Operational energy of opaque ventilated façades in Brazil

Abstract

Energy efficient buildings require envelopes designed to fit the local and the climate zone while the greatest benefit of opaque ventilated façades is the ability to reduce cooling thermal loads. The natural convection in the air chambers and the protection against solar incidence provided by the external layer reduces the energy consumed by the artificial systems used for environmental conditioning (HVAC systems). This research investigates the energy benefit of opaque ventilated façades compared to cladding façades in multi-floor residential buildings located in nine climate zones, according to the Köeppen-Geiger classification, in Brazil. To this end, computational simulations using software from the same company, capable of automatically synchronizing the modeling data and energy analysis of a whole year were used. Also, the cost of implementing the system in different locations was determined in order to analyze the cost-benefit of the system against the yearly energy benefits. The greatest energy benefits, as well as the best cost-benefits, were found in the hottest regions, demonstrating that this system is relevant for the climate conditions in Brazil and its use should be encouraged since the largest area of the country is located in hot climate zones. Despite the similar results found for cities in the same climate regions, there were also significant differences among them so an individual analysis taking into account the influence of wind speed and rainfall should be performed as well. The study evaluated a wide sampling, 16 cities from all climatic zones, unlike the current studies that were conducted between 2010 and 2018 in Europe, having as main contribution the analysis of an entire building over the period of one year, becoming the most complete research to date, conducted with great speed enabled by the adopted computer simulation methods. This research shows that the behavior of ventilated façade is an improvement in terms of passive cooling of the building compared to cladding facades, offering energy electric savings up to 43% yearly, in the hottest cities.