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BUILDING ENERGY MANAGEMENT
Building Energy Management Systems
(BEMS)
M.S. in Energy Systems
Ch 4
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Building Energy Management Systems
Costas A. Balaras, PhD
Dr Mechanical Engineer, Research Director
[email protected]
www.facebook.com/GRoupEnergyConservation
GRoup Energy Conservation (GR.E.C.)
www.energycon.org
Building energy management systems
Dedicated function modules
Historical development of BEMS
What functions can a BEMS provide?
How do BEMS save energy?
BEMS hardware
Communications
Services controlled by the BEMS
INSTITUTE FOR ENVIRONMENTAL RESEARCH & SUSTAINABLE DEVELOPMENT (IERSD)
www.meteo.noa.gr
NATIONAL OBSERVATORY
OF ATHENS (NOA)
www.noa.gr
Athens 2016
Chapter 4
Building Energy Management Systems
(BEMS)
Building Energy Management Systems
(BEMS)
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BEMS - Building Energy Management Systems, controls and
monitors most of the energy consuming activities of a building
(heating, cooling, ventilation, lighting, electrical power usage, boiler /
chiller sequencing) and indoor environmental conditions
More sophisticated than conventional controls (e.g.
BMS - Building Management Systems, in addition to the above
include other functions (safety, access, lifts, security, fire security);
also known as
• IBMS – Integrated Building Management Systems
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and in industry as
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EMS - Environmental Management Systems, similar to BEMS but installed in a factory,
and control other energy consuming industrial processes (kilns, furnaces, electrical
machinery)
optimum / desirable conditions (improve occupant comfort)
minimize energy consumption and CO2 emissions
minimize cost
operate building services plant more effectively
transfer data to other functions, such as monitoring and
targeting software and maintenance management software
 A poorly performing BMS will fail to deliver these benefits
This can increase energy consumption & reduce occupant comfort
… the brains of modern buildings …
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control only one function, i.e. heating or lighting) since they can be
programmed to control all energy consuming systems in a
building to provide:
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Building Energy Management Systems
(BEMS)
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Building Energy Management Systems
(BEMS)
- Keep the BEMS simple
Energy savings vary depending on the specific
application & operating conditions
As necessary for successful building operation
 Complex systems are a waste of money
- Need properly trained staff
Technicians are often reluctant to use a BEMS due to lack of training and experience
in the use of BEMS. Some technicians still feel that the use of BEMS is something
that should be left to specialists
- Continuous maintenance, proper sensor calibration
Planned preventive maintenance (PPM) or some times condition-based
maintenance (CBM) is also used (some failure modes give warning signals that
a failure or deterioration has started to happen; by detecting these signals it is
possible to take evasive action before the failure occurs or serious
deterioration sets in. For example, filter differential pressure monitoring, etc
Typical energy savings range from 10-30%, if properly used
Anticipated savings:
 15-30% of fossil fuel consumption compared with conventional controls
 8-14% of electrical energy consumption
Additional cost benefits can result from maintenance
 A plant that is maintained in an optimal way has increased reliability
 This will give an extended return on the investment (ROI)
- Commissioning
A perfect operating system that meets the owner’s design intents
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STANDARDS
Building Energy Management Systems
(BEMS)
• Compatibility & Communication Protocols
Products
A complete system includes a central station, outstations and
sensors, that need to work together, although they may be from
different manufacturers
 EN 15500: Electronic individual zone control equipment
European Building Automation
and Controls Association
www.eubac.org
 EN 12098: Control equipment for hot water heating systems
 Products certified by eu.bac
Systems
BACnet
 ISO EN 16484: Building automation and control systems, including BACnet protocol
Data Communications Protocol for Building Automation & Control Networks. An ASHRAE, ANSI, and ISO
standard protocol. BACnet was designed specifically to meet the communication needs of building
automation and control systems for HVAC applications, lighting control, access control, and fire detection
systems and their associated equipment. The BACnet protocol provides mechanisms by which computerized
