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Quantifying energy symbiosis of building-integrated agriculture in a mediterranean rooftop greenhouse
... Various studies and their findings related to the environmental assessment and economic profitability of RTGs in different locations are discussed [12,[49][50][51][52][53][54][55][56][57][58][59][60]. It is noteworthy that while RTGs may have higher initial costs associated with the greenhouse structure, they can offer lower environmental impacts, reduced transportation and distribution losses, increased food security, and potential productivity gains. ...
... Muñoz-Liesa et al. [56] reported the energy benefits of BIA through (i) a calibrated energy model and (ii) a thermal analysis of a selected building with IRTG in a Mediterranean region. The case study was previously assessed with a calibrated energy model that quantified the recovered heat from the building and the IRTG. ...
... Muñoz-Liesa et al. [56] 2020 RTG South Korea LCA on tomato production comparing conventional greenhouse and RTG revealed that RTG required 19 % less energy for heating and 38 % more for cooling than a greenhouse. Total energy load reduction for RTG was 13 % due to smaller heat losses of RTG during colder months. ...
The environmental impacts of food systems will increase in tandem with rapid urban population growth, which calls for alternative solutions, such as urban agriculture, to reach the United Nations Sustainable Development Goals. Among several urban agriculture systems, rooftop farming and its subset, rooftop greenhouses, are promising technologies. They optimize land use, increase profitability for building owners, deliver good yields per unit area, increase water use efficiency, and reduce the energy use of both greenhouse and host buildings while mitigating the urban heat island effect. A systematic literature review of the rooftop greenhouse technology was carried out to examine the benefits and challenges associated with this technology. This review was based on 45 articles, covering themes such as the impact of rooftop greenhouse technology on yields, energy use, water use, environmental impacts, and life-cycle costs; some benefits identified are the symbiotic heat, water, and CO2 exchanges between the rooftop greenhouse and its host building, and the possibility of delivering year-round production. The additional investment, operational costs, limited availability of flat roofs, and various regulations were challenges to overcome. The relevance of symbiosis between rooftop greenhouses and buildings to enhancing sustainability, and meeting the SDGs was explored. This review also outlines that rooftop greenhouses are increasing in scale, system diversity, societal acceptance and popularity among commercial operations in large cities. The future of rooftop farming lies in customizing the right technology for selected building typologies globally, where food production is fully integrated into the urban landscape.
... Examples of these synergies include nutrient recovery from the sewage system (Wielemaker et al., 2018), and the use of carbon dioxide (CO 2 ) from production processes to increase crop yields (Marchi et al., 2018). At the building scale, bidirectional synergies between a rooftop greenhouse and an office building with laboratories have been identified and quantified by Muñoz-Liesa et al. (2020. The greenhouse functioned as a heat and cold sink by reusing the building's exhaust air for heating during colder months and cooling during warmer months, and as a solar collector that supplied excess heat to the building. ...
... The greenhouse functioned as a heat and cold sink by reusing the building's exhaust air for heating during colder months and cooling during warmer months, and as a solar collector that supplied excess heat to the building. Furthermore, this greenhouse reduced heat losses through the building's roof (Muñoz-Liesa et al., 2020), and the CO 2 -concentration of the greenhouse was increased using the building's exhaust air (Sanjuan-Delmás et al., 2018). Using these principles, urban agriculture can increase the sustainability of cities, buildings, and food systems (Kozai and Niu, 2020). ...
... The results suggest that the bidirectional exchange of energy between a VF and a building can decrease total annual energy use of the climate systems collectively by between 12 and 51% when compared to the cumulative baseline approaches of both functions. This positive effect of energy synergies between urban agriculture and buildings was also found in previous studies that investigated energy exchange between rooftop greenhouses and buildings (Muñoz-Liesa et al., 2020Jans-Singh et al., 2021;Ledesma et al., 2022). The energy synergy in this research was most effective when the building contrasted the VF in terms of energy demand. ...
Vertical farms use some resources very efficiently. However, their electricity use is considerable, and a significant amount of waste heat is produced. This paper investigates how the integration of vertical farms in buildings could reduce the use of energy, water, and nutrients collectively across both entities by leveraging potential resource synergies. The paper considered the integration of vertical farms in apartments, offices, restaurants, swimming pools, and supermarkets located in the Netherlands. For each typology, the floor area heated and the amount of building users fed by one m2 of one production layer within the vertical farm was calculated, along with required outputs of water and nutrients from the building to sustain the vertical farm. The energy savings of different integration strategies were calculated for each building typology in comparison to a non-integrated approach. Results showed that the synergetic integration of vertical farms with buildings reduced the year-round energy use of the climate systems of both entities collectively by between 12 and 51%. The integration of vertical farms with buildings decreases the use of energy, water, and nutrients from external sources and offers great potentials to reduce the environmental impacts of both entities, whilst producing food in urban environments.
... Transpiration was represented in the BES through an evaporative cooling pad with pre-determined load. The 'living lab' rooftop greenhouse in the ICTA building in Barcelona was also modelled with EnergyPlus (Nadal et al. 2017;Muñoz-Liesa et al. 2020). However, because the model focuses on the exchange of the warm air from the building to the rooftop greenhouse and vice versa, the transpiration was simplified to a function of the day of the year through a system variable, and had negligible effects. ...
