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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - URBANFLUXES (URBan ANthrpogenic heat FLUX from Earth observation Satellites)

Teaser

Summary

Energy enters, passes through and leaves a city in several ways and in numerous physical states and forms (fuels, electricity, radiation and heat). The Urban Energy Budget (UEB) includes the anthropogenic heat flux (resulting from vehicular emissions, space heating and cooling of buildings, industrial processing and metabolic heat release by people) and therefore reflects the functionality of the city. Consequently, UEB is an important parameter for urban planning and design that should be taken into account in urban interventions aiming to improve thermal comfort and energy efficiency. Both urban planning and Earth System Science communities need spatially disaggregated UEB data, at neighbourhood scale. Such information is practically impossible to derive by in-situ fluxes measurements, whereas the potential of Earth Observation (EO) to provide UEB patterns at local scale (i.e. 100 m x 100 m) was unexploited. Thus, the main problem being addressed by the URBANFLUXES project is the innovative exploitation of satellite observations to estimate UEB spatiotemporal patterns at local scale.
URBANFLUXES generated novel methods for estimating spatiotemporal variations of UEB components, enabling its integration into applications and operational services. Î¤he project met its objectives by developing EO-based approaches for estimating each UEB component separately, under the assumption of limited advection, using also standard meteorological observations from the Wireless Sensors Networks that were deployed in the three cities: London, Basel and Heraklion. In the general case however, the energy balance closure still remains challenging, leading to underestimations of the turbulent sensible heat flux and therefore of the anthropogenic heat flux. Therefore, beyond its important findings, URBANFLUXES has opened new research questions related to more robust EO-based estimation of the anthropogenic heat flux in complex urban settings, where the inherent uncertainties in estimating aerodynamic resistance make the assessments of the turbulent sensible heat flux challenging.

Work performed

During the three years of URBANFLUXES project, it advanced significantly the current knowledge of the UEB components estimation methods and assessed their behaviour in space and time. Extended analyses of various methodologies and a vast amount of meteorological, micro-meteorological and geospatial (mainly EO-based) data took place in London, Basel and Heraklion. Sophisticated models were developed to investigate the potential of the current satellite missions to retrieve UEB fluxes, validated by direct flux measurements. It indicated an overall excellent agreement between satellite and in-situ derived net all-wave radiation; and identified that wall facet fraction and urban materials type are the most important parameters for estimating heat storage in urban canopy.
In summary, the main achievements of the project concern: the development of new synergistic algorithms for analysis of EO data; the implementation of new urban surface parameterization schemes; the EO-based estimation of UEB fluxes, validated in three case studies; the successful estimation of anthropogenic heat flux relative spatial patterns; the involvement of users via Community of Practice and organization of successful demonstrations; the advancement of the current knowledge of the role of the different UEB fluxes on UHI and hence on urban climate and energy consumption; the production of results capable of supporting the development of Sentinels-based downstream services towards informing policy-making.
URBANFLUXES outcomes can lead to further scientific exploitation in identifying the contribution of urbanization to temperature trends and emerge EO-based optimization/evaluation of the implementation of mitigation technologies and strategies. In addition, the anthropogenic heat flux patters is a valuable information for the science of urban climatology. URBANFLUXES thus prepared the ground for further innovative exploitation of European space data in a wide range of scientific activities, by both EO scientists and urban climatologists, as well as in future emerging applications in the broader context of urban sustainability research.

Final results

URBANFLUXES developed EO-based methods easily transferable to any city, having the potential to support sustainable planning strategies, since knowledge of UEB spatiotemporal patterns at neighbourhood level is needed in urban planning (e.g. to identify emission hot spots), health studies (e.g. to estimate the impact on thermal comfort) and future proofing (e.g. to plan and implement interventions towards reduction of the heat emissions). URBANFLUXES has also the potential to enrich planning tools, such as Urban Climatic Maps and Climatope Maps, with information on anthropogenic heat flux patterns. This type of mapping is expected to help planners, developers and policy makers make better decisions on mitigation and adaptation. Furthermore, during the last decades, numerous heat waves have occurred and UHI exacerbates such warming. Temperatures in cities are predicted to rise even more, resulting in increased energy demand for cooling systems in low and mid-latitude cities. A positive feedback cycle occurs, where higher temperatures result in more energy being used for cooling, which in turn adds to heat emissions and raises temperatures further during heat waves. The URBANFLUXES satellite-based approach is expected to advance the current knowledge of the impacts of heat fluxes on energy consumption in cities, leading to the development of tools and strategies to mitigate these impacts, improving thermal comfort (social benefit) and energy efficiency (economic benefit).
The wider societal implications of the project, lie on the ability of its outcomes to support policies resulting from the EU Strategy for Sustainable Development and the 7th Environmental Action Plan (7th EAP), such as the Thematic Strategies on urban environment, energy and sustainable use of resources. The 7th EAP Priority 2 (resource-efficient economy), among others, requires full delivery of the climate and energy package to achieve the 20-20-20 targets, the targets of the 2030 Energy Strategy, and agreement on the next steps for climate policy beyond 2030. The URBANFLUXES approach on UEB is capable to support monitoring and reporting activities needed by the above targets. More specifically, the analysis of heat emissions is important, as climate change mitigation policies may reduce CO2 emissions at the point of energy production, but not necessarily heat emissions associated with the user, such as the anthropogenic heat emissions. The 7th EAP Priority 8 (sustainable cities) aims to develop a more systematic approach to new and emerging risks (i.e. heat waves), as well as to ensure that most cities in the EU are implementing policies for sustainable urban planning. URBANFLUXES has an implication on this Priority, since the turbulent sensible heat flux (that partially includes the anthropogenic heat flux) is an indicator of urban heat emissions, related to sustainable urban planning, as it has been demonstrated by the FP7 project BRIDGE (http://www.bridge-fp7.eu/), that was focused on urban metabolism.