equipment of arbitrary function may exchange information, regardless of the particular building service it
performs. As a result, the BACnet protocol may be used by head-end computers, general-purpose direct digital
controllers, and application specific or unitary controllers with equal effect
 ISO/IEC DIS 14908: LonTalk protocol
Ref: www.bacnet.org
 EN13321, EN50090: KNX protocol
 EN 15232/2012: Impact Building Automation on energy efficiency
www.cen.eu
Πληροφορίες: Σταύρος Μπουλταδάκης, Ολοκληρωμένες εφαρμογές αυτοματισμού για την εξοικονόμηση ενέργειας σε κτήρια, Ημερίδα ASHRAE, Θεσσαλονίκη, Μάιος 9, 2015. www.ashrae.gr
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EN 15232
EN 15232
Energy performance of buildings – Impact of Building Automation, Controls & Building Management
Energy performance of buildings – Impact of Building Automation, Controls & Building Management
ΕΛΟΤ EN 15232/2012 Ενεργειακή λειτουργία των κτηρίων – Επίδραση του αυτοματισμού κτηρίων, των συσκευών ελέγχου και της διαχείρισης κτηρίων
ΕΛΟΤ EN 15232/2012 Ενεργειακή λειτουργία των κτηρίων – Επίδραση του αυτοματισμού κτηρίων, των συσκευών ελέγχου και της διαχείρισης κτηρίων
 Correction factors for thermal or/and cooling loads
Energy Classes for Building Automation & Control Systems (BACS) & Technical
Building Management Systems (TBM)
 Correction factors for the final electrical energy of secondary systems
Values depend on the type of Η τιμή του συντελεστή διόρθωσης διαμορφώνεται
ανάλογα το είδος των διατάξεων αυτομάτου ελέγχου και τον αριθμό των Η/Μ
συστημάτων του κτιρίου που ελέγχονται
A
Class A: High energy performance BACS & TBM
B
Class B: Advanced BACS και TBM
Από κατηγορία Γ προς B
 Four classes
 Must comply with all required functions
Αερισμός: Αλλαγή ελέγχου από χρονοπρόγραμμα σε
έλεγχο βάσει ζήτησης (CO2)
Σύστημα θέρμανσης: Έλεγχος αντλίας μεταβλητής
ταχύτητας με σταθερό DP
 If some are missing, then ranking moves
to the previous class
C
Class C: Standard BACS (used as reference)
D
Class D: Non energy efficient BACS
Σύστημα ψύξης: ελεγκτές δωματίου για A/C
διασυνδεμένοι σε BACS και συνδεμένοι με τις
κρατήσεις
Φωτισμός: αυτόματη ανίχνευση Auto ON/OFF
Class C: Standard Building
Automation & Control Systems BACS
(used as reference)
Πληροφορίες: Σταύρος Μπουλταδάκης, Ολοκληρωμένες εφαρμογές αυτοματισμού για την εξοικονόμηση ενέργειας σε κτήρια, Ημερίδα ASHRAE, Θεσσαλονίκη, Μάιος 9, 2015. www.ashrae.gr
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Dedicated Function Modules
Dedicated Function Modules
Stand-alone (conventional) Controls
Dedicated Stand-alone (conventional) Controls
Before BEMS … proper modules were developed to control individual
functions to improve performance & energy conservation (even used
today in most buildings)
Available for:
o Temperature control
o Humidity control
o Time of day switching
o Power management
o Optimum start/stop
o Light switching
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Compared against BEMS:
A simple example
Indoor Temp sensor to control heating
Sensor S1 detects a deviation below the indoor temperature set
point and sends a signal to actuator A1 to open switch V1
(two position on/off or proportional control)
- Not necessarily cheap
- Data not available for output elsewhere
- Fixed algorithms
- No centralized control
Relevant information is available only from S1 to A1
V1 is controlled only by the information from S1 via A1
The only other information controlling the system might be a
timer limiting the off period to certain hours during the day
Conventional control of a single-zone
constant air volume (CAV) all fresh air
ventilation system
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Dedicated Function Modules
HISTORICAL DEVELOPMENT of BEMS
Dedicated Stand-alone (conventional) Controls
Example more sophisticated control
Control boiler operation
Open Loop Control:
 Sensor S1 senses the temperature of the hot water
leaving the boiler
 Sensor S2 senses outdoor temperature and through
controller C1 regulates the hot water temperature S1 by
cycling the burner ON/OFF
The space temperature sensed by sensor S3 may be used to
influence control & improve overall effectiveness
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Enable individual items to be controlled from the central console via
data gathering panels (use same cable for a number of data gathering
panels)
Monitor status of valves (open/shut) visually using lights on a mimic
diagram of the plant
Changes depended on an operator to read data & take decisive actions
Developments in microelectronics advanced the capabilities of central
stations; computers perform calculations & make decisions based on
the outcome, to actuate valves, switch on heaters, according to a flexible
pre-determined program
T water flow
Compensation Control:
Compensated ON/OFF boiler control
Started as hard-wired centralized control systems to a central
indicator console with lights showing the state of each system.
