This work evaluates the potential for the reduction of energy demand in residential buildings by acting on the exterior envelope, both in newly constructed buildings and in the retrofitting of existing stock. It focuses on analysing social housing buildings in Mediterranean areas and on quantifying the scope of that reduction in the application of different envelope design strategies, with the purpose of prioritizing their application based on their energy efficiency. The analyses and quantifications were made by means of the generation of energy models with the TRNSYS tool for simple or combined solutions, identifying possible potentials for reduction of the energy demand from 20% to 25%, basically by acting on the windows. The case study was a newly built social housing building of a closed block type located in Seville (Spain). Its constructive techniques and the insulation level of its envelope are standardized for current buildings widespread across Mediterranean Europe.

The main aim of this article is to analyze the precision of several lighting simulation programs regularly used in daylighting studies for architecture, following the methodology established in the CIE test cases document. The 3DS Max Design 2014, Daylight Visualizer 2.6, DaySim 3.1b, Design Builder 3.0, Dialux 4.8, Ecotect Analysis 2011, Lightscape 3.2 and Relux Pro programs are analyzed. In order to establish the precision for each program, the sky component is measured at different points of study on the floor of a room, taking variable sizes and positions of openings into consideration. The results are contrasted with the analytical calculation of the sky component using Tregenza algorithms and the test cases established by the CIE, considering the models for Traditional and Standard Overcast Sky. Following the analysis of the sky component using the CIE test cases, it is concluded that the 3DS Max Design 2014 and Daylight Visualizer 2.6 programs present a maximum relative difference from the analytical model of close to 10%, while the DaySim 3.1b, Dialux 4.8 and Lightscape 3.2 programs show a margin of relative error lower than 30% in all case studies. Design Builder 3.0, Ecotect Analysis 2011 and Relux Pro show inadequate results.

This paper analyses the influence of different perforated solar screens (PSS) in annual daylight conditions expressed using climate-based daylight metrics. The PSS design require parametric studies that are often complex and time consuming due to a large number of simulations. Hence, a new methodology is proposed to optimize PSS design by applying Design of Experiments using Orthogonal Arrays (DOA). A case study from the DOA perspective has been conducted, which involves an office space in Seville, Spain. The goal is to assess the effect of the following PSS design variables in daylighting performance: perforation percentage, matrix, shape and orientation. DOA results reveal that optimized PSS can increase daylit area by 33% and reduce over lit area by 35%, compared with reference models with no PSS. DOA method reduces the number of simulations from the 256 required to 16, so it could save time during the initial stages of building design.

In recent years, the building sector has been turning towards intervening in the existing city building stock. In fact, it is generally accepted that the refurbishment of buildings and the urban regeneration based on sustainability must form the axis of reformulation of the building sector. Nowadays, achieving sustainable urban development inevitably involves improving existing buildings, thereby preventing the need for city growth, and for the emptying of established neighbourhoods. Furthermore, considering the whole life cycle, it is well known the great amount of greenhouse emissions derived from the construction sector, so in order to reach a decarbonized society it is important to provide eco-efficient construction materials and solutions, adding the principles of circular economy and resource efficiency. The articles of this special issue show different aspects to be considered in order to reach a decarbonized and circular building stock.

During the first stages of building design, issues such as local climate, surrounding buildings and orientation are determining factors. The impact of these boundary conditions on daylight illuminances in an open-plan office space is studied in terms of daylight factor, daylight autonomy and useful daylight illuminances. Climate conditions in the location determine the characteristics of the daylight source, such as the ratio between diffuse lighting and global lighting. However, surrounding buildings and elements which may block daylight in the space hold more weight than the orientation of glazed façades, but are not always taken into consideration in daylighting studies.