Image Processing Reference
In-Depth Information
or chillers) in particular come packaged with customized controllers. Typical sensors measure flow
and space temperatures, humidity, air quality, channel air pressure, or presence.
Systems for visual comfort have the task of providing just the right amount of light for occu-
pants. Artificial light can be modulated to fill in for missing daylight. Shading limits the amount
of daylight which enters the interior to avoid excessive light intensity and glare. Typical actuators
and sensors involved are load switches, incandescent dimmers, controllable ballasts, sunblind drives,
and presence detectors, luxmeters, and anemometers (for protection of outside blinds). Recently,
electrochromic windows have become available commercially, whose translucence is continuously
adjustable by applying a low voltage.
In safety and security alarm systems, alarm conditions have to be detected and passed on to appro-
priate receiving instances. his includes local alarms as well as automatically alerting an appropriate
intervention force. Precisely distinguishing nonalarm from alarm situations is essential. Example sen-
sors are motion and glass break sensors from the security domain, water sensors for false floors from
the property safety domain, and smoke detectors, heat detectors, and gas sensors from the life safety
domain. Alarms are announced by klaxons or playback of prerecorded evacuation messages. Emer-
gency lighting is also related to this field. Related areas of importance with a certain overlap with the
HVACdomainareiredampermonitoringandcontrolaswellasactivesmokecontrol.
29.3 Building Automation and Its Benefits
The task of building automation systems (BAS) is to provide automatic feedback control as well
as central (and remote) monitoring and access to building systems. Automatic control is typically
performedintheHVACandlightingdomains.
By applying optimized strategies in these highly energy intensive areas, considerable savings in
operational cost can be made. Good HVAC control strategies can optimize the consumption of pri-
mary energy by capitalizing on information about thermal comfort conditions as well as properties of
the building structure (high or low thermal inertia) and systems. Comprehensive sensor data (auto-
mated strategies may also automatically take air quality into account) and provisions for fine-grained
controlalsoworktowardthisgoal.
Example functionality related to power-saving operation is optimum start and stop control (auto-
matic shutdown of air-conditioning equipment during nonoffice hours, but starting earlier and
stopping sooner to allow for system inertia) and night purge (ventilate with % outdoor air at
night).heamountofprimaryenergytobeconvertedinboilersandchillerscanbeautomatically
adjustedbasedoncalendardataorinresponsetowhatisrequiredbytheindividualzones.
Demand control of lighting systems can also significantly contribute to energy saving. In func-
tional buildings (e.g., office buildings, hospitals, department stores), these benefits—calculated over
the entire building life cycle—will easily justify the required investments. Only a minor fraction
(typically about %) of the total building life-cycle cost accrues from the construction phase.
Positive environmental effects are another aspect to consider, and legislation requiring energy
efficient buildings is increasingly found.
Also, increased comfort must be mentioned as a benefit that cannot be easily quantified, but should
not be underestimated. Increased comfort will improve workforce motivation and productivity, and
will raise the perceived property value. his appeals to tenants concerned with their image and allows
building owners and tenants to set themselves apart from the competition by offering higher value.
Obviously, central access also reduces cost. his allows problems to be narrowed down more eas-
ily and quickly. Preventive as well as corrective measures can be planned more efficiently. Remote
access is particularly useful when building sites are spread over a large area. Alert messages may
be forwarded to the operator via cellular text message gateways or electronic mail. Travel time and
costs are avoided and faults can, ideally, be resolved without being on site. Optimum scheduling of
