Networking Working Group J. Martocci
Internet-Draft Johnson Controls Inc.
Intended status: Informational Anthony Schoofs
Expires: January 8, 2011 University College Dublin
Peter van der Stok
Philips Research Laboratories
July 8, 2010
Commercial Building Applications Requirements
draft-martocci-6lowapp-building-applications-01
Abstract
Building management systems have evolved toward IP communication at
the enterprise level during the past decade. IP implementation at
the real-time control and sensor layers would provide a single
pervasive protocol usable across the entire system increasing
flexibility and code reuse. This document will describe the topology
of these building networks, the application protocols widely used in
their deployment and the application use cases.
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Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Terminology....................................................4
2. Overview.......................................................5
3. FMS Topology...................................................6
3.1. Introduction..............................................6
3.2. Sensors/Actuators.........................................8
3.3. Area Controllers..........................................8
3.4. Zone Controllers..........................................9
3.5. Building Controllers......................................9
4. FMS Communication Media........................................9
5. FMS Communication Protocols...................................10
5.1. Controller/Sensor/Actuator Communication Protocol........10
5.2. Enterprise Communication Protocol........................11
5.2.1. Peer-to-peer Controller Communication...............11
5.2.2. Enterprise Communication............................11
6. FMS Device Density............................................11
6.1. HVAC Device Density......................................12
6.2. Fire Device Density......................................12
6.3. Lighting Device Density..................................12
6.4. Physical Security Device Density.........................13
7. FMS Installation Methods......................................13
8. Building Application Use Cases................................14
8.1. Fire and Smoke Abatement.................................14
8.2. Evacuation...............................................15
8.3. Occupancy/shutdown.......................................16
8.4. Energy Management........................................17
8.5. Fault Detection and Diagnostics..........................17
9. Building Application Protocol Requirements....................18
9.1. Physical Layer Requirements..............................18
9.1.1. Wired and Wireless Implementations..................18
9.1.2. Cost Effective Wired Installation...................18
9.1.3. Cost Effective Wireless Installation................18
9.1.4. Global Wireless Applicability.......................18
9.1.5. Constrained Power Sensors...........................18
9.2. Network Layer Requirements...............................19
9.2.1. TCP/UDP.............................................19
9.2.2. Fragmentation.......................................19
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9.2.3. Data Rate Performance...............................19
9.2.4. Interference Mitigation.............................19
9.2.5. Real-time Performance Measures......................19
9.2.6. Packet Reliability..................................19
9.2.7. Packet Routing......................................20
9.3. Installation and Commissioning Requirements..............20
9.3.1. Device Setup Time...................................20
9.3.2. Unavailability of an IT network.....................20
9.4. Application Layer Object/Node Requirements...............20
9.4.1. Object Model........................................20
9.4.2. Object Location.....................................20
9.4.3. Node Discovery......................................20
9.4.4. Object Discovery....................................20
9.4.5. Object List.........................................21
9.4.6. Property List.......................................21
9.4.7. Service List........................................21
9.4.8. Consistent Error Reporting..........................21
9.5. Application Layer Solicited Service Requirements.........21
9.5.1. Reading Datum.......................................21
9.5.2. Reading Data from an Object.........................21
9.5.3. Reading Data from Multiple Objects..................21
9.5.4. Reading Data with Wild Cards........................22
9.5.5. Reading Large Data Items............................22
9.5.6. Object Creation and Deletion........................22
9.5.7. Object Property Writing.............................22
9.5.8. Atomic Object Property Writing......................22
9.5.9. Object Property List Writing Addition...............22
9.5.10. Object Property List Writing Deletion..............23
9.5.11. Downloads..........................................23
9.6. Application Layer Unsolicited Service Requirements.......23
9.6.1. Property Value(s) Change Notification...............23
9.6.2. Alarm Notification..................................23
10. Traffic Pattern..............................................23
11. Security Considerations......................................24
12. IANA Considerations..........................................24
13. Acknowledgments..............................................24
14. References...................................................24
14.1. Normative References....................................24
14.2. Informative References..................................24
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1. Terminology
Actuator: A field device that controls and/or modulates a flow
of a gas or liquid; or controls electrical
distribution.
BACnet: Building Automation Control Network. A ISO
application protocol used in building management
systems.
Channel: Radio frequency sub-band used to transmit a modulated
signal carrying packets.
DALI: Digital Addressable Lighting Interface. A protocol
used in lighting systems.
Fire: The term used to describe building equipment used to
monitor, control and evacuate an internal space in
case of a fire situation. Equipment includes smoke
detectors, pull boxes, sprinkler systems and
evacuation control.
