Multi-criteria decision analysis to assess the environmental and economic performance of using recycled gypsum cement and recycled aggregate to produce concrete: the case of Catalonia (Spain)

The production of virgin raw materials used in construction and the generation of construction and demolition waste (CDW) are key environmental issues in the construction industry. Portland cement and concrete are used extensively in the construction sector. Processing of CDW to produce recycled gypsum cement and recycled aggregates (RA) and their use in the production of structural and non-structural concrete are one way of slowing natural resource depletion and reducing the amount of CDW landfilled. This study proposes the application of multi-criteria decision analysis (MCDA) to compare the production of “green” concretes made from recycled gypsum cement (RGC) and RA with the production of conventional concrete made from natural aggregate and ordinary Portland cement. The VIKOR MCDA method was employed to determine the best or a set of good alternative(s) for concrete production, considering environmental and economic criteria. The life cycle assessment method was used to select the environmental evaluation criteria, and the reference cost of producing concrete alternatives in Spain was used to determine economic criteria. The results of this study, in which environmental and economic criteria were considered of equal weight, or one of the two criteria was given greater weight, showed that the best option for structural and non-structural concrete was the use of RGC and RA. In both cases, the worst alternative was conventional concrete. In conclusion, we found that the use of RGC and RA in concrete production is positive because it replaces the original raw material, reduces the environmental impact, and lowers the economic costs.Postprint (published version

Estudio y modelización del edificio Biblioteca del Campus Terrassa mediante métodos simplificados y datos monitorizados

El presente trabajo trata sobre el estudio de la certificación a partir de datos monitorizados como un método válido para la certificación energética de un edificio existente. Para ello, se realizaran tres certificaciones sobre un mismo edificio, dos mediante métodos simplificados utilizando el programa CE3x y una certificación basada en el consumo de energía real del edificio que está monitorizado. Después de realizar las diferentes certificaciones se compararan los resultados obtenidos en cada una de ellas. Los principales parámetros de comparación son las horas dedicadas, el coste, la calificación y las hipótesis admitidas para cada certificación

Volcano and ship tracks indicate excessive aerosol-induced cloud water increases in a climate model

Aerosol-cloud interaction is the most uncertain mechanism of anthropogenic radiative forcing of Earth’s climate, and aerosol-induced cloud water changes are particularly poorly constrained in climate models. By combining satellite retrievals of volcano and ship tracks in stratocumulus clouds, we compile a unique observational dataset and confirm that liquid water path (LWP) responses to aerosols are bidirectional, and on average the increases in LWP are closely compensated by the decreases. Moreover, the meteorological parameters controlling the LWP responses are strikingly similar between the volcano and ship tracks. In stark contrast to observations, there are substantial unidirectional increases in LWP in the Hadley Centre climate model, because the model accounts only for the decreased precipitation efficiency and not for the enhanced entrainment drying. If the LWP increases in the model were compensated by the decreases as the observations suggest, its indirect aerosol radiative forcing in stratocumulus regions would decrease by 45%

Experiencias con herramientas de gamificación en la docencia de proyectos en la enseñanza universitaria

Este artículo presenta una serie de experiencias con la herramienta de gamificación kahoot en sesiones de teoría de asignaturas del área de proyectos de ingeniería y analiza los resultados de su implementación. La primera experiencia presentada es el uso de la herramienta Kahoot para evaluar los ejercicios intermedios de una sesión de teoría. La segunda experiencia presentada es el uso de la herramienta para evaluar los conceptos de teoría explicados durante una clase de teoría. La última experiencia es el uso de la herramienta para repasar el temario hecho hasta el momento justo al inicio de una sesión de teoría. Los resultados demuestran la buena acogida que tienen estos tipos de actividades entre el alumnado. Además, la herramienta permite dinamizar las sesiones de teoría y conseguir una mayor atención de los estudiantes. De todos modos, el uso de este tipo de herramientas tiene sus riesgos. El hecho que Kahoot sea una herramienta competitiva provoca que los estudiantes se desconcentren y sea difícil que estos presten atención a las explicaciones del profesor. A nivel tecnológico no se reportaron problemas significativos ya que actualmente todos los estudiantes van a clase con un móvil, tableta u ordenador compatible con el sistema usado.Peer ReviewedPostprint (published version

