particular, AC Power Quality measurements have been
reused from IEC 61850-7-4. The concept of Accuracy Classes for
measure of power and energy has been adapted from ANSI C12.20
and IEC standards 62053-21 and 62053-22.
4.1.2. DMTF
The Distributed Management Task Force (DMTF)[DMTF] has
standardized management solutions for managing servers and PCs,
including power-state configuration and management of elements
in a heterogeneous environment. These specifications provide
physical, logical and virtual system management requirements for
power-state control.
The EMAN Framework references the DMTF Power Profile and Power
State Set.
4.1.2.1. Common Information Model Profiles
The DMTF uses CIM-based (Common Information Model) 'Profiles' to
represent and manage power utilization and configuration of
managed elements (note that this is not the 61850 CIM). Key
profiles for energy management are 'Power Supply' (DSP 1015),
'Power State' (DSP 1027) and 'Power Utilization Management' (DSP
1085).These profiles define monitoring and configuration of a
Power Managed Element's static and dynamic power saving modes,
power allocation limits and power states, among other features.
Reduced power modes can be established as static or dynamic.
Static modes are fixed policies that limit power use or
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utilization. Dynamic power saving modes rely upon internal
feedback to control power consumption.
Power states are eight named operational and non operational
levels. These are On, Sleep-Light, Sleep-Deep, Hibernate, Off-
Soft, and Off-Hard. Power change capabilities provide
immediate, timed interval, and graceful transitions between on,
off, and reset power states. Table 3 of the Power State Profile
defines the correspondence between the ACPI and DMTF power state
models, although it is not necessary for a managed element to
support ACPI. Optionally, a TransitingToPowerState property can
represent power state transitions in progress.
4.1.2.2. DASH
DMTF DASH [DASH] (Desktop And Mobile Architecture for System
Hardware) addresses managing heterogeneous desktop and mobile
systems (including power) via in-band and out-of-band
communications. DASH provides management and control of managed
elements like power, CPU, etc. using the DMTF's WS-Management
web services and CIM data model.
Both in service and out-of-service systems can be managed with
the DASH specification in a fully secured remote environment.
Full power lifecycle management is possible using out-of-band
management.
4.1.3. ODVA
The Open DeviceNet Vendors Association (ODVA) is an association
for industrial automation companies and defines the Common
Industrial Protocol (CIP). Within ODVA, there is a special
interest group focused on energy.
The Open DeviceNet Vendors Association (ODVA) is developing an
energy management framework for the industrial sector. There
are synergies between the ODVA and EMAN approaches to energy
management.
There are many similar concepts between the ODVA and EMAN
frameworks towards monitoring and management of energy aware
devices. In particular, one of the concepts being considered
different energy meters based on if the device consumes
electricity or produces electricity or a passive device.
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ODVA defines a three-part approach towards energy management:
awareness of energy usage, consuming energy more efficiently,
and exchanging energy with the utility or others. Energy
monitoring and management promote efficient consumption and
enable automating actions that reduce energy consumption.
The foundation of the approach is the information and
communication model for entities. An entity is a network-
connected, energy-aware device that has the ability to either
measure or derive its energy usage based on its native
consumption or generation of energy, or report a nominal or
static energy value.
4.1.4. Ecma SDC
The Ecma International committee on Smart Data Centre (TC38-TG2
SDC [Ecma-SDC]) is in the process of defining semantics for
management of entities in a data center such as servers,
storage, and network equipment. It covers energy as one of many
functional resources or attributes of systems for monitoring and
control. It only defines messages and properties, and does not
reference any specific protocol. Its goal is to enable
interoperability of such protocols as SNMP, BACNET, and HTTP by
ensuring a common semantic model across them. Four power states
are defined, Off, Sleep, Idle and Active. The standard does not
include actual energy or power measurements in kWor kWh.
The 14th draft of SDC process was published in March 2011 and
the development of the standard is still underway. When used
with EMAN, the SDC standard will provide a thin abstraction on
top of the more detailed data model available in EMAN.
4.1.5. IEEE-ISTO Printer Working Group (PWG)
The IEEE-ISTO Printer Working Group (PWG) defines SNMP MIB
modules for printer management and has recently defined a "PWG
Power Management Model for Imaging Systems v1.0" [PWG5106.4] and
a companion SNMP binding in the "PWG Imaging System Power MIB
v1.0" [PWG5106.5]. This PWG model and MIB are harmonized with
the DMTF CIM Infrastructure [DSP0004] and DMTF CIM Power State
Management Profile [DSP1027] for power states and alerts.
