The building sector is one of the largest consumers of natural resources and energy in the world. Strategies to improve the energy efficiency are a solution to improve the performance of a building. However, in most cases, such strategies are assessed only at the operational phase of a building. The life-cycle energy analysis can be an important tool to allow choosing the best strategy. The objective of this paper is to assess the energy performance of four window shading systems in a house using life-cycle energy analysis. Life-cycle cost analysis was also used to determine not only the most energy-efficient strategy, but also the most economically feasible one. A house located in Florianópolis, southern Brazil, was evaluated based on a 63-year lifespan. The four window shadings analysed were: punctured concrete blocks, aluminium double sliding shutters, PVC roller shutters and wooden double open shutters. The EnergyPlus computer programme was used to estimate only the annual energy consumption for air-conditioning with and without the shading strategies. National and international databases were used to perform the life-cycle analysis. For the life cycle cost analysis, the cost of each strategy was obtained through a survey in local stores. The average inflation rate in the last ten years in Brazil was used to estimate the future costs. The results showed that the use of wooden double open shutters and PVC roller shutters are the most suitable solutions for window shading, both in terms of energy and costs, if they are not replaced during the lifespan of the building. This paper pointed out the need of using the proposed methodology to assure the right choice of strategies for energy efficiency in buildings.

Energy consumption and thermal comfort in buildings are heavily affected by weather conditions. This study investigated the impact of climate change on thermal comfort conditions and on heating and cooling energy demand in dwellings in three cities in Brazil. Scenario A2 of the Intergovernmental Panel on Climate Change was selected to be used in the study. To quantify the impact, the Climate Change World Weather File Generator was used to produce weather data for future typical meteorological years, such as 2020, 2050 and 2080. The EnergyPlus computer programme was used to estimate the indoor air temperature and the annual heating and cooling energy demand in the future. In order to maintain the energy consumption in the houses at the level it is nowadays, passive design strategies such as solar shading, low absorptance and thermal insulation were assessed. Results show that there will be an increase in the annual energy demand ranging from 19%–65% among the three cities in 2020; 56%–112% in 2050; and 112%–185% in 2080. In the coldest city, the annual heating energy demand will decrease by 94% in 2080 due to an increase in the average temperature and global solar radiation. The use of passive design strategies may reduce up to 50% the future annual cooling and heating energy demand in houses in Brazil.

The building sector is one of the largest consumers of natural resources and energy in the world. Design strategies to improve the energy efficiency can decrease the negative impacts of a building. In order to evaluate and select the most appropriate design strategies for buildings, they should be analysed through a multidisciplinary approach based on sustainable development. The objective of this study is to propose a method that combines adaptive thermal comfort, climate change, life cycle assessment, life cycle cost analysis and multi-criteria decision making to help selecting the best design strategies to improve the sustainability of buildings. The method presented herein is based on a system of indicators that allows a comprehensive evaluation of design strategies. A multi-family social building, located in Milan, northern Italy, was used as a case study considering a 100-year lifespan. Six design strategies were evaluated. The EnergyPlus computer programme was used to estimate the annual energy demand for air-conditioning alone, with and without the design strategies. Three different databases were used to perform the life cycle analysis. For the life cycle cost analysis, the cost of each strategy was estimated based on the pricelist of the Milan Chamber of Commerce (Camera di Commercio di Milano). The results show that there will be an average increase of 53% in the cooling energy demand and a decrease of 49% in the heating energy demand in 2080 compared to the consumption in 2017. The design strategy with the highest level of sustainability was a reinforced concrete frame with rectified bricks, followed by a reinforced concrete frame with cellular concrete blocks and by cross-laminated timber (X-Lam) and wood fibre. This research highlighted the need for the use of a multi-criteria method to ensure the right selection of design strategies to obtain more sustainable buildings.