Efficiency of green roofs and green walls as climate change mitigation measures in extremely hot and dry climate: Case study of Qatar

The main goal of this study is to assess the potential of green roofs and walls as a mitigation measure for the climate-change-driven growth of building energy consumption in extremely hot climates. A comprehensive, interdisciplinary methodology was developed that bridged climate change and building modeling. The residential building stock of Qatar was considered, with a two-story residential villa selected as a representative of the stock and consequently a case study. Weather scenarios were created for the years 2020, 2050, and 2080, and four building renovation scenarios were developed. The findings suggested that without any mitigation measures, residential building energy consumption in Qatar could increase by up to 9%, 17%, and 30% in 2020, 2050, and 2080, respectively. The addition of 5-cm expanded polystyrene and the installation of energy-efficient windows proved to be far more efficient than the addition of green walls and roofs under the climate conditions (30% reduction in energy consumption vs. 3%). Additionally, the environmental impact of green wall and roof maintenance, specific to Qatar, should be considered. However, in the final judgment, other positive effects of a green infrastructure (such as the effect on air quality, heat island effect, and health of the inhabitants) should be considered. •Setpoint shift from 18°C to 22°C can save as much energy as insulation implementation.•EPS insulation is more effective than integrated greenery in extremely hot climate.•Extreme future temperatures will render EPS insulation, green roofs and green walls ineffective.•Increased future temperature will necessitate air conditioning in winters.