# A Review of Systems and Technologies for Smart Homes and Smart Grids
## 4 Classification Criteria for the Selection of Smart Home Technologies  
The existing communication networks strive to increase the exchange of information among utilities, home appliances, and users. The diverse directionality and complexity of the existing communication devices represent a challenge. The growing trend is the development of bidirectional communication using a Home Automation Network (HAN) to monitor and control home appliances; _de facto_ realizing a demand-response (DR) system. According to a report published by the American Council for an Energy-Efficient Economy [42], some of the systems from among the new feedback initiatives that make energy resources visible to residential users achieve the maximum feedback-related savings. If all systems are to do this, they will require a combination of useful technologies with well-designed programs that successfully inform, engage and motivate the users via the following determining factors [43]:  
* Data collection: the technology allows the collection of all relevant data and provides access to them;
* Data processing: the technology allows the processing and analyzing of relevant data and can combine them;
* Data representation: the technology allows the relevant data to be made accessible to the users;
* Control and interaction capabilities: the technology enables users to access the status and monitor the functions of related technologies (bidirectional communication and interaction).  
These factors need to be considered when tailoring the data that should be provided to end-users [44; 45]. Collected data can be shown to users as: (i) _direct feedbacks_, which are the representation of the collected data typically provided in real-time; and/or (ii) _indirect feedbacks_, which are derived from a post-processing task and provided after the energy usage has occurred. Direct feedbacks are: real-time plus feedback (_i.e._, real-time information about the level of energy used by the appliance), real-time feedback (_i.e._, real-time premise level information), while indirect feedbacks are daily or weekly feedback, which is that are household-specific information and advice on a daily or weekly basis, estimated feedback (_i.e._, typically web-based energy audits with information supplied on an on-going basis), and enhanced billing (_i.e._, household-specific information and advice) [42]. Figure 1 shows the percentages of annual household electricity savings based on 36 studies implemented between 1995 and 2010 [42].  
Data can be presented in different ways, for example energy, peak power, cost, ecological footprint _etc._ and they can be compared with benchmarks and historical trends, but, to be effective, feedbacks to the end-users should be:  
* Direct: the more immediate the feedback is, the more effective it is, but it requires a certain degree of knowledge and preparation from users;
* Personalized: the way of presenting data is customized to end-users' needs;
* Comparable: end-users can compare their actual electricity usage with benchmarks as well as with their historical data;
* Flexible: the feedback technology needs to be continually improved, in response to users' suggestions and requests.  
It is also clear from the literature that the way to communicate the feedbacks to the end-users involves two main approaches:  
* Systemic: the house exists in a systemic context, and the data, retrieved by means of a smart grid, are presented at an individual household level and compared with the average system performance [45].
* Gamification: the feedback is presented by using elements and concepts that are typical in computer games and is often integrated in a graphical user interface (GUI).  
In the following sections, the most relevant technological devices and integrated software or applications today available on the market for improving the interaction between users and home appliances are presented, compared and discussed.