scholarly journals Influence of the Height in a Colombian Multi-Tunnel Greenhouse on Natural Ventilation and Thermal Behavior: Modeling Approach

2021 ◽  
Vol 13 (24) ◽  
pp. 13631
Author(s):  
Edwin Villagrán ◽  
Jorge Flores-Velazquez ◽  
Mohammad Akrami ◽  
Carlos Bojacá
Keyword(s):  
Natural Ventilation ◽  
Economic Cost ◽  
Numerical Results ◽  
Behavior Modeling ◽  
Tropical Region ◽  
Local Climate ◽  
Climate Conditions ◽  
Covered Area ◽  
Lower Height ◽  
Architectural Characteristics

The dimensions of a passive greenhouse are one of the decisions made by producers or builders based on characteristics of the available land and the economic cost of building the structure per unit of covered area. In few cases, the design criteria are reviewed and the dimensions are established based on the type of crop and local climate conditions. One of the dimensions that is generally exposed to greater manipulation is the height above the gutter and the general height of the structure, since a greenhouse with a lower height has a lower economic cost. This has led some countries in the tropical region to build greenhouses that, due to their architectural characteristics, have inadequate microclimatic conditions for agricultural production. The objective of this study was to analyze the effect on air flows and thermal distribution generated by the increase of the height over gutter of a Colombian multi-tunnel greenhouse using a successfully two-dimensional computational fluid dynamics (CFD) model. The simulated numerical results showed that increasing the height of the greenhouse allows obtaining temperature reductions from 0.1 to 11.7 °C depending on the ventilation configuration used and the external wind speed. Likewise, it was identified that the combined side and roof ventilation configuration (RS) allows obtaining higher renovation indexes (RI) in values between 144 and 449% with respect to the side ventilation (S) and roof ventilation (R) configurations. Finally, the numerical results were successfully fitted within the surface regression models responses.

scholarly journals Impact of Air Infiltration on IAQ and Ventilation Efficiency in Higher Educational Classrooms in Spain

2021 ◽  
Vol 13 (12) ◽  
pp. 6875
Author(s):  
Irene Poza-Casado ◽  
Raquel Gil-Valverde ◽  
Alberto Meiss ◽  
Miguel Ángel Padilla-Marcos
Keyword(s):  
Natural Ventilation ◽  
Well Being ◽  
Cold Season ◽  
Climate Conditions ◽  
Air Infiltration ◽  
Ventilation Efficiency ◽  
Educational Buildings ◽  
Set Up ◽  
Total Volatile Organic Compounds ◽  
The Impact

Indoor air quality (IAQ) in educational buildings is a key element of the students’ well-being and academic performance. Window-opening behavior and air infiltration, generally used as the sole ventilation sources in existing educational buildings, often lead to unhealthy levels of indoor pollutants and energy waste. This paper evaluates the conditions of natural ventilation in classrooms in order to study how climate conditions affect energy waste. For that purpose, the impact of the air infiltration both on the IAQ and on the efficiency of the ventilation was evaluated in two university classrooms with natural ventilation in the Continental area of Spain. The research methodology was based on site sensors to analyze IAQ parameters such as CO2, Total Volatile Organic Compounds (TVOC), Particulate Matter (PM), and other climate parameters for a week during the cold season. Airtightness was then assessed within the classrooms and the close built environment by means of pressurization tests, and infiltration rates were estimated. The obtained results were used to set up a Computational Fluid Dynamics (CFD) model to evaluate the age of the local air and the ventilation efficiency value. The results revealed that ventilation cannot rely only on air infiltration, and, therefore, specific controlled ventilation strategies should be implemented to improve IAQ and to avoid excessive energy loss.

scholarly journals Solar Chimney Applications in Buildings

Encyclopedia ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 409-422
Author(s):  
Haihua Zhang ◽  
Yao Tao ◽  
Long Shi
Keyword(s):  
Natural Ventilation ◽  
Energy System ◽  
Assisted Ventilation ◽  
Building Envelope ◽  
Building Structures ◽  
Solar Chimney ◽  
Climate Conditions ◽  
And Performance ◽  
Modern Building ◽  
Ventilation Systems