... However, because the model focuses on the exchange of the warm air from the building to the rooftop greenhouse and vice versa, the transpiration was simplified to a function of the day of the year through a system variable, and had negligible effects. However, the further study on this building by Muñoz-Liesa et al. (2020) found that transpiration of plants needed improved modelling as it may have repercussions on air-conditioning demand. There is currently no complete simulation methodology to quantify and optimize the integration of a greenhouse with a building as a thermodynamic element. ...
... For the same yields, energy demand for a standalone greenhouse would thus be double, highlighting the benefits of the integration of the greenhouse to the building design. Past BIA models had focused on Mediterranean climates (Muñoz-Liesa et al. 2020), but the large demand for heating in more temperate climates such as in the UK highlights the large potential for heat recovery in different settings. ...
Recent findings suggest that rooftop greenhouses could be more efficient when combined with waste streams in buildings, but there is a gap in quantification of the combined performance of building integrated greenhouses. This paper addresses this deficit for school buildings in London, UK, where urban agriculture is of increasing interest. A building energy simulation (BES) of an archetype school building is developed in EnergyPlus and co-simulated with a validated greenhouse energy simulator (GES). The performance of different greenhouse-building coupling configurations is evaluated to estimate the potential for crop growth, heat recovery and reduction in ventilation demand, through a sensitivity analysis and parametric study. Our results show that a 250 m2 greenhouse on the top floor of the school could produce 6t lettuce with half the energy demand of the same standalone greenhouse. Trade-offs across increase in humidity, yields, and energy efficiency indicate the importance of modelling to ensure optimal designs.
... Overall, GHG emissions from energy consumption were estimated at 33.1 billion tons in 2018, and 39% of the global GHG emissions were from buildings [8]. In 2018, the government of South Korea planned to reduce total GHG emissions by 26.3% until 2030 [9]. Among the various industries generating GHG, the reduction ratio of GHG in the building sector was aimed to be 32.8%, ...
... Urban agriculture was suggested as one of the countermeasures, which represents a new concept of agriculture that spatially integrates rural and urban areas such as vertical farms, rooftop greenhouses (RTGs), plant factories, and building farms [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. ...
Building-integrated rooftop greenhouses (BiRTGs) are innovative vertical farms consisting of a greenhouse on the roof of a building. BiRTGs can provide environmental benefits by recycling energy, carbon dioxide, and water between the greenhouse and the building. Moreover, BiRTGs can reduce cooling and heating loads by reducing the exposure of the building surface to heat gains/losses through the roof. However, the benefits of BiRTGs have not yet been completely elucidated from an energy perspective. This study aimed to analyse the energy-saving efficiency of BiRTGs using building energy simulations (BES) and computational fluid dynamics (CFD) techniques. BES is a calculation method for analysing the heating and cooling loads of buildings; however, it was difficult to consider time-dependent changes in the ventilation characteristics in the BES model. CFD can be used to calculate more detailed ventilation characteristics of an experimental facility. Thus, CFD and the BES were combined to obtain more accurate BES-based data. The BES-computed annual energy load for a single-span greenhouse in which tomatoes were grown was 490,128 MJ, whereas the annual energy load for growing tomatoes in a BiRTG resulted in a 5.2% reduction, on average (464,673 MJ). The energy-saving effects were positive from October to April because the BiRTG helped transmit heat energy transmitted from the building to the greenhouse. Regarding the total energy load in the BiRTG after alternating the air temperature management (ATM), the heating energy load was reduced in the winter. ATM was expected to apply from November to March, with average energy savings of 11.8%.
... Building greenhouses on unused rooftops can be another potential space for urban farming. Integrated rooftop greenhouses take up the role of the sink for waste heat by integrating the building HVAC systems with the greenhouses (Muñoz-Liesa et al., 2020). Despoina Avgoustaki and Xydis affirmed that Indoor and outdoor vertical farming is more profitable with higher energy savings than greenhouses (Avgoustaki & Xydis, 2020). ...
The concept of green cities has been getting sustained focus for some time, intending to transform dispersed cities into environmentally, ecologically, and socially healthier spaces to live. The concept interlinks different domains of urban development, such as spatial planning, transport, water and sanitation services, urban greenery, renewable energy, sustainable building construction, and socioeconomic growth through green solutions. Energy planning and management play a vital role in transforming urban areas into environmentally sustainable cities. Integrating energy management as a key aspect of green city strategies from the pre-planning to post-implementation stages can expedite the process. This paper attempts to comprehend the intertwined role of energy management in green city planning through a comprehensive literature review. Relevant articles that discuss energy and management in interdisciplinary domains under the green city concept were identified and reviewed for the period—2000–2021. Diverse energy-efficient management measures and techniques are reviewed under seven domains of green city planning: green spatial planning, transportation, public infrastructure, urban agriculture, buildings, energy, and growth. The summarized literature emphasizes the relevance and significance of efficient energy management in the transition toward a green city. The study also discusses the need for a gradual transition and the challenges in successfully implementing and managing sustainable strategies. The successful implementation of climatic and environmental solutions through policy-level strategic interventions demands continuous effort and monitoring to achieve the long-term goal of sustainability. Energy-efficient urban development practices, with the foundation of a policy framework, can act as sustainable solutions to maintain the synergy between energy independence and urban development. Expediting the transformation of green cities with the adoption of energy-efficient strategies and renewables to decarbonize the energy supply is an accomplishable vision for every city.
