On the green adaptation of urban developments in Egypt; predicting community future energy efficiency using coupled outdoor-indoor simulations

• Published in: Energy and buildings 2017-10, Vol.153, p.241-261
• Main Authors: Fahmy, Mohammad, El-Hady, Hany, Mahdy, Mohamed, Abdelalim, Marwa F.
• Format: Article
• Language: English
• Subjects: Adaptation; Air temperature; Case studies; Climate change; Climate effects; Climatic zones; Communities; Computer simulation; Cost engineering; Coupling methodology; Coverage; Energy conservation; Energy consumption; Energy efficiency; EPW; Facades; Green adaptation; Green buildings; Green roofs; Indoor environments; Microclimate; Plantations; Power efficiency; Residential energy; Roofs; Spots; Studies; Thermal comfort; Trees; Urban areas; Urban development; Urban microclimate; Vegetation effects; Weather
• ISSN: 0378-7788; 1872-6178
• DOI: 10.1016/j.enbuild.2017.08.008

•Even if TMY3 is available, it won’t account for urban street canyon details.•Outdoor-indoor simulations applied to let weather files account for urban greenery.•LAI and Albedo were measured to numerically model local environment urban trees.•Compared to its un-adapted case; site two energy efficiency reached 23.8% in 2080.•Cost of urban trees with green facades and roofs were paid back in 20 years. This research aims to investigate adaptation opportunities of Egyptian urban communities for climate change by the application of green cover and its effect on domestic energy efficiency in present and future. Coupled outdoor-indoor simulations were applied to overcome the incapability of packages to do both jobs in one tool and to account for the effects of adaptation of urban greenery on the indoor performance since indoor simulations tools does not consider microclimatic interactions. In addition to the three types of urban trees which modeling parameters were measured, green roofs and facades were applied. Present and future (2020, 2050 and 2080) microclimatic effects of the green cover of two case studies in different climatic zones were compiled conjunctionally in a TMY2 weather files to relate ENVI-metV4.0 simulations (accounting for outdoor conditions) with indoor simulations using DesignBuilderV4.2 which has been applied to predict sites' energy efficiency. Results show that even if TMY3 weather files are available, which is not for many countries including Egypt, it will not account for urban microclimate and vegetation effects of local sites when only indoor simulations take place. Thermal comfort (PMV) and air temperature (Ta) maps' results of both cases outdoor adapted conditions showed cool spots at the center of communities. Those cool spots improvements decrease by 2080 due the effects of climate change. Whole site averages of (Ta) showed increased records for the adapted cases owed to the suggested green façade coverage which draws attention to the sensitive plantation of building walls as well as the coverage percentage of urban trees that might traps heat. In comparison to their un-adapted cases, the least energy efficiency result for whole site was 10.0% corresponding to 23.8% cost saving at 2080 in case two whereas the maximum was 21.3% corresponding to 35.7% cost savings at present day. Summing energy savings until the end of century, case one payback period was 20 years (in 2037) and case two was 15 years (in 2032).