Any changes to settings were done manually
T outdoor
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HISTORICAL DEVELOPMENT of BEMS
 “Distributed Intelligence”
Increase in computing power and development of intelligent outstations
with some processing power of their own enabled them to operate and
make decisions largely independently
Outstations can be connected through phone lines or even wireless
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FUNCTIONS of BEMS
Control of Plant
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Automatic switch on/off of HVAC, lighting etc
Optimization of plant operation & services
Optimization of fuel/air mixtures for boilers (oxygen trim)
Maximum use of outside air for cooling
Assist in Commissioning
Monitor Plant Status & Environmental Conditions
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FUNCTIONS of BEMS
Sense flows and temperatures
Give alarms
Assess state of plant (filters etc)
Take more rapid remedial actions
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HARDWARE of BEMS
Provisions of Energy Management Information
 Type of data communicated
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1. From outstation to central station
Energy flows & consumption
Identify trends
Assess effectiveness of measures
Assess comfort conditions
- Summary describing condition of plant controlled by the outstation
- Results of calculations performed by the outstation
- Requests for data (e.g. temperature setpoint)
- Historic plant data for analysis
- Programs stored by the outstation, needed by control
- Failure reports
Energy Savings
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Minimize unnecessary plant use
Optimize efficiency of plant
Enable improved standard of operational maintenance
Enable improved standards of overall energy management
Enhance energy awareness – Good housekeeping
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2. From the central station to the outstation
- Requests for information on plant status and values of variables
- Control instructions and data (e.g. setpoints)
- Programs to download to the outstation
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HARDWARE of BEMS
Typical BEMS Configurations
CPU makes all the decisions
… or wireless …
For many simple installations
 Outstations are merely boards which collect cables or data and transmit
signals from “sensors to CPU” or to “actuators from CPU”
Intelligent Outstations - Distributed Intelligence
For large sites with several independent buildings
 Outstation can make some decisions, all information transmitted to/from CPU
 Local manager can override local control from CPU, if necessary
Radial System
Distributed Intelligence with wireless link
For buildings scattered in large areas (e.g. schools in a municipality)
 Use modems (or wireless) to connect the central stations to outstations
 One outstation could control each building
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Distributed Intelligence System
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Building Energy Management Systems
(BEMS)
Services Controlled by BEMS
Electrical Load Management
Control electrical peak loads
 Staggering machine start-ups (e.g. start one at a time like
chillers, AHUs) & shedding electrical loads according to pre-set
priorities can reduce maximum demand penalties
Advantages
for a BMS operator:
 central interface (operator workstation)
 portable interfaces available
 Load shifting of non-essential items of equipment at times of high
demand
Does not always save energy
 relatively simple graphical interface
 tailored user interfaces for energy managers, facilities
managers, maintenance managers and security staff (with
appropriate access levels)
 operator workstations can be used to monitor plant operations
to verify that the building services systems are performing
effectively
but
Reduces operating costs
Ref: Kevin Pennycook, The Effective BMS A guide to improving system performance, AG 10/2001, BSRIA
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Building Energy Management Systems
(BEMS)
Building Energy Management Systems
(BEMS)
Advantages
for a building tenant/operator:
Advantages
for Maintenance Staff:
 energy saving control functions leading to lower energy bills
 remote (including off-site) monitoring of building services systems
 plant troubleshooting facility through the use of trend logs
 rapid information on plant status, in particular alarm condition
 automatic generation of monitoring & targeting reports direct
from logged data
 ability to override specific items of plant & simulate inputs to
assist in fault finding
 closer control of IEQ (internal environmental quality conditions)
 plant failures reported immediately so can react effectively
