Microclimatic conditions inside urban areas depend on the result of the interaction of the regional climate with the whole urban area and on the local characteristics of the urban development. ...Inadequate human thermal comfort conditions can affect quality of life and the use of public open spaces. In this study, outdoor thermal conditions are examined through three field campaigns in Bilbao in the north of the Iberian Peninsula. Climate variables are measured in four different areas of the city in different regional climate conditions. Thermal comfort evaluation is undertaken by means of the thermal index PET (Physiological Equivalent Temperature). Measurements are compared with estimated values derived from ENVI-met model. Results show that the differences between modelled and measured climatic variables can imply a relevant deviation in PET (i.e. difference between modelled and measured values). Regression and correlation analyses account for the importance of the deviation of each climatic variable in the deviation of PET values. Deviation of PET appears to be highly conditioned by the deviation of mean radiant temperature values especially during clear sky days. Under overcast conditions deviation of wind speed also becomes a relevant aspect. Consequently, reliable estimation of these variables is required if modelling techniques are to be used in the assessment of thermal comfort in outdoor urban spaces.
•ENVI-met can lack accuracy in Tmrt and WS estimations.•Differences between measured and modelled thermal comfort levels can be relevant.•Knowing limitations of models used for thermal comfort evaluation is essential.
•Different thermal comfort indices were compared based on the fundamentals.•Field surveys were carried out for validation of the thermal comfort indices.•The relationships between the indices and ...MTSV were undetermined for hot outdoor environments.•The ranges of heat stress category and PMV need to be modified for hot outdoor environments.
Comfortable and healthy outdoor microclimates are beneficial to sustainable urban development. Based on a comprehensive comparison of some currently frequently used thermal comfort indices, including PMV, WBGT, PET, SET*, and UTCI, the differences among these indices are significant in dealing with the fundamental energy balance model, descriptive equations, and application boundary conditions. In order to validate these indices, a subjective questionnaire survey with field measurements was carried out on a university campus in Guangzhou in southern China. Results revealed strong linear relationships between operative temperature and mean radiant temperature (Tmrt), WBGT, PET, SET*, UTCI, as well as PMV. However, the relationships between these thermal comfort indices and the mean thermal sensation vote (MTSV) are not clear for a hot outdoor environment, especially when the operative temperature was above 34 °C. The ranges of the heat stress category and PMV need to be modified for the evaluation of hot outdoor environments.
Key research effort was dedicated toward zero-energy buildings. Recent interest is switching from single-building to inter-building scale, to enhance the whole district economic-environmental ...sustainability. This upscaling opens the doors to further optimization strategies thanks to outdoor microclimate mitigation aimed at reducing winter thermal losses and summer overheating. This work proposes a novel design-stage replicable method for multiscale microclimate improvement correlated to building thermal-energy analysis in a residential near-zero-energy district in central Italy. Cool surface installation and conscious greenery design in the outdoors were used in the district of single-family houses. Therefore, a microclimate simulation was performed to elaborate realistic weather files to be used in the second-stage dynamic thermal-energy simulation at building level, in order to evaluate the impact of the local microclimate on building thermal-energy performance and renewables’ production. Microclimate analysis demonstrated how local conditions affect outdoor comfort and that they may be considered in the same way as traditional energy-efficiency improvement early-stage design strategies at building scale, being able to reduce building energy need for HVAC up to 10% in the studied conditions. Therefore, new potentialities of inter-building scale analyses for energy efficiency enhancement and renewable energy exploitation are expected while downscaling microclimate assessment toward building thermal-energy performance.
•Novel microclimate mitigation approach combined to energy efficiency is proposed.•Residential near-zero-energy settlement in central Italy is simulated by CFD.•Tailored mitigation cool-green solutions are investigated in the city settlement.•Local urban design conditions affect outdoor thermal comfort and energy need.•Building energy saving up to 9.8% is produced by microclimate design.
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•An urban building energy model was integrated with an urban fast fluid dynamics model for resilience study.•City fast fluid dynamics is the new urban fast fluid dynamics model with ...graphics processing unit computing.•City building energy model is the new urban energy model with extensive building archetypes.•1971 snowstorm of the century was modeled for vulnerability and survivability study.•Retrofitting measure was analyzed to evaluate improved urban resilience.