FMS: Facility Management System. A global term applied
across all the vertical designations within a building
including, Heating, Ventilating, and Air Conditioning
also referred to as HVAC, Fire, Security, Lighting and
Elevator control.
HVAC: Heating, ventilation and air conditioning. This term
is broadly used to define anything in the building
that addresses air flow and occupant comfort.
Intrusion Protection: A term used to protect resources from
external infiltration. Intrusion protection systems
Lighting: The term used to describe building equipment used to
monitor and control an internal or external lighted
space. Equipment includes occupancy sensors, light
switches and ballasts.
Luminaire: Another term for a light fixture installed in a
ceiling.
MS/TP: Master Slave Token Passing; the EIA-485 data link used
in BACnet. This data link uses a software token
passing mechanism allowing for multiple multi-dropped
masters on the network. A master node can only access
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the media while it secures the token. MS/TP also
supports slave nodes. These less complicated devices
never receive the token and can only address the media
when requested from a master node.
Security: The term used to describe building equipment used to
monitor and control occupant and equipment safety
inside a building. Equipment includes window tamper
switches, door access systems, infrared detection
systems, and video cameras.
2. Overview
Facility Management systems (FMS)are deployed in a wide variety of
commercial building topologies, including single buildings, multi-
building single site environments such as university campuses and
widely dispersed multi-building multi-site environments such as
franchise operations. These buildings range in size from 100K square
feet (10k square meters) structures (5 story office buildings), to
multi-million sqft skyscrapers (110 story Shanghai World Financial
Center) to complex government facilities (Pentagon). The described
topology is meant to be the model to be used in all these types of
environments, but clearly must be tailored to the building class,
building tenant and vertical market being served.
The following sections describe the FMS system architecture from the
lowest layer to the highest layers in the hierarchy. Each section
describes the basic functionality of the layer, its networking model,
power requirements and a brief description of the communication
requirements. The entire section references the block diagram noted
in Figure 1. This figure depicts six major subsystems comprising an
FMS. These subsystems all have layered solutions starting at the
sensor layer and moving upward in complexity toward the enterprise
network layer. While these six subsystems are common to many
facilities, they are by no means the exhaustive list - a chemical
facility may require a complete fume hood management system; a
manufacturing facility may require interfacing to the PLC subsystem;
or a multi-tenant facility might require a comprehensive power
management subsystem. The objective in the architecture is to
integrate all common functions into the system yet allow maximum
flexibility to modify these systems and add other subsystems as
dictated by the customer.
Commercial buildings have been fitted with pneumatic and subsequently
electronic communication pathways connecting sensors to their
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controllers for over one hundred years. Pneumatics were displaced by
simple electronics and dry contacts in the 1960's. Smart processor
based sensors displaced simple contacts in the 1970's. Localized
digital control, introduced in the 1980's allowed applications to
operate independently from the upper layers of the system. Multi-
dropped twisted pair sensor/controller communication networks
displaced high cost cabled networks.
The 1990's ushered in the use of Ethernet IP networks at the
enterprise level. This transition allowed the previously independent
proprietary communication networks to coexist on the enterprise IP
LAN network. This migration reduced installation costs and allowed
pertinent building data to be injected onto the enterprise
application suite. Proprietary protocols were displaced by industry
standard application protocols such as BACnet and LON for HVAC; and
DALI for Lighting.
Recent economic and technical advances in wireless communication
allow facilities to increasingly utilize a wireless solution in lieu
of a wired solution; thereby reducing installation costs while
maintaining highly reliant communication. Wireless solutions will be
adapted from their existing wired counterparts in many of the
building applications including, but not limited to HVAC, Lighting,
Physical Security, Fire, and Elevator systems. These devices will be
developed to reduce installation costs; while increasing installation
and retrofit flexibility. Sensing devices may be battery, scavenged,
or mains powered. Actuators and area controllers will be mains
powered. Today, different networks based on their own standard (e.g.
BACnet, DALI) do not share cabling, sensors or actuators easily. The
arrival of IP for building control will coalesce these topologies.
The objective of this draft is to describe topologies, protocols and
application use cases. It will describe the application benefits and
concerns in converting to pervasive IP networks. It will further
describe the IP services required to operate these systems. Finally,
it will describe how the building data and IT data models might
converge to allow a free flowing of data on the converged FMS/IT
network.
3. FMS Topology
3.1. Introduction
To understand the network systems requirements of an FMS in a
commercial building, this document uses a framework to describe the
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basic functions and composition of the system. An FMS is a
horizontally layered system of sensors, actuators, controllers and
user interface devices orchestrated to work together over selected
communication media. Additionally, an FMS may also be divided
vertically across alike, but different building subsystems such as
HVAC, Fire, Security, Lighting, Shutters and Elevator control systems
as denoted in Figure 1. These distinct areas are termed 'silos'.
