Modeling the heating and cooling energy demand of urban buildings at city scale

Reducing the energy consumption of buildings is a priority for carbon emissions mitigation in urban areas. Building stock energy models have been developed to support decisions of public authorities in renovation strategies. However, the burdens of renovation interventions and their temporal distribution are mostly overlooked, leading to potential overestimation of environmental benefits. Life Cycle Assessment (LCA) provides a holistic estimation of environmental impacts, but further developments are needed to correctly consider spatio-temporal aspects.We propose a spatio-temporal LCA framework to assess renovation scenarios of urban housing stocks, integrating: 1) a geospatial building-by-building stock model, 2) energy demand modelling, 3) product-based LCA, and 4) a scenario generator.Temporal aspects are considered both in the lifecycle inventory and the lifecycle impact assessment phases, by accounting for the evolution of the existing housing stock and applying time-adjusted carbon footprint calculation.We apply the framework for the carbon footprint assessment of housing renovation in Esch-sur-Alzette (Luxembourg). Results show that the renovation stage represents 4% to 16% of the carbon footprint in the residual service life of existing buildings, respectively after conventional or advanced renovations. Under current renovation rates, the carbon footprint reduction would be limited to 3-4% by 2030. Pushing renovation rates to 3%, enables carbon reductions up to 28% by 2030 when combined with advanced renovations. Carbon reductions in the operational stage of buildings are offset by 8-9% due to the impacts of renovation. Using time-adjusted emissions, results in higher weight for the renovation stage and slightly lower benefits for renovation.

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“…An extended state of the art is available in the Supplementary Material (section SM1). Statistical, engineering, hybrid [7][8][9][10][11][12].…”

Section: State Of the Artmentioning

confidence: 99%

“…They are in the need of reliable tools to assess the effect of policies on the carbon mitigation of the building sector. In recent times, significant efforts have been put on the development of building stock energy models to assess energy demand and energy saving potentials of building renovations [7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

A spatio-temporal life cycle assessment framework for building renovation scenarios at the urban scale

Mastrucci

Marvuglia

Benetto

et al. 2020

Renewable and Sustainable Energy Reviews

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“…Considering the advances in computational resources, along with the need of high spatial modeling accuracy in microclimate studies, several numerical methods have been developed over the past decades. In this section, only a brief overview of the main computational techniques is presented, whereas an extended analysis on the possibilities and limitations of the various computational methods is provided in previous review papers [58,60,61]. The computational methods towards the analysis of the urban microclimate involved initially the simplified approach of the surface energy balance model (SEBM), which was based on the law of conservation energy for a specific control volume and following the principles of the surface energy balance and proposed by Oke back in 1982 [6].…”

Section: Methodsmentioning

confidence: 99%

Urban Warming and Cities’ Microclimates: Investigation Methods and Mitigation Strategies—A Review

et al. 2020

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The increased rates of urbanization and industrialization of the 20th and 21st centuries have dramatically changed the land use and cover of modern cities, contributing to the degradation of the urban microclimate and the rise of the ambient urban air temperatures. Given the multiple negative energy, environmental and social consequences of urban warming, the present paper summarizes the findings of previous studies, assessing the main causes of the phenomenon along with the key investigation methods involving experimental and computational approaches. There follows a description of the most common mitigations, and adaption strategies towards the attenuation of urban warming are described. The analyzed elements include the addition of green spaces such as trees, grass and green roofs; changes on the albedo of the urban surfaces and water-based techniques, as well as a combination of them. The discussion of the reported findings in the existing literature clearly reflects the impact of urban morphology on the outdoor thermal environment, providing also useful information for professionals and urban planners involved at the phase of decision-making.

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“…Simulating spatiotemporal patterns of building energy demand at urban-scale is more complex than at building-scale. On the one hand large amounts of information about built structures are needed and the urban environment of each building has to be considered, while on the other hand also the diversity of occupant behavior at the urban-scale influences the spatiotemporal patterns of energy demand [16]. It is for example well known that the maximal total power demand in a district is different from the sum of the individual buildings' maximal power demands [17].…”

Section: Key Challenges In Simulating On the Urban-scale Versus The Bmentioning

confidence: 99%

A review on occupant behavior in urban building energy models

Happle

Fonseca

Schlueter

2018

Energy and Buildings

160

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Urban building energy models aspire to become key planning tools for the holistic optimization of buildings, urban design, and energy systems in neighborhoods and districts. The energy demand of buildings is largely influenced by the behavior of the occupants. The insufficient consideration of occupant behavior is one of the causes to the "performance gap" in buildings -the difference between the simulated and the actually observed energy consumption. On the urban-scale impacts of different occupant behavior modeling approaches onto the various purposes of urban building energy models are still largely unknown. Research shows that the inappropriate choice of occupant behavior model could result in oversized district energy systems, leading to over-investment and low operational efficiency. This work therefore reviews urban building energy models in terms of their occupant behavior modeling approaches. Three categories of approaches are established and discussed: (1) deterministic space-based approaches, (2) stochastic space-based approaches, and (3) stochastic person-based approaches. They are further assessed in terms of their strategy to consider diversity in occupant behavior. Stochastic models, especially stochastic person-based models, seem to be superior to deterministic models. However, there are no stochastic models available yet that can be used for case studies of mixed-districts, comprising buildings of various occupancy types. In the reviewed urban-scale approaches, only single-use residential or office districts are modeled with stochastic techniques. However, people interact with various buildings on a daily basis. Their activities relate to their presence in different spaces at the urban-scale and to their use of appliances in those spaces. Their individual levels of comfort and behavioral patterns govern the control actions towards building systems. Therefore, a novel activity-based multi-agent approach for urban occupant behavior modeling is proposed as alternative to current approaches.Keywords: urban building energy model, energy-related occupant behavior, occupancy, occupant behavior model IntroductionUrban areas house more than half of the global population and cities are responsible for more than 70% of the global carbon dioxide emissions. At the same time, cities are crucial actors in the transition towards sustainable energy Email address: happle@arch.ethz.ch (Gabriel Happle)

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Modeling the heating and cooling energy demand of urban buildings at city scale

Cited by 163 publications

References 71 publications

A spatio-temporal life cycle assessment framework for building renovation scenarios at the urban scale

A spatio-temporal life cycle assessment framework for building renovation scenarios at the urban scale

Urban Warming and Cities’ Microclimates: Investigation Methods and Mitigation Strategies—A Review

A review on occupant behavior in urban building energy models

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