In greenhouses, CO2 gains are proportional to the losses in classrooms, though with lower concentrations because of the larger greenhouse area. Fig. 9 displays the hourly effects on CO2 levels and air temperature due to airflow integration, and Table 8 depicts the maximum and average CO2 concentrations. Average CO2 levels decrease only 133.35 ppm in classrooms and increase 74.89 ppm in greenhouses. Air exhaustion lowers peak levels in classrooms by 1943.6 ppm and 817.3 ppm for schools A and B, respectively. The maximum gains in greenhouses are 1001 ppm in archetype A and 366 ppm gains in archetype B. This difference between schools is due to classrooms and greenhouse sizes.Fig. 10 shows the theoretical thermal load and EUI for both archetype schools and assessed RFs. Heating is provided by centralized gas boilers with a coefficient of performance  of 0.92 and cooling by electrical splits with a 2.6 COP. For comparison purposes, conventional insulated roofs were included. Only considering the thermal load, RTGs are the most efficient solution achieving an average 48.2% reduction, followed by iRTGs  and lastly, eGRs. Authors do not expect optimized eGRs could surpass RTGs performance because soil thickness only affects energy load by 0.02% for depths between 5 cm and 60 cm, and water content only 13.2% for saturations between 20 and 100%. A similar trend was shown for eGRs and soil RTGs in Italy, where the latter outperform other roofing systems for non-cooling scenarios. However, that study showed that insulated roofs have a better annual performance because, even thoug RTGs and eGRs reduce energy demand by 50% in summer,nft growing system in winter their performance is lacking.

However, in Quito, vegetated roofs outperform insulation due to their active heat sink effect through which plants process energy according to their immediate needs. Similar results were obtained for moderate climates in North America, comparable to Quito’s climate.For Quito schools, RTGs raise the operative temperature in classrooms by 0.8 ◦C for 112 schools and by 1.25 ◦C for 102 schools. This temperature increment represents an annual thermal load decrement of 45% or 7872.67 MWh. At the city scale, iRTGs show only 5% lower thermal performance than RTGs but improve air quality in classrooms by decreasing in half the number of occupancy hours when the concentration of CO2 exceeds recommended levels. iRTGs operational electricity demand is 1813.85 MWh for the hydroponic cultivation system and 399.81 MWh for mechanical ventilation. This demand represents an increment of 15.6% and 3.5% from the current educational stock electricity demand. While the thermal load improvement far surpasses the electricity demand for RTGs and iRTGs, their operation is still a liability due to increased economic expenditure. The literature suggests that RTGs have better environmental performance than conventional greenhouses because negative impacts are amortized between the host building and the farm. However, for retrofitting free-running buildings, iRTGs environmental impacts need to be considered independently. A previous study on Quito’s schools showed that eGRs were preferable due to their social acceptance, water storage and runoff reduction capacity, and compliance with local urban and construction codes. Additionally, eGRs installation and maintenance costs are lower than RTGs compliant with building construction codes. In RTGs, the LDPE envelope requires replacement every 3–4 years and the hydroponic system every ten years, thus increasing its life-cycle costs. With a focus on harvesting, eGRs require tight control for irrigation, fertilization, waste management, pest control, wind exposure and weeding to keep a productive state. However, the operation of hydroponic farms has a higher environmental impact because of the chemical fertilizers and artificial substrates. Consequently, protected GRs or soil cultivation in RTGs may provide the best compromise between thermal comfort improvement and electricity demand.The proposed co-simulation is a step forward in the energy modelling for BIA as it inputs crops’ energy balance into host buildings’ energy simulation. This strategy takes advantage of the capabilities of two software tools: complete building energy modelling in E+ and complex mathematical functions in MATLAB for crop’s modelling.

Table 9 summarizes the pros and cons of the proposed co-simulation. Its main advantages are: 1) using indoor climate as the boundary condition for the crop’s sub-models which enhances model performance by up to 20%; 2) including radiant and advective terms for plant’s energy balance which is of particular importance for naturally ventilated greenhouses; and, 3) implementing a dynamic LAI to model transpiration which allows a more accurate simulation of crop’s heat balance throughout its growth stages. The E+ EcoRoof module used for eGRs requires fixing crop and soil parameters. The workaround proposed in this article allowed researchers to include a dynamic LAI and plant height – through a concatenation of multiple simulations runs – but soil’s thermal characteristics could not be altered. Moisture content can vary substrate’s specific heat by 1.5 times and double its thermal conductivity from dry to saturated conditions. Although EcoRoof includes water balance models, substrate properties are assumed constant and can produce errors of 2 ◦C in surface temperature. The conduction transfer algorithm in the E+ EcoRoof model has numerical limits for some plant parameters and, therefore, extreme values cannot be set, e.g. LAI between 0.001 and 5.0. Such is the case for pre-harvest lettuce that surpasses LAI’s upper limit, therefore under calculating the crop’s energy balance in pre-harvest. However, as extreme high LAIs are only proper for enclosed crops, other plants should not be limited by this. The EcoRoof model is based on the Army Corps of Engineers’ FASST atmospheric vegetation model but adapted to be used with a thin soil layer. The Stanghellini model is an adaptation of PM model for use in protected environment farms. Both models require crop-specific parameters and resistances that are difficult to quantify, which is why many studies on greenhouse climate management use simplified PM models that rely on weighting coefficients. A key point of this co-simulation is the capability to simulate different evapotranspiration models according to data availability and environmental conditions. On this matter, Penman-Monteith and a simplified PM model were modelled in MATLAB alongside the Stanghellini model described previously. Fig. G.1 in Appendix G depicts the crops’ heat fluxes and greenhouse indoor air temperature using these three transpiration models. For LAIs below 4, the PM model predicts higher latent heat fluxes. As LAI increases, PM and Stanghellini latent heat flux estimations become similar. The simplified PM model always underestimates heat flux but to a lesser degree during the first growth stages. The higher temperature estimates using both PM models suggest more substantial heat gains for RTG and iRTG scenarios, beneficial for indoor comfort in classrooms but disadvantageous for lettuce crops due to overheating risk – 24 ◦C maximum temperature. The Stanghellini model consistently predicts a higher sensible heat loss from the air to the crop, generating a temperature drop during sunlight hours. These higher values are due to the direct use of LAI in the Stanghellini model, whereas PM uses effective LAI. Vegetation cover fraction accounts for the effective agriculture area and should be further considered in transpiration models. This parameter is usually proportional to LAI, but for closed crops such as lettuce, both parameters are non-linear. For lettuce, the cover fraction increases rapidly during the first growth stages and then remains constant despite leaves densify.