Currently, the separation between the silos is rather sharp. Gateways
provide connections between the silos to support all encompassing
applications. With future IP deployment applications will have a flat
addressing space for accessing all nodes in any silo.
Much of the makeup of an FMS is optional and installed as required by
the customer. These systems are expensive and must be designed to
allow for incremental purchases as dictated by the customer's budget
cycle.
Sensors and actuators have no standalone functionality. All other
devices support partial or complete standalone functionality. These
devices can optionally be tethered to form a more cohesive system.
The customer requirements dictate the level of integration within the
facility. This architecture provides excellent fault tolerance since
each node is designed to operate independently but will accept
overrides from the higher layers when the higher layers are
available.
Heating, Ventilation and Air Conditioning (HVAC); Fire; Security and
Lighting are components that can be tethered together into a cohesive
set of all encompassing applications tailored to the customer's whim.
Shutter control is an emerging application domain prevalent in the
European market. These major subsystems are connected logically
through application software called Building Applications.
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+------+ +-----+ +------+ +------+ +------+ +------+
Bldg App'ns | | | | | | | | | | | |
| | | | | | | | | | | |
Building Cntl | | | | | S | | L | | S | | E |
| | | | | E | | I | | H | | L |
Zone Control | H | | F | | C | | G | | U | | E |
| V | | I | | U | | H | | T | | V |
Area Control | A | | R | | R | | T | | T | | A |
| C | | E | | I | | I | | E | | T |
Actuators | | | | | T | | N | | R | | O |
| | | | | Y | | G | | S | | R |
Sensors | | | | | | | | | | | |
+------+ +-----+ +------+ +------+ +------+ +------+
Figure 1 - Building Systems and Devices
3.2. Sensors/Actuators
An FMS may be composed of many functional stacks or silos that are
interoperably woven together via Building Applications. Each silo
has an array of sensors that monitor the environment and actuators
that effect the environment as determined by the upper layers of the
FMS topology. The sensors typically are the leaves of the network
tree structure providing environmental data into the system. The
actuators are the sensors' counterparts modifying the characteristics
of the system based on the input sensor data and the applications
deployed.
3.3. Area Controllers
An area describes a small physical locale within a building,
typically a room. Public spaces such as hallways and atria are also
controlled by area controllers. The HVAC, Security and Lighting
functions within a building address area or room level applications
running in the area controllers. Area controls are fed by sensor
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inputs that monitor the environmental conditions within the room.
Common sensors found in many rooms that feed the area controllers
include temperature, occupancy, lighting load, solar load and
relative humidity. Sensors found in specialized rooms (such as
chemistry labs) might include air flow, pressure, CO2 and CO particle
sensors. Room actuation includes temperature setpoint, lights and
blinds/curtains.
3.4. Zone Controllers
Zone Control supports a similar set of characteristics as the Area
Control albeit to an extended space. A zone is normally a logical
grouping or functional division of a commercial building. A zone may
also coincidentally map to a physical locale such as a floor.
Zone Control may have direct sensor inputs (smoke detectors for
fire), controller inputs (room controllers for air-handlers in HVAC)
or both (door controllers and tamper sensors for security). Like
area/room controllers, zone controllers are standalone devices that
operate independently or may be attached to the larger network for
more synergistic control.
3.5. Building Controllers
Building Controllers orchestrate the overall building control. These
devices provide higher level functionality such as web servers,
scheduling, time series data archival, energy monitoring and
reduction, and alarm management. Additionally they will cooperate
with the other silos to provide synergistic applications as noted in
the use case sections that follow.
4. FMS Communication Media
Today most FMSs communicate over four media; DALI, EIA-485, Ethernet
and wireless.
For HVAC instrumentation, sensors, actuators, area controllers, zone
controllers, and building controllers most often connect via EIA-485
3-wire twisted pair serial media operating nominally at 38400 to
76800 baud. This allows runs to 5000 ft without a repeater. With the
maximum of two repeaters, a single multi-dropped communication trunk
can serpentine 15000 ft.
For lighting the DALI standard provides a 5-wire cable containing
control and power-supply lines. Up to 64 control units can be
connected to one line. The maximum distance between two directly
connected DALI devices is 300m operating at 1200 bits/s.
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The HVAC, Fire, Access, Intrusion and Lighting subsystems are
integrated using LAN based Ethernet technology. These enterprise
devices connect to standard Cat-5e through workgroup switches. WLAN
communications can replace the Ethernet connection if the application
can operate within the WLAN performance characteristics. Currently
building controllers typically support a RJ-45 connection. WLAN
connections require an external wireless bridge. Multi-building
sites can also connect onto the facility intranet if the intranet
performance matches the application requirements.