... The authors stated that the numeral model of the single-family resident could be used for thermal co-simulations since it met the requirements of the ASHRAE standard. Sethi [11] presented a calibrated energy model of a rooftop greenhouse, an example of building integrated agriculture, to provide the heating demand of the greenhouse for three different scenarios. The simulations revealed that increasing the insulation layer thickness of the greenhouse provides an energy savings of 35 kWh/m 2 . ...
... However, despite the potential environmental and economic benefits, production in an urban i-RTG may present some limitations due to the shading of surrounding buildings, as well as the bulky structural items, and the loss of transmissivity of fireproof covering materials (e.g., polycarbonate). In fact, given the integration in a city context, the structure must comply with the municipality's structural and fire safety codes, with consequent constraints affecting the greenhouse light environment [8,9]. ...
The metabolism of a building can be connected to a rooftop greenhouse, exchanging energy, water and CO2 flows, therefore reducing emissions and recycling cultivation inputs. However, integrating a rooftop greenhouse onto a building requires the application of stringent safety codes (e.g., fire, seismic codes), to strengthen and secure the structure with safety elements such as thick steel pillars or fireproof covering materials. These elements can shade the vegetation or reduce solar radiation entering the rooftop greenhouse. Nevertheless, application of additional LED light can help to overcome this constraint. The present study evaluated supplemental LED light application in an integrated rooftop greenhouse (i-RTG) at the ICTA-UAB research institute, located in Barcelona (Spain), for tomato cultivation (Solanum lycopersicum cv. Siranzo). The experiment explored the effects of three LED lighting treatments and a control cultivated under natural light only (CK). Applied treatments, added to natural sunlight, were: red and blue (RB), red and blue + far-red (FR) for the whole day, and red and blue + far-red at the end-of-day (EOD), each for 16 h d−1 (8 a.m.–12 a.m.) with an intensity of 170 µmol m−2 s−1. The results indicate that LED light increased the overall yield by 17% compared with CK plants. In particular, CK tomatoes were 9.3% lighter and 7.2% fewer as compared with tomatoes grown under LED treatments. Fruit ripening was also affected, with an increase of 35% red proximal fruit in LED-treated plants. In conclusion, LED light seems to positively affect the development and growth of tomatoes in building integrated agriculture in the Mediterranean area.
... All used a range of technologies and closed due to the completion of research projects or financial issues in commercial installations. For example, the Fertilecity Project, an integrated rooftop greenhouse in Belterra, Spain, was mentioned in 10 articles and is now closed as the research was completed [8,29,[71][72][73][74][75]. ...
The literature on agricultural technology (ag-tech) for urban agriculture (UA) offers many narratives about its benefits in addressing the challenges of sustainability and food security for urban environments. In this paper, we present a literature review for the period 2015–2022 of research carried out on currently active UA installations. We aim to systematise the most common narratives regarding the benefits of controlled environment agriculture (CEA) and soil-less growing systems in urban buildings and assess the existence of peer-reviewed data supporting these claims. The review was based on 29 articles that provided detailed information about 68 active UA installations depicting multiple types of ag-tech and regions. The results show that most research conducted for commercial UA-CEA installations was carried out in North America. Standalone CEA greenhouses or plant factories as commercial producers for urban areas were mostly found in Asia and Europe. The most often cited benefits are that the integration of multiple CEA technologies with energy systems or building climate systems enables the transfer of heat through thermal airflow exchange and CO2 fertilisation to improve commercial production. However, this review shows that the data quantifying the benefits are limited and, therefore, the exact environmental effects of CEA are undetermined.
... With the recent advancement of Information and Communication Technology convergence technology such as digital twin or IoT(Internet of Things) in the construction sector, the market for smart farm production systems has become a major part of the global market (Joan, 2020;Yoon, 2020;Ramli, 2020;Cor, 2021). As a smart farm, a greenhouse has high cooling and heating loads due to the greenhouse effect and solar radiation in summer (Ali, 2019;Chen, 2020 ) and for maintaining the appropriate growth temperature respectively (UN, 2007). ...
... The solar radiation reached inside the greenhouse is modelled with an Energy Plus v9.2 model previously calibrated with temperature, relative humidity and energy consumption data (Muñoz-Liesa et al., 2020;Nadal et al., 2017). The same platform integrates the Radiance engine to calculate daylight iRTG levels and thus assess solar radiation gains achieved with different covering materials according to their optical properties. ...
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.
... [8][9][10] In this manner, almost solar, wind, biomass, and geothermal energy resources (GERs) are integrated to meet the energy need for that specific purpose. [10][11][12][13] GER is not applicable in some regions, however, this energy resource has been identified in 80 countries and the feasibility study of this energy has been studied in more than 58 countries across the globe. [14][15][16][17] Regarding biomass energy resources, it is estimated that the share of these energy sources is about 35% in developing countries and it raises to 14% of primary energy sources in the world. ...
The emission of greenhouse gases from fossil fuels is the main environmental impact of energy resources. Moving toward the use of renewable energy resources is the only solution to tackle these problems. In this paper, a configuration of the hybrid biomass and geothermal energy resource is examined for cooling and electricity generation. In this study, water as a geothermal working fluid is heated up due to combustion of syngas produced in a digester and produce power in a steam turbine. So, the remaining heat of this geofluid runs an absorption chiller for cooling production. The results reveal that the energy and exergy efficiencies of this proposed cycle are 30.8% and 15.5%, respectively. Moreover, the economic analysis of this cycle concludes that the payback period is 2.8 years and the simple payback period for this configuration is 2.6 years. Moreover, the highest exergy destruction rate of 52.4% belongs to the absorption refrigeration cycle. Whereas the lowest exergy destruction of the steam line is the lowest value of 17.4%.