Análisis del ciclo de vida del sistema de gestión de residuos municipales de la Ciudad de México

El Análisis del Ciclo de Vida (ACV) es una herramienta metodológica que determina los potenciales impactos ambientales asociados con un producto o servicio, desde la extracción de la materia prima hasta su disposición final. El objetivo de este estudio es evaluar los potenciales impactos ambientales asociados a cada uno de los proceso del sistema de gestión de residuos sólidos de la Ciudad de México, mediante la aplicación del software TEAM, se evaluó las siguientes categorías de impacto: acidificación, disminución del ozono estratosférico, eutrofización, efecto invernadero (directo, 100 años), formación de foto-oxidantes, toxicidad terrestre, efectos carcinogénicos y efectos respiratorios. Los resultados sugieren que el sistema de manejo de residuos sólidos de la Ciudad de México presenta impactos relevantes en los procesos de vertedero controlado, vertederos no controlados y reciclado de vidrio; el proceso de fabricación de compost se presenta como una opción favorable debido a que no presenta impactos ambientales significativos. El ACV realizado sugiere la siguiente jerarquía de tratamientos de residuos municipales: fabricación de compost, incineración, reciclaje y vertedero controlado. La peor alternativa es el vertido no controlado de residuos debido a que se trata de superficies donde los residuos son depositados de forma clandestina y no cuentan con ningún tipo de control de la contaminación.Preprin

Building-integrated greenhouses raise energy co-benefits through active ventilation systems

Buildings and greenhouses consume vast amounts of energy and natural resources for heating and ventilation. It is still unclear how the synergetic effect of combining greenhouses and buildings' forced waste airflows could improve both systems' energy efficiency. This study quantified the energy recovery potential of exchanging airflows in a rooftop greenhouse (iRTG) integrated with an office building HVAC system in a Mediterranean climate. Using monitored and calibrated energy model data, the results showed that the iRTG can act as a solar collector and as a sink for a building's low-grade waste heat. The magnitude of harvested thermal energy that could be recirculated into the building by the integrated HVAC system was 205.2 kWh/m2y-1 and was limited by greenhouse low transmissivity (54%). The magnitude of building exhaust air was 198 kWh/m2y-1 at temperatures sufficient to heat and cool the iRTG. Compared to a passive ventilated configuration, the integration of active ventilation strategies doubled the energy benefits. Building ventilation requirements directly determined building and greenhouse waste flows and energy benefits, which increased by 63.1% when air changes per hour moved from 1.59 to 3.16. Overall, this demonstrates that greenhouse and building functionalities could be coupled to contribute to urban circularity and sustainability.The authors are grateful to the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya (Catalonia) for the award of a research scholarship (FI-DGR 2020) to Joan Muñoz-Liesa. Authors also acknowledge financial support from the Secretaria d'Universitats i Recerca del Departament de Recerca i Universitats de la Generalitat de Catalunya for the grant awarded under AGAU 2020 PANDE 00021 and the Spanish Ministry of Science, Innovation and Universities, through the “María de Maeztu” program for Units of Excellence in R&D [CEX2019-000940-M]. This work was additionally enabled by the Càtedra JG Ingenieros – Universitat Politècnica de Catalunya and the UK Engineering and Physical Sciences Research Council grant EP/P001173/1. Authors are also grateful to Elisa López-Capel, Sostenipra research group and ICTA-UAB staff for the very valuable support, advice and help.Peer ReviewedObjectius de Desenvolupament Sostenible::11 - Ciutats i Comunitats SosteniblesObjectius de Desenvolupament Sostenible::7 - Energia Assequible i No ContaminantPostprint (published version

Improving urban metabolism: bi-directional energy and environmental benefits of rooftop greenhouse and building integration

