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The energy-saving benefits of Building Energy Management Systems
are well known. BEMS systems can improve comfort levels in
buildings, enable better maintenance and deliver financial
savings of up to 20%. This, in turn, reduces impact on the
environment caused by emissions of greenhouse gases –
giving both financial and environmental benefits. The savings
created through using a BEMS can be substantial and recur
year after year.
What
is a BEMS?
Building Energy Management Systems (BEMS) are computer systems,
which enable the system operator to monitor and control building
services including heating, air conditioning and lighting.
The BEMS collects information on the building including temperature,
pressure, light level, water level, valve or damper position
and uses this information to make decisions on when and how
to operate energy consuming systems in an efficient manner.
The BEMS can be configured to match any building size and
to meet the user’s requirements.
Building
Energy Management Systems are reliable and flexible systems
that take advantage of current hardware and software technology.
Additional features and monitoring points can easily be added
to existing systems. Since the BEMS is computer based, the
data and the decisions being made can be readily presented
in graphical form on a standard PC, and can be made available
on a business network or the worldwide web if desired.
Critical
or urgent data can be sent via SMS text message, e-mail, or
bleeper to maintenance staff either in the building or on
the far side of the country. As much or as little data can
be presented to as many or as few people as required, such
that people receive just the information they need. Traditional
controls cannot provide these features.
The
computerized nature of the systems makes them capable of using
sophisticated logic to make decisions, which help save energy.
The systems can be re-programmed to follow new logic if required.
Traditional controls use fixed hardware to control plant and
are expensive and difficult to alter.
What
is the “Point”?
Each item, which a BEMS monitors, or controls is called a
“point”. “Points” can either be “inputs”,
(for instance temperatures), pressures or “outputs”
(for instance pump start/stop or open/close heating valves).
A small building may have a BEMS with 10 or less points. A
large BEMS may have thousands of points. An organization may
have BEMS on multiple sites around the country that are linked
to a central location, which can then monitor thousands of
points.
Through the graphic or keypad displays, staff can input desired
conditions and set operating times. Users can view diagrams
or picture of the various systems with real-time information
such as internal and external temperatures. As soon as conditions
drift outside prescribed limits, the BEMS notifies the maintenance
staff, allowing them to carry out essential maintenance.
The
BEMS operator can view live or recorded data in detail in
a graphical form, such as a graph of a room temperature over
24 hours, which might clearly show that the heating is operating
when not required. This might be more difficult to detect
if a BEMS was not in place. The BEMS can be used to identify
electrical equipment that operates when not required, which
typically might be at night or at weekends, as it can record
electrical energy at regular intervals, such as every 15 minutes.
BEMS
– Growing Technology with Shrinking Costs
Since finding its first commercial use more than 20 years
ago, the BEMS technology has vastly improved while the actual
costs of installing systems have made BEMS much more cost
effective for smaller buildings. A small inexpensive system
can be cost-effective in buildings with annual energy bills
as low as €10,000. The cost of a new BEMS system is competitive
with installing less efficient traditional control systems.
For large organisations with buildings of various sizes spread
across a wide area – such as supermarket chains - an
outstation at each site can be linked to a single overall
control location via mobile phone, landline or the Internet.
With the spread of always-on broadband, the BEMS data from
remote sites can be also be “always available”,
rather than having to dial into the system to gain access.
Recent advances in BEMS technology allow further savings in
costs through innovations such as web-page serving, allowing
any standard PC with a web browser to interface with the systems.
This not only reduces capital costs, but also enables more
people to interface with the system, with less training required.
Optimum
Heating Systems Control
One of the most important areas influenced by BEMS is heating
or air conditioning control and the benefits here of using
BEMS can be very marked. The traditional way of controlling
the on and off times of this plant was with a time clock.
To cater for the coldest (or hottest) day of the year, the
time clock had to be set to switch the plant on perhaps an
hour or two before occupancy began, and to keep the plant
on until the occupants left.
With a BEMS, the system monitors room and outdoor temperatures.
The BEMS learns the characteristics of the space from this
data to determine the last possible moment to bring a plant
item on and the earliest possible moment to switch an item
off, whilst maintaining required conditions during occupied
periods. In this way, on mild days, the plant might be brought
on just minutes before occupancy begins, and plant might be
switched off hours before occupants leave. The energy saving
are significant. Moreover, plant maintenance is reduced due
to shorter plant operating hours per year.
