**1. Introduction**

For several decades, strong processes of globalization of economies, intensive interconnections between countries have influenced the interaction between consumption patterns [1,2]. It seems clear that as fossil fuel resources are depleted, greater use of renewable energy sources (RES) will become necessary. [3,4]. In the last decades of the 20th century, the cost of household investment in renewable energy sources was extremely high and, thus, out of reach for many consumers. The progress in research and development activities resulting in creation numerous innovative solutions [5,6], as well as financial support from EU funds led to the situation that RES began to play more and more increasing role as energy carriers in households.

Renewable energy sources are the basis for sustainable economic development. Between 2004 and 2019, in the EU-28 countries, the usage of renewable energy sources by all sectors of the economy in final energy consumption increased from 5.1% in 2004 to 10.2% in 2019, while in the household sector from 10.8% to 18.2% [7].

Sustainable development is a basic and main objective of the European Union. The EU sustainable development strategy aims for the continuous improvement of quality of life for society [8]. Sustainable production and consumption patterns are important elements in tackling climate change. Reduction in energy consumption and changes in the fuel mix, by switching to less carbon-intensive energy sources, is linked to lower CO2 emissions. Transition to a low carbon economy would be an important stage towards meeting this demand for climate stability.

**Citation:** Piekut, M. The Consumption of Renewable Energy Sources (RES) by the European Union Households between 2004 and 2019. *Energies* **2021**, *14*, 5560. https:// doi.org/10.3390/en14175560

Academic Editor: Adélio Rodrigues Gaspar

Received: 3 August 2021 Accepted: 1 September 2021 Published: 6 September 2021

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The use of energy from renewables brings numerous advantages: decrease in the cost of energy supply, reducing both environmental pollution and the pressure on fossil fuel energy production, and also more convenient form of energy production and supply [9,10]. It can also contribute to energy poverty alleviation [11,12]. Replacing fossil fuels with renewable energy sources also reduces particular countries need for energy imports and their dependence on countries exporting non-renewable fuels [13].

The paper covers the issue of renewable energy sources (RES) consumed by European Union households. It considers the use of RES as a whole and also its different type categories in the household sector from 2004 to 2019, and (in some parts of the analysis) the time range also includes 1990.

The main purpose of the paper is to determine the development trends in the use of RES in the EU countries household sector in 2004–2019, to recognize the state of development and functioning of the studied area as well as to indicate their successes and shortcomings in observed reality.

In view of the research goals the following research questions were formulated:

**Research Question 1.** What changes have occurred in the use of renewable energy between 2004 and 2019?

**Research Question 2.** What groups of countries can be distinguished according to the category of renewable energy sources used in the household sector?

**Research Question 3.** How is the use of renewable and non-renewable energy sources changing in the household sector from selected EU-28 countries?

The undertaken research topic is important for several reasons. Households are one of the important sectors consuming energy. In 2019, households accounted for 26.9% of final energy consumption [7] in the EU-28 countries. Thus, from a practical point of view, involving them in the process of improving environmental quality can contribute towards climate improvement by reducing emissions of harmful substances into the atmosphere. Observing the changes in the household sector in terms of RES consumption gives an overview of the situation of individual EU members and can be a wake-up call for those who have accomplished little in the period under study to involve citizens in initiatives to install new technological solutions based on cleaner energy. From a theoretical point of view, the diagnosis of the situation of RES use in households is cognitively interesting, since analyses of RES use, as a rule, appear only for their overall use in the economy or in relation to transport. Moreover, the use of energy commodities in households can also be associated with responsible consumption. The problem addressed is also important from the point of view of the 17 Goals of Sustainable Development [14,15] formulated by the United Nations.

The originality of the presented article in comparison to the existing literature data lies in the emphasis on the important role of households in energy consumption and related problems. The novelty is also the presentation of the author's types of households observed in the EU-28 countries, according to the patterns of RES categories.
