Intelligent Buildings Technology

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Intelligent Buildings Technology
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Intelligent Buildings Technology

• Introduction-Energy Management
• Energy used in buildings accounts for almost half
  of the total amount of energy consumed in the
  European Community today.
• Almost 85 of the energy used in buildings is for
  low temperature applications such as space and
  water heating.
• Appropriate building designs involving clean and
  efficient technologies are already available and
  there use may help to reduce future energy
  consumption as well as to provide a better
  quality of life for citizens.

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Intelligent Buildings Technology

• Introduction-Energy Management
• With fossil fuels the primary energy source, the
  building sector currently produces 22 of total
  CO2 emissions in the EC. This is more than that
  produced by the industrial sector.
• Intelligently designed buildings are those that
  involve environmentally responsive design taking
  into account the surroundings and building usage
  and involving the selection of appropriate
  building services and control systems to further
  enhance building operation with a view to the
  reduction of energy consumption and environmental
  impact over its lifetime.

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Intelligent Buildings Technology

• Energy in Buildings
• Buildings are inherently linked to their usage
  and surroundings and hence their indoor
  environment is the result of a range of
  interactions affected by seasonal and daily
  changes in climate and by the requirements of
  occupants varying in time and space.
• The design of buildings in the mid-late twentieth
  century has sought to eliminate the effect of
  outdoor daily and seasonal changes through the
  use of extensive heating, cooling, lighting and
  ventilation equipment, resulting in spiraling
  energy consumption and environmental impact.

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Intelligent Buildings Technology

• Energy in Buildings
• A more climate sensitive approach linked to the
  use of advanced control systems allows the
  building occupants to control their indoor
  environment whilst maximising the contribution of
  ambient energy sources to the creation of a
  comfortable indoor environment through the use of
  a more climate sensitive design approach.
• Under almost all circumstances it is necessary at
  some point in time to provide some form of
  auxiliary heating, cooling, lighting or
  ventilation since natural sources cannot always
  cover the requirements for thermal comfort,
  visual comfort and IAQ that are the prerequisite
  for a well balanced, comfortable and healthy
  indoor environment.

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Intelligent Buildings Technology

• Energy in Buildings
• The purpose of energy management in buildings,
  and hence the role of the building energy
  manager, is to identify the areas in building
  stock where energy is used in excess.
• Energy consumption in building is required for
  the following uses
• Heating
• Cooling
• Ventilation
• Lighting
• Equipment and machinery
• Domestic hot water

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Intelligent Buildings Technology

• Indoor Comfort
• Thermal comfort
• Visual Comfort
• Indoor air quality

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Thermal Comfort
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Intelligent Buildings Technology

• Thermal Comfort
• Comfort is defined as the sensation of complete
  physical and mental well being.
• Thermal neutrality, where an individual desires
  neither a warmer nor a colder environment, is a
  necessary condition for thermal comfort.
• The factors affecting comfort are divided into
  personal variables
• activity
• Clothing
• and environmental variables,
• (air temperature,
• mean radiant temperature
• air velocity
• air humidity

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Intelligent Buildings Technology
Thermal Comfort Energy Balance
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Intelligent Buildings Technology

• Thermal Comfort Personal Variables
• Clothing describes the occupants thermal
  insulation against the environment. This thermal
  insulation is expressed in clo units.

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Intelligent Buildings Technology

• Thermal Comfort Personal Variables
• Activity The metabolic rate is the amount of
  energy produced per unit of time by the
  conversion of food. It is influenced by activity
  level and is expressed in mets (1 met seated
  relaxing person).

