The intra urban temperature climate in the city of Göteborg, situated on the Swedish west coast (... more The intra urban temperature climate in the city of Göteborg, situated on the Swedish west coast (57 o N11 o E) is investigated in comparison to urban geometry. The purpose of this study is to examine different methods in order to determine thermal variations within the city using urban geometry derived from a 3D GIS database. The climatic information about air and surface temperature was obtained from automobile traverse measurements. The study is part of an ongoing multidisciplinary project that investigates urban public spaces with focus on weather/climate and people's cognitions, emotions and actions. Preliminary results from the study and future plans will be presented at the conference.
Subjective thermal comfort and physical and climatic preferences in two outdoor public spaces - o... more Subjective thermal comfort and physical and climatic preferences in two outdoor public spaces - one park and one square in a satellite city northeast of Tokyo - have been investigated by structured interviews and comprehensive micrometeorological measurements. Additionally, the use and outdoor activity were investigated by unobtrusive observations. The thermal environment has been analysed using the air temperature (Ta), the
ABSTRACT The urban environment is a complex structure with interlinked social, ecological and tec... more ABSTRACT The urban environment is a complex structure with interlinked social, ecological and technical structures. Global warming is expected to have a broad variety of impacts, which will add to the complexity. Climate changes will force adaptation, to reduce climate-related risks. Adaptation measures can address one aspect at the time, or aim for a holistic approach to avoid maladaptation. This paper presents a systematic, integrated approach for assessing alternatives for reducing the risks of heat waves, flooding and air pollution in urban settings, with the aim of reducing the risk of maladaptation. The study includes strategies covering different spatial scales, and both the current climate situation and the climate predicted under climate change scenarios. The adaptation strategies investigated included increasing vegetation; selecting density, height and colour of buildings; and retreat or resist (defend) against sea-level rise. Their effectiveness was assessed with regard to not only flooding, heat stress and air quality but also with regard to resource use, emissions to air (incl. GHG), soil and water, and people’s perceptions and vulnerability. The effectiveness of the strategies were ranked on a common scale (from -3 to 3) in an integrated assessment. Integrated assessments are recommended, as they help identify the most sustainable solutions, but to reduce the risk of maladaptation they require experts from a variety of disciplines. The most generally applicable recommendation, derived from the integrated assessment here, taking into account both expertise from different municipal departments, literature surveys, life cycle assessments and publics perceptions, is to increase the urban greenery, as it contributes to several positive aspects such as heat stress mitigation, air quality improvement, effective storm-water and flood-risk management, and it has several positive social impacts. The most favourable alternative was compact, mid-rise, light coloured building design with large parks/green areas and trees near buildings.
ABSTRACT How people live, work, move from place to place, consume and the technologies they use a... more ABSTRACT How people live, work, move from place to place, consume and the technologies they use all affect heat emissions in a city which influences urban weather and climate. Here we document changes to a global anthropogenic heat flux (QF) model to enhance its spatial (30′′ × 30′′ to 0.5° × 0.5°) resolution and temporal coverage (historical, current and future). QF is estimated across Europe (1995–2015), considering changes in temperature, population and energy use. While on average QF is small (of the order 1.9–4.6 W m−2 across all the urban areas of Europe), significant spatial variability is documented (maximum 185 W m−2). Changes in energy consumption due to changes in climate are predicted to cause a 13% (11%) increase in QF on summer (winter) weekdays. The largest impact results from changes in temperature conditions which influences building energy use; for winter, with the coldest February on record, the mean flux for urban areas of Europe is 4.56 W m−2 and for summer (warmest July on record) is 2.23 W m−2. Detailed results from London highlight the spatial resolution used to model the QF is critical and must be appropriate for the application at hand, whether scientific understanding or decision making.
