Special Issue: Recent Advances in Energy Efficiency of Buildings

1. Introduction

Buildings are important consumers of energy; in fact, they represent 30–45% of global energy use and one-third of total greenhouse gas (GHG) emissions [1,2] and make an important contribution to the urban heat island effect (UHI). In this context, the correct design and execution of buildings, the adequate use of energy sources, and the development of new materials are necessary to reduce energy demand and operating costs, as well as to reduce the emission of greenhouse gases during the life cycle of buildings.

This special issue collects a set of papers which show important efforts focused to improve the energy-efficient of buildings, in accordance with circular economy policies and their following life cycle phases: (i) the design phase, taking into account climatic parameters and climatic zones; (ii) the construction phase, using new materials for building, which include recycled waste; and (iii) the use phase, reducing energy consumption. These initiatives are summarized below.

2. Design Phase of Building: Analysis of Climate-Oriented Research in Building

Many aspects of the construction and operation of buildings depend on climatic parameters and climatic zones, so they are fundamental for adapting to and mitigating the effects of climate change [3]. In fact, a broad spectrum of themes directly and indirectly related to climate and climatic zones and buildings have shown that 88% of all climate-oriented investigations are within the scope of the general topic of energy conservation [3]. Consequently, a thorough understanding of all climate-dependent aspects will help in designing dwellings appropriately in different climate zones.

In this sense, and in the current context of the climate crisis, it is essential to design buildings that can cope with climate dynamics throughout their life cycle because it will ensure the development of sustainable and resilient building stock. Because of the higher global and surface temperature during the last 100 years, and projections of future climate conditions, it is necessary to determine the setting of new energy budgets and to transform the energy performance of buildings and cities [4,5]. To do that, and given the importance of precision in the assignment of a climatic zone when correctly sizing domestic hot water, heating and cooling systems, and the appropriate selection of the construction materials used, it is essential to take climate dynamism into account in the building design phase [6].

Thus, in the case of the cities of peninsular Spain, the allocation of climatic zones currently included in the Edification Technical Code [7] is not suitable for current and future climatic conditions. In fact, taking into account the climate data recorded in the 2015–2018 period, 80% of cities today have a different climate zone to that of the CTE [6]; moreover, it is expected that by the year 2085 and under the forecasts recorded in the RCP 4.5 and RCP 8.5 scenarios, practically all cities in mainland Spain observe a change in their climate zone to a warmer one [6]. It should be noted that the consequences observed in peninsular Spain can be extrapolated to other areas, so it is possible to conclude that significant climate change will reduce the heating energy demand of dwellings, but increase the demand for cooling. Therefore, architectural and construction standards must adapt to the urban environment’s actual conditions and consider the main scenarios, in order to lead to a building design that mitigates climate change and adapts to it. Hence, it is necessary to develop new climate zones and build recommendations to preserve the correct thermal conditions of future periods [6].

3. Construction Phase of Building: Using New Materials for Building That Include Recycled Waste

The creation of economic and environmentally friendly materials based on the integration of secondary materials as substitutes represents an opportunity to reduce waste disposal and the consumption of natural resources in the building industry.

For example, innovative porous materials (PM) could be synthesized by bottom ash and silica fume (as raw materials) to promote a circular economy, and new solutions could be proposed to improve urban air quality, reducing PM concentrations [8]. Another example is the integration of glass in the fabrication of ceramic materials as fine particles with optimal dosage and particle size, in order to enhance their physical, mechanical, and thermal properties and improve the solar reflectance performance [9]. The design of ceramic tiles with recycled glass could contribute to the production of friendly construction materials to be applied in the design of cool surfaces [10], i.e., surfaces with reflective materials and coatings that reflect the solar energy radiation that hits building envelopes and urban areas [11], including roofs, facades, and pavements. Such materials are able to reduce the thermal infrared radiation outflow in the atmosphere, as well as the temperature and the solar heat gain, in order to palliate the UHI effect [12].

4. Use Phase of Building: Reducing Energy Consumption

Finally, the household sector plays a significant role in energy conservation and environmental sustainability in terms of using energy-saving goods [13], so products that swiftly dissipate energy are considered important in achieving efficiency and reducing carbon emissions [14]. However, energy saving in the residential sector is dependent on users’ technological and habitual behavior; in fact, energy-efficient home appliances (EEHA) offer more energy efficiency and sustainability than the habitual correction of turning off appliances when not in use [15]. In this sense, a significant relationship between environmental concern, environmental knowledge, subjective norms, eco-labeling, and attitude towards buying has been detected. It has been also confirmed that the green self-identity moderates the existent relationship between the attitude and buying intention of energy-efficient home appliances, while environmental knowledge does not [16].