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Intelligent Buildings Technology

• Thermal Comfort Environmental Variables
• Temperature
• The average air temperature from the floor at a
  height of 1.1 m.
• Mean Radiant TemperatureThe average temperature
  of the surrounding surfaces, which includes the
  effect of the incident solar radiation.
• Air VelocityWhich affects convective heat loss
  from the body, i.e. air at a greater velocity
  will seem cooler.
• Air HumidityWhich affects the latent heat losses
  and has a particularly important impact in warm
  and humid environments

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Intelligent Buildings Technology

• Thermal Comfort Indices
• Although the four parameters of air temperature,
  radiant temperature, relative humidity and air
  movement are generally recognized as the main
  thermal comfort parameters, indoor environmental
  conditions in terms of thermal comfort can
  generally be assessed through three classes of
  environmental indices, namely
• Direct indices
• Rationally derived indices
• Empirical indices

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Intelligent Buildings Technology

• Thermal Comfort Indices
• Direct indices
• dry-bulb temperature
• dew-point temperature
• wet-bulb temperature
• relative humidity
• air movement
• Rationally derived indices
• mean radiant temperature
• operative temperature
• heat stress, and
• thermal stress
• Empirical indices

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Intelligent Buildings Technology

• Thermal Comfort PMV Index
• The perceived need for both heating and cooling
  is to achieve accepted standards of thermal
  comfort, usually defined (directly or indirectly)
  by temperature limits.
• Controversy exists as to what these standards of
  thermal comfort are. It has been observed that
  there has been an apparent discrepancy between
  comfort predictions using models derived from
  laboratory experiments, such as those by Fanger
  (1970), and subjective assessments of comfort
  found in field studies. It has been found in a
  compilation of results from field studies in
  predominantly in warm and hot climates by
  Humphreys (1978) that the preferred comfort
  temperature in buildings was a function of the
  average monthly outdoor temperature (To is the
  mean monthly temperature)

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Intelligent Buildings Technology

• Thermal Comfort PMV Index
• The Predicted Mean Vote (PMV) is a widely
  accepted mathematical expression of thermal
  comfort. This index is a real number and comfort
  is obtained if it lies within the specific limits
  of the comfort range. Since 1984, the index
  which is calculated through a complex
  mathematical function of human activity, clothing
  and environmental parameters has been the basis
  of the international standard ISO-7730.
• This PMV is an index which predicts the mean
  value of the votes of a large group of people,
  and is directly related to the percentage of
  people dissatisfied (PPD), on the following seven
  point thermal sensation scale 3 Hot, 2 Warm,
  1 Slightly Warm, 0 Neutral, - 1 Slightly Cool,
  - 2 Cool, - 3 Cold.

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Intelligent Buildings Technology
Thermal Comfort PMV Index
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Intelligent Buildings Technology

• Thermal Comfort PMV Index
• The result of using Fangers equations seems to
  predict the need for much more closely controlled
  conditions than are usually found in free running
  buildings, in which people still seem to be
  comfortable. Some of the possible explanations
  for the apparent discrepancy between the
  prediction of the Fanger model and the findings
  of the Humphreys survey, are
• The thermal comfort parameters, air temperature,
  radiant temperature and air movement vary
  spatially in a room, and the actual values
  experienced by an occupant may not be those
  described by a "room-average value".
• Thermal comfort parameters vary with time whereas
  the Fanger model predicts a response for steady
  conditions.
• The description of clothing level assumed in the
  use of the Fanger equation may not be the same as
  is actually worn in the real situation.
• The insulation value of the clothing may not be
  as predicted from the description of the clothing
  ensemble.
• The metabolic rate as assumed from the
  description of the activity may not be the same
  as the actual metabolic rate.

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Visual comfort
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Intelligent Buildings Technology

• Visual Comfort
• Visual comfort is the main determinant of
  lighting requirements.
• Good lighting provide a suitable intensity and
  direction of illumination on the task area,
  appropriate colour rendering, the absence of
  discomfort and, in addition, a satisfying variety
  in lighting quality and intensity from place to
  place and over time.
• Peoples lighting preferences vary with age,
  gender, time and season. The activity to be
  performed is critically important.
• Various agencies (ASHRAE, CIBSE, etc.) and text
  books list optimal illuminances for different
  activities. These are generally based on uniform
  and constant levels of artificial light falling
  on the working plane.

