Environment impact of nitrogen losses from agriculture under different management practices

Nitrogen (N) fertilization is playing a vital role in increasing crop production and ensuring food security. The global population which is growing exponentially has reached nearly 7.5 billion in 2015 (from 1.65 billion in 1900).The sole reason behind this is synthetic nitrogen fertilizer, it alone supported 3.5 billion people otherwise it would be somewhere around 3.5-4 billion. Imbalanced use of N fertilizer leads to N deficient condition which affects plants growth and development also in N surplus condition it has a huge negative impact on environment and human welfare. It includes negative effects on biodiversity, eutrophication, nitrate accumulation in waters, acidification of soil and water bodies, nitrous oxide emissions and risks to human health due to exposure to ozone and particulate matter. In agricultural systems, when fertilizer is applied to crop is mainly prone to losses through ammonia (NH3) volatilisation, nitrate (NO3-) leaching and denitrification. Loss of N in the form of NH3 and NO3- mainly depends on various factors like temperature, soil pH, soil moisture, soil properties, plant characteristics, seasonal fluctuations. An integrated approach is must to minimize N losses and increase crop yield. In broader sense, options to minimize NH3 volatilization and NO3 leaching are fertilizer, soil and irrigation based management strategies. Fertilizer management options like 4R nutrient stewardship concept applying the Right Source of nutrients, at the Right Rate, at the Right Time and in the Right Place. Managing soil by practicing conservational tillage with crop based scheduled irrigation. This small change in nutrient, soil and irrigation management find way to make improvements in the nutrient use efficiency, profitability in farming, environmental safety and sustainable ecosystem with fertilizers in the developing world.

Interrelationship between thermal conditions and indoor pollutants in primary schools of Himachal Pradesh

Thermal conditions in primary school buildings are very important to ensure healthy aproductive learning environment in primary classrooms. In addition to thermal conditions, poor indoor air quality (IAQ) may decrease productivity, reduced ability of learning, health threats, lack of attentiveness etc. This study is an attempt to discover the interrelationship of the thermal conditions with indoor pollutants in primary schools of Himachal Pradesh, India. The study summarizes the investigation of eight naturally ventilated schools in Hamirpur city of Himachal Pradesh (India). The on-site investigation was performed to monitor the concentration of Carbon monoxide (CO), Carbon dioxide (CO2), Particulate Matter (PM2.5) as indoor pollutants and Indoor Temperature, Humidity and Ventilation rate for thermal conditions. The Higher concentration of indoor Particulate Matter (PM2.5) has found associated with humidity and ventilation rate. However, the CO2 concentration has found directly associated with temperature and ventilation rate. Indoor pollutants were also found associated with some building design parameters of the primary school building. Based on the data analysis, some recommendations are made to reduce the exposure of pollutants to the occupants in the conclusion.

The evolution of botanical biofilters: Developing practical phytoremediation of air pollution for the built environment

Indoor air quality is of emerging importance due to the rapid growth of urban populations that spend the majority of their time indoors. Amongst the public, there is a common perception that potted-plants can clean the air of pollutants. Many laboratory-based studies have demonstrated air pollution phytoremediation with potted-plants. It has, however, been difficult to extrapolate these removal efficiencies to the built environment and, contrary to popular belief, it is likely that potted-plants could make a negligible contribution to built environment air quality. To overcome this problem, active green walls have been developed which use plants aligned vertically and the addition of active airflow to process a greater volume of air. Although a variety of designs have been devised, this technology is generally capable of cleaning a variety of air pollutants to the extent where comparisons against conventional air filtration technology can be made. The current work discusses the history and evolution of air phytoremediation systems from potted-plants through to practical botanical air filtration.

