## 1 Introduction  
During the past two decades, primary energy consumption has grown by 49% and CO\({}_{2}\) emissions by 43%, with an average annual increase of 2% and 1.8%, respectively. Current predictions show that this growth will continue. The energy used by nations with emerging economies will grow at an average annual rate of 3.2% and will exceed that for developed countries by 2020, with an average growth rate of 1.1%. In particular, mainland Asia's energy consumption will continue to grow at an average rate of 3.7%. As a response to the challenge of climate change, several research and modeling exercises have been performed, mostly discussing options such as a shift towards low carbon fuels, renewable energy and improvements in the efficiency of energy transformation and end-use technologies. However, engineering cannot provide all of the solutions; cultural and behavioral change that alters the demand for energy services is necessary in order to meet the stringent targets for climate change mitigation [1]. A reduction in energy-service demands will, _ceteris paribus_, result in lower energy consumption and a consequent reduction in CO\({}_{2}\) emissions for the entire energy system [2]. The development of energy saving technologies to suppress reduce energy use is an effective way to overcome the threat of climate change. The improvement of a building's envelope and the energy consumption patterns of humans represent the two most feasible methods of increasing energy efficiency and reducing gas emissions. China reduced its energy consumption by one third, during the period 1978-1990, simply by employing elementary design and construction technologies [3]. Electricity consumption for the needs of everyday life accounts for 20 percent of total electricity consumption in Taiwan. Other users of electricity, such as the industrial and commercial sectors, petrochemical, steel, cement, paper and man-made fiber industries, account for 25% of Taiwan's total electricity consumption. In the year 2000, the electricity demand in Taiwan was 2,042.6 billion kWh, and this figure is estimated to increase to 2,759.8 billion kWh by 2019. The annual average growth rate is 3.4%, so an extra 7.2 billion kWh of electricity is required, annually, in order to meet the electricity requirements for future economic development [4]. Information technology-enabled monitoring and control systems can assist in mitigating energy use in residences, by more efficiently allocating the delivery of services, in terms of time and location. A great deal of energy is wasted in the inefficient delivery of services to residents, for example the heating or cooling of unoccupied spaces, overheating/undercooling for whole-house comfort, leakage current and inefficient appliances. The initial estimate is that more than 39% of residential primary energy is wasted [5]. Energy saving is an important issue, as energy prices increase. Products and services provided by the information and communication technology (ICT) sectors allow greater energy efficiency and the emission of reductions. The use of ICT in a residential area results in a smart building environment. Ecological and smart building networks should not only improve the quality of human life in terms of health care, security and the efficient management of energy and resource consumption, but should also provide convenience and personal fulfillment, through easy communication with others in the community, sophisticated entertainment options and opportunities for continuous education. A smart building in a smart grid represents the latest evolution of the principle of ICT usage in a building [6]. A wireless sensor network is composed of a large number of tiny sensor nodes [7]. The main task of a wireless sensor node is to sense and collect data from a certain area, process these data and transmit them to a sink node, where further processing of the collected data can be performed [8]. Sensor nodes are small-scale and cost effective devices with limited capabilities.