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Intelligent Buildings Technology

• Visual Comfort Illuminance levels

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Intelligent Buildings Technology

• Visual Comfort
• Natural light is a fluctuating source of light.
  It depends on the hour of the day, the season,
  the climate and the latitude of the location.
• The objective of a daylight technique consists of
  providing the best possible indoor luminous
  environment as often as possible.
• A luminous environment should be appropriate to
  the function of the room there should be enough
  light for reading, writing, or filing documents.
• Illuminance of 300 to 400 lux on a desk are often
  considered as minimum required levels for most of
  office tasks. Hallways might require lower
  levels, 100 lux, and commercial centres higher
  levels, 700 lux. These requirements are defined
  by CIE.
• Performance does not depend only on these
  illuminance levels. The location of the source of
  light with respect to the direction of
  observation may require higher illuminance, for
  instant when the observer faces a window.

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Intelligent Buildings Technology

• Visual Comfort
• The luminous environment should be comfortable,
  which means that sources of glare should be
  avoided.
• Oversized glazed windows with clear glazing are
  sources of glare, and this can be fought in using
  multiple apertures, if possible on different
  walls.
• Glossy materials and inappropriate shading
  devices might bring excessive amount of light in
  the field of vision.
• Also, psychological aspects such as the quality
  of the vision to the outside, the beauty of the
  design and the attractiveness of the space are
  very important.

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Intelligent Buildings Technology

• Visual Comfort
• Natural light comes from three directions
• Direct Sunlight
• Diffuse light from the sky, and
• Light Reflections from the Environment

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Intelligent Buildings Technology

• Visual Comfort
• The daylight factor is a measure of the daylight
  level at any position indoors as a percentage of
  the illuminance levels outdoors. The daylight
  factor at any point on a working plane is
  calculated in terms of light coming directly from
  the sky (the sky component), light reflected from
  outdoor surfaces (the externally reflected
  component) and light reflected form surfaces
  within the room (the internally reflected
  component). The average daylight factor in a
  space can be calculated from

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Intelligent Buildings Technology
Visual Comfort Indoor lighting distribution
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Intelligent Buildings Technology

• Visual Comfort
• If a predominately daylit appearance is required,
  then the daylight factor should be 5 or more if
  there is to be no supplementary artificial
  lighting, or 2 if supplementary lighting is
  provided.
• Discomfort is caused when the eye has to cope
  with, simultaneously, great differences in light
  levels, the phenomenon we know as glare. Maximum
  recommended values for the ratio between
  different parts of a visual field, the luminance
  ratio, as shown in the following table.

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Indoor air quality
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Intelligent Buildings Technology

• Indoor air Quality
• A conflict has always existed between adequate
  ventilation and energy costs has long existed.
• During the last three decades, decreased
  ventilation rates for energy conservation, along
  with increased use of synthetic (i.e. man-made)
  materials in buildings have resulted in increased
  health complaints from building occupants.
  However, energy efficiency and good indoor air
  quality in buildings need not be mutually
  exclusive.
• Good indoor air quality is a function of a number
  of parameters including the initial design and
  continuous maintenance of HVAC systems use of
  low toxic emittance building materials and
  consideration of all sources of indoor air
  pollution such as occupant activities, operation
  of equipment and use of cleaning products.
• In fact, in 1986 the WHO (World Health
  Organisation) reported that "energy-efficient but
  sick buildings often cost society far more than
  it gains by energy savings".
• The result of the reductions in ventilation rates
  in buildings have led to the so called "Sick
  Building Syndrome" (SBS) and "Building Related
  Illness" (BRI).

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Intelligent Buildings Technology

• Indoor air Quality Indoor pollutants
• Every building has a number of potential sources
  of indoor air contaminants.
• Some sources, such as building materials and
  furnishings, release contaminants more or less
  continuously. Other sources are related to
  occupant activities and therefore release
  contaminants intermittently.
• Such activities include cooking, smoking, use of
  solvents, pesticides, paint, and cleaning
  products, and operation of office machines and
  equipment.
• High concentrations of pollutants can remain in
  the indoor air for long periods after they are
  emitted. Although some sources may be common in
  all building types, office and commercial
  buildings vary greatly from residential buildings
  in terms of design, air handling systems and
  occupant activities and therefore certain indoor
  air pollutant sources may be more prevalent in
  some types of buildings.