... Mahmood et al. [11] realised effective energy-saving of the greenhouse by changing the control strategy of heating, ventilating and air conditioning (HVAC) system, which reduced energy in winter and summer by 7.70% and 16.57% over two days. Muñoz-Liesa et al. [12] presented an energy symbiosis method to integrate greenhouses into building HVAC to improve energy efficiency. Gorjian et al. [13] investigated the integration of advanced renewable energy technologies and their thermal storage methods to achieve a close to net-zero greenhouse. ...
A greenhouse is an energy-intensive sector with substantial greenhouse gas emissions and extensive energy consumption. Energy-saving greenhouse strategies become particularly important on the premise of ensuring effective crop production to achieve sustainable energy development. This paper aims to deliver a comprehensive review on crucial energy-saving strategies from greenhouse design to operational stage. This contribution analyses effective energy-saving methods for greenhouse design considering greenhouse structures, ventilation and lighting systems. It details the energy-saving operation of greenhouses by summarising renewable energy technologies and integration systems, including photovoltaic modules, solar collectors, heat pumps and other integrated modules. These environment-friendly technologies achieve the purpose of environment protection and energy conservation of greenhouse. The research findings reveal that more than half of the energy is saved through appropriate greenhouse renovation. Control strategies for improving the energy efficiency of the greenhouse in aspects of monitoring system management and control algorithms have been discussed as well. The neural network combined with other control algorithms is a suitable approach to solve nonlinear control problems with a good control accuracy. In the final part, the life cycle environmental impacts and environmental footprints assessment of greenhouse is discussed. Life cycle assessment of modern integrated greenhouse is expected to be further studied. This review provides valuable insights and suggestions for the design and transformation of modern sustainable greenhouses.
... Similar assertions have also been highlighted for the use of heat from the vertical farm by Barge (2020). Similar findings from energy-integrated rooftops greenhouses have also been found to save energy and heating requirements for buildings (Bass and Baskaran, 2001;Sanjuan-Delmás et al., 2018;Muñoz Liesa et al., 2020). ...
Vertical farms have expanded rapidly in urban areas to support food system resilience. However, many of these systems source a substantial share of their material and energy requirements outside their urban environments. As urban areas produce significant shares of residual material and energy streams, there is considerable potential to explore the utilization of these streams for urban agriculture in addition to the possibility of employing underutilized urban spaces in residential and commercial buildings. This study aims to explore and assess the potential for developing more circular vertical farming systems which integrate with buildings and utilize residual material and energy streams. We focus on the symbiotic development of a hypothetical urban farm located in the basement of a residential building in Stockholm. Life cycle assessment is used to quantify the environmental performance of synergies related to energy integration and circular material use. Energy-related scenarios include the integration of the farm's waste heat with the host building's heating system and the utilization of solar PV. Circular material synergies include growing media and fertilizers based on residual materials from a local brewery and biogas plant. Finally, a local pickup system is studied to reduce transportation. The results point to large benefits from integrating the urban farm with the building energy system, reducing the vertical farm's GHG emissions up to 40%. Synergies with the brewery also result in GHG emissions reductions of roughly 20%. No significant change in the environmental impacts was found from the use of solar energy, while the local pickup system reduces environmental impacts from logistics, although this does not substantially lower the overall environmental impacts. However, there are some trade-offs where scenarios with added infrastructure can also increase material and water resource depletion. The results from the synergies reviewed suggest Martin et al. Urban Symbiotic Vertical Farming that proximity and host-building synergies can improve the material and energy efficiency of urban vertical farms. The results provide insights to residential building owners on the benefits of employing residual space for urban food provisioning and knowledge to expand the use of vertical farming and circular economy principles in an urban context.
... Furthermore, increasing green spaces in cities by implementing RUA has been demonstrated to be one of the key approaches for mitigating UHI effects (Alexandri & Jones, 2008;Lee et al., 2014;Susca et al., 2011). In addition, RUA decreases energy consumption due thermal properties and insulating effects, creating energy savings for both cooling and heating buildings (Muñoz-Liesa et al., 2020;Nadal, Oriol, et al., 2018;Susca et al., 2011). ...
The main objective of this study is to analyze the perceived barriers and opportunities with regard to the implementation of urban agri-green roofs (UAGR) in cities. The case study was conducted in Barcelona, a Mediterranean compact city. The World Café method was used in this work. Five categories of barriers and opportunities were discussed (social, environmental, legal/administrative, technological/architectural, and economic) by interdisciplinary stakeholders.
A total of 129 barriers and opportunities were identified. The main barriers identified were as follows: the lack of information and social cohesion regarding UAGR projects; the Mediterranean climate; the lack of specific regulations and protocols; the initial investment; and the pre-condition of the roof and its load bearing capacity. The main opportunities were social cohesion; improved life quality; new specific regulations; the profits derived from UAGR projects; and aesthetic improvement.