Recently sensors, area controllers and zone controllers have been
deployed on wireless mesh systems. 802.15.4 based mesh systems seem
to be the technology of choice by most manufacturers due to the cost
point of the radio technology and communication robustness.
5. FMS Communication Protocols
5.1. Controller/Sensor/Actuator Communication Protocol
The sensors, actuators, area controllers, zone controllers, and
building controllers all utilize BACnet, DALI, or LON protocol.
BACnet is an ISO world-wide Standard application layer protocol
designed to maximize interoperability across many products, systems
and vendors in commercial buildings. BACnet was conceived in 1987
and released in 1995 for the HVAC industry. Since that time Fire,
Security and Lighting functionality has been added.
BACnet supports six media types including Ethernet (802.3 and IP),
EIA-485, Arcnet, LON, RS-232 and ZigBee.
BACnet supports all expected network services including functions
such as device and object discovery; unicast and broadcast messaging;
full routing; flow control and fragmentation; and network security.
BACnet MS/TP is the BACnet data link for EIA-485 networks. MS/TP is
a token passing protocol (implemented in software) allowing
master/slave and peer-to-peer communication simultaneously. Devices
must designate themselves as slaves or masters on the network. Slave
devices may only access the network when solicited by a master
device. Masters may communicate to any node on the network whenever
it holds the token. BACnet MS/TP has a 1-octet MAC address allowing
for a maximum of 254 devices per network segment. (Address 255 is
reserved for broadcast designation).
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BACnet/IP addressing currently supports IPv4 addressing only. An
IPv6 working group has been commissioned by the BACnet Committee to
develop the needed changes for BACnet to support IPv6.
The DALI standard was conceived in the late 1990 and consolidated in
the IEC 62386 standard (formerly IEC 60929). DALI network is ordered
in 16 groups of each maximally 64 devices. 16 scenes can be defined
grouping sets of devices together to receive the same command
sequences. A DALI network is usually a lighting subnet connected to
the building network with a LON DALI gateway.
5.2. Enterprise Communication Protocol
Multiple protocols are supported at the enterprise level of the FMS
since this layer supports both the embedded control operation and the
user interface.
5.2.1. Peer-to-peer Controller Communication
Building Controllers orchestrate the overall FMS system operations.
Control and data access functions implemented at this level utilize
BACnet IP. BACnet IP provides the complete building object model and
requisite services across all the FMS silos. Since BACnet is
deployed on the lower layers of the system, utilizing it to control
operations at the highest layer of the system is prudent. BACnet IP
implements UDP/IP with its own transport layer. It is designed to
operate efficiently and transparently on all IP networks.
5.2.2. Enterprise Communication
While BACnet and LON are the control protocols of choice; it is out
of scope for most enterprise applications. Web Services and SNMP
frequently is added to the enterprise layer to assist in integration
with end-user applications and Network Management Systems
respectively. The enterprise level also supports most ancillary IT
protocols such as SMTP, SNTP, DHCP and DNS.
6. FMS Device Density
Device density differs depending on the application and code
requirements. The following sections detail typical installation
densities for different applications.
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6.1. HVAC Device Density
HVAC room applications typically have sensors and controllers spaced
about 50ft apart. In most cases there is a 3:1 ratio of sensors to
controllers. That is, for each room there is an installed
temperature sensor, flow sensor and damper controller for the
associated room controller.
HVAC equipment room applications are quite different. An air handler
system may have a single controller with upwards to 25 sensors and
actuators within 50 ft of the air handler. These sensors may include
a discharge air temperature, a static pressure sensor, a CO sensor, a
CO2 sensor, a return air temperature and a mixed air temperature.
A chiller or boiler is also controlled with a single equipment
controller instrumented with 25 sensors and actuators. Each of these
devices would be individually addressed. Air handlers typically
serve one or two floors of the building. Chillers and boilers may be
installed per floor, but many times service a wing, building or the
entire complex via a central plant. Sensors typically instrumented
on a chiller include chilled water temperature, condenser water
temperature, and pump status.
These numbers are typical. In special cases, such as clean rooms,
operating rooms, pharmaceuticals and labs, the ratio of sensors to
controllers can increase by a factor of three. Tenant installations
such as malls would opt for packaged units where much of the sensing
and actuation is integrated into the unit. Here a single device
address would serve the entire unit.
6.2. Fire Device Density
Fire systems are much more uniformly installed with smoke detectors
installed about every 75 feet. This is dictated by local building
codes. Fire pull boxes are installed uniformly about every 150 feet.
