Cool Roof Impact on Building Energy Need: The Role of Thermal Insulation with Varying Climate Conditions

Abstract

Cool roof effectiveness in improving building thermal-energy performance is affected by different variables. In particular, roof insulation level and climate conditions are key parameters influencing cool roofs benefits and whole building energy performance. This work aims at assessing the role of cool roof in the optimum roof configuration, i.e., combination of solar reflectance capability and thermal insulation level, in terms of building energy performance in different climate conditions worldwide. To this aim, coupled dynamic thermal-energy simulation and optimization analysis is carried out. In detail, multi-dimensional optimization of combined building roof thermal insulation and solar reflectance is developed to minimize building annual energy consumption for heating-cooling. Results highlight how a high reflectance roof minimizes annual energy need for a small standard office building in the majority of considered climates. Moreover, building energy performance is more sensitive to roof solar reflectance than thermal insulation level, except for the coldest conditions. Therefore, for the selected building, the optimum roof typology presents high solar reflectance capability (0.8) and no/low insulation level (0.00-0.03 m), except for extremely hot or cold climate zones. Accordingly, this research shows how the classic approach of super-insulated buildings should be reframed for the office case toward truly environmentally friendly buildings.

Combined Effect of Outdoor Microclimate Boundary Conditions on Air Conditioning System’s Efficiency and Building Energy Demand in Net Zero Energy Settlements

“…In detail, the system operation is expected from morning to evening, with an air supply temperature 10 K lower than the indoor set-point temperature, i.e., equal to 16°C. Furthermore, the definition of internal heat gains is essential for HVAC system operation and end-use energy performance, especially during the hot season [30]. In line with the aim of this study, occupancy profiles were modeled according to the ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) standard for residential buildings [31,32].…”

Applicability of Building Information Modelling (BIM) in the Sustainable Design of Commercial and Office Buildings. A Case Study from Tehran, Iran

“…BIM can create intelligent connections between different design components and enables the examination of different varieties and audit scenarios (Dincer, 2000). The application of different insulation methods to reduce energy consumption (Piselli et al, 2019;Wi et al, 2019), and changing the thickness of the insulation used in the walls of the buildings are some of the existing scenarios in this regard. To reach the sustainable design goals in this area, BIM can be used to analyze the possible scenarios much faster than using traditional methodologies.…”

Influence of Traditional and Solar Reflective Coatings on the Heat Transfer of Building Roofs in Mexico

“…The maximum increase in annual energy consumption due to winter heating was only 4.4 kWh/m 2 . Piselli et al [14] assessed the effectiveness of cool roofs with optimal insulation levels in different weather conditions worldwide. The authors coupled a dynamic energy simulation tool with an optimization technique to find the best-combined building roof thermal insulation and solar reflectance and minimize the annual energy consumption.…”