Rapid global urbanisation in 21st century results in cities consuming vast resources but also offering unique opportunities for more integrated and circular resource management. This work investigates potential benefits of urban agriculture and buildings integration through a demonstrator building (ICTA). Actual building and integrated Rooftop Greenhouse (iRTG) data demonstrate wide thermal profiles across ICTA six levels and the potential for heat exchange within the building. Calibrated model monthly results indicate reduced building heating needs resulting from iRTG inclusion. However, more modest GSHP electrical cooling reductions resulting from plant transpiration showed reversing potential which requires more in-depth analysis of underlying principles.The authors are grateful to the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya for the award of a research scholarship (FI-DGR 2016) to Joan Muñoz Liesa; the Spanish Ministry of Economy and Competitiveness (MINECO) for the financial support of the research project Fertilectiy II “Integrated rooftop greenhouses: energy, waste and CO2 symbiosis with the building. Towards foods security in a circular economy” (CTM2016-75772-C3-1-R; CTM2016-75772-C3-2-R) and the María de Maeztu program for Units of Excellence in R&D (MDM-2015-0552).Peer ReviewedPostprint (published version

Near real time evaluation of the spanish air quality forecast system: CALIOPE

The WRF-ARW/HERMES-EMEP/CMAQ/BSC-DREAM8b modelling system provides high resolution air quality predictions for 48h in Europe –EU12- (12x12 km2, 1h), the Iberian Peninsula and Balearic Islands –IP4- (4x4 km2, 1h) and Canary Islands –CAN2- (2x2 km2, 1h) since July 2007, under the framework of the CALIOPE project (Baldasano et al., 2008; http://www.bsc.es/caliope/). A near real time evaluation system has been developed and it is on-line and in operation since January, 2009. Non validated near real time air quality data from more than 400 surface stations are compared to ground-concentration predictions in Spain. Seven ozonosondes are used to test the performance of the model in reproducing O3 vertical structures in Europe, Spain and Canary Islands. Additionally, OMI images are used to qualitatively assess the vertical column densities of NO2 predicted for Europe.Postprint (published version

The circular economy in the construction and demolition waste sector: a review of initiatives in Spain

La Economía Circular (EC) es un concepto recientemente desarrollado que ha ganado un importante reconocimiento en el ámbito político, de negocios y academia, debido a que es considerada una alternativa innovadora aplicable a diversos sectores y que permite satisfacer necesidades de producción y consumo de forma más sostenible. En el sector de la construcción y demolición, la implementación de la EC no ha sido investigada ampliamente y está limitada a enfoques parciales de estudio, abordando especialmente alternativas de recuperación. Existe la necesidad de desarrollar investigaciones más extensas que consideren la aplicación de estrategias circulares en el ciclo de vida completo de las actividades de construcción y demolición. El objetivo central de este trabajo es proveer un análisis de las iniciativas de Economía Circular existentes en España, a nivel estatal y regional, y que tienen una influencia directa en el sector de la construcción y demolición. Para entender el funcionamiento de la EC y las principales iniciativas, se realizó una revisión sistemática de la literatura. Las estrategias identificadas están enfocadas particularmente en la gestión de residuos y el uso de materiales recuperados como materiales secundarios.Postprint (published version

Urban greenhouse covering materials: assessing environmental impacts and crop yields effects

Solar radiation transmissivity in greenhouses is a key property largely determined by covering materials. This study compared tomato crop yields and their environmental performance of a polycarbonate rooftop greenhouse with alternative covering materials displaying higher solar transmissivity and lifetime performance. An integrated approach using experimental data with structural, energy modeling was used to model average lifetime crop productivities. At building functional unit (per m2·year), impacts varied between -29.0% and +24.0% compared to the current polycarbonate. Lifetime transmissivities improved up to 20.5% (4 mm-antireflective glass), leading to +46.6% of tomato yields (19.9 ± 2.2 kg/m2), and up to -33.9% of environmental impacts. Ethylene tetrafluoroethylene 60 µm-film resulted in 19.2 ± 2.3 kg tomatoes/m2 but improved environmental performance up to 41.7%. These results demonstrate the importance of employing integrated and life-cycle approaches to combine multiple trade-offs and dynamics within environmental assessments of greenhouse crops. The results are intended to contribute to improving greenhouse cultivation and sustainability.Peer ReviewedPostprint (published version