A fire controller will service a floor or wing. The fireman's fire
panel will service the entire building and typically is installed in
the atrium.
6.3. Lighting Device Density
Lighting is also very uniformly installed with ballasts installed
approximately every 10 feet. A lighting panel typically serves 48 to
64 zones. Wired systems typically tether many lights together into a
single zone. Wireless systems configure each fixture independently
to increase flexibility and reduce installation costs.
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6.4. Physical Security Device Density
Security systems are non-uniformly oriented with heavy density near
doors and windows and lighter density in the building interior space.
The recent influx of interior and perimeter camera systems is
increasing the security footprint. These cameras are atypical
endpoints requiring upwards to 1mbps data rates per camera as
contrasted by the few kbps needed by most other FMS sensing
equipment. To date, camera systems have been deployed on a
proprietary wired high speed network or on enterprise VLAN. Camera
compression technology now supports full-frame video over wireless
media.
7. FMS Installation Methods
Wired FMS installation is a multifaceted procedure depending on the
extent of the system and the software interoperability requirement.
Unlike most IP installations, FMSs are installed from the outside-in.
That is the sensors, actuators and controllers are installed first.
Later the Zone Controllers are installed; and finally the system is
connected to the enterprise network.
At the sensor/actuator and controller level, the procedure is
typically a two or three step process. Most FMS equipment is 24 VAC
equipment that can be installed by a low-voltage electrician. He/she
arrives on-site during the construction of the building prior to the
sheet wall and ceiling installation. This allows him/her to allocate
wall space, easily land the equipment and run the wired controller
and sensor networks. The Building Controllers and Enterprise network
are not normally installed until months later. The electrician
completes his task by running a wire verification procedure that
shows proper continuity between the devices and proper local
operation of the devices.
For lighting networks this means that light sensor, presence sensor,
switches, and luminaires are all connected within a room and
sometimes already connected to a room controller. Commissioning is
for DALI executed with a laptop to map network addresses to physical
devices.
Later in the installation cycle, the higher order controllers are
installed, programmed and commissioned together with the previously
installed sensors, actuators and controllers. In most cases the IP
network is still not operable. The Building Controllers are
completely commissioned using a crossover cable or a temporary IP
switch together with static IP addresses.
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Once the IP network is operational, the FMS may optionally be added
to the enterprise network. Wireless installation will necessarily
need to keep the same work flow. The electrician will install the
products as before and run continuity tests between the wireless
devices to assure operation before leaving the job. The electrician
does not carry a laptop so the commissioning must be built into the
device operation.
8. Building Application Use Cases
The Building Application layer is a software layer that binds the
various system silos into a cohesive systemic application. This
discussion in not meant to be inclusive. Rather it is meant to show
how these diverse systems can be coordinated to provide innovated
synergistic applications for the customer safety and comfort.
8.1. Fire and Smoke Abatement
Most local codes now require commercial buildings to incorporate
comprehensive fire and life/safety systems into a building. It is
well documented that loss of life in a building is mainly caused by
smoke inhalation rather than the fire itself. Agencies, such as UL
(in the US market), have developed fire certification programs that
govern fire and smoke operations in commercial buildings. These
programs require very rigorous interactive testing for certification.
In addition to the obvious need to minimize life/safety situations in
a building, facility operators are highly encouraged to implement
these systems due to insurance cost reductions.
The fire and smoke abatement application requires a highly
coordinated interaction between the fire silo and the HVAC silo. The
fire system detects the smoke or fire and reports it to the HVAC
system. While the fire system is issuing evacuation notices,
sounding the alarms and flashing the strobes; the HVAC system
automatically shuts down all fan systems in the immediate area (to
starve the fire) while simultaneously opening all external dampers
and ratcheting up the fans in the adjacent areas to purge the smoke.
Meanwhile, the lighting systems will immediately turn on all safety
lights in the area to assure safe passage for the occupants. It will
also create light trails to assist occupants to the doors.
The physical security system will unlatch all doors to assure
immediate egress of the occupants.
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The elevator control system will either shut off entirely or bypass
normal operation to assist with the emergency responders.
The fire and smoke systems operate in either a manual or automatic
mode. The automatic mode is a preprogrammed set of events that
control the fire automatically. The manual mode provides critical
fire and smoke information at a centralized display to be controlled
by a Fire Marshal. In practice, the fire system will be set to
automatic mode and operate accordingly until the Fire Marshall
arrives. At that point the system is normally overridden to manual
mode so that the Fire Marshall can control operations from the
command center as deemed necessary.