A solar chimney is a renewable energy system used to enhance the natural ventilation in a building based on solar and wind energy. It is one of the most representative solar-assisted passive ventilation systems attached to the building envelope. It performs exceptionally in enhancing natural ventilation and improving thermal comfort under certain climate conditions. The ventilation enhancement of solar chimneys has been widely studied numerically and experimentally. The assessment of solar chimney systems based on buoyancy ventilation relies heavily on the natural environment, experimental environment, and performance prediction methods, bringing great difficulties to quantitative analysis and parameterization research. With the increase in volume and complexity of modern building structures, current studies of solar chimneys have not yet obtained a unified design strategy and corresponding guidance. Meanwhile, combining a solar chimney with other passive ventilation systems has attracted much attention. The solar chimney-based integrated passive-assisted ventilation systems prolong the service life of an independent system and strengthen the ventilation ability for indoor cooling and heating. However, the progress is still slow regarding expanded applications and related research of solar chimneys in large volume and multi-layer buildings, and contradictory conclusions appear due to the inherent complexity of the system.

Skill assessment of post-processing methods for ECMWF SEAS5 seasonal forecasts over Europe

2021 ◽  
Author(s):  
Alice Crespi ◽  
Marcello Petitta ◽  
Lucas Grigis ◽  
Paola Marson ◽  
Jean-Michel Soubeyroux ◽  
...  
Keyword(s):  
Large Scale ◽  
Production Management ◽  
Spatial Scales ◽  
Research Field ◽  
Skill Assessment ◽  
Post Processing ◽  
Seasonal Forecasts ◽  
Climate Services ◽  
Local Climate ◽  
Climate Conditions

<p>Seasonal forecasts provide information on climate conditions several months ahead and therefore they could represent a valuable support for decision making, warning systems as well as for the optimization of industry and energy sectors. However, forecast systems can be affected by systematic biases and have horizontal resolutions which are typically coarser than the spatial scales of the practical applications. For this reason, the reliability of forecasts needs to be carefully assessed before applying and interpreting them for specific applications. In addition, the use of post-processing approaches is recommended in order to improve the representativeness of the large-scale predictions of regional and local climate conditions. The development and evaluation downscaling and bias-correction procedures aiming at improving the skills of the forecasts and the quality of derived climate services is currently an open research field. In this context, we evaluated the skills of ECMWF SEAS5 forecasts of monthly mean temperature, total precipitation and wind speed over Europe and we assessed the skill improvements of calibrated predictions.</p><p>For the calibration, we combined a bilinear interpolation and a quantile mapping approach to obtain corrected monthly forecasts on a 0.25°x0.25° grid from the original 1°x1° values. The forecasts were corrected against the reference ERA5 reanalysis over the hindcast period 1993–2016. The processed forecasts were compared over the same domain and period with another calibrated set of ECMWF SEAS5 forecasts obtained by the ADAMONT statistical method.</p><p>The skill assessment was performed by means of both deterministic and probabilistic verification metrics evaluated over seasonal forecasted aggregations for the first lead time. Greater skills of the forecast systems in Europe were generally observed in spring and summer, especially for temperature, with a spatial distribution varying with the seasons. The calibration was proved to effectively correct the model biases for all variables, however the metrics not accounting for bias did not show significant improvements in most cases, and in some areas and seasons even small degradations in skills were observed.</p><p>The presented study supported the activities of the H2020 European project SECLI-FIRM on the improvement of the seasonal forecast applicability for energy production, management and assessment.</p>

scholarly journals Diverse local epidemics reveal the distinct effects of population density, demographics, climate, depletion of susceptibles, and intervention in the first wave of COVID-19 in the United States

2020 ◽  
Author(s):  
Niayesh Afshordi ◽  
Benjamin Holder ◽  
Mohammad Bahrami ◽  
Daniel Lichtblau
Keyword(s):  
United States ◽  
Population Density ◽  
The United States ◽  
Effective Response ◽  
Susceptible Population ◽  
Local Climate ◽  
Climate Conditions ◽  
Mortality And Morbidity ◽  
Social Distancing ◽  
The Impact