The UAGR's scale of impact results showed a homogeneous distribution between “building” and “city”, while the “global” scale remains residual. Regarding the stage of the UAGR life cycle at which barriers and opportunities emerge, the results highlight how most opportunities appear during the “use” stage of the roof, whereas barriers do so during the “project” stage.
... Additionally, this meant that the steel needed for automation mechanisms could be differentiated from that which strictly belongs to the structure that could be improved from this paper's structural assessment perspective. To achieve this, direct measurements and project data were used to account for such mechanisms and the electronic equipment needed, as reported by Muñoz-Liesa et al. (2020b). Space allocation was applied to part of the automation subsystem components that also operate the rest of the passive climate building controls. ...
A R T I C L E I N F O Keywords: Life cycle assessment Material flow analysis Resource use efficiency Structural modeling Urban agriculture Urban metabolism A B S T R A C T Urban and building systems are awash with materials. The incorporation of green infrastructure such as integrated rooftop greenhouses (iRTGs) has the potential to contribute to buildings' and cities' circularity. However, its greater sophistication than conventional agriculture (CA) could lead to a shift in environmental impacts. One of the key elements for greenhouse building-integrated agriculture (BIA) and CA to achieve high levels of environmental performance is their structural design, which largely impacts the economic and environmental life-cycle costs (by up to 63%). In this context, the study assessed iRTGs life-cycle material and energy flows and their environmental burdens at structural level (m-2 y-1) within life cycle assessment (LCA), based on a case study in Barcelona. A structural assessment following European standards allowed the identification of key design factors to minimize the environmental impacts of RTGs' structure within improvement scenarios. The assessment revealed that a steel structure in a business-as-usual (BAU) scenario contributed from 31.5 to 67.3% of the impact categories analyzed, followed by the polycarbonate covering material (from 21.8 to 45.9%). The key design factors responsible for these environmental impacts were ground height, ventilation design, building integration and urban location. The improvement scenarios compensated for additional steel inputs by up to 35.9% and decreased environmental impacts that might occur in the BIA context by 24.1% compared with the BAU scenario. The assessment also revealed that urban environments do not imply shifting environmental impacts per se, as greenhouse BIA structures can benefit from their advantageous characteristics or be compensated by optimized greenhouse structures.
... Outcomes show that obtained energy saving ranged from 15.5% to 90.1% for low-insulation houses, between 19.9% and 93.7% for medium-insulation houses, and from 23.8% to 93.1% for high-insulation houses (being also dependant on domestic hot water demands). Muñoz-Liesa et al. [9] investigated a building rooftop integrated solar greenhouse system. A multi-floor sample building in Spain (conceived for agricultural crop, laboratories, and office uses) was considered as demonstrator. ...
Today, the use of renewable energies in buildings represents one of the main ways to reach a sustainable world. Whilst present buildings are still often energivorous systems, in the near future they will have to be converted to (or replaced by) zero energy buildings, also capable to export green energy (produced on-site by renewables) towards other buildings and/or users.
This review article focuses on a selection of research papers, presented at the 16th International Conference on Building Simulation (BS 2019), regarding renewable energy applications, energy saving and comfort techniques for buildings. BS 2019 conference was organized in collaboration with the International Building Performance Simulation Association (IBPSA) and it was held at the Angelicum Congress Centre (San Tommaso d’Aquino Pontifex University) in Rome, Italy, during September 2-4, 2019. The conference was attended by 912 researchers and experts, with 660 presented research papers.
The above-mentioned selection of papers is included in a dedicated Special Issue of the Renewable Energy - An International Journal (RENE), titled “Renewable energies: simulation tools and applications”. Reported studies are mostly dedicated to models, simulations, and optimization procedures of renewable energy devices. Specifically, photovoltaic systems, building integrated photovoltaic collectors, hybrid photovoltaic/thermal systems, solar thermal collectors as well as other energy efficiency tools are analysed through different simulation approaches and suitable optimization procedures. Attention is also paid to specific case studies related to innovative combinations of renewable energy devices and innovative envelope materials in different building typologies and weather zones. In some papers, solar energy is exploited for space heating and cooling purposes, while in other articles renewables or other energy tools are studied to achieve comfort targets, low grid dependencies, smart building/communities, and mainly the zero energy building goal.
The Special Issue of Renewable Energy Journal dedicated to Building Simulation Conference – BS2019, titled “Renewable energies: simulation tools and applications” is now complete and available electronically on ScienceDirect:
https://www.sciencedirect.com/journal/renewable-energy/special-issue/10SQLJ9C0V7.
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... To analyse the performance of circular strategies with real data, we used a rooftop greenhouse (RTG) as the UA case study. RTGs are greenhouses located on buildings that usually benefit from building integration at several levels (Pons et al., 2015;Muñoz-Liesa et al., 2020). This 122.8 m 2 RTG is located on the top floor of the Institute of Environmental Science and Technology (ICTA-ICP) on the campus of the Universitat Autònoma de Barcelona (41.497681N, 2.108834E) in the Mediterranean region and the north-eastern part of the Iberian Peninsula. ...