Urban form and pandemic spread: Reflections from Ahmedabad

Covid-19 which has been declared a pandemic by the World Health Organization has impacted all the spheres of human life including health, economy, education, social life, etc. The spread of the virus has been found to be primarily due to human movement and human contact. Certain areas like slums and other highly dense areas of the city having narrow streets, high density housing, compact social spaces and poor sanitation, have shown rapid spread and long duration of stay of the virus. Tracing Covid-19 spread, one finds an underlying link between Covid-19 cases and city’s urban form. Today, reconsideration on different aspects of planning seems necessary. The objective of this paper is to find the link between spread of Covid-19 cases and various urban forms existing within Ahmedabad. Ahmedabad being one of the most populated metropolitan city of Gujarat, India and also acknowledged for its rich heritage culture and built-forms, stands suitable for this study giving opportunity to explore and study varied urban spatial forms ranging from heritage settlements known as ‘Pols’ existing in the inner core city to the new townships developed in the recent years. The study relies on secondary data for tracing spread of Covid-19 in Ahmedabad and on primary study and analysis of different selected neighbourhoods. This study urges to adopt newer approaches to bring resilience in urban form through planning during such pandemic.

Influence of solar radiation on the energy consumption of large buildings on a university campus

This paper reports the numerical study on the influence of solar radiation on the energy consumption of large buildings on a university campus. The actual campus is located in the south of Portugal, in a Mediterranean type environment, and consists of 6 educational buildings. These six buildings have a total area of 27,599 m2 and 595 compartments, where 6,529 opaque surfaces (doors, walls, etc.) and 983 transparent ones (windows) were identified. This study aims to assess numerically how solar radiation transmitted on windows affects the energy consumption of the Heating, Ventilation, and Air-Conditioning (HVAC) systems, controlled by the PMV (Predicted Mean Vote) index, of each of these buildings, and the thermal comfort level of the occupants. Software developed by the authors is used to simulate the thermal behavior of buildings with complex topology. This software evaluates indoor air quality inside the spaces, thermal comfort of the occupants, thermal energy consumption of the HVAC system, and solar radiation distribution outside the buildings and inside the compartments, among others. The HVAC control system based on the PMV index applied in this work was designed to maintain the PMV comfort index within category C of ISO 7730, with a maximum of 15% of people dissatisfied. In order to evaluate the indoor comfort level of the occupants, the totals of cold and warm uncomfortable hours were calculated. Two different weather conditions, typical of the region, were set as inputs for the simulation performed in this study: a typical winter day, and a typical summer day. The outputs obtained were the daily evolution of total solar radiation transmitted on windows, total uncomfortable hours for the occupants, and total HVAC system energy consumption for each building. The results obtained show that, for typical winter conditions, an increase in the transmitted solar radiation on windows causes a decrease in HVAC system energy consumption, and also in the number of uncomfortable hours, which is a favorable situation. On the other hand, for typical summer conditions, it is observed that when transmitted solar radiation on windows increases, HVAC system energy consumption, and the total number of uncomfortable hours increase as well, configuring an unfavorable situation. It is also found that the values of solar radiation transmitted on windows are higher in winter than in summer conditions. In summer, the lowest values of solar radiation transmitted on windows occur at noon. The last two observations lead to the conclusion that, overall, these buildings have correctly positioned passive shading elements, a technique that contributes to an adequate solar passive architectural design.

Experimental and numerical study on the solar gain and heat loss of typical existing and refurbished German buildings