In the past decade, urban building energy models have been developed to address the increasing concerns over energy consumption and greenhouse gas emission due to rapid urbanization and building resilience as a result of climate change. These models can estimate energy consumption, GHG emission and resilience response of buildings in an urban area, and evaluate retrofit strategies for architects, engineers, researchers and policy makers. It has been recognized that local microclimate and neighborhood effects play an important role in urban building energy modeling. Creating an urban building energy model also requires the collection of extensive building data, which is a time-consuming process. In this study, we developed an integrated platform by combining CityFFD (City Fast Fluid Dynamics), an urban-scale fast fluid dynamics model for microclimate modeling, and CityBEM (City Building Energy Model), a new urban building energy model with a library of 1700 building archetypes for facilitating urban model creation. Local aerodynamics and heat transfer information are exchanged between both models at each time step. Graphics processing unit computing is also applied to CityFFD for simulation speedup. The simulation of the 1971 Montreal snowstorm of the century was conducted as a case study of more than 1500 buildings of an island near Montreal, Canada for the investigation of their resilience against the three-day power outage due to the storm. Building retrofit analysis was also conducted to evaluate the added level of resilience. The results show that the proposed platform can produce high-resolution results of building thermal load, microclimate condition, and building behavior during weather extremes.
With the increased urbanization in most countries worldwide, the urban heat island (UHI) effect, referring to the phenomenon that an urban area has higher ambient temperature than the surrounding ...rural area, has gained much attention in recent years. Given that Beijing is developing rapidly both in urban population and economically, the UHI effect can be significant. A long-term measured weather dataset from 1961 to 2014 for ten rural stations and seven urban stations in Beijing, was analyzed in this study, to understand the detailed temporal and spatial characteristics of the UHI in Beijing. The UHI effect in Beijing is significant, with an urban-to-rural temperature difference of up to 8 °C during the winter nighttime. Furthermore, the impacts of UHIs on building design and energy performance were also investigated. The UHI in Beijing led to an approximately 11% increase in cooling load and 16% decrease in heating load in the urban area compared with the rural area, whereas the urban heating peak load decreased 9% and the cooling peak load increased 7% because of the UHI effect. This study provides insights into the UHI in Beijing and recommendations to improve building design and decision-making while considering the urban microclimate.
•Temporal and spatial characteristics of urban heat island in Beijing is studied.•Statistical analysis of the 50-year 17-station weather data is performed.•Correlation is found between UHI and the occurrence of extreme events.•Impacts of UHI on peak demand and energy use in buildings are evaluated using simulation.•It is recommended to use local weather data for building design and performance simulation.
The integration of microclimatic information and physical properties of the materials into urban design is essential for adequately addressing the challenges related to climate change and to ...adaptation of urban environment to new climatic loads. Especially, the thermal and optical properties of materials used in the urban fabric play a fundamental role in determining the microclimate and building's energy balance. The present research approach aims at analyzing the thermal characteristics of the materials and the surface temperature distribution using airborne multispectral imaging sensors mounted on Unmanned Aerial Vehicle (UAV). Aerial surveys and in-situ measurements have been carried out in April 2016 at the Municipality of Ymittos in Athens (Greece). The applied multi-sensory survey included high resolution imaging of the materials in the visible and near infrared (VIS/NIR) wavelength region and IR part of the spectrum. The images have been analysed to form maps of surface temperature distribution and of material properties. The derived thermal maps show the changes in surface temperatures of the urban materials during a diurnal heating cycle. In addition, ground measurements of VIS/NIR reflection and albedo from the survey area were obtained and an albedo map and a map of apparent thermal inertia were derived. Thermal scanning of the asphalt in the area, allowed the estimation of the state of decay due to weathering and traffic. The combined maps of surface temperature, albedo and apparent thermal inertia give new perspectives of the urban features and enhance the classification of fine urban material and the energy balance models.
•For urban aerial survey the use of UAV as a sensor platform is novel and enhances microscale measurements.•The combined maps of surface temperature, albedo and apparent thermal inertia give new perspectives of the urban features.•Thermal scanning of the asphalt in the area allowed the estimation of the state of decay due to weathering and traffic.•Results demonstrate that the high resolution imagery obtained is essential to classify urban materials.
•Study of the adaptation of the PV panels to the canarian greenhouses.•Study of the PV panel effects on the microclimate under the canarian greenhouse.•Study of the PV panel on the tomato production ...under the canarian greenhouse.•Investigation on the of the PV panel effects on the development of T. absoluta.•No significant effect on the climatic parameters with 10% of PV panel occupancy rate.•No significant effect on the agronomic parameters with 10% of PV panel occupancy rate.