 Transfer information (e.g. alarms, operating hours etc) to computerbased maintenance management systems
 easier & central coordination of maintenance teams
 plant schematics simplify analysis procedures
 automatic generation of BMS system documentation (if
available)
Ref: Kevin Pennycook, The Effective BMS A guide to improving system performance, AG 10/2001, BSRIA
Chapter 4
Ref: Kevin Pennycook, The Effective BMS A guide to improving system performance, AG 10/2001, BSRIA
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Building Energy Management Systems
(BEMS)
Building Energy Management Systems
(BEMS)
Control – Manage - Monitor
Save energy & money
Improve IEQ
Advantages
for
Occupants:
 improved occupant comfort through optimum control
 individual room control by occupants via set-point
adjustment devices (may include additional functions such as
local over-ride of pre-programmed occupancy period)
 more rapid & effective response to building services related
complaints due to central monitoring capability
IF properly operated
Ref: Kevin Pennycook, The Effective BMS A guide to improving system performance, AG 10/2001, BSRIA
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More information …
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HARDWARE of BEMS
European Installation Bus Association - European Home Systems Association - BatiBUS Club International www.knx.org
The European Installation Bus (EIB) is an open, comprehensive system, which covers all aspects of Building Automation. This protocol is similar with the BACnet
protocol and is manage by EIB Association.
The European Installation Bus (EIB) is designed as a management system in the field of electrical installation for load switching, environmental control and security, for
different types of buildings.
Its purpose is to ensure the monitoring and control of functions and processes such as lighting, window blinds, heating, ventilation, air-conditioning, load management,
signaling, monitoring and alarms.
European Standard EN 15232: Energy performance of buildings – Impact of Building Automation, Controls and Building
Management, February, 2012. www.cen.eu
This European Standard specifies: a structured list of control, building automation and technical building management functions which have an impact on the energy
performance of buildings; a method to define minimum requirements regarding the control, building automation and technical building management functions to be
implemented in buildings of different complexities; detailed methods to assess the impact of these functions on a given building. These methods enable to introduce the
impact of these functions in the calculations of energy performance ratings and indicators calculated by the relevant standards; a simplified method to get a first
estimation of the impact of these functions on typical buildings.
ANSI/ASHRAE Standard 135-2012, BACnet® - A Data Communication Protocol for Building Automation and Control Networks
ASHRAE, Atlanta, Georgia. www.ashrae.org
 Temperature measurements
 Flow measurements
 Pressure measurements
Intelligent Sensors
 Undertake a degree of processing of raw data
 For example, convert flow meter frequency directly to a flow rate
 Temperature sensors may contain A/D or binary converter
The purpose of this Standard is to define data communication services and protocols for computer equipment used for monitoring and control of HVAC&R and other
building systems and to define, in addition, an abstract, object-oriented representation of information communicated between such equipment, thereby facilitating the
application and use of digital control technology in buildings.
A. Martin, BMS Maintenance Guide, BSRIA Guidance Note, Berkshire: Building Services Research and Information Association
www.bsria.co.uk
An analog-to-digital converter (ADC, A/D or A to D) is an electronic circuit that converts continuous signals to discrete digital numbers. The
reverse operation is performed by a digital-to-analog converter (DAC). Typically, an A/D is an electronic device that converts an input analog
voltage (or current ) to a digital number. The digital output may be using different coding schemes, such as binary and two's complement
binary.
Κώστας Καραγιάννης, Εξοικονόμηση Ενέργειας σε Κτίρια μέσω Συστημάτων Ενεργειακής Διαχείρισης BEMS (Building Energy
Management System) www.ashrae.gr/seminaria.html
The binary numeral system, or base-2 number system, is a numeral system that represents numeric values using two symbols, usually 0
and 1. More specifically, the usual base-2 system is a positional notation with a radix of 2. Owing to its straightforward implementation in
electronic circuitry, the binary system is used internally by virtually all modern computers.