Therefore, LAI should be corrected to reflect better the transpiring surface.Arsenic  is a potentially hazardous element that can pose serious risks to living organisms and the environment. It is a non-essential element for plants and often produces strong phytotoxicity,which can be caused both directly, through phosphate replacement by arsenate in some biochemical reactions and arsenite binding to sulfhydryl groups in proteins,and indirectly, through the formation of free radicals and other reactive oxygen species  during As detoxification. As a consequence, plants subjected to As stress due to exposure to As-rich waters or contaminated soils undergo oxidative damage. Plant cell disruption due to As toxicity may arise through membrane integrity alteration, inhibition of photosynthesis and respiration, and metabolic disturbance. The remediation of soils and waters contaminated with As has become a major environmental issue. A suitable option for environmental restoration, in many cases, is phytoremediation, a cost-effective technique based on the use of plants for the treatment of a wide range of pollutants in the environment. In particular, the potential for phytoremediation of wetland plants has attracted increasing attention, as some of them can grow naturally in contaminated areas and in constructed wetlands. Common reed  Trin. ex Steud, a macrophyte species with a very wide geographical distribution, possesses several characteristics of interest regarding the accumulation and sequestration of pollutants. High biomass production, a well-developed roots and rhizomes system, and high tolerance to potentially toxic elements  confer on common reed its suitability for the remediation of aquatic and soil environments contaminated by PTEs. However, high concentrations of PTEs in this species may still lead to oxidative stress, including DNA damage and misfolding and loss of functionality of key enzymes and proteins. In this sense, further understanding of how common reed responds at the physiological level to PTEs toxicity may be crucial regarding its possible use in future phytoremediation actions. Although the efficiency of common reed with regard to PTEs phytoremediation is widely reported in the literature, its detoxification of As has received less attention and needs to be studied further. The use of common reed rhizofiltration represents an interesting choice for As removal from contaminated groundwater. In addition, new approaches like the formation of an iron plaque in the roots to increase As retention  or the use of common reed biomass for the generation of bioenergy  make this species of particular interest regarding phytostabilization. However, nft hydroponic system the roles of the different As species in the tolerance and/or accumulation of this element by common reed remain largely unknown. The effects of As in plants have been studied previously, as it is known to be the dominant species in waterlogged and organic matter rich soils. Contrastingly, very little information can be found regarding.

As uptake and toxicity in common reed plants, even though As has been found to be the only species present in pore water  extracted from flooded and unflooded strongly oxidized contaminated mine soils  and in water extracts of compost and biochar amended mine soils. We hypothesized that the response of common reed plants to As may differ along a gradient of toxicity, and that this would be reflected in their physiological and oxidative status and in the transformation of As and its compartmentalization as different As species. Therefore, the aim of this study was to elucidate novel aspects of common reed As tolerance by exposing plants to distinct As concentrations in an original hydroponic experiment. The effects of As accumulation on the plants were evaluated through nutritional and oxidative stress parameters, which were finally related to the concentrations of the major As species in the different plant compartments.The presence of As in the nutrient solution did not cause any evident damage in the common reed plants, as no significant differences were found for the growth and yield parameters between the control and the different As treatments. Nevertheless, the roots showed a certain sensitivity to the As mass concentration in the nutrient solution, with the lowest increase in length occurring at the highest treatment dose. The photosynthetic pigments analyzed  did not show significant differences among the different treatments  and external symptoms of toxicity in the plants were not observed. The Chl-a mass fractions determined were within the range found for this species in previous studies. The ratio Chl a/b, used as an indicator of contaminant-induced plant stress,ranged from 2.7 to 3.1 in our plants  and was very close to the ratios previously reported for common reed plants exposed to Cu and Cd contamination. Detoxifying mechanisms might have efficiently mitigated the adverse effects of As exposure, since the plant growth and photosynthetic rate, two of the most common indicators of PTEs toxicity in plants, were barely affected. Plant nutrition can be altered by PTEs toxicity, in turn affecting transport processes of the cellular membrane and transpiration. The fact that phosphate and arsenate ions have the same charge and chemical structure is responsible for most of the toxicity due to As, based on its capacity to disrupt cell functions. In the present experiment, the levels of P in the roots slightly increased when common reed plants were exposed to 0.5 mg As L− 1,but then decreased significantly as the As mass concentration in the nutrient solution increased. These results point to the competition of arsenate for phosphate transporters in plant roots. Contrastingly, the levels of P in the aerial part of the plants were very similar in all the treatments, indicating that As did not compete with P for carriers involved in translocation.