###### Abstract  
Researchers have used passive strategies, such as the implementation of thermal insulation and the use of phase change materials (PCM), in several studies, but some problems have not yet been solved. It is the case of showing the real effect of external shading combined with thermal insulation and phase change materials to improve the thermal performance and energy efficiency of office buildings in tropical coastal areas. Another pending problem to be solved is to define the impact produced by passive strategies on the performance of workers in office buildings in coastal zones. It is with a view to answering all these questions that this study was envisaged with the main objective of evaluating, analyzing, comparing, and discussing the effect of thermal insulation and phase change materials on thermal comfort and energy demand in coastal areas of hot and humid tropical climates located in the island of Madagascar. In this sense, hourly climate data for the past 30 years have served as the basis for assessing environmental conditions of future climate. It was found that the PCMs have a more significant effect on the coastal zone of hot climates than humid tropical climates. The results of the statistical analyses showed that the application of passive strategies stabilizes indoor air temperatures to between 23 \({}^{\circ}\)C and 28 \({}^{\circ}\)C in the offices, which is the recommended comfort range in these regions. In the coastal regions of Madagascar, up to 30% of cooling energy is expected to be reduced by combining the introduction of thermal insulation and PCM materials. thermal performance; office buildings; passive strategies; coastal regions; tropical climates +
Footnote †: journal: Applied  
in energy consumption for heating and cooling in habitats [3,4]. Given the risks of a shortage of fossil fuel sources and taking into account global population growth, newbuildings must meet more requirements than usual [5,6]. It is, therefore, a question of proposing residential buildings capable of ensuring acceptable comfort with a minimum of energy consumed, or even zero [7]. In most countries of the world, buildings currently represent 40% of the total energy consumption and 36% of total CO\({}_{2}\) emissions [8]. Predicting the energy consumption of residential buildings is fundamental to propose strategies to improve their energy performance with the aim of saving energy and reducing the environmental impacts of the buildings. Despite this, it is known that the energy system of buildings is very complex due to the great difference between them [8]. The application of passive strategy techniques, such as the use of phase change materials, is a novel idea for improving indoor air [9]. Indeed, the performance of new materials makes it possible to better conduct numerous experiments in the laboratory or in places with harsh climatic conditions [10]. Nowadays, some studies can be simultaneously realized in residential buildings [11]. The integration of these materials in building walls, making it possible to obtain a significant inertia in a reduced volume and under a small temperature interval, gave rise to new solutions to the problem of passive solar heating [12]. The phase change material (PCM) represents a sustainable alternative to reducing energy consumption [12,13] and, at the same time, increases the thermal comfort of occupants [14]. By consequence, its incorporation to reduce the heating and cooling energy demand of buildings has aroused the particular interest of many scientists, as it makes it possible to store and release large amounts of energy in the form of heat during the material melting and solidification process [14]. Air conditioning is not the ideal solution for lowering the temperature in a building, because it further increases energy consumption and requires rigorous maintenance to ensure air quality [15].