While the smoke abatement operation could be the province of the fire
system alone, economics dictate that the fire system off-loads the
smoke abatement operation to the HVAC system. In practice, the fire
system will receive the initial fire indication by one or more of its
smoke detectors. It will then inform the HVAC system of the physical
locale of the fire. The HVAC system will then take charge of the
smoke abatement operation by automatically adjusting the air handlers
and dampers. The HVAC system must incorporate a comprehensive
prioritization scheme throughout its system. This prioritization
scheme must allow all smoke operations to take control precedence
over all other control operations including manual operator control.
All affected devices must support a supervision policy that assures
that all operations requested were executed properly. The system
must automatically return to well-defined normal operational state
once the smoke situation has abated.
8.2. Evacuation
Evacuation is another systemic operation that may be activated as
part of the Fire/Smoke Control application, or may be activated for
other reasons such as terrorist threats. Evacuation requirements
most often will activate subsystems of the Fire, Security and
Lighting silos. The Fire system normally supports the intercom
subsystem in the facility. The intercom system will then trigger the
recorded voice evacuation instructions. This may be in concert with
the fire system audio indications if a fire situation is active or
standalone. The lighting subsystem will be activated to turn on the
lights and evacuation paths to aid in the evacuation. The security
system will coincidentally open all doors to allow a smooth safe
egress from the building. If the building also supports elevator
control, the elevators will operates as directed by a preprogrammed
evacuation policy.
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8.3. Occupancy/shutdown
A major energy saving technique in commercial buildings is to
automatically commence HVAC and lighting operations prior to building
occupancy. Conversely, building shutdown allows the systematic
reduction in HVAC and lighting operations as the building becomes
unoccupied.
The HVAC system is usually charged with defining occupied and
unoccupied times. The Fire and Security operations are always
operable and lighting is most often subservient to HVAC.
Occupied/unoccupied schedules are typically programmed into the
system by facility operations; however, it could be learned
adaptively by the security's access control system. The target
occupancy time drives the HVAC subsystem to turn on all ventilation
equipment at an optimal time so that each space is ready for
occupancy at the prescribed time. These algorithms will be adaptive
over time but also include systemic instrumentation such as outdoor
air and relative humidity to turn on the equipment at the last
possible moment yet still meet the target environmental needs just
before occupancy.
The lighting systems are turned on/off as a function of the overall
room light intensity and the presence of persons within the room.
Switching on is immediate on arrival of persons, switching off is
done with a suitable delay, possibly involving dimming of lights.
Conversely, the HVAC systems will also determine the earliest
possible time it can shut down heating/cooling yet still control the
setpoints to meet the requisite parameters. Lighting again gets off
easier since the lights can be extinguished as soon as they are not
needed.
Building owners may use the lighting systems to pace the janitorial
service providers by defining a strict timetable that the lights will
be on in a given area. Here, the janitorial service providers will
need to keep in step to complete their work prior to the lights being
turned off.
Facility Management Systems often include a telephone interface that
allows any late workers to override the normal HVAC and lighting
schedules simply by dialing into the system and specifying their
locale. The lights and fan system will continue to operate for a few
extra hours in the immediate vicinity. The same applies to occupancy
sensors in meeting rooms. Either by automatic sensing or a simple
push of the occupied switch, the HVAC and lighting schedules will
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extend the normal schedule for the meeting room.
8.4. Energy Management
The occupancy/shutdown applications noted above optimize runtime of
large equipment. This in itself is a major component of energy
savings. However, even during occupancy large equipment can be
modulated or shutoff temporarily without affecting environment
comfort. This suite of applications run in the HVAC domain, however
the HVAC silo will interact with the lighting system to reduce the
lighting load to help in the overall reduction of energy.
The load rolling, demand limiting and demand response applications
allow for the sequencing of equipment to reduce the overall energy
profile or to shave off peak energy demands in the facility. The FMS
system will constantly monitor real-time energy usage and
automatically turn unneeded equipment off (or reduce the control
setpoint) to stave off peaking the facility's electrical profile.
Demand peaks set by commercial facilities are frowned upon heavily by
utilities and are often accompanied by huge energy charge increases
for upwards to 1 year.
Recently real-time pricing has furthered the ability to save energy.
This allows a facility to proactively either use or curtail energy
based on the price/KWH of the energy. Again, the HVAC subsystem
takes the lead in this application. It can either poll the price
structure from the Utility off the Internet, or the current pricing
will be forwarded to the facility by the Utility. The HVAC subsystem
can then automatically defer unneeded operation or temporarily reduce
the cooling or lighting load as the cost warrants. As always, the
HVAC subsystem is charged with seamlessly returning the components to
their normal operating conditions at the close of the energy event.