This communication introduces an experimental setup for investigating the effect of solar radiation on the reduction of transmission heat losses and the steady state thermal conductance of uninsulated and insulated multi-layer wall samples. The setup consists of two adjacent climatic chambers, which share a common wall, in which the multi-layer wall samples are mounted. A solar simulator is applied within the outdoor air climatic chamber, whose radiation spectrum and radiation intensity are approximately equivalent to those of the sun. The first tests have been carried out on a wall sample with a typical structure of existing buildings from the year 1930 in Germany. In addition, a high-performance insulating plaster layer has been applied on a basic test sample (with existing building structure) to replicate and assess the refurbished scenario. Furthermore, a numerical investigation on the transient heat transfer process is carried out by using the simulation software COMSOL Multiphysics®. The experimental results of both uninsulated and insulated wall samples are validated against 1D and 3D models. As seen, the uninsulated wall, whose thermal conductance was experimentally determined to be equal to 1.79 W/(m²K), absorbs a heat flux of 208 W/m² through its external wall surface over a period of 8 hours. A fraction of 9.8 % of the absorbed heat arrives as a gain on the internal wall and reduces the transmission heat losses by 11.7 % over a period of 55 hours. On the other hand, the thermal conductivity of the insulation layer of the refurbished wall sample with micro hollow glass spheres was estimated by a parameter estimation procedure using the 3D model and the obtained experimental data. Using the estimated thermal conductivity, a thermal conductance of 0.42 W/(m²K) has been obtained for the refurbished wall sample.

Impact of roof shading on building energy performance in warm & humid climatic places of India

With the rise in awareness of energy efficient buildings and adoption of mandatory energy conservation codes across the globe, significant change is being observed in the way the buildings are designed. With the launch of Energy Conservation Building Code (ECBC) in India, climate responsive designs and passive cooling techniques are being explored increasingly in building designs. Of all the building envelope components, roof surface has been identified as the most significant with respect to the heat gain due to the incident solar radiation on buildings, especially in tropical climatic conditions. Since ECBC specifies stringent U-Values for roof assembly, use of insulating materials is becoming popular. Along with insulation, the shading of the roof is also observed to be an important strategy for improving thermal performance of the building, especially in Warm and humid climatic conditions. This study intends to assess the impact of roof shading on building’s energy performance in comparison to that of exposed roof with insulation. A typical office building with specific geometry and schedules has been identified as base case model for this study. This building is simulated using energy modelling software ‘Design Builder’ with base case parameters as prescribed in ECBC. Further, the same building has been simulated parametrically adjusting the amount of roof insulation and roof shading simultaneously. The overall energy consumption and the envelope performance of the top floor are extracted for analysis. The results indicate that the roof shading is an effective passive cooling strategy for both naturally ventilated and air conditioned buildings in Warm and humid climates of India. It is also observed that a fully shaded roof outperforms the insulated roof as per ECBC prescription. Provision of shading over roof reduces the annual energy consumption of building in case of both insulated and uninsulated roofs. However, the impact is higher for uninsulated roofs (U-Value of 3.933 W/m2K), being 4.18% as compared to 0.59% for insulated roofs (U-Value of 0.33 W/m2K).While the general assumption is that roof insulation helps in reducing the energy consumption in tropical buildings, it is observed to be the other way when insulation is provided with roof shading. It is due to restricted heat loss during night.

Evaluation of comfort levels in office space equipped with HVAC system based in personalized ventilation system using energy produced in DSF systems