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Intelligent Buildings Technology

• Indoor air Quality Ventilation
• There are two types of ventilation natural and
  mechanical.
• Natural ventilation includes the movement of
  outdoor air through intentional openings such as
  doors and windows and through unintentional
  openings in the building shell scuch as cracks
  which result in infiltration and exfiltration.
• Mechanical or forced ventilation is intentional
  ventilation supplied by fans or blowers. These
  fans are usually part of the buildings HVAC
  system which heats, cools, mixes and filters the
  air being supplied to the building.

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Intelligent Buildings Technology
Climate
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Intelligent Buildings Technology

• Climate
• Climate responsive design in buildings takes into
  account the following climatic parameters which
  have direct influence on indoor thermal comfort
  and energy consumption in buildings
• The air temperature,
• The humidity,
• The prevailing wind direction and speed,
• The amount of solar radiation and the solar
  path.
• Long wave radiation between other buildings and
  the surrounding environment and sky also plays a
  major role in building performance.

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Intelligent Buildings Technology

• Climate
• The outdoor air temperature has a significant
  effect on building thermal losses due to
  conduction through the walls and roof of the
  building, as well as affecting ventilation and
  infiltration losses due to either desirable or
  undesirable air changes.
• In warm climates the relative humidity plays an
  important role in determining thermal comfort
  levels, since during warm weather the high
  pressure of water vapour prevents the evaporation
  of perspiration from the body thereby inhibiting
  the body from being maintained at a comfortable
  temperature.

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Intelligent Buildings Technology

• Climate
• Prevailing wind speed and direction affect
  significantly the building thermal losses during
  the heating season, increasing both convection at
  exposed surfaces and hence encouraging envelope
  losses and also by increasing the air change rate
  due to natural ventilation and infiltration.
  During the cooling season, the knowledge of both
  the direction and wind speed permits the design
  of the building to facilitate passive cooling.
• The sun-path and the cloud cover determine the
  amount of solar radiation impinging on
  differently inclined surfaces and since the
  sun-path changes from season to season, so does
  the amount of direct solar radiation impinging on
  these different surfaces.

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Intelligent Buildings Technology

• Macroclimate is a term referring to the general
  climatic character of a region in terms of
  temperature, humidity, precipitation, wind,
  sunshine and cloud cover. An appreciation of the
  overall characterisation of the climate of a
  region is a fundamental requirement for climate
  responsive building design, this affecting the
  general design principles which should be
  followed.
• Regional climatic factors are strongly affected
  by the local topography, vegetation and the
  nature of the area, resulting in deviations from
  the regional macroclimate. The effect of such
  factors results in climatic characteristics known
  as the mesoclimate. Heavily vegetated or densely
  built-up areas have a significant impact on the
  climate of a specific location.
• The conditions of the climatic parameters of a
  specific site or around a building are termed the
  microclimate. Temperature, humidity, wind speed,
  and solar radiation around a building can be
  affected by the deliberate placement of
  vegetation, landscaping, water and fountains, and
  positioning of constructions

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Intelligent Buildings Technology

• Building Climate interaction

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Intelligent Buildings Technology

• Building Envelope
• The building envelope responds dynamically to the
  impact of the outdoor climate on the envelope
  exterior and the effect of the occupancy pattern
  and building usage on the interior.
• However, the performance of the heating,
  ventilation and air-conditioning systems,
  artificial lighting, fenestration opening and
  shading can be harmonized and optimized in
  response to occupancy needs and climatic
  conditions through a building energy management
  system which allows direct control of the
  necessary actuators either manually or
  automatically.
• In this manner the individual components of the
  building can be controlled to produce the best
  possible indoor environment with minimum energy
  consumption.