8.5. Fault Detection and Diagnostics
HVAC primary equipment such as air handlers or chillers often have
capital expenditure costs in the $100k range. These systems are
critical to operation of the building and comfort to its tenants.
Contemporary HVAC subsystems can track usage and performance
operation of these devices in time and trigger alarms if the
performance characteristics fall outside the expected statistic usage
profile. This fault detection application can be further enhanced by
adding automatic diagnostic modes that define the source problem.
The diagnostics evaluation may suggest changing clogged air filters,
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inspecting a failed pump or even rebuilding the chiller mechanics due
to erratic vibration analysis.
9. Building Application Protocol Requirements
This section contains the overall set of building application
requirements as dictated by the previous discussion.
9.1. Physical Layer Requirements
9.1.1. Wired and Wireless Implementations
The protocol MUST support both wired and wireless IP implementations.
9.1.2. Cost Effective Wired Installation
The protocol MUST support wired media that is readily installable by
electricians. Its amortized per connection installed cost SHOULD NOT
exceed of the cost of the end device. That is, if the cost of the
device is $X; the total installed cost shall not exceed $2X, where X
is typically < $75.
9.1.3. Cost Effective Wireless Installation
The protocol MUST support wireless mesh that is readily installable
by electricians. Its amortized per connection installed cost SHOULD
NOT exceed of the cost of the end device. That is, if the cost of
the device is $X; the total installed cost shall not exceed $1.5X,
where X is typically < $75.
9.1.4. Global Wireless Applicability
Wireless devices MUST be supportable on unlicensed bands (such as the
2.4Ghz)that are applicable globally.
9.1.5. Constrained Power Sensors
The protocol MUST support wireless end devices that operate with
battery power or by energy scavenging. These devices will likely
sleep with a 99% duty cycle.
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9.2. Network Layer Requirements
9.2.1. TCP/UDP
Connection based and connectionless services MUST be supported.
9.2.2. Fragmentation
Packet fragmentation must be supported.
9.2.3. Data Rate Performance
An effective data rate of 20kbps is the lowest acceptable operational
data rate acceptable on the control networks.
9.2.4. Interference Mitigation
The wireless network MUST automatically detect interference and
migrate the network to a better channel to improve communication.
Channel changes and nodes response to the channel change MUST occur
within 60 seconds.
9.2.5. Real-time Performance Measures
A node transmitting a 'request with expected reply' to another node
MUST send the message to the destination and receive the response in
not more than 120 msec. This response time SHOULD be achievable with
5 or less hops in each direction. This requirement assumes network
quiescence and a negligible turnaround time at the destination node.
9.2.6. Packet Reliability
Reliability MUST meet the following minimum criteria :
< 1% MAC layer errors on all messages; After no more than three
retries
< .1% Network layer errors on all messages;
After no more than three additional retries;
< 0.01% Application layer errors on all messages.
Therefore application layer messages will fail no more than once
every 100,000 messages.
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9.2.7. Packet Routing
Unicast packets MUST be routable across any two nodes of the network.
9.3. Installation and Commissioning Requirements
9.3.1. Device Setup Time
Network setup by the installer MUST take no longer than 20 seconds
per device installed.
9.3.2. Unavailability of an IT network
Product installation and local commissioning MUST be performed by an
application engineer prior to the installation of the IT network
including switches, routers, DNS and DHCP servers.
9.4. Application Layer Object/Node Requirements
9.4.1. Object Model
The application protocol must adhere to a well defined object model.
This model must support generic objects (e.g. AI, BI, AO, BO) and
semantic objects (e.g. temperature sensor, pump, door lock, light
ballast)
9.4.2. Object Location
The protocol MUST optionally support determination of the physical
location of a device.
9.4.3. Node Discovery
The protocol MUST support the discovery and binding of other nodes
anywhere on the internetwork by name or address by using a single
broadcast or multicast request packet.
9.4.4. Object Discovery
The protocol MUST support the discovery and binding of two or more
objects anywhere on the internetwork by either name or address.
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9.4.5. Object List
The protocol MUST support supplying the entire object list of all
objects created in a given node.
9.4.6. Property List
The protocol MUST support a node returning a complete property list
of all mandatory and optional properties defined for a given node.
9.4.7. Service List
The protocol MUST support supplying the entire list of services
supported for a given node.
9.4.8. Consistent Error Reporting
The protocol must support a rigorous error reporting mechanism that
is consistent across all objects and nodes.
9.5. Application Layer Solicited Service Requirements
9.5.1. Reading Datum
The application protocol MUST support a means to read a single piece
of data (property) from a targeted node and object. Read requests
must be validated via an ACL. The default ACL allows reading of any
property.