In this study the numerical simulation of a Heating, Ventilating and Air Conditioning (HVAC) system, based in a personalized ventilation system, installed in an occupied office desk is made. The energy is produced in a Dual Skin Facades (DSF) system installed in the outdoor environment. The personalized ventilation system, placed above and below the writing area, installed in the desk central area. The office desk is occupied by eight virtual manikins. The numerical simulation is made in a winter typical day. This numerical study considers a coupling of a differential numerical model and an integral numerical model. The differential numerical model simulates the Computational Fluids Dynamics (CFD), evaluates the air velocity, air temperature, turbulence intensity and carbon dioxide concentration and calculates the indoor air quality. The integral numerical model simulates the Multi-Node Human Thermo-physiology Model, evaluates the tissue, blood and clothing temperatures distribution and calculates the thermal comfort level. The HVAC system, based on a DSF system, is built using three DSF unities, is equipped with internal venetian blinds. Each one, installed in a virtual chamber, is turned to south. The personalized ventilation system, made with eight upper and eight lower air terminal devices, is installed in the desk central area. On each table top two upper and two lower air terminal devices are considered in the left and right manikin area, while on each side of the table two upper and two lower air terminal devices are placed between the manikins. The office desk is occupied by eight virtual manikins, one sitting on each table top and three sitting on each side of the meeting table. In this numerical study, carried out in winter conditions, the occupants’ clothing level is 1 clo. In these situations a typical activity level of 1.2 met is considered. The evolution of indoor environmental conditions, in the DSF and in the office room, are calculated during a full winter typical day. The thermal comfort, the indoor air quality, the effectiveness for heat removal, the effectiveness for contaminant removal and the Air Distribution Index (ADI), are evaluated. In accordance with the obtained results the thermal comfort levels increase when the air renovation rate increases and the indoor air quality level increases when the air renovation rate increases. However, the ADI is quite constant when the inlet airflow rate increases, because the thermal comfort number decreases when the inlet airflow rate increases and the air quality number increases when the inlet airflow rate increases.

How to assess ecodistrict resilience to urban heat stress under future heatwaves? A case study for the city of Paris

It is now well-known that the frequency, intensity and duration of heatwaves will strongly increase along the XXIth century, which introduces the urban built environment resilience as a new paradigm. In Paris, the intense 2003 heatwave demonstrated that warm urban temperatures could result in serious adverse health issues. Temperatures were particularly elevated during nighttime, due to the urban heat island effect. Since air-conditioning has not penetrated yet in residential French buildings, studying the potential of combined mitigation strategies at the district and building scale to increase the neighbourhood and buildings resilience in strong urbanized areas under future heatwaves is a key subject matter. The climate change aspect is integrated through a future heatwave weather file, re-assembled from dynamically downscaled multi-year regional climate change projections from the EURO-CORDEX project. The new ecodistrict Clichy-Batignolles in central Paris is chosen as a case study, recognized as innovative for low-energy and environmental solutions. It is composed of high-rise residential and commercial buildings, large green areas, cool surfaces, and reduced anthropogenic sources. We used an Urban Canyon Model (Urban Weather Generator) to model the neighbourhood and different design configurations (building height and density, green and cool surfaces). The designs and measures were evaluated through a sensitivity analysis to analyse their potential to mitigate the urban local microclimate air temperature during the heatwaves. We quantified the neighbourhood resilience and found that the ecodistrict is exposed to a strong urban heat stress under the future intense heatwave. These results highlight how outdoor overheating assessment can be used to evaluate the district mitigation and adaptation strategies. This approach can be used for urban planning, while the modelled future urban heatwaves can be used as an input for building simulations and evaluate the resilience of the buildings to urban heat stress.

Optimisation of insulation and solar control strategies as function of building’s intended use in the retrofit of massive buildings

In temperate climates, such as most Italian ones, the need to limit both winter heat losses of buildings and their overheating in other periods is present. The second requirement is particularly relevant in the presence of high internal and solar gains. In these climates, it is not convenient to exceed the insulation thickness. Therefore, when the energy renovation of an old building with heavy masonry is performed it is a question of optimizing the position (internal or external) and the thickness of the additional insulation. Another question is the choice of a solar control strategy, if extended glazed surfaces are present. Both of these problems are present in old Italian public buildings, particularly in schools. This paper presents a computerized methodology for optimizing these choices. The case study consists in a typical school building from the early 1900s with a heavy structure and large glass surfaces in a climate of Northern Italy (Bologna), with cold winter and hot summer. The results show that the external insulation is the best performing, and that there is an optimal thickness when the building is a school. If the building is reused for offices, due to the lower internal gains, the energy convenience of the external insulation increases, but its optimal thickness becomes excessive. Small slats inserted between the glasses are the best performing solar control device from both an energy and visual comfort point of view; on the other hand, the external slats provide better thermal comfort in the warmer period.