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HARDWARE of BEMS
Signal processing
Output from sensors
• An intelligent sensor or an outstation can reduce the communication
necessary to the central station
Electrical signal to an outstation or central station (readable by computer)
Standard outputs required:
• A/D conversion
Current 4 – 20 mA
Voltage 0 – 5 V DC
• Signal filter & condition
• Check signal against upper / lower limits
• Check rate of change of signal against limits
• Issue an alarm if limits are exceeded
• Compute mean & standard deviation of one or several parameters
• Process raw data to meaningful form (flow rate converted to heat flow rate)
• Auto calibrate & error correction
The RS232 signals are represented by voltage levels with respect to a system common (power / logic ground). The "idle"
state (MARK) has the signal level negative with respect to common, and the "active" state (SPACE) has the signal level
positive with respect to common. RS232 has numerous handshaking lines (primarily used with modems), and also
specifies a communications protocol.
RS232 data is bi-polar.... +3 TO +12 volts indicates an "ON or 0-state (SPACE) condition" while A -3 to -12 volts indicates
an "OFF" 1-state (MARK) condition.... Modern computer equipment ignores the negative level and accepts a zero
voltage level as the "OFF" state. In fact, the "ON" state may be achieved with lesser positive potential. This means
circuits powered by 5 VDC are capable of driving RS232 circuits directly, however, the overall range that the RS232
signal may be transmitted/received may be dramatically reduced.
Ref: http://www.arcelect.com/rs232.htm
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HARDWARE of BEMS
Services Controlled by BEMS
Heating Controls
Typical control functions
Output to actuators
Electrical signals must be sent to a device actuator to switch on items of the
plant or adjust valves
Devices to be controlled include:
- Relays & contactors; on/off of fans, pumps, motors, compressors etc
- Motorized dampers; open/close or fully variable
- Closed valves; open/close or fully variable
- Closed loop controllers; electronic or pneumatic
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Services Controlled by BEMS
• Time based on/off switching of
hot water circulation pumps
• Modulation of circulation water
temperature using three way mixing
valves and an external temperature
compensator
• Space temperature set-point
control using standard room
thermostats
• Programmable microprocessor
systems provide several on/off
switching over long periods. Use
thermistors which are more accurate than
bimetallic thermostats, with a smaller
dead-zone, thus smaller control differential
Αισθητήριο και
προγραμματιστής χώρου
Εξωτ. αισθητήρας
θερμοκρασίας
Αντιστάθμιση με
χρονοδιακόπτη
Αισθητήριο επαφής
θερμοκρασίας
Ηλεκτροβάνα
αντιστάθμισης
Λέβητας
Standard
Programmable
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Services Controlled by BEMS
Heating Controls
Air-Conditioning Controls
 Several thermistors can be used to monitor space
temperatures in different areas / zones of the building
Averaging can provide a much more representative measurement
• High internal heat gains can cause overheating in modern
deep-plan office or retail buildings
• Many A/C plants are oversized to cover peak loads
 Can be programmed over long periods
e.g. even account for weekends, holidays etc
Chillers run most of the time at part load & reduced efficiency
/ performance
 If possible, replace pumps, fans etc with smaller ones
 If entire HVAC system needs replacement, then:
 With microprocessor control they can all be monitored
from one central control station
Microprocessor units have a self-adapting software that learns the
thermal behavior by comparing actual temperatures with the target at a
given time  make appropriate adjustments so that the difference is
gradually reduced
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 First reduce loads by implementing appropriate energy conservation measures
 Consider sizing equipment to best match loads
 Consider single zone (all areas are treated the same, controlled from only one
space, may result to some savings on plant, but energy consumption may increase
since unoccupied spaces may be conditioned; occupants can’t adjust local indoor
conditions)
or multizone system (great flexibility to meet occupant requirements; controlled by
settings in each zone or occupants)
 Select energy efficient systems
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Services Controlled by BEMS
Air-Conditioning Controls
• Simultaneous heating & cooling of different parts of a
building, or even in the same room, is wasteful
• Terminal Reheat Systems
 The air is heated at the individual zone/room in response to the indoor thermostat
 Provide cooling with a constant air volume (CAV) system, and then reheat the air at the
terminal
 Very energy inefficient
• Dual Duct Systems
 Air is both heated and cooled and then delivered to the zone/room.
 Mixing is determined by the indoor thermostat
 Very high energy use
• Variable Air Volume (VAV) Systems
 Supply air volume and temperature are regulated according to the indoor conditions (meet
variable loads)
 More energy efficient
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