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Intelligent Buildings Technology

• Heat transfer
• Conduction - C
• Radiation - R
• Convection - C

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Intelligent Buildings Technology

• Heat transfer Conduction
• Conductive heat transfer is a process by which
  thermal energy is transmitted by direct molecular
  communication.
• It is the only mechanism by which heat flows in
  an opaque solid. Conduction in a translucent
  solid is accompanied by radiation, whilst heat
  transfer through stagnant gases and liquids takes
  place by conduction with some radiation.
  Convection enhances the thermal equilibrium
  process in moving fluids. The thermal
  conductivity k of a substance determines its
  ability to conduct heat.
• Conductive heat transfer with respect to
  buildings concerns the heat losses through the
  building envelope the walls, windows and doors.
• Heat transfer is caused by a temperature
  difference across the envelope, always in the
  direction of the temperature gradient, with
  energy entering the one surface at a higher
  temperature and leaving the other surface at a
  lower temperature. Therefore, buildings are
  generally affected by envelope losses in the
  winter and envelope gains in the summer.

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Intelligent Buildings Technology

• Heat transfer Conduction

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Intelligent Buildings Technology

• Heat transfer Convection
• Convection is a process of heat transfer by the
  combined action of heat conduction, energy
  storage and mixing motion.
• Convection is combined to fluids only and
  requires an external force -either forced or
  natural (buoyancy)- to be present.
• The rate of heat transfer depends on the
  temperature difference between the fluid and the
  surface and the convective heat transfer
  coefficient h.
• The convective heat transfer co-efficient is a
  function of
• 1) the geometry of the system,
• 2) the velocities and mode of fluid flow,
• 3) the physical properties of the fluid and
• 4) possibly on the temperature difference.
• The convective heat transfer is therefore not
  constant or uniform over the whole surface,
  although for all intensive purposes in building
  physics it is often considered to be so.

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Intelligent Buildings Technology

• Heat transfer Convection

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Intelligent Buildings Technology

• Heat transfer-Radiation
• All bodies emit radiation. Heat transfer via
  radiation occurs when a body converts part of its
  internal energy (a result of its temperature)
  into electromagnetic waves.
• In buildings heat transfer due to radiation is
  most apparent with transparent elements, where a
  large amount of the impinging radiation coming
  from the sun is transmitted to the building
  material.
• Radiative heat transfer can also contribute to
  the cooling of external surfaces through exposure
  to the night sky, wherin these surfaces emit net
  radiation towards the clear sky, or in the effect
  of discomfort associated with sitting next to hot
  or cold surfaces (i.e. cold windows).

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Intelligent Buildings Technology
Heat transfer-Radiation
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Intelligent Buildings Technology

• Thermal storage
• The ability of a material to store energy is
  characterised by its specific heat (cp, J/kgK).
  The specific heat of a material is defined as the
  amount of heat necessary to raise a unit mass of
  the material by one degree. The heat that is
  stored in the mass of the material, m, for a
  temperature change, ?T, is given by

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Intelligent Buildings Technology

• Energy Management Systems

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Intelligent Buildings Technology

• Intelligent Building-Definitions
• EIBG (European Intelligent Building Group) One
  that incorporates the best available concepts,
  materials, systems and technologies integrating
  these to achieve a building which meets or
  exceeds the performance requirements of the
  building stakeholders, which include the owners,
  managers and users, as well as the local and
  global community.
• Also from EIBG but more often quoted One that
  maximizes the efficiency of its occupants and
  allows effective management of resource with
  minimum life costs

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Intelligent Buildings Technology

• Intelligent Building-Definitions
• IBI (The Intelligent Buildings Institute in
  Washington DC, US) one that provides a
  productive and cost-effective environment through
  optimization of its four basic components -
  structure, systems, services and management - and
  the interrelationships between them.

