**Preface to "Demand-Response in Smart Buildings"**

Smart buildings and communities are currently in the spotlight of the scientific community due mainly to their potential for creating a more sustainable and livable future through the application of smart energy management. Demand response (DR) offers the capability of applying changes in the energy usage of consumers—from their normal consumption patterns—in response to changes in energy pricing over time. This leads to lower energy demand during peak hours or during periods when an electricity grid's reliability is put at risk. Therefore, demand response is a reduction in demand designed to reduce peak load or avoid system emergencies. Hence, demand response can be more cost-effective than adding generation capabilities to meet the peak and/or occasional demand spikes. The underlying objective of Demand response is to actively engage customers in modifying their consumption in response to pricing signals. Demand response is expected to increase energy market efficiency and the security of supply, which will ultimately benefit customers by way of options for managing their electricity costs, leading to reduced environmental impact.

This Special Issue entitled "Demand-Response in Smart Buildings" was published in *Energies*, and includes 5 international scientific contributions comprising 3 research papers and 2 review papers. Studies on energy retrofitting, consumer to fog to cloud framework, genetic algorithm optimisation models, energy policy, and energy legislations are collected and presented in this book. We would like to express our gratitude to all the authors and reviewers who have significantly contributed to this Special Issue. A special thanks also goes to the editorial team of *Energies* (MDPI) for offering us the opportunity to publish this book, especially Mr. Mark Guo, Senior Assistant Editor of *Energies*.

This book represents the Special Issue of *Energies*, entitled "Demand-Response in Smart Buildings", that was published in the section "Energy and Buildings". This Special Issue is a collection of original scientific contributions and review papers that deal with smart buildings and communities.

Demand response (DR) offers the capability to apply changes in the energy usage of consumers—from their normal consumption patterns—in response to changes in energy pricing over time. This leads to a lower energy demand during peak hours or during periods when an electricity grid's reliability is put at risk. Therefore, demand response is a reduction in demand designed to reduce peak load or avoid system emergencies. Hence, demand response can be more cost-effective than adding generation capabilities to meet the peak and/or occasional demand spikes. The underlying objective of DR is to actively engage customers in modifying their consumption in response to pricing signals. Demand response is expected to increase energy market efficiency and the security of supply, which will ultimately benefit customers by way of options for managing their electricity costs leading to reduced environmental impact.

> **Denia Kolokotsa, Gloria Pignatta, Kostas Gobakis** *Special Issue Editors*