Local food production through urban agriculture (UA) is promoted as a means to make cities more sustainable. However, UA does not come free of environmental impacts. In this sense, optimizing urban resources through circular economy principles offers the opportunity to close loops and improve production systems, but an assessment of these systems through a combination of circularity and environmental tools is missing from the literature. The goal of our study is to analyse the environmental and circularity performance of applying circular strategies in UA systems. We use Life Cycle Assessment (LCA) and the Material Circularity Indicator (MCI) to assess the baseline scenario of a Mediterranean rooftop greenhouse and the application of 13 circular strategies. The results show that the MCI score for all strategies was biased by overweighting of the water subsystem in the mass balance. Based on this finding, we propose a series of modifications to the circularity assessment, calculating specific MCI scores for every subsystem before coupling them with environmental life cycle indicators. The outcome is a set of indicators that use the Linear Flow Index (LFI), where decreasing the values as much as possible will correspond to a decrease both in environmental impact and linearity of the system (the inverse of circularity). The use of these indicators provides a simple understanding of the circular and environmental performance of these systems while being fully adaptable. With these indicators, the uses of nutrient recircu-lation, struvite fertilizer or recycled materials were the best strategies to improve urban agriculture.
Endüstri Devrimi ile birlikte başlayan ve gelecekte de hızlı bir şekilde devam edeceği düşünülen kırsaldan kente göç hareketi kentsel, sosyal ve ekonomik açıdan birtakım olumsuzluklar doğurmaktadır. Kentlerdeki hızlı nüfus artışının beraberinde getirdiği konut ihtiyacı, kentsel yaşam alanlarındaki yeşil dokunun azalmasına sebep olurken kırsal alanlarda da tarımsal faaliyetlerin azalmasına sebep olmuştur. Bu gibi nedenler kentlerde hem yeşil doku oluşturacak hem de tarımsal faaliyetlerde kullanılacak alanlara ihtiyacı gündeme getirmiştir. Bitki çatılar çok eski yıllardan beri çeşitli sebeplerle yapıların çatılarında kullanılmaya başlanmış olup günümüzde de kullanımı devam etmektedir. Bununla birlikte kentsel tarım, çatı tarımı, topraksız tarım gibi kavramlarla ortaya çıkan ve kullanıcısının yerel gıda ihtiyacının bir bölümünü karşılayan, tarımsal faaliyetlerin binaların çatılarında yapıldığı uygulamalar son dönemlerde önem taşımaktadır. Çatı tarımı ile hem kent alanlarında yeşil doku artırılmış olup hem de yerel gıda ihtiyacı karşılanarak güvenilir gıdaya ekonomik bir şekilde ulaşım sağlanmış olacaktır. Daha gelişmiş bir yeşil çatı türü olan çatı tarımının kentsel alanlarda kullanımını örnek projeler üzerinden inceleyen bu çalışmada; çatı tarımının kent ekonomisine katkı sağlayacağı, yerel gıda tüketimini arttıracağı, insanların psikolojisi üzerinde olumlu etki yaratarak daha mutlu bir toplum yaratacağı ve sosyalleşme imkanlarını arttıracağı görülmüştür. Yapılacak olan çatı tarımı projeleri ve çalışmaları ile halkın ve tasarımcıların teşvik edilmesi, üretici firmaların bilgilendirme toplantıları yapması ve çatı tarımı uygulamalarının kentsel dönüşüm ve sürdürülebilir kent çalışmaları kapsamında ele alınarak planlamalara entegre edilmesi önerilmektedir.
Agriculture consumes 30% of the world’s fossil fuels and 70% of freshwater. About one third of all greenhouse gas emissions come from the Built Environment, and uses about 20% of total energy. Urban Agriculture promises to minimize food and water waste utilizing Building Performance Simulation (BPS) tools that assess crop yields, water usage and energy needs for Building Integrated Agriculture (BIA). However, BIA may attain better efficiencies if agriculture and buildings share their waste products. Here, we introduce Building Integrated Agriculture Simulation (BIA-SIM), a framework for software that visualizes and quantifies early-stage design outcomes of BIA that combines circular waste flows of building and farms. Users can determine which resources – food, water, air, and energy – are most important to co-optimize based on their ecological and economic concerns. BIA-SIM user input includes location, 3D site model, site and building details, number of occupants, farm type and crops. Greywater, CO2 from occupants and building energy usage are calculated. Outputs demonstrate how a software framework informed by an extensive database of plants, their properties and theirfarming requirements can be utilized to identify, design and exploit feedback loops between building and urban agriculturewaste products. To demonstrate several use scenarios, a site in New Delhi, India was chosen for an urban agriculture-integrated residential building. In one example, using 60% of building grey water for irrigation of tomato, we found 47%of the maximum buildable surface area would be needed for tomato production. More than 100% of the CO2 emitted by building occupants could be absorbed, and the plants’ thermal mass could save 50% of cooling energy using farm layouts that, in turn, enhanced food output based on solar exposure. Several other scenarios will be shown that demonstrate the broader benefits urban agriculture can have for the built environment beyond food production.
This paper introduces the integrated Small-Scale Plant-Based Air Filtration (SPAF) system, a novel integration of air filtration and urban agriculture, specifically designed for edge computing free cooling in urban environments. The SPAF's modular design enables extensive customization to meet various air quality requirements and agricultural needs. Through evaluation across different scenarios, the system has proven its effectiveness in particulate matter reduction, with a single unit showcasing substantial initial filtration efficiency, and even greater performance when multiple units are utilised in series. Beyond its air filtration capabilities, the SPAF system also contributes to urban agriculture, expanding planting areas and supporting the growth of local produce, thereby aligning with global sustainability objectives. Despite its promising applications, challenges such as the variability in filtration performance across different plant species, external climates, and the inability to ensure complete particulate matter removal, underscore the need for further research and potential integration with other purification technologies.
