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Intelligent Buildings Technology 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 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 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 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 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 Intelligent Buildings Technology Indoor Comfort  Thermal comfort  Visual Comfort  Indoor air quality Thermal Comfort 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 Intelligent Buildings Technology Thermal Comfort – Energy Balance Intelligent Buildings Technology Heat transfer-Radiation 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, ΔT, is given by: Intelligent Buildings Technology Energy Management Systems 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 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 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) 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  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 Intelligent Buildings Technology Building Energy Management SystemsHow much energy can be saved Intelligent Buildings Technology Building Energy Management Systems- Hardware 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) Intelligent Buildings Technology BEM Systems – Software [1]   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 Intelligent Buildings Technology BEM Systems – Software [2] 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  Intelligent Buildings Technology BEM Systems – Architecture [1]  General Architecture Central Unit Sensors Actuators Intelligent Buildings Technology BEM Systems – Architecture [2]  General Architecture Central Unit Local Controller Sensors Actuators Local Controller Sensors Actuators Local Controller Sensors Actuators 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"