The PWG would like its MIBs to be harmonized as closely as
possible with those from EMAN. The PWG covers many topics in
greater detail than EMAN, as well as some that are specific to
imaging equipment. The PWG also provides for vendor-specific
extension states (i.e., beyond the standard DMTF CIM states.)
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4.1.6. ASHRAE
In the U.S., there is an extensive effort to coordinate and
develop standards related to the "Smart Grid". The Smart Grid
Interoperability Panel, coordinated by the government's National
Institute of Standards and Technology, identified the need for a
building side information model (as a counterpart to utility
models) and specified this in Priority Action Plan (PAP) 17.
This was designated to be a joint effort by American Society of
Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)
and National Electrical Manufacturers Association (NEMA), both
ANSI approved SDO's. The result is to be an information model,
not a device level monitoring protocol.
The ASHRAE effort addresses data used only within a building as
well as data that may be shared with the grid, particularly as
it relates to coordinating future demand levels with the needs
of the grid. The model is intended to be applied to any
building type, both residential and commercial. It is expected
that existing protocols will be adapted to comply with the new
information model, as would any new protocols.
There are four basic types of entities in the model: generators,
loads, meters, and energy managers.
The metering part of this model overlaps with the EMAN framework
to a large degree, though there are features unique to each.
The load part speaks to control capabilities well beyond what
EMAN covers. Details of generation and of the energy management
function are outside of EMAN scope.
A public review draft of the ASHRAE standard is expected soon,
and at that point detailed comparison of the two models can be
made. There are no apparent major conflicts between the two
approaches, but there are likely areas where some harmonization
is possible, and regardless, a description of the
correspondences would be helpful to create.
4.1.7. ZigBee
The Zigbee Smart Energy 2.0 effort[ZIGBEE] focuses on wireless
communication to appliances and lighting. Zigbee 1.x is not
based on IP, whereas Zigbee 2.0 is supposed to interoperate with
IP. It is intended to enable building energy management and
enable direct load control by utilities.
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ZigBee protocols are intended for use in embedded applications
requiring low data rates and low power consumption. ZigBee
defines a general-purpose, inexpensive, self-organizing mesh
network that can be used for industrial control, embedded
sensing, medical data collection, smoke and intruder warning,
building automation, home automation, etc.
Zigbee is currently not an ANSI recognized SDO.
The EMAN framework addresses the needs of IP-enabled networks
through the usage of SNMP, while Zigbee looks for completely
integrated and inexpensive mesh solution.
4.2. Measurement
4.2.1. ANSI C12
The American National Standards Institute (ANSI) has defined a
collection of power meter standards under ANSI C12. The primary
standards include communication protocols (C12.18, 21 and 22),
data and schema definitions (C12.19), and measurement accuracy
(C12.20). European equivalent standards are provided by IEC
62053-22.ANSI C12.20 defines accuracy classes for watt-hour
meters.
All of these standards are oriented toward the meter itself, and
are therefore very specific and used by electricity distributors
and producers.
The EMAN standard references ANSI C12 accuracy classes.
4.2.2. IEC62301
IEC 62301, "Household electrical appliances Measurement of
standby power", [IEC62301] specifies a power level measurement
procedure. While nominally for appliances and low-power modes,
many aspects of it apply to other device types and modes and
it is commonly referenced in test procedures for energy using
products.
While the standard is intended for laboratory measurements of
devices in controlled conditions, many aspects of it are
informative to those implementing measurement in products that
ultimately report via EMAN.
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4.3. Other
4.3.1. ISO
The ISO [ISO] is developing an energy management standard, ISO
50001, to complement ISO 9001 for quality management, and ISO
14001 for environment management. The intent of the framework is
to facilitate the creation of energy management programs for
industrial, commercial and other entities. The standard defines
a process for energy management at an organization level. It
does not define the way in which devices report energy and
consume energy.
ISO 50001 is based on the common elements found in all of ISO's
management system standards, assuring a high level of
compatibility with ISO 9001 (quality management) and ISO 14001
(environmental management). ISO 50001 benefits includes:
o Integrating energy efficiency into management practices and
throughout the supply chain
o Energy management best practices and good energy management
behaviors
o benchmarking, measuring, documenting, and reporting energy
intensity improvements and their projected impact on
reductions in greenhouse gas (GHG) emissions
o Evaluating and prioritizing the implementation of new energy-
efficient technologies
ISO 50001 has been developed by ISO project committee ISO/PC
242, Energy management. EMAN is complementary to ISO 9001.