With the world population estimated to reach 9.7 billion by 2050, of which 68% are expected to live in urban areas, there is an urgent need to reorganise the food system for urban areas. The COVID-19 pandemic lay bare the vulnerabilities in the current food systems, clearly showing their inabilities to cope with shocks and extreme events. The urban poor, living in informal settlements, are at the greatest risk of malnutrition as well as extreme heat due to the urban heat island phenomenon. Urban food production has immense potential to alleviate the problems of food insecurity and malnutrition but is hindered by various challenges including lack of time, space and expertise. In some cases, regulations imposed by urban authorities may impede urban food production. Technologies and innovations such as vertical farming systems including green walls and rooftop farming with the use of containers and soilless substrates can overcome the challenge of lack of space. Water shortage challenge can be overcome through use of water saving technologies such as hydroponic systems, capillary wick irrigation and wicking bed gardens. Technologies and innovations such as mushroom cultivation, microgreens and sprouts, aquaponics, cuniculture (rabbit rearing) and insect rearing have potential to provide nutrient dense foods rich in protein and other vital nutrients to the urban dwellers. Several of these technologies can utilise waste streams generated in the urban areas, thereby contributing to waste management in the urban areas. Several cities around the world have recognised the critical role that urban farming can play in dealing with various challenges in urban areas and have begun initiatives to promote urban farming. For instance, widespread growing of edible plants and vegetables in urban areas can be found in Europe, Japan, China, South Korea and the USA. In Japan, the Pasona Urban Farm owned by Pasona Group demonstrates the feasibility of urban food production. Urban farming should be integrated in the African food system to address the urban food insecurity. Initiatives to create awareness about technologies available for farming in the urban areas should be enhanced. Capacity building should be undertaken to produce a generation of agricultural practitioners that recognise and appreciate urban farming. Research should be conducted to optimise the various technologies and customise them to suit different situations. Policy makers should recognise and appreciate the importance of urban farming and develop friendly policies to enhance adoption for food and nutrition security with minimum environmental impacts.KeywordsUrban farmingUrbanisationClimate changeVertical farmingNutrition sensitive agricultureFoodscaping
The energy consumed by the heating, ventilation, and air conditioning (HVAC) system accounts for a large part of the energy consumption of buildings. Solar energy technologies in buildings have attracted more and more attention from scholars and architects because of their significant advantages in sustainable development, such as energy saving, environmental protection, and cost reduction. Sunspace has been studied for many years as a passive solar heating and ventilation technology. Nevertheless, there are also some problems associated with sunspace, such as overheating in summer and heat loss at night. The main objective of the work is to review the application of sunspace in buildings for heating and cooling, and possibly inspire more future works. This research adopts the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method. The novelty of this work is to categorize different types of sunspaces according to the integration relationship with buildings and different configurations, materials and functions, and further analyze all the possible factors that can affect the performance of a sunspace. This paper concludes that sunspace can be divided into ventilated and unventilated sunspace based on the main utilization methods. According to their integration relationship with buildings, sunspace can also be divided into two types: façade and roof sunspace. Based on different configurations, materials and functions, façade sunspace further includes glazed sunspace, membrane sunspace, phase change material (PCM) sunspace; and roof sunspace includes on-top sunspace, courtyard sunspace, and integrated rooftop greenhouse. There are eight factors affecting sunspace performance that are further evaluated from the perspective of energy, environment, and economy. Directions of potential studies of sunspace are suggested. The authors hope that this research will be helpful to scholars and architects and promote the development of the multifunctional sunspace system.
It is widely accepted that urban agriculture provides multiple benefits to society. Rooftop greenhouses are a form of urban agriculture that takes advantage of urban resources (urban land, sunlight spaces) and waste flows (energy, nutrients) to provide food and other ecosystem services to cities. However, the integration of urban greenhouses within buildings is a complex issue that must be addressed in-depth. Compared to the well-known conventional greenhouses, the urban environment requires an assessment to later optimize greenhouse structures and covering materials. The aim of our study was to environmentally assess rooftop greenhouses and propose improving scenarios. Life cycle assessment was used to detect environmental hotspots and to evaluate different impact categories of an iRTG case study in the Barcelona area. Results showed that the greenhouse environment and ventilation design directly determine greenhouse structures and environmental impacts. Optimized strategies showed a potential reduction of up to 35% of the amount of structural steel used, while less improvement potential existed for covering materials (5%). Compared to conventional greenhouses, 1.6 times more steel and up to 8 times more energy were required to build the urban greenhouse in this study. The assessment revealed that these differences can be reduced by optimizing greenhouse structures to avoid a shift of material flows and environmental impacts from building urban greenhouses compared to conventional greenhouses. In turn, the assessment presented here provides guidelines on how to design and plan urban greenhouse constructions in future assessments. That will facilitate the incorporation of urban agriculture in cities based on consistent environmental assessments, ultimately contributing to the low-carbon future development of cities.