The SARS-CoV-2 pandemic has caused significant mortality and morbidity worldwide, sparing almost no community. As the disease will likely remain a threat for years to come, an understanding of the precise influences of human demographics and settlement, as well as the dynamic factors of climate, susceptible depletion, and intervention, on the spread of localized epidemics will be vital for mounting an effective response. We consider the entire set of local epidemics in the United States; a broad selection of demographic, population density, and climate factors; and local mobility data, tracking social distancing interventions, to determine the key factors driving the spread and containment of the virus. Assuming first a linear model for the rate of exponential growth (or decay) in cases/mortality, we find that population-weighted density, humidity, and median age dominate the dynamics of growth and decline, once interventions are accounted for. A focus on distinct metropolitan areas suggests that some locales benefited from the timing of a nearly simultaneous nationwide shutdown, and/or the regional climate conditions in mid-March; while others suffered significant outbreaks prior to intervention. Using a first-principles model of the infection spread, we then develop predictions for the impact of the relaxation of social distancing and local climate conditions. A few regions, where a significant fraction of the population was infected, show evidence that the epidemic has partially resolved via depletion of the susceptible population (i.e., “herd immunity”), while most regions in the United States remain overwhelmingly susceptible. These results will be important for optimal management of intervention strategies, which can be facilitated using our online dashboard.

scholarly journals Applications of Models and Tools for Mesoscale and Microscale Thermal Analysis in Mid-Latitude Climate Regions—A Review

2021 ◽  
Vol 13 (22) ◽  
pp. 12385
Author(s):  
Gabriele Lobaccaro ◽  
Koen De Ridder ◽  
Juan Angel Acero ◽  
Hans Hooyberghs ◽  
Dirk Lauwaet ◽  
...  
Keyword(s):  
High Temperatures ◽  
Numerical Models ◽  
Spatial Scales ◽  
Built Environments ◽  
Local Climate ◽  
Climate Conditions ◽  
The Social ◽  
Climatic Environment ◽  
Intense Solar Radiation ◽  
Mobile Measurements

Urban analysis at different spatial scales (micro- and mesoscale) of local climate conditions is required to test typical artificial urban boundaries and related climate hazards such as high temperatures in built environments. The multitude of finishing materials and sheltering objects within built environments produce distinct patterns of different climate conditions, particularly during the daytime. The combination of high temperatures and intense solar radiation strongly perturb the environment by increasing the thermal heat stress at the pedestrian level. Therefore, it is becoming common practice to use numerical models and tools that enable multiple design and planning alternatives to be quantitatively and qualitatively tested to inform urban planners and decision-makers. These models and tools can be used to compare the relationships between the micro-climatic environment, the subjective thermal assessment, and the social behaviour, which can reveal the attractiveness and effectiveness of new urban spaces and lead to more sustainable and liveable public spaces. This review article presents the applications of selected environmental numerical models and tools to predict human thermal stress at the mesoscale (e.g., satellite thermal images and UrbClim) and the microscale (e.g., mobile measurements, ENVI-met, and UrbClim HR) focusing on case study cities in mid-latitude climate regions framed in two European research projects.

scholarly journals Millennial variations of atmospheric CO<sub>2</sub> during the early Holocene (11.7–7.4 ka)

2021 ◽  
Author(s):  
Jinhwa Shin ◽  
Jinho Ahn ◽  
Jai Chowdhry Beeman ◽  
Hun-Gyu Lee ◽  
Edward J. Brook
Keyword(s):  
North Atlantic ◽  
Ice Core ◽  
Polar Front ◽  
Equatorial Pacific ◽  
Early Holocene ◽  
Atmospheric Co2 ◽  
Solar Forcing ◽  
Local Climate ◽  
Climate Conditions ◽  
Siple Dome

Abstract. We present a new high-resolution record of atmospheric CO2 from the Siple Dome ice core, Antarctica over the early Holocene (11.7–7.4 ka) that quantifies natural CO2 variability on millennial timescales under interglacial climate conditions. Atmospheric CO2 decreased by ~10 ppm between 11.3 and 7.3 ka. The decrease was punctuated by local minima at 11.1, 10.1, 9.1 and 8.3 ka with amplitude of 2–6 ppm. These variations correlate with proxies for solar forcing and local climate in the South East Atlantic polar front, East Equatorial Pacific and North Atlantic. These relationships suggest that weak solar forcing changes might have impacted CO2 by changing CO2 outgassing from the Southern Ocean and the East Equatorial Pacific and terrestrial carbon storage in the Northern Hemisphere over the early Holocene.

