Networking Working Group J. Martocci
Internet-Draft Johnson Controls Inc.
Intended status: Informational Anthony Schoofs
Expires: April 16, 2010 University College Dublin
October 16, 2009
Commercial Building Applications Requirements
draft-martocci-6lowapp-building-applications-00
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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.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in (RFC2119).
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..........................................8
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............................................12
6.1. HVAC Device Density......................................12
6.2. Fire Device Density......................................12
6.3. Lighting Device Density..................................13
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. Locking and Unlocking the Building.......................17
8.6. Building Energy Conservation.............................18
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9. Building Requirements.........................................18
9.1. Additional Commercial Product Requirements...............18
9.1.1. Wired and Wireless Implementations..................18
9.1.2. World-wide Applicability............................18
9.1.3. Energy Harvested Sensors............................18
9.2. Additional Installation and Commissioning Requirements...18
9.2.1. Device Setup Time...................................18
9.2.2. Unavailability of an IT network.....................19
9.3. Additional Network Requirements..........................19
9.3.1. TCP/UDP.............................................19
9.3.2. Data Rate Performance...............................19
9.3.3. Interference Mitigation.............................19
9.3.4. Real-time Performance Measures......................19
9.3.5. Packet Reliability..................................19
10. Traffic Pattern..............................................20
11. Open issues..................................................20
12. Security Considerations......................................21
13. IANA Considerations..........................................21
14. Acknowledgments..............................................21
15. References...................................................21
15.1. Normative References....................................21
15.2. Informative References..................................21
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1. Terminology
For the description of the general terminology used in this
specification, please see [I-D.ietf-roll-terminology].
Specific terminology used in this document is defined below:
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 facility 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.
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.
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.
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2. Overview
Facility Management systems 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
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
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application suite. Proprietary protocols were displaced by industry
standard application protocols such as BACnet for HVAC, DALI for
Lighting and LON as general backbone.
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 change this picture.
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
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.
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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.
+------+ +-----+ +------+ +------+ +------+ +------+
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 | | | | | | | | | | | |
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+------+ +-----+ +------+ +------+ +------+ +------+
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; although 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 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.
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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.
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 communication trunk can serpentine 15000 ft. Figure 2 defines
a representative sampling of the devices and protocols of an FMS
wired network based on BACnet. 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. In Figure 2 the field bus can be replaced
with DALI for lighting purposes.
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
all building controllers support only 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.
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NOTE: Figure 2 deleted from this version of the draft, awaiting
author's agreement on figure's content.
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Figure 2 Media Types and Wired Protocols
5. FMS Communication Protocols
5.1. Controller/Sensor/Actuator Communication Protocol
The sensors, actuators, area controllers, zone controllers, and
building controllers all utilize BACnet (Building Automation Control
Network), DALI (Digital Addressable Lighting Interface), 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). Table 1 describes the network
parameters in tabular form.
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
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sequences. A DALI network is usually a lighting subnet connected to
the building network with a LON DALI gateway
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. This proposal
has been written and is scheduled for Public Review in January 2010.
*********************************************************************
NOTE: Table 1 deleted from this version of the draft, awaiting
author's agreement on figure's content.
*********************************************************************
Table 1 Typical FMS Communication Parameters
5.2. Enterprise Communication Protocol
Multiple protocols are supported at the enterprise level of the FMS
since this layer supports not only the embedded control operation but
also the user interface and end-user enterprise applications.
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
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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.
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. 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.
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 50 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.
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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.
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 bottom up.
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.
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.
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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.
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.
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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. 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 manual mode provides critical fire and smoke information
on a display to be controlled by a Fire Marshal. The automatic mode
is a preprogrammed set of events that control the fire automatically.
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
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egress from the building. If the building also supports elevator
control, the elevators will operates as directed by a preprogrammed
evacuation policy.
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. These times
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 function of the overall light intensity and the
presence of persons inside 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 and demand limiting 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.
8.5. Locking and Unlocking the Building
The member of the cleaning staff arrives first in the morning
unlocking the building (or a part of it) from the control room. This
means that several doors are unlocked; the alarms are switched off;
the heating turns on; some lights switch on, etc. Similarly, the
last person leaving the building has to lock the building. This will
lock all the outer doors, turn the alarms on, switch off heating and
lights, etc.
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8.6. Building Energy Conservation
A room that is not in use should not be heated, air conditioned or
ventilated and the lighting should be turned off. In a building with
366 rooms it can happen quite frequently that someone forgets to
switch off the HVAC and lighting. This is a real waste of valuable
energy. To prevent this from happening, the janitor can program the
building according to the day's schedule. This way, lighting and
HVAC is turned on prior to the use of a room, and turned off
afterwards.
9. Building Requirements
This section contains the overall set of building application as
dictated by the previous discussion.
9.1. Additional Commercial Product Requirements
9.1.1. Wired and Wireless Implementations
Solutions MUST support both wired and wireless implementations.
9.1.2. World-wide Applicability
Wireless devices MUST be supportable on unlicensed bands such as the
2.4Ghz.
9.1.3. Energy Harvested Sensors
Sleeping devices SHOULD target for operation using viable energy
harvesting techniques such as ambient light, mechanical action, solar
load, air pressure and differential temperature.
9.2. Additional Installation and Commissioning Requirements
9.2.1. Device Setup Time
Network setup by the installer MUST take no longer than 20 seconds
per device installed.
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9.2.2. Unavailability of an IT network
Product commissioning MUST be performed by an application engineer
prior to the installation of the IT network.
9.3. Additional Network Requirements
9.3.1. TCP/UDP
Connection based and connectionless services MUST be supported
9.3.2. Data Rate Performance
An effective data rate of 20kbps is the lowest acceptable operational
data rate acceptable on the network.
9.3.3. Interference Mitigation
The network MUST automatically detect interference and migrate the
network to a better 802.15.4 channel to improve communication.
Channel changes and nodes response to the channel change MUST occur
within 60 seconds.
9.3.4. 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.
9.3.5. 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.
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Therefore application layer messages will fail no more than once
every 100,000 messages.
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.
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.
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 occasionally for sensor data or
to coordinate across systems. Normally, though, 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. Open issues
Other items to be addressed in further revisions of this document
include:
Need to describe the set of application protocol service
requirements and the correlation to IP services.
Need to define security policy requirements for building
applications
Need to fully document these needs into well defined application
requirements.
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12. Security Considerations
TBD
13. IANA Considerations
This document includes no requirement to IANA.
14. Acknowledgments
This document was prepared using 2-Word-v2.0.template.dot.
15. References
15.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
15.2. 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
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