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In hot dry regions, the building envelope receives abundant solar radiation, which contributes to heat stress and indoor thermal discomfort. To mitigate overheating inside spaces, cooling is the main basic requirement during most of the year. However, due to the harsh climatic conditions, buildings fail to provide passively the required comfort conditions. Consequently, they are fully dependent on-air conditioning systems, which are huge energy consumers. As roofs are exposed to the sun throughout the daytime, they are estimated to be the main source of heat stress. In return, they can contribute significantly to achieve optimum comfort and energy savings when efficient design strategies are used in an early design stage. To examine the potential for cooling load reduction and thermal comfort enhancement by using cooling roof techniques in residential buildings, a study was performed in the city of Biskra (southern Algeria). Accordingly, an in-field measurement campaign was carried out on test-cells during five days in summer. Three different cooling roof techniques were addressed: (a) cool reflective white paint (CR), (b) white ceramic tiles (CT) and (c) a cool-ventilated roof (C-VR). These roofing alternatives were investigated by monitoring both roof surface temperatures and indoor temperatures. Comparative analysis showed that a cool-ventilated roof is the most efficient solution, reducing the average indoor temperature by 4.95 °C. A dynamic simulation study was also performed based on TRNSYS software to determine the best roofing system alternatives in terms of thermal comfort and energy consumption, considering the hottest month of the year. Simulation tests were run on a base-case model representing the common individual residential buildings in Biskra. Results showed that a double-skin roof combined with cool-reflective paint is the most efficient roofing solution. By comparison to a conventional flat roof, meaningful improvements have been achieved, including reducing thermal discomfort hours by 45.29% and lowering cooling loads from 1121.91 kWh to 741.09 kWh. [ABSTRACT FROM AUTHOR]

The energy consumption and thermal comfort in buildings are heavily affected by weather conditions. Therefore, the aim of this paper is to analyze the bioclimatic potential of Algerian climate zones. This analysis was made based on eight representative locations using recent weather datasets (2003–2017). The thermal comfort and passive design potential analysis were based on a psychometric chart applying the adaptive comfort model ASHRAE 55–2017. In addition, an evaluation of the bioclimatic potential was conducted using simulations of a monitored and calibrated residential building model in Algeria using EnergyPlus. The building model has been tested in eight previously selected locations. The heating and cooling energy load results were calculated for each climatic zone and compared. The results allow architects and urban planners to better understand the climate and provide practical design guidance. • The bioclimatic potential of the six climate zones of Algeria was calculated. • A monitoring-based simulation model was created and calibrated. • A strong correlation exists between the bioclimatic potential and performance. • The average percentage of discomfort hours in Algerian households is between 58% and 75%. • Our study confirms the need for a new bioclimatic zoning map for Algeria. [ABSTRACT FROM AUTHOR]

Highlights • Reflective glazed façades have an important influence on the urban microclimate. • Reflected sunbeams increase air temperatures. • Cooling load is strongly impacted by the local solar radiation environment. • Main reason is the high reflectance of the curtain-wall. Abstract The urban landscape of the city of Algiers, Algeria, has seen a spread of reflective glass façades of new and rehabilitated office buildings. This type of glass can create visual glare in outdoor spaces and may lead to indoor thermal discomfort. The objective of this paper is to investigate experimentally and numerically the impact of the reflective glass façade of an existing building on the neighboring microclimate and the building cooling load. The modeling of the microclimate around the case study building is performed with ENVI-met software. The impact of the microclimate is investigated by calculating the cooling load of the case study building with three weather data files. The cooling load is calculated with the building energy simulation software Ecotect for a typical summer day. The weather data files investigated are the experimental data from the reference station of Algiers airport, experimental data measured on the case study building roof, and the data modeled by ENVI-met taking into account the microclimate created by the glazed building. It is found that the air temperature surrounding the building significantly increases due to the multiple reflections of the radiation heat flux, leading to an increase in the cooling demand. [ABSTRACT FROM AUTHOR]