Experimental study of the basin type solar still under local climate conditions

2000 ◽  
Vol 41 (9) ◽  
pp. 883-890 ◽  
Author(s):  
Bilal A Akash ◽  
Mousa S Mohsen ◽  
Waleed Nayfeh
Keyword(s):  
Experimental Study ◽  
Solar Still ◽  
Local Climate ◽  
Climate Conditions

The influence of global climate and local hydrological features over streamflow extremes.  Case of study in a tropical Andean basin

2021 ◽  
Author(s):  
Alex Avilés ◽  
Juan Contreras ◽  
Daniel Mendoza ◽  
Jheimy Pacheco
Keyword(s):  
Global Climate ◽  
Standardized Precipitation Index ◽  
Additive Models ◽  
Mitigation Strategies ◽  
Climate Indices ◽  
Local Climate ◽  
Climate Conditions ◽  
Lulc Changes ◽  
Daily Streamflow ◽  
Floods And Droughts

&lt;p&gt;Hydrological extremes such as floods and droughts are the most common and threatening natural disasters worldwide. Particularly, tropical Andean headwaters systems are prone to hazards due to their complex climate conditions. However, little is known about the underlying mechanisms triggering such extremes events. In this study, the Generalized Additive Models for Location, Scale and Shape (GAMLSS) were used for investigating the relations between the Annual- Peak-Flows (APF) and Annual-Low-Flows (ALF), respecting to climate and land use/land cover (LULC) changes. Thirty years of daily streamflow data-sets taken from two Andean catchments of southern Ecuador are used for the experimental research. Global climate indices (CI), describing the large-scale climate variability were used as hypothetical drivers explaining the extreme&amp;#8217;s variations on streamflow measures. Additionally, the Antecedent-Cumulative-Precipitation (AP) and the Standardized-Precipitation-Index (SPI), and LULC percentages were also included as possible direct drivers &amp;#8211; synthetizing local climate conditions and localized hydrological changes. The results indicate that AP and SPI clearly explain the extreme streamflow variability. Nonetheless, global variables play a significant role underneath the local climate. For instance, ENSO and CAR exert influence over the APF, while ENSO, TSA, PDO and AMO control ALF. Furthermore, it was found that LULC changes strongly influence both extremes; although this is particularly important for relative more disturbed catchments. These results provide valuable insights for future forecasting of floods and droughts based on precipitation and climate indices, and for the development of mitigation strategies for mountain catchments.&lt;/p&gt;

Climate controlled root zone parameters show potential to improve water flux simulations by land surface models

2021 ◽  
Author(s):  
Fransje van Oorschot ◽  
Ruud van der Ent ◽  
Andrea Alessandri ◽  
Markus Hrachowitz
Keyword(s):  
Land Surface ◽  
Root Zone ◽  
Surface Model ◽  
Water Fluxes ◽  
Land Surface Models ◽  
Climate Control ◽  
Local Climate ◽  
Climate Conditions ◽  
Surface Models ◽  
Zone Parameters

