Technology that makes a difference
Energy management has been one of the hottest issues in recent years. This concern has been raised as we notice some significant changes in our daily life. Global warming, energy crisis, sea-level rise are some phenomena causing the increasing cost of energy. Numerous scientists have warned us about the serious disaster of global warming over the years, for example the loss of white sea ice will expose greater areas of dark sea increasing the accelerated warming of the planet. The Earth is screaming to humans that global warming is coming. However there are actions we can take and building and sensor technology in the humble office can be part of this change.
the problems as they stand
Since the start of the industrial era, human activity has caused most of the increase in atmospheric greenhouse gases, particularly CO2. Fossil fuel burning has produced about three-quarters of the increase in CO2 from human activities over the past 20 years. As weather gets warmer, the hot and humid conditions makes energy guzzling airconditioning a necessity. These phenomena are continuous rather than temporary problems, hence humans need to take action.
In addition, non-renewable energy sources are being depleted at a rapid rate. As cheaper energy sources disappear, more expensive sources cause consistently increasing costs. Petroleum for example, has inflated to a record high of over one hundred dollars per barrel dollars (over 10 times) since 1999. Heavy demand and oil depletion are the main reasons leading to the hefty price increase. As such according to a recent survey of heads of finance conducted by CFO Research and American Express “the rising cost of energy proves to be an urgent concern among respondents globally, outstripping other worries that could affect the production and delivery of goods and services, including the cost of capital, labor and raw materials, by a fairly large margin.”
In the case of electrical energy, most household and office devices are primarily electricity driven. As average energy usage level increases, the peaks and large fluctuations generally increases overloading the supplying utility. Thus the supplying utilities will have to make large capital investments to meet the loading. With no action undertaken, the story of oil price hikes will definitely be repeated in electricity bills in future years. It is highly desirable to reduce energy usage during peak hours and apply an energy management concept in every office, home or other facility we manage.
a solution in the form of wireless energy trends:
From both environmental and economic aspects, scarce energy resources have to be used efficiently to alleviate the existing problems. Energy management is of the utmost importance for the future development of building automation system. One efficient energy management systems is the adoption of wireless sensors to control the status of electronic and other devices installed in the building. Currently, there are numerous forms of energy management concepts in the market. Using wireless monitoring is desirable and the enabling technology is reaching maturity.
Using a Wireless Sensor Network (WSN) has become a popular solution for energy management using building automation in recent years. Wireless sensor developers require technical sophistication, however greater costefficiencies while maintaining high levels of functionality and reliability are also high on the priority list. While wireless systems reduce the wiring and labour cost found when implementing building automation technologies, there is an urgent need to enhance power efficiency and the range of the wireless digital signal transmission. ‘Wireless mesh’ networking technology is likely to address the issue surrounding wireless signal attenuation and offer better quality wireless signals. As building automation installation and maintenance expenses continue to rise, developers of wireless sensors will have to lay emphasis on affordability in addition to individual comfort, design, flexibility, and security.
Apart from the possible cost benefits, ease of deployment, retrofitting applications, and scalability of the network are spurring interest in wireless sensors. Whether used in new construction or retrofit, flexibility is the ultimate benefit in deploying a wireless system as opposed to a wired network in offices. It is because the sensors can be located and relocated easily to optimize system performance, increase customer comfort, and adapt to changing floor plans.
which system to choose?
ZigBee is a standard providing specifications for communication protocols of a network layer based on the IEEE 802.15.4 standard for wireless personal area networks (WPANs). The protocols are intended for use in embedded applications requiring low data rates and low power consumption. ZigBee is developed for networking control and sensor nodes because a network node can be built for a few dollars using a single-chip radio and a microcontroller. As a result, ZigBee is an ideal solution for wireless sensor networking. This standard also supports ad hoc mesh networking, in which separate nodes form a network by discovering each other’s presence over the air. Messages are then passed from node to node until the signals arrive at the right destination. Hence no special expertise is needed to build a ZigBee network – simply place sufficient nodes within radio range of each other and the network of meshed communicating nodes forms. Moreover, there are multiple routing paths from source node to destination node. When one node fails, messages are routed around the blockage rather than being simply dumped.
 |
Due to these characteristics, the technology of ZigBee represents a wireless network which is highly reliable, networking, secure, low data-rate, low power consumption, low cost, and fast. ZigBee makes it possible to design easy-to-install network kits (especially good for home usage) and its network capability allows easy network expansion to cater for future ZigBee deployment. This adds up to make ZigBee an ideal technology for energy management applications.
in practice saving energy
A ZigBee Energy Management (ZEM) system has been developed. ZEM is versatile and can be applied to both office and residential buildings. The following explains why WSN is adopted by the ZEM, as well as the system design and energy management approach of ZEM. A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants, at different locations.
The development of wireless sensor networks was originally motivated by military applications such as battlefield surveillance. However, wireless sensor networks are now used in many civilian application areas, including environment and habitat monitoring, healthcare applications, home automation, and traffic control. Since WSN can monitor the physical environment, WSN is adopted by ZEM as shown in Fig. 1. According to a recent survey, 32.95 percent and 14.9 percent of electricity in buildings is consumed by air-conditioning and lighting respectively. Therefore, ZEM was designed to monitor energy consumption from these sources. As shown in Fig. 1, light intensity sensors and thermostats fitted with ZigBee modules are distributed accross different locations. The sensors collect environmental data such as brightness and room temperature. The collected data travels along the Zigbee Network to the control unit of ZEM, namely Energy Master (EM. The EM is a central server loaded with a ZigBee module. The EM has been preset with An energy consumption target. Moreover, the EM is equipped with an energy saving algorithm called Energy Consumption Manager (ECM). It optimizes the energy consumption by controlling the status of different electrical appliances. EM will update the status of each appliance based on the collected data. After applying the algorithm, EM will send a control command back through the network to each appliance, which will automatically update its status according to the instruction from EM.
 |
In an energy management system, an algorithm with artificial intelligence is important to manage the whole system energy consumption. Energy Consumption Manager (ECM) is the artificial intelligence algorithms which enable the EM to avoid the energy wastage. It comprises an:
- energy consumption monitor
- energy consumption analyzer
- energy consumption advisor
The ZEM monitor collects the data that feeds into these systems from the sensor and device by two methods: Polling and events.
“Polling” means an algorithm is set to actively request the status of sensor or devices at a regular interval. An “events” driven methodology actively informs the EM whenever the device changes status . The collected data is filtered by Energy Consumption Monitoring and stored to the corresponding database. Energy Consumption Analysis extracts the recorded data of energy consumption monitoring and it then classifies devices into different priority classes and can be set to predict user habits. Energy Consumption Advisory provides suggestion to users and helps determine redundant devices especially during peak-hours.
Dr. KF Tsang, Associate Professor, Department of Electronic Engineering, City University of Hong Kong explains how the Zigbee Energy Management system can improve a building’s environmental performance.
