Life cycle carbon emissions inventory of brick masonry and light steel framing houses in Brasilia: proposal of design guidelines for low-carbon social housing

Lucas Rosse Caldas,Rosa Maria Sposto,Pedro Corrêa de Melo,Júlia Santiago de Matos Monteiro Lira

doi:10.1590/s1678-86212017000300163

Lucas Rosse Caldas, Rosa Maria Sposto + Show 2 more

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https://doi.org/10.1590/s1678-86212017000300163

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Abstract

Abstract This study evaluated the CO2eq emissions during the life cycle of two social housing projects in the city of Brasilia. A house of ceramic brick masonry was compared to a light steel framing one. The life cycle carbon emissions assessment (LCCO2A) with a cradle-to-grave approach was used. The relation between the thermal performance of the wall systems and CO2eq emissions in the operational phase of the houses were evaluated using the DesignBuilder software. In addition, six scenarios composed of three CO2eq emission factors from the Brazilian electrical grid and two schedules of occupation of houses (full and part time) were evaluated. The brick masonry house presented less CO2eq emissions than the light steel framing one. For both houses, the operational phase was the most significant regarding the total CO2eq emissions (50% to 70%), followed by the construction (20% to 30%), maintenance (11% to 20%) and end-of-life (lower than 1%) phases. The results also showed the importance of considering different CO2eq emission factors for the Brazilian context in the operational phase. Finally, based on the results obtained, design guidelines for low carbon social housing were proposed.

Highlights

In 2010, buildings accounted for 32% of the total global final energy use and 19% of energy-related greenhouse gas (GHG) emissions (LUCON et al, 2014)
The Functional unit (FU) for this study is a house located in Brasília – DF, with 4 residents (2 adults and 2 children), an internal floor area of 46 m2 and a 50-year lifespan (minimum value stipulated in the NBR 15575-1 (ABNT, 2013))
The results found for air conditioning energy consumption were: (a) brick masonry house with part- time schedules of occupation: 768.21 kWh/year; (b) brick masonry house with full-time schedules of occupation: 2228.78 kWh/year; (c) light steel framing house with part-time schedules of occupation: 1271.05 kWh/year; and (d) light steel framing house with full-time schedules of occupation: 3219.14 kWh/year

Summary

Introduction

In 2010, buildings accounted for 32% of the total global final energy use and 19% of energy-related greenhouse gas (GHG) emissions (LUCON et al, 2014). Despite failures and criticism mainly related to the quality of the houses built, this program was responsible for the construction of thousands of new homes for people in need, alleviating the housing deficit in the country. These social housing programs mainly used the brick masonry system. New building systems, which may be more rational and productive, are being considered, such as precast and prefabricated concrete, concrete walls and light steel framing The latter has been imported from the USA and its use is becoming widespread in the country, due to higher productivity and the dry construction process (LIMA, 2016)

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