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Intelligent Buildings Technology

• Intelligent Building-Definitions
• An Intelligent Building is one that
• Provides a productive and cost-effective built
  environment through optimization of its four
  basic components - structure, systems, services
  and management - and the interrelationships
  between them. (focused on the benefit of the
  Owners)Creating Desired indoor environment)
• So as to maximize the efficiency of its occupants
  (focused on the benefit of the Users) (Influence
  of creating desired indoor environment on
  occupants)
• And to allow effective management of resource
  with minimum life costs (focused on the benefit
  of the Managers) (Environmental and economic
  impact of creating desired indoor environment)

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Intelligent Buildings Technology

• Building Energy Management Systems-Definitions
• Building Energy Management Systems aim to
  optimise the use of energy in buildings by
  maintaining at the same time the indoor
  environment under comfort conditions
• Practically, a BEMS is a computerised system that
  attempts to control all or some of the energy
  consuming operations in a building
• HVAC systems (Heating Ventilating and Air
  Conditioning)
• Lighting systems (natural and artificial)
• Indoor climate

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Intelligent Buildings Technology

• Building Energy Management Systems-Definitions
• BEMS are now available with a wide range of
  building automation facilities and in many
  installations BEMS have replaced hardwired
  controls, with control strategies implemented in
  software
• BEMS can combine many technologies
• Passive heating and cooling
• Efficient daylight penetration by using suitable
  shading devices
• Efficient appliances that reduce the electricity
  consumption
• High efficiency windows (e.g. electrochromic)
• Natural ventilation for indoor air quality and
  passive cooling
• Improvements in building services for HVAC
• Building Energy Management and Control

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Intelligent Buildings Technology

• Building Energy Management Systems- How much
  energy can be saved

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Building Energy Management Systems- Hardware
Intelligent Buildings Technology

• The basic architecture consists of
• Multiple programmable control panels, called
  Network Control Units (NCUs) each NCU manages an
  area of the building facility
• Operator WorkStations (OWSs) that communicate
  with each other over a high speed communication
  network normally a standard PC
• This communication network is called Local Area
  Network (LAN)
• NCU capacity can be increased with remote panels
  called Network Expansion Units (NEUs)
• The NCUs and NEUs directly control central plant
  equipment, while the management of smaller air
  handlers, heat pumps, lighting circuits and other
  building services systems is delegated to a
  family of Application Specific Controllers (ASCs)

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BEM Systems Software 1
Intelligent Buildings Technology

• Direct Digital Control (DDC) is the major concept
  of Building Automation System (BAS) in nowadays
• DDC control e.g. loops for damper operation are
  available to provide ventilation requirements or
  to utilize outdoor air for cooling
• Building energy management features are available
  inside a modem BAS
• e.g. the duty cycle program reduces electrical
  energy consumed by the fan by cycling it on and
  off
• The unoccupied period program, e.g night cycle
  program, is a function that can reduce the indoor
  temperature of a space by applying night
  ventilation

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BEM Systems Software 2
Intelligent Buildings Technology

• The enthalpy program monitors the temperature and
  relative humidity or dew-point of the outdoor and
  return air and then positions the outdoor air and
  return air dampers to use the air source with the
  lowest total heat or least enthalpy
• The load reset program controls heating and/or
  cooling to maintain comfort conditions in the
  building while consuming a minimum amount of
  energy
• The zero- energy band program saves energy by
  avoiding simultaneous heating and cooling of air
  delivered to spaces
• The occupied-unoccupied lighting control is a
  time-based program that schedules the on/off time
  of lights for a building or zone to coincide with
  the occupancy schedules

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BEM Systems Architecture 1
Intelligent Buildings Technology

• General Architecture

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BEM Systems Architecture 2
Intelligent Buildings Technology

• General Architecture

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Intelligent Buildings Technology

• BEM Systems Architecture 3
• The structures of BEMS change with evolution of
  technologies and products.
• Early BEMS were centralized energy management
  systems and first appeared in the 1970s, having
  been developed in the USA. The central station
  was based on a minicomputer, which contained the
  only computing power or "intelligence" in the
  system, with "dumb" or unintelligent outstations
  which were boxes or cabinets for relays and
  connections to sensors and actuators.
• Since about 1980, with the rapid development of
  technologies, the outstations became as powerful
  as the previous minicomputer, if not more so.
• Also, the outstations have gained considerably in
  processing power giving them "intelligence".