4.3.2. EnergyStar
The US Environmental Protection Agency (EPA) and US Department
of Energy (DOE) jointly sponsor the Energy Star program [ESTAR].
The program promotes the development of energy efficient
products and practices.
To qualify as Energy Star, products must meet specific energy
efficiency targets. The Energy Star program also provides
planning tools and technical documentation to encourage more
energy efficient building design. Energy Star is a program; it
is not a protocol or standard.
For businesses and data centers, Energy Star offers technical
support to help companies establish energy conservation
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practices. Energy Star provides best practices for measuring
current energy performance, goal setting, and tracking
improvement. The Energy Star tools offered include a rating
system for building performance and comparative benchmarks.
There is no immediate link between EMAN and EnergyStar, one
being a protocol and the other a set of recommendations to
develop energy efficient products. However, Energy Star could
include EMAN standards in specifications for future products,
either as required or rewarded with some benefit.
4.3.3. SmartGrid
The Smart Grid standards efforts underway in the United States
are overseen by the US National Institute of Standards and
Technology [NIST].NIST is responsible for coordinating a public-
private partnership with key energy and consumer stakeholders in
order to facilitate the development of smart grid standards. The
NIST smart grid standards activities are monitored and
facilitated by the SGIP (Smart Grid Interoperability Panel).
This group has working groups for specific topics including
homes, commercial buildings, and industrial facilities as they
relate to the grid. A stated goal of the group is to harmonize
any new standard with the IEC CIM and IEC 61850.
When a working group detects a standard or technology gap, the
team seeks approval from the SGIP for the creation of a Priority
Action Plan (PAP), a private-public partnership to close the
gap. There are currently 17 PAPs. PAP 17 is discussed in
section 4.1.6.
PAP 10 addresses "Standard Energy Usage Information".
Smart Grid standards will provide distributed intelligence in
the network and allow enhanced load shedding. For example,
pricing signals will enable selective shutdown of non critical
activities during peak-load pricing periods. These actions can
be effected through both centralized and distributed management
controls.
There is an obvious functional link between SmartGrid and EMAN
in the form of demand response, even if the EMAN framework does
not take any specific step toward SmartGrid communication. As
EMAN framework enables control, it can be used to realize power
savings in the demand response through translation of a signal
from an outside entity.
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5. Limitations
EMAN Framework addresses the needs of energy monitoring in terms
of measurement and, considers limited control capabilities of
energy monitoring of networks.
EMAN does not create a new protocol stack, but rather defines a
data and information model useful for measuring and reporting
energy and other metrics over SNMP.
The EMAN framework does not address questions regarding
SmartGrid, electricity producers, and distributors even if there
is obvious link between them.
6. Security Considerations
EMAN shall use SNMP protocol for energy management and thus has
the functionality of SNMP's security capabilities. SNMPv3
[RFC3411] provides important security features such as
confidentiality, integrity, and authentication.
7. IANA Considerations
This memo includes no request to IANA.
8. Acknowledgements
Firstly, the authors would like thank Emmanuel Tychon for taking
the lead on this draft and his contributions towards to this
draft.
The authors would like to thank Jeff Wheeler, Benoit Claise,
Juergen Quittek, Chris Verges, John Parello, and Matt Laherty,
for their valuable contributions.
The authors would like to thank Georgios Karagiannis for use
case involving energy neutral homes, Elwyn Davies for off-grid
electricity systems, and Kerry Lynn for the comment on the
Demand/Response scenario.
9. Open Issues
OPEN ISSUE 1: Relevant IEC standards for application for EMAN
Applicability Statement document can provide guidance on the
issue of what is appropriate standard used by EMAN
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IEC 61850-7-4 has been extensively used in EMAN WG documents.
The other IEC documents referred for possible use are IEC
61000-4-30, IEC 62053-21 and IEC 62301.
There is feedback that IEC 61850-7-4 applies only to sub-
stations ?
OPEN ISSUE 2: Should review ASHRAE SPC 201P standard when it is
released for public review
. Need to review ASHRAE information model and the use cases
and how it relates to EMAN
OPEN ISSUE 3: Review ALL requirements to ensure that they can be
traced to a use case
. Missing is an use case for power characteristics
OPEN ISSUE 4: Should the Applicability Statement cover concepts
that are only developed to implement the requirements in the
framework, or only cover concepts that already are well-defined?
If the latter, this would suggest not including "energy object"
(instead refer to devices and components), and not include
"parent/child" (instead refer generically to relationships).
