Retrofitting the building roof of the Shanghai Worker Village is one of the governmental projects in Shanghai to improve the city appearance and energy efficiency of existing buildings. The roof is one of the most important building components to determine the energy performance. Hence, how to appropriately select the roof insulation level is a key question to answer to achieve the optimal performance in the building retrofit. Using the building simulation tool such as EnergyPlus, engineers typically run the deterministic simulation to evaluate the effectiveness of different roof insulation levels in the practice. However, this approach could result in bias due to the insufficiency of the deterministic approach in dealing with the complexity in the building performance simulation. In this study, to better mimic the real scenarios of buildings especially for the urban-level retrofit project, we utilized the uncertainty analysis considering impacts of urban heat island effect, material and building operation uncertainties to conduct a thorough evaluation of possible roof insulation retrofit scenarios. The results indicate that as we further increase the insulation levels, the effectiveness of adding insulation on the heating and total HVAC load saving decease significantly. In the uncertainty analysis, there exists a high probability of overlap in terms of the load saving if sufficient amount of insulation is already attached to the roof. Also, considering the characteristics of the retrofit building and weather conditions, adding extra roof insulation alone might only result in limited impact on the overall energy saving of a building. A further lifecycle analysis is necessary to determine the most efficient way of adding insulation for the roof retrofit.@en

This chapter investigates a model to integrate performance measure and urban design in the context of a high-density urban environment. The objective of this research is to discuss how performance-based modeling can be used for addressing problems of energy self-sufficiency and thermal comfort in a vertical and complex urban environment, in which increasing density may cause climate and ecological consequences. An urban neighborhood in Misono of Tokyo’s metropolitan region is studied to test the relationship between vertical urban form and energy performance. Benchmarking the performance behind urban form and neighborhood typologies leads to criteria of high performance and low carbon emission. The chapter discusses the policy implications of performance-based urban design and development in the context of the Misono Smart City Project, a site for Tokyo’s 2020 Olympics, and proposes a transformative approach to generate better performance for an energy resilient and sustainable urban future.@en

Typologies of the building roof influence the form and the view of a city, and have an impact on its energy performance. “From Flat to Slope Roof” is a governmental project in Shanghai to renovate workers’ villages over the past two decades. The project aimed to change monotonous appearance of the urban roofscape by replacing the flat roof with the slop roof, and to bring benefits of passive cooling through the slide roof to reduce energy demand caused by excessive air-conditioning. However, how different roofing typologies affect the building energy performance requires further investigation. Previous test results have shown that near 6% reduction of total annual building energy consumption could be achieved with the substitution of the polymer material on flat roofs, compared with the reduction by 3% on walls, and the reduction by 2% on floors. In this paper, the numerical modeling with EnergyPlus was applied to test the variation of roofing types and how they would affect the total energy consumption from level of a building to the entire whole community. The results show a connection between the thermal insulation of roof morphology and building energy performance, which conclude an energy reduction strategy through urban design in a neighborhood scale.@en