Zone
and Time Control
BEMS are used to great effect in controlling the central heating
or other systems in buildings, which can be divided into various
zones. Using any networked PC, staff can schedule room occupancy
times in advance and have a room (such as a conference room
or cafeteria), an area (such as function rooms of a hotel
open to the public only part time) or floor (such as particular
floors in a high-rise building rented out to tenants) of a
building at conditions most beneficial to user needs. When
zones are not occupied the heating for that zone or area can
be easily turned off without affecting the remainder of the
building.
Bank holidays can be programmed using the BEMS. In many buildings
with conventional controls, the plant continues to operate
on bank holidays because it is too time consuming to switch
plant off. This alone can lead to 8 working days out of about
200 per year where the plant might be operating unnecessarily.
The
Electronic Engineer - Alarm Reporting
The BEMS allows system engineers to monitor all the systems
without the need to visit the various plant rooms. It notifies
the engineers of problems often before the occupants are aware
of them. For example, as soon as a temperature is higher or
lower than prescribed limits, the building maintenance staff
are alerted either at a PC, via text message, or bleeper.
The problem can be corrected before the building occupants
are aware of a noticeable temperature difference. By monitoring
system faults from the various specialist systems around the
building from a central point, maintenance is faster and more
responsive.
The
Electronic Engineer - Monitor and Targeting
Throughout an organization, electricity meters can monitor
electricity use in various areas such as lighting, compressed
air or air conditioning. Using the information, graphs of
electricity usage can be plotted which allows management to
formulate the optimal electricity usage plan. The usage can
be analyzed against other parameters appropriate to the building
such as number of residents in a hotel, units of production
in a factory, or number of occupied beds in a nursing home.
Similarly, fuel meters, water meters, heat meters and so on,
can be monitored and analyzed against similar parameters.
Once a norm is established, such as electricity usage per
bed-night, the BEMS can be programmed to alert when energy
usage drifts away from the norm. The data can also be used
to see the effect of operational changes or energy saving
investments.
The
Electronic Engineer - Maintenance
BEMS bring together the various engineering systems in a building
under a single system to report faults and adjust controls
remotely. These can include areas such as food refrigerator
temperatures; gas detection systems, water treatment and emergency
lighting.
The
BEMS monitors the air filters in air-handling units indicating
when the filter needs changing or cleaning. This not only
reduces the need for routine maintenance checks, but also
ensures that filters are not allowed to clog up, helping to
maintain air quality and reduce fan energy use.
The number of hours each item of plant operates can be counted
and preventative maintenance carried out after a fixed number
of running hours.
The
Electronic Engineer – Procuring a BEMS
A wide range of European and Irish companies manufactures
the hardware and software that go into BEMS. Usually systems
are bought from local distributors who design the system including
hardware and software for each particular building. These
distributors, sometimes referred to as system houses, provide
all the necessary equipment, install, test and commission
the system, train the client in its use, provide operation
and maintenance manuals, and provide an ongoing maintenance
service.
There are two main routes to procuring a system. Either the
user can approach system houses themselves and invite tenders,
or ask a consulting mechanical and electrical engineer to
prepare a specification which describes what is required against
which tenders can be obtained.
In the first case, care should be taken to ensure that the
user understands what is being offered from each company.
One company may offer a lower cost system but this may have
fewer monitoring and control points and less features than
other systems.
In the second case, the consulting mechanical and electrical
engineer will obtain tenders, compare them, recommend a contractor,
administer the contract, and see through the installation,
commissioning and training.
BEMS
– Keeping the Business Fit
A BEMS can act as a master system that combines all of the
different engineering systems in a building under a unified
control. All aspects of energy usage and plant items costs
can be monitored and kept functioning optimally.
BEMS
– Further Reading
Several Good Practice Case Studies are available on the Sustainable
Energy Ireland web site, or directly from Sustainable Energy
Ireland (SEI), including ones covering BEMS use at University
College Dublin and the Mater Private Hospital Dublin. BEMS
have been central to controlling energy costs and improving
the reliability of systems at these exemplary sites and at
numerous other locations. These users have been able to save
energy and money whilst guaranteeing the highest level of
building occupant comfort and a healthy environment. A booklet,
BEMS Good Practice Guide 1, is also available from SEI |
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