Photovoltaic greenhouses are mixed systems, combining electricity and agricultural production in the same area. Moreover, this type of greenhouse conserves all the properties of a conventional greenhouse, as well as offering the possibility of producing and selling electricity.
The aim of the present study is to assess both the impact of the shade caused by the photovoltaic panels on the microclimate and the quality of fruits in the greenhouse. Measurements were carried out in an experimental Canary type greenhouse covered with flexible photovoltaic panels on 10% of its total roof area.
Results illustrate that this occupancy rate of the photovoltaic panels arranged in checkerboard pattern does not have a significant effect on the agronomic parameters e.g. height, stem diameter and tomato yield, and climatic parameters under the greenhouse cover. Additionally, the presence of photovoltaic panels has a negative effect on the development of the population of Tuta absoluta.
An appropriate sleep environment is critical to achieve adequate quality and quantity of sleep. General sleep hygiene recommendations suggest that individuals should maintain a cool, dark, quiet ...sleep environment. Our goal was to conduct a review of the evidence surrounding the optimal characteristics for the sleep environment in the categories of noise, temperature, lighting, and air quality in order to provide specific recommendations for each of these components. We found that all forms of noise in the sleep environment should be reduced to below 35 dB. The optimal ambient temperature varies based on humidity and the bedding microclimate, ranging between 17 and 28 °C at 40–60% relative humidity. Complete darkness is optimal for sleep and blue light should be avoided during the sleep opportunity. Sea level air quality, with ventilation is optimal for sleep and supplemental oxygen is a useful countermeasure for improving sleep quality at altitude. Architectural design that incorporates these elements into bedroom design may improve sleep quality among inhabitants of such environments.
Daily weather affects total visitation to parks and protected areas, as well as visitors' experiences. However, it is unknown if and how visitors change their spatial behavior within a park due to ...daily weather conditions. We investigated the impact of daily maximum temperature and precipitation on summer visitation patterns within 110 U.S. National Park Service units. We connected 489,061 geotagged Flickr photos to daily weather, as well as visitors' elevation and distance to amenities (i.e., roads, waterbodies, parking areas, and buildings). We compared visitor behavior on cold, average, and hot days, and on days with precipitation compared to days without precipitation, across fourteen ecoregions within the continental U.S. Our results suggest daily weather impacts where visitors go within parks, and the effect of weather differs substantially by ecoregion. In most ecoregions, visitors stayed closer to infrastructure on rainy days. Temperature also affects visitors' spatial behavior within parks, but there was not a consistent trend across ecoregions. Importantly, parks in some ecoregions contain more microclimates than others, which may allow visitors to adapt to unfavorable conditions. These findings suggest visitors' spatial behavior in parks may change in the future due to the increasing frequency of hot summer days.
The growth of cities intensifies the urban heat island effect by obstructing and weakening the incoming wind and thus deteriorates thermal comfort in the pedestrian level. The elevated building ...design is believed to be able to create some localized comfort spots at precinct scale, but no researches on pedestrians' thermal perceptions in the area underneath an elevated building (UEB) have been reported. In this study, simultaneous on-site meteorological measurements and questionnaire surveys of 1107 human subjects were conducted in a university campus in Hong Kong. Three outdoor thermal comfort models, PET, UTCI and UC-Berkeley model, were compared. The survey results indicate that the UEB area is significantly (α = 0.05) more comfortable in hot weather without extra discomfort in cold weather. All three models outputs correlate well with the subjects' mean thermal sensation votes in linear regression (R2 ≈ 0.9). Yet, shifts in neutral indices (6.2 K, 5.8 K and 1.1 respectively for PET, UCTI and UC-Berkeley model) appeared when comparing the correlation results separately for the UEB areas and open areas, indicating that the impacts of solar radiation and wind or the lack of them on pedestrian's thermal comfort perceptions have not been well predicted by the three models. These investigations, on the one hand, characterize the benefits that elevated building designs have on the pedestrian-level microclimate and provide references and inspirations for urban planners to enhance pedestrian thermal comfort by altering building designs; on the other hand, indicate the need to refine the thermal comfort models for better outdoor thermal comfort assessment.
•Underneath-elevated-building and open areas mainly differ in radiation and wind.•Area underneath elevated building is significantly more comfortable in hot weather.•PET, UTCI and UC-Berkeley outputs correlate well with Mean Thermal Sensation Vote.•Extra considerations of radiation and wind are required to improve model predictions.
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