ABSTRACT The extent of the surface area sunlit is critical for radiative energy exchanges and the... more ABSTRACT The extent of the surface area sunlit is critical for radiative energy exchanges and therefore for a wide range of applications that require urban land surface models (ULSM), ranging from human comfort to weather forecasting. Here a computationally demanding shadow casting algorithm is used to assess the capability of a simple single-layer urban canopy model, which assumes an infinitely long rotating canyon (ILC), to reproduce sunlit areas on roofs, walls and roads over central London. Results indicate that the sunlit road areas are well-represented but somewhat smaller using an ILC, while sunlit roofs areas are consistently larger, especially for dense urban areas. The largest deviations from real world sunlit areas are for roofs during mornings and evenings. Sunlit fractions on walls are overestimated using an ILC during mornings and evenings are found. The implications of these errors are dependent on the application targeted. For example, (independent of albedo) ULSMs used in numerical weather prediction applying ILC representation of the urban form will overestimate outgoing shortwave radiation from roofs due to the overestimation of sunlit fraction of the roofs. Complications of deriving height to width ratios from real world data are also discussed.
ABSTRACT A new model, Solar Energy on Building Envelopes (SEBE) for estimating shortwave irradian... more ABSTRACT A new model, Solar Energy on Building Envelopes (SEBE) for estimating shortwave irradiance on ground, roofs and building walls is presented. SEBE adopts a 2D raster modelling approach to derive 3D irradiance information, which makes it possible to compute extensive areas up to city scale. High resolution digital surface models (DSMs) are used to describe the urban geometry and additional DSMs including 3D vegetation structures can also be incorporated. Inclusion of vegetation is shown to be essential when modelling irradiances for wall surfaces within the urban environment. To obtain a detailed description of input forcing conditions, the model utilizes observed hourly data of shortwave radiation as meteorological input information. The model is evaluated for a tilted roof as well as for a wall location in Göteborg, Sweden. The overall performance of the model is high, both for the roof and wall evaluation point. Application of the model is exemplified by 3D visualisation and city scale model output presentation.
Subjective thermal comfort and outdoor activity in a park and a square in a satellite city northe... more Subjective thermal comfort and outdoor activity in a park and a square in a satellite city northeast of Tokyo were investigated through structured interviews, observations, and comprehensive micrometeorological measurements. Results showed that the park was on an average 1.1°C cooler than the square. The relatively warmer thermal conditions in the square in comparison to the park resulted in a heat
The intra urban temperature climate in the city of Göteborg, situated on the Swedish west coast (... more The intra urban temperature climate in the city of Göteborg, situated on the Swedish west coast (57 o N11 o E) is investigated in comparison to urban geometry. The purpose of this study is to examine different methods in order to determine thermal variations within the city using urban geometry derived from a 3D GIS database. The climatic information about air and surface temperature was obtained from automobile traverse measurements. The study is part of an ongoing multidisciplinary project that investigates urban public spaces with focus on weather/climate and people's cognitions, emotions and actions. Preliminary results from the study and future plans will be presented at the conference.
Subjective thermal comfort and physical and climatic preferences in two outdoor public spaces - o... more Subjective thermal comfort and physical and climatic preferences in two outdoor public spaces - one park and one square in a satellite city northeast of Tokyo - have been investigated by structured interviews and comprehensive micrometeorological measurements. Additionally, the use and outdoor activity were investigated by unobtrusive observations. The thermal environment has been analysed using the air temperature (Ta), the
ABSTRACT The urban environment is a complex structure with interlinked social, ecological and tec... more ABSTRACT The urban environment is a complex structure with interlinked social, ecological and technical structures. Global warming is expected to have a broad variety of impacts, which will add to the complexity. Climate changes will force adaptation, to reduce climate-related risks. Adaptation measures can address one aspect at the time, or aim for a holistic approach to avoid maladaptation. This paper presents a systematic, integrated approach for assessing alternatives for reducing the risks of heat waves, flooding and air pollution in urban settings, with the aim of reducing the risk of maladaptation. The study includes strategies covering different spatial scales, and both the current climate situation and the climate predicted under climate change scenarios. The adaptation strategies investigated included increasing vegetation; selecting density, height and colour of buildings; and retreat or resist (defend) against sea-level rise. Their effectiveness was assessed with regard to not only flooding, heat stress and air quality but also with regard to resource use, emissions to air (incl. GHG), soil and water, and people’s perceptions and vulnerability. The effectiveness of the strategies were ranked on a common scale (from -3 to 3) in an integrated assessment. Integrated assessments are recommended, as they help identify the most sustainable solutions, but to reduce the risk of maladaptation they require experts from a variety of disciplines. The most generally applicable recommendation, derived from the integrated assessment here, taking into account both expertise from different municipal departments, literature surveys, life cycle assessments and publics perceptions, is to increase the urban greenery, as it contributes to several positive aspects such as heat stress mitigation, air quality improvement, effective storm-water and flood-risk management, and it has several positive social impacts. The most favourable alternative was compact, mid-rise, light coloured building design with large parks/green areas and trees near buildings.