&lt;p&gt;The root zone storage capacity (S&lt;sub&gt;r&lt;/sub&gt; ) is the maximum volume of water in the subsurface that can potentially be accessed by vegetation for transpiration. It influences the seasonality of transpiration as well as fast and slow runoff processes. Many studies have shown that S&lt;sub&gt;r&lt;/sub&gt; is heterogeneous as controlled by local climate conditions, which affect vegetation strategies in sizing their root system able to support plant growth and to prevent water shortages. Root zone parameterization in most land surface models does not account for this climate control on root development, being based on look-up tables that prescribe worldwide the same root zone parameters for each vegetation class. These look-up tables are obtained from measurements of rooting structure that are scarce and hardly representative of the ecosystem scale. The objective of this research was to quantify and evaluate the effects of a climate-controlled representation of S&lt;sub&gt;r&lt;/sub&gt; on the&amp;#160; water fluxes modeled by the HTESSEL land surface model. Climate controlled S&lt;sub&gt;r&lt;/sub&gt; was here estimated with the &quot;memory method&quot; (hereinafter MM) in which S&lt;sub&gt;r&lt;/sub&gt; is derived from the vegetation's memory of past root zone water storage deficits. S&lt;sub&gt;r,MM&lt;/sub&gt; was estimated for 15 river catchments over Australia across three contrasting climate regions: tropical, temperate and Mediterranean. Suitable representations of S&lt;sub&gt;r,MM&lt;/sub&gt; were then implemented in HTESSEL (hereinafter MD) by accordingly modifying the soil depths to obtain a model S&lt;sub&gt;r,MD &lt;/sub&gt;that matches S&lt;sub&gt;r,MM&lt;/sub&gt; in the 15 catchments. In the control version of HTESSEL (hereinafter CTR), S&lt;sub&gt;r,CTR&lt;/sub&gt; was larger than S&lt;sub&gt;r,MM&lt;/sub&gt; in 14 out of 15 catchments. Furthermore, the variability among the individual catchments of S&lt;sub&gt;r,MM&lt;/sub&gt; (117&amp;#8212;722 mm) was considerably larger than of S&lt;sub&gt;r,CTR&lt;/sub&gt; (491&amp;#8212;725 mm). The HTESSEL MD version resulted in a significant and consistent improvement version of the modeled monthly seasonal climatology (1975--2010) and inter-annual anomalies of river discharge compared with observations. However, the effects on biases in long-term annual mean fluxes were small and mixed. The modeled monthly seasonal climatology of the catchment discharge improved in MD compared to CTR: the correlation with observations increased significantly from 0.84 to 0.90 in tropical catchments, from 0.74 to 0.86 in temperate catchments and from 0.86 to 0.96 in Mediterranean catchments. Correspondingly, the correlations of the inter-annual discharge anomalies improved significantly in MD from 0.74 to 0.78 in tropical catchments, from 0.80 to 0.85 in temperate catchments and from 0.71 to 0.79 in Mediterranean catchments. Based on these results, we believe that a global application of climate controlled root zone parameters has the potential to improve the timing of modeled water fluxes by land surface models, but a significant reduction of biases is not expected.&amp;#160;&lt;/p&gt;

scholarly journals Strategies for school buildings refurbishment in Portuguese climate

2020 ◽  
Vol 172 ◽  
pp. 18007
Author(s):  
Francisca Cavaleiro Barbosa ◽  
Vasco Peixoto de Freitas ◽  
Manuela Almeida
Keyword(s):  
Energy Consumption ◽  
Natural Ventilation ◽  
Sensitivity Study ◽  
School Buildings ◽  
Local Climate ◽  
Before And After ◽  
Insulation Thickness ◽  
Free Running ◽  
Near Future

Portuguese school buildings are generally characterized by an in-service thermal discomfort, due to the poor envelope thermal properties and the lack of resources for paying energy consumption. Most Portuguese schools are free-running buildings with a natural ventilation strategy. Hundreds of high and basic schools have not been refurbished and still have problems or anomalies and inadequate in-service conditions and need to be rehabilitated in the near future. There will be, therefore, an opportunity to apply the acquired knowledge of comfort, habits, energy consumption and costs that have been studied since the last refurbishments (2008). This work studies the Portuguese Brandão schools model (from the ’70s), including about 100 non-refurbished basic schools. A prototype classroom was prepared in a Brandão school, in Porto. The in situ experimental campaign consisted of temperature, relative humidity, CO2 concentration and energy consumption measurements. The main tasks of this work are: (1) the validation of an advanced hygrothermal model with experimental measurements before and after the prototype refurbishment; (2) development of a sensitivity study in order to choose the best refurbishment and heating strategies for these buildings, regarding their typology, the local climate features and the actual capacity to support the operating costs; (3) assessment of the roof insulation thickness in Brandão schools; (4) quantification of discomfort indicators.

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