- Buildings Guide
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Building Energy Management (BEM) is a systematic process to monitor, control and benchmark the energy consumption of a building and its systems, to implement energy efficiency improvement actions, and to optimise the operation of the building in order to minimise energy use. These systems control, monitor and optimize energy consumption of comfort systems, lighting, hot water and appliances in a building over time and augment energy savings already obtained by the use of passive and active measures. An important tool for BEM is Building Automation & Control systems (BAC)/Building Energy Management systems (BEM), which is the focus of this bigEE section. By complying to ‘Class A’(high energy performance) classification of the standard EN 15232 (Energy performance of buildings - Impact of Building Automation, Controls and Building Management) there can be potentially up to 30% energy and cost savings with added benefits of thermal comfort and safety (Siemens, 2010). Other studies show that by employing building automation and energy management techniques 60% of annual energy savings could be obtained with a pay back period of 2-10 years in commercial buildings (Becker, Bollin & Eicker, 2010).
With the increased number of service systems and appliances in modern buildings, it has become a complex task to manually overlook and control all of them. This potentially results in mix-ups, negligence and human error and thus lead to unwarranted energy wastage. State of the art intelligent buildings aid passive heating, cooling, natural ventilation and daylighting through sophisticated controls by responding to both building’s internal and external environment dynamically. They enable efficient daylight penetration, provide glare control, and optimize the use of heating, ventilation and air conditioning systems, lighting systems and equipment in a building by using demand response and load management technologies while ensuring human comfort at minimum energy consumption levels possible.
At least some degree of deploying Building Energy Management in service sector buildings like office, hotel, retail and other multi-functional buildings is gaining ground worldwide, especially making quick foray in rapid growth markets of Asia Pacific. In residential buildings, building automation and energy management is acquiring popularity in Europe and USA, which already have a market for sophisticated energy, and appliance systems in residences, while it is almost unheard of in the residential sector in rest of the world.
Home automation is also known as domotics, and deals with residential building automation. In home automation, ergonomics and ease of use are of particular importance and the controls, are often image-based with easily understandable user interfaces. Energy management in residences could include simple systems such as dimmers for lighting and adjustable thermostats for temperature regulation to more complex systems such as Home Automation Networks (HAN). HAN enables real-time energy consumption monitoring through hourly (or sub hourly) timestep data to the homeowner on the energy consumption of various end uses. HAN is a network within the home that enables communication between “smart” devices including HVAC, security, lighting, and appliances. This also provides the home user with ability to remotely control devices within the HAN (such as adjusting a thermostat or turning off lights). This helps consumers to better manage consumption and cost, and utilities to better manage supply and demand, and to react quickly during emergencies.
Intelligent building control systems ensure energy optimization in office buildings while ensuring individual occupant comfort and security. Sick building syndrome can be reduced by maintaining optimum ventilation levels for fresh air adapted to the needs and thereby avoiding oversupply, the use of automatic blinds and shades for daylight penetration etc. Contemporary green building rating systems also recognize the energy saving potential of such systems and award points towards the use of sophisticated lighting, shading and heating, cooling and ventilation system controls. In commercial and office buildings sophisticated facility monitoring and control systems allow monitoring of various end uses in real time. The Efficiency Valuation Organization (EVO) publishes the International Performance Measurement and Verification Protocol (IPMVP) to increase investment in energy and water efficiency, demand management and renewable energy projects around the world. It provides an overview of current best practice techniques available for verifying savings and lays special emphasis on the use of Energy Management Systems for the purpose of Energy measurement. The IPMVP allows building owners, energy service companies, and financiers of energy efficiency projects to quantify the energy savings performance of Energy Conservation Measures (ECMs).
The growth of the BMS market has been extremely large in recent years. It is estimated that the revenue growth of smart HVAC control market for various products and components (sensors, controllers and actuators) reaches €14.52 ($26.60) billion by 2020 at an estimated Compound Annual Growth Rate of 8.22% from 2014 to 2020. Owing to the rate of construction and development activity in the Asia Pacific region, it leads the smart HVAC controls market, which is followed, by the Americas and Europe (MarketsandMarkets.com, 2014).
Lifestyle changes, ease of use and perception of better comfort are few factors for creating demand for sophisticated HVAC and lighting controls. The growing demand for energy efficiency in buildings has also been one of the key drivers for the industry. Various green building rating systems like LEED, BREAM etc. encourage the use of automation controls and Building Energy Management systems to effectively optimize energy consumption in buildings.
Typical Building Energy Management (BEM) installation would have three main constituents. They are sensors, a logical monitoring and control unit and actuators. The operation of a BEM system is a three step process. Sensors are attached to all the systems that need to be monitored and controlled and the data is relayed to monitoring and control system. Monitoring and control system continuously evaluates the performance of various systems and sends out signals to actuators to take any necessary action. This enables live controlling of devices through actuators and also enables to continuously monitor energy consumption data by its end use.
The three key components of a building energy management system are sensors, monitoring and controller unit and actuators.
Sensors are used to monitor various aspects such as temperature, light levels, humidity levels, occupancy, air quality etc. Sensors are made up of thermostats, electro-mechanical/chemical devices, pneumatic devices, photosensitive devices etc. Accuracy of the sensor and the quick response time are the major indicators of the efficiency of a sensor. Sensors continuously gather the data and relay it to the central monitoring and control unit. Depending on the type of sensor it can either be directly integrated into the field wiring and can communicate with the control or include a special micro processor and transmitter to convert the sensor information into industry standard signals for communication. For example thermostats are integrated into the wiring as a part of the circuit while photo sensors include a special microprocessor to transmit relay signals. The information can be conveyed to the controller via wired or wireless connections.
Monitoring and control unit
A monitoring and controller unit is responsible for receiving the signal from a sensor, analyse the signal and send an appropriate control action to the actuator to perform. This process can be automated or can be overridden by manual control. Controllers generally consist of a pre programmed microprocessor device capable of carrying out the relay transmissions. Local control devices could be wall mounted within the space and controls for large facilities typically consist of large display panels showing various components of the building management systems. In residential units advanced monitoring systems also work with multi purpose remote controls and via Internet Protocol through smartphones and laptops.
An actuator is a device that physically controls the end use system. A simple actuator could be a remotely operated on/off switch. The data from the sensors is conveyed to the controller. The controller analyses and provides an output command signal to an actuator, which locally controls the physical movement of the target systems and components. Actuators are typically electrical, mechanical or pneumatic. Actuators perform tasks like tuning on & off the end use, increasing or decreasing the speed of end use motors, fans etc.
Energy consumption in a building can be optimized only if it is measured effectively. Monitoring and measurement represents a very important function of the BEM system and is done through advanced metering techniques using appropriate sub meters and smart meters. Sophisticated facility monitoring and control systems allow monitoring of various end uses in real time. The Efficiency Valuation Organization (EVO) publishes the International Performance Measurement and Verification Protocol (IPMVP) to increase investment in energy and water efficiency, demand management and renewable energy projects around the world. It lays special emphasis on the use of Energy Management Systems and allows building owners, energy service companies, and financiers of energy efficiency projects to quantify the energy savings performance of energy conservation measures (ECMs).
The energy consumption output data that are available from central monitoring and measurement unit can be analysed periodically for optimizing various processes. The analysis typically takes into account external weather data, occupancy schedules, automation schedules, user behaviour data and system performance. Based on this data a schematic step-by-step approach is followed in order to optimize one or all of the above described parameters in conjunction or in isolation. In some cases the whole system can be optimized by just recalibrating the system and adjusting the controls to suit updated user behaviour patterns.