ABSTRACT How people live, work, move from place to place, consume and the technologies they use a... more ABSTRACT How people live, work, move from place to place, consume and the technologies they use all affect heat emissions in a city which influences urban weather and climate. Here we document changes to a global anthropogenic heat flux (QF) model to enhance its spatial (30′′ × 30′′ to 0.5° × 0.5°) resolution and temporal coverage (historical, current and future). QF is estimated across Europe (1995–2015), considering changes in temperature, population and energy use. While on average QF is small (of the order 1.9–4.6 W m−2 across all the urban areas of Europe), significant spatial variability is documented (maximum 185 W m−2). Changes in energy consumption due to changes in climate are predicted to cause a 13% (11%) increase in QF on summer (winter) weekdays. The largest impact results from changes in temperature conditions which influences building energy use; for winter, with the coldest February on record, the mean flux for urban areas of Europe is 4.56 W m−2 and for summer (warmest July on record) is 2.23 W m−2. Detailed results from London highlight the spatial resolution used to model the QF is critical and must be appropriate for the application at hand, whether scientific understanding or decision making.
ABSTRACT The extent of the surface area sunlit is critical for radiative energy exchanges and the... more ABSTRACT The extent of the surface area sunlit is critical for radiative energy exchanges and therefore for a wide range of applications that require urban land surface models (ULSM), ranging from human comfort to weather forecasting. Here a computationally demanding shadow casting algorithm is used to assess the capability of a simple single-layer urban canopy model, which assumes an infinitely long rotating canyon (ILC), to reproduce sunlit areas on roofs, walls and roads over central London. Results indicate that the sunlit road areas are well-represented but somewhat smaller using an ILC, while sunlit roofs areas are consistently larger, especially for dense urban areas. The largest deviations from real world sunlit areas are for roofs during mornings and evenings. Sunlit fractions on walls are overestimated using an ILC during mornings and evenings are found. The implications of these errors are dependent on the application targeted. For example, (independent of albedo) ULSMs used in numerical weather prediction applying ILC representation of the urban form will overestimate outgoing shortwave radiation from roofs due to the overestimation of sunlit fraction of the roofs. Complications of deriving height to width ratios from real world data are also discussed.
ABSTRACT A new model, Solar Energy on Building Envelopes (SEBE) for estimating shortwave irradian... more ABSTRACT A new model, Solar Energy on Building Envelopes (SEBE) for estimating shortwave irradiance on ground, roofs and building walls is presented. SEBE adopts a 2D raster modelling approach to derive 3D irradiance information, which makes it possible to compute extensive areas up to city scale. High resolution digital surface models (DSMs) are used to describe the urban geometry and additional DSMs including 3D vegetation structures can also be incorporated. Inclusion of vegetation is shown to be essential when modelling irradiances for wall surfaces within the urban environment. To obtain a detailed description of input forcing conditions, the model utilizes observed hourly data of shortwave radiation as meteorological input information. The model is evaluated for a tilted roof as well as for a wall location in Göteborg, Sweden. The overall performance of the model is high, both for the roof and wall evaluation point. Application of the model is exemplified by 3D visualisation and city scale model output presentation.
Subjective thermal comfort and outdoor activity in a park and a square in a satellite city northe... more Subjective thermal comfort and outdoor activity in a park and a square in a satellite city northeast of Tokyo were investigated through structured interviews, observations, and comprehensive micrometeorological measurements. Results showed that the park was on an average 1.1°C cooler than the square. The relatively warmer thermal conditions in the square in comparison to the park resulted in a heat
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