Environmental concerns worldwide (climate change, global warming, etc.) are pushing to reduce the consumption of fossil fuels. The building sector is responsible for a third of greenhouse gas emissions (40% in France). In tropical countries, the main share of energy consumption in buildings is due to air conditioning systems. Indeed, in a resort of high standing, 60% of energy consumption is due to air conditioning. In the Indonesian context, which welcomes growing real estate projects on more or less isolated islands, it becomes important to put in place passive or autonomous buildings and the corresponding energy solutions. The energy efficiency of buildings is based on two pillars: an efficient building’s design and on the effectiveness of the air conditioning system to achieve energy independency in a tropical environment. Considering the decreasing cost of PV cells, the solution to reduce the energy consumption of air conditioning proposed in this article covers a vapour-compression refrigeration system electrically powered by solar cells. To avoid the use of electric batteries, not sustainable in terms of carbon footprint (construction and recycling of batteries) and to overcome the problem of intermittency of solar energy, the choice fell on a variable speed compressor and a storage in a mixture of fatty acids (derived from coconut oil) as phase change material embedded in expanded graphite. The work also focuses on the energy performance of the storage system. This study describes the context and the air conditioning system chosen as a solution for a sustainable resort application in a tropical region. The design and characterization of the coupled PCM and compressed expanded graphite in a latent heat thermal energy storage is also detailed. It uses a TRNSYS simulation for the assessment of the cooling demand. Calculations for a prototype of 25 m2 apartment showed that with a chiller of 8000 W and a surface of 14 m2 of photovoltaic panels, it is possible to cool a hotel bedroom with solar energy. The consortium members work jointly at designing and optimizing the system: Indonesian members are focused on the PCM storage and French members are more dedicated to the hygrothermal behaviour of the hotel bedrooms.
Keywords: air conditioning, hotel, net-zero energy, PCM.