District-scale building energy models can be a powerful tool for the integration of renewable energy sources and efficiency measures in urban areas. One key limitation of these models, however, has been their rather simplified treatment of building occupants. Since it is their activities which create the needs for energy in an area, an improved analysis of the effects of occupants on demand at the district scale is needed.

This paper presents a novel population-based approach (PopAp) inspired by agent-based transportation models, in which a population of occupants was defined based on class and employee registers and each was given an individual daily schedule. This approach was then used to assess the effect of occupant presence modeling on district-scale energy demand simulations by comparing the data-centric PopAp method to standard-based deterministic and stochastic approaches.

The maximum number of occupants in the area was found to be 33% higher for the deterministic model compared to the data-centric PopAp results, a deviation that was especially pronounced in education buildings. The results for space heating, space cooling and electricity demand for lighting and appliances show that while the mean deviation between models on a yearly basis is within 10% for all demands, on an hourly scale the deviation for space cooling and electricity exceeded 15%. Given the importance of the hourly scale for peak demand prediction for technology sizing, more detailed occupant modeling approaches should be considered when planning energy systems.@en

This paper describes an assessment of the effects of spatial heterogeneity on the future performance and resilience of an urban area. For this, indicators of environmental performance and resilience of critical infrastructures (energy and transportation systems) are explored. The approach combines established methodologies of building performance simulation, energy systems analysis, and environmental impact assessment of buildings and transportation systems. The study is centered on future urban design scenarios for an industrial neighborhood in Switzerland. For this case study, multi-functionality is proportional to the performance and resilience of critical infrastructures. Mono-functionality improves the resilience and performance of energy systems with a negative effect on that of transportation systems. Building intensity, and resource intensive users were found to play a higher role into the future performance and resilience of the area. The findings of this research could complement planning approaches of sustainable and resilient urban areas.@en

Urban Building Energy Models are powerful tools for estimating future states of energy consumption and energy generation in buildings. Due to the complexity of these systems, large amounts of data are required, which are often incomplete or unavailable. Through the implementation of building archetypes, models such as the City Energy Analyst minimize the amount of input data. However, these simplifications inherently increase the uncertainty of the expected results.

This paper presents a sensitivity analysis of architectural properties (window-to-wall ratio, occupant density and envelope leakiness), thermal properties (U-values, G-values, thermal mass and emissivity of building surfaces), operating parameters (set point temperatures and ventilation rates) and internal loads (heat gains due to occupancy, appliance use and lighting). For this, the study combines a two-step process of sensitivity analysis with Saltelli's extension of the Sobol method and the City Energy Analyst. The methodology is applied to a case study area in central Zurich, Switzerland, comprising 284 buildings with predominantly educational, hospital and residential uses.

The results showed that the cooling demand in the area was very strongly influenced by the set point temperature, with other variables having a relatively minor influence. For the heating case a larger number of variables were needed in order to explain variations in demand, primarily the thermal properties of the envelope and air exchange rates of the buildings. This was generally true for all occupancy types, shapes, sizes and locations, showing the importance of accurate estimates of these parameters in urban building energy modeling. On a broader sense, the results contribute to the development of urban energy simulations that are both practical and accurate.@en

Cities can be seen as systems of organized complexity formed by interrelated and highly dynamic sub-systems. This paper reflects on the interactions and tensions between socio-ecological and/or socio-technical sub-systems in cities and their capacity to either improve or block urban processes. In this context, spatial heterogeneity could enhance or hinder the performance and resilience of critical urban sub-systems such as transport and energy. The consequence of this interaction might be detrimental to environmental quality (air and acoustic) and the livability of urban areas. This rationale may improve political and expert decision-making processes toward sustainable, resilient and livable cities.@en