Abstract
Input uncertainty is one of the major obstacles urban building energy models (UBEM) must tackle. The aim of this paper was to quantify the effects of two of the main sources of stochastic uncertainty, namely building occupants and urban microclimate, on electrical and thermal supply system sizing at the district scale. In order to analyze the effects of the former, three different methods of occupant modeling were implemented in a UBEM. The effects of the urban heat island on system sizing were studied through the use of measured temperature data from a weather station in the case study district compared to measured data from a national weather station. The methods developed were used to assess the sizing and costs of centralized and decentralized technologies for a case study in central Zurich, Switzerland. The choice of occupant modeling approach was found to affect the district’s total annualized costs for space heating and cooling by ±5%, whereas for the costs of electricity the variation was ±8%. Regarding outdoor temperature, the effects on the heating demands proved be negligible, however the costs of the cooling alternatives were found to vary by about 4% at the district scale due to the effect of urban climate, for individual buildings this deviation was as high as 40%.
Highlights
District energy systems can be one of the least-cost and most-efficient solutions for reducing primary energy demand and greenhouse gas emissions, with the potential to contribute up to 58% of the required CO2 emission reductions required in the energy sector by 2050 [1]
Urban building energy modeling (UBEM) can be a powerful tool to assess the current and projected demands of urban areas in order to support the planning of interventions at a variety of scales, such as building retrofits, urban form modifications and district energy system implementation
District energy modeling and supply system simulation were carried out using the City Energy Analyst (CEA), an open-source software for the analysis and optimization of urban energy systems [30]
Summary
District energy systems can be one of the least-cost and most-efficient solutions for reducing primary energy demand and greenhouse gas emissions, with the potential to contribute up to 58% of the required CO2 emission reductions required in the energy sector by 2050 [1]. Interconnecting buildings through district-scale energy systems provides opportunities to exploit synergies between buildings with different uses and demand profiles, as well as allowing the integration of distributed energy producers. Achieving these benefits, requires a detailed understanding of the types and dynamics of energy demand in buildings at high spatial and temporal resolution. Urban building energy modeling (UBEM) can be a powerful tool to assess the current and projected demands of urban areas in order to support the planning of interventions at a variety of scales, such as building retrofits, urban form modifications and district energy system implementation. Urban areas cannot be analyzed as an aggregation of single buildings as complex interactions between the components of the urban system arise when scaling from the
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