9.5.2. Reading Data from an Object
The application protocol MUST support a means to read multiple data
items from a targeted node and object with a single request. Read
requests must be validated via an ACL. The default ACL allows
reading of any properties.
9.5.3. Reading Data from Multiple Objects
The application protocol MUST support a means to read multiple data
items from multiple objects on the same node with a single request.
Read requests must be validated via an ACL. The default ACL allows
reading of any properties.
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9.5.4. Reading Data with Wild Cards
The application protocol MUST support a means to read multiple data
items from multiple objects on the same node using a wild card
mechanism. Read requests must be validated via an ACL. The default
ACL allows reading of any properties.
9.5.5. Reading Large Data Items
Whenever an array or list can get larger than what is supported by
the MTU or fragmented packet; the object MUST support a means to
allow reading the data over multiple requests.
9.5.6. Object Creation and Deletion
The application protocol MUST support a means to create and delete
objects. Creation requests must be validated via an ACL. The default
ACL does not allow object creation or deletion.
9.5.7. Object Property Writing
The application protocol MUST support a means to write for the first
time or to modify the current value of a property. Property writing
requests must be validated via an ACL. The default ACL does not
allow object property writing. Properties are the province of the
server and hence, the server may at anytime and for any reason
prohibit property writing.
9.5.8. Atomic Object Property Writing
The application protocol MUST support a means to write for the first
time or to modify the current value of multiple properties
atomically. Property writing requests must be validated via an ACL.
The default ACL does not allow object property writing. Properties
are the province of the server and hence, the server may at anytime
and for any reason prohibit property writing.
9.5.9. Object Property List Writing Addition
The application protocol MUST support a means to write for the first
time or to modify the current value of a list property. Property
writing requests must be validated via an ACL. The default ACL does
not allow object list property writing. Properties are the province
of the server and hence, the server may at anytime and for any reason
prohibit property writing.
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9.5.10. Object Property List Writing Deletion
The application protocol MUST support a means to delete an element
from an existing list. The service SHALL error out if the requested
list item to be removed is not a element of the list.
9.5.11. Downloads
The application layer MUST support a means to download data and
programs. Download requests are validated by an ACL.
9.6. Application Layer Unsolicited Service Requirements
9.6.1. Property Value(s) Change Notification
The application protocol MUST support a means to request data
callbacks on a change to a specified property or object.
Subscriptions may timeout at a periodic basis or may be cancelled by
the client at any time. Subscriptions must persist a reboot.
9.6.2. Alarm Notification
The application protocol MUST support clients requesting alarm
notification to selected objects. When the object transitions into
the 'alarm' state for a predefined time, nodes subscribing to this
alarm will be notified of the state change. Alarm subscriptions may
timeout at a periodic basis or may be cancelled by the client at any
time. Subscriptions must persist a reboot.
10. Traffic Pattern
The independent nature of the automation systems within a building
plays heavy onto the network traffic patterns. Much of the real-time
sensor data stays within the local environment. Alarming and other
event data will percolate to higher layers as alarm events occur.
Systemic data may be either polled or event based. Polled data
systems will generate a uniform packet load on the network. This
architecture has proven not scalable. Most vendors have developed
event based systems which passes data on event. These systems are
highly scalable and generate low data on the network at quiescence.
Unfortunately, the systems will generate a heavy load on startup
since all the initial data must migrate to the controller level.
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They also will generate a temporary but heavy load during firmware
upgrades. This latter load can normally be mitigated by performing
these downloads during off-peak hours.
Devices will need to reference peers for sensor data or to coordinate
across systems. Data will migrate from the sensor level upwards
through the local, area, then supervisory level. Bottlenecks will
typically form at the funnel point from the area controllers to the
supervisory controllers.
11. Security Considerations
TBD
12. IANA Considerations
This document includes no requirement to IANA.
13. Acknowledgments
This document was prepared using 2-Word-v2.0.template.dot.
14. References
14.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
14.2. Informative References
[I-D.ietf-roll-terminology]Vasseur, J., "Terminology in Low power And
Lossy Networks", draft-ietf-roll-terminology-00 (work in progress),
October 2008.
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Authors' Addresses
Jerry Martocci
Johnson Controls
507 E. Michigan Street
Milwaukee, Wisconsin, 53202
USA
Phone: 414.524.4010
Email: jerald.p.martocci@jci.com
Anthony Schoofs
CLARITY Centre for Sensor Web Technologies
University College Dublin,
Dublin 4 Ireland
Phone: +353 1 7162488
Email: anthony.schoofs@ucdconnect.ie
Peter van der Stok
Philips Research
High Tech Campus
Eindhoven, 5656 AA
Netherlands
Email: peter.van.der.stok@philips.com
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