OPEN ISSUE 5: Should the terminology document be referenced,
since it will disappear once the definitions are put into each
relevant draft?
OPEN ISSUE 6: Should use cases be included if they do not add
any requirements and so are redundant with previous use cases?
10. References
10.1. Normative References
[RFC3411] An Architecture for Describing Simple Network
Management Protocol (SNMP) Management Frameworks, RFC
3411, December 2002.
[RFC3621] Power Ethernet MIB, RFC 3621, December 2003.
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10.2. Informative References
[DASH] "Desktop and mobile Architecture for System Hardware",
http://www.dmtf.org/standards/mgmt/dash/
[NIST] http://www.nist.gov/smartgrid/
[Ecma-SDC] Ecma TC38 / SDC Task Group, "Smart Data Centre
Resource Monitoring and Control (DRAFT)", March 2011.
[EMAN-AS] Tychon, E., B. Schoening, Mouli Chandramouli, Bruce
Nordman, "Energy Management (EMAN) Applicability
Statement", draft-tychon-eman-applicability-statement-
05.txt, work in progress, October 2011.
[EMAN-REQ] Quittek, J., Winter, R., Dietz, T., Claise, B., and
M. Chandramouli, "Requirements for Energy Management ",
draft-ietf-eman-requirements-05 (work in progress),
October 2011.
[EMAN-MONITORING-MIB] M. Chandramouli, Schoening, B., Dietz, T.,
Quittek, J. and B. Claise "Power and Energy Monitoring
MIB ", draft-ietf-eman-energy-monitoring-mib-00,
October 2011.
[EMAN-AWARE-MIB] J. Parello, and B. Claise, "draft-ietf-eman-
energy-aware-mib-03", work in progress, October 2011.
[EMAN-FRAMEWORK] Claise, B., Parello, J., Schoening, B., and J.
Quittek, "Energy Management Framework", draft-ietf-
eman-framework-03 , October 2011.
[EMAN-BATTERY-MIB] Quittek, J., Winter, R., and T. Dietz,
"Definition of Managed Objects for Battery Monitoring"
draft-ietf-eman-battery-mib-04.txt, October 2011.
[EMAN-DEF] J. Parello"Energy Management Terminology", draft-
parello-eman-definitions-03.
[DMTF] "Power State Management ProfileDMTFDSP1027 Version 2.0"
December2009.
http://www.dmtf.org/sites/default/files/standards/docum
ents/DSP1027_2.0.0.pdf
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[ESTAR] http://www.energystar.gov/
[ISO] http://www.iso.org/iso/pressrelease.htm?refid=Ref1434
[ASHRAE] http://collaborate.nist.gov/twiki-
sggrid/bin/view/SmartGrid/PAP17Information
[ZIGBEE] http://www.zigbee.org/
[ISO] http://www.iso.org/iso/pressrelease.htm?refid=Ref1337
[DSP0004] DMTF Common Information Model (CIM) Infrastructure,
DSP0004, May 2009.
http://www.dmtf.org/standards/published_documents/DSP00
04_2.5.0.pdf
[DSP1027] DMTF Power State Management Profile, DSP1027, December
2009.
http://www.dmtf.org/standards/published_documents/DSP10
27_2.0.0.pdf
[PWG5106.4] IEEE-ISTO PWG Power Management Model for Imaging
Systems v1.0, PWG Candidate Standard 5106.4-2011,
February 2011.ftp://ftp.pwg.org/pub/pwg/candidates/cs-
wimspower10-20110214-5106.4.mib
[PWG5106.5] IEEE-ISTO PWG Imaging System Power MIB v1.0, PWG
Candidate Standard 5106.5-2011, February 2011.
[IEC62301] International Electrotechnical Commission, "IEC 62301
Household electrical appliances Measurement of standby
power", Edition 2.0, 2011.
[MODBUS] Modbus-IDA, "MODBUS Application Protocol
Specification V1.1b", December 2006.
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Authors' Addresses
Brad Schoening
44 Rivers Edge Drive
Little Silver, NJ 07739
USA
Email:brad@bradschoening.com
Mouli Chandramouli
Cisco Systems, Inc.
Sarjapur Outer Ring Road
Bangalore,
India
Phone: +91 80 4426 3947
Email: moulchan@cisco.com
Bruce Nordman
Lawrence Berkeley National Laboratory
1 Cyclotron Road, 90-4000
Berkeley 94720-8136
USA
Phone: +1 510 486 7089
Email: bnordman@lbl.gov
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