Industrial symbiosis (IS) is an approach that aims to use resources efficiently by cooperating between independent enterprises in raw materials, energy, and similar sectors. As a result of cooperation, businesses gain economic, environmental, and social benefits. Especially in recent years, IS applications have become widespread due to the problems experienced in the supply of resources. The presence of more than one enterprise in cooperation creates a complex network structure in IS applications. In this complex system, many decision problems are encountered in establishing and effectively maintaining the industrial symbiosis network. Operations research techniques are at the forefront of the methods used to solve decision problems. This study examined studies using operations research techniques in industrial symbiosis. Studies were divided into four classes according to the methods they used: exact methods, heuristic methods, multi-criteria decision-making, and simulation. In the literature review, the studies in the Web of Science (WOS) database are systematically presented by scanning with the determined keywords. As a result of the study, it was analyzed which method was preferred and where the methods could be applied in industrial symbiosis.
The construction of innovative urban agriculture systems in cities has increased due to food and environmental concerns. While the environmental performance of urban agriculture has been extensively studied, research on the life cycle costs urban agriculture systems is still limited, which constraints sustainability-oriented decision-making processes. This paper analyses the economic viability of tomato production cycle in an innovative building with an integrated urban agriculture system in rooftop by applying the life cycle cost methodology. The data was collected from direct measurements and internal and external sources. To calculate labour costs, a customised data collection sheet was created. The results are presented by life cycle stage, cost category and type of cost (fixed & variable). Results indicate that the main cost drivers for tomato production are labour (24.7%), the rooftop greenhouse structure (15%), the external pest control (12.6%), and rainwater consumption (9.5%), accounting altogether for 61.8% of the total costs. Accordingly, cost reduction solutions are evaluated through the development of sensitivity scenarios (rooftop greenhouse structure design, tap water use and rainwater tank size), including the consideration of another relevant aspect, such as the role of the production level output, as it can greatly influence the economic viability and profitability. Finally, the main environmental and social aspects of these urban production systems are also included.
Industrial symbiosis (IS) is an approach that aims to use resources efficiently by cooperating between independent enterprises in raw materials, energy, and similar sectors. As a result of cooperation, businesses gain economic, environmental, and social benefits. Especially in recent years, IS applications have become widespread due to the problems experienced in the supply of resources. The presence of more than one enterprise in cooperation creates a complex network structure in IS applications. In this complex system, many decision problems are encountered in the establishment and effective maintenance of the industrial symbiosis network. Operations research techniques are at the forefront of the methods used in the solution of decision problems. In this study, studies using operations research techniques in the industrial symbiosis were examined. Studies were divided into four classes according to the methods they used: mathematical modeling, heuristic methods, multi-criteria decision making, and simulation. In the literature review, the studies in the Web of Science (WOS) database are systematically presented by scanning with the determined keywords. As a result of the study, it was analyzed which method was preferred and where the methods could be applied in industrial symbiosis.
This paper aims to present an original assessment tool developed to diagnose industrial symbiosis (IS) readiness. It is expected that industries with greater symbiotic readiness are more likely to have success in implementing a circular business model. A bibliographic analysis was conducted in order to identify the IS variables and dimensions, mentioned in the literature, as necessary for implementation of a circular business model. Two dimensions were defined in this study: (i) exchange resources and (ii) exchange capacity. The exchange resources dimension diagnoses the company's ability to have the necessary exchange resources to IS implementation (water, energy, by-products, and waste). The exchange capacity dimension diagnoses the company's enabler factors to IS implementation (trust, information, access conditions, and infrastructure). After the definition of dimensions and their respective variables, an assessment tool to diagnose industrial symbiosis readiness was developed. The assessment tool is presented as a checklist format - Symbiotic Readiness Checklist (SRC). This was applied to six co-located industries in the State of São Paulo (Brazil). The proposed SRC could be used to: (a) diagnose the readiness of companies or organizations to implement industrial symbiosis; (b) be a tool in enterprise or organizational strategic planning; (c) assist the development of mechanisms to measure the number of resources consumed and waste produced in the supply chain; (d) assess the circularity of resources.
Lemnaceae, i.e., duckweed species, have gained considerable attention as a sustainable source of high-quality nutrition, biofuel, and pharmaceuticals, as well as effective organisms for phytoremediation of wastewaters. A protein content of up to 45% makes duckweed biomass nutritionally interesting as an ingredient for animal feeds or human food. Outdoor duckweed cultivation has become common in recent decades but can be difficult to optimise and to control operationally. Yet, duckweeds also represent a suitable crop for indoor farming, with most species due to their flat structure particularly suited for cultivation in multi-level (stacked) systems that use indoor floor space efficiently. Here we propose construction of stacked systems with up to 15 m² of duckweed per m² of floorspace. Such stacked systems are facilitated by limiting the water depth to about 5 cm. Indoor cultivation can maximise yields, and doubling times as short as 1.24 days have been reported under indoor conditions. Indoor cultivation also extends the scope for crop manipulation and enables cultivation under pest-free and even sterile conditions. Yet, the technical and operational parameters required for effective large-scale indoor cultivation of Lemnaceae have received scant attention in the literature. Here, it is concluded that technological advances in urban and/or vertical farming can be exploited to enable design and operation of novel duckweed cultivation systems. Recirculating, flow through technology can optimise nutrient supply and growth, while sensor support systems with artificial intelligence can facilitate autonomous cropping and even harvesting. Furthermore, advanced understanding of duckweed-biology can, amongst others, inform selection of (wastewater-based) media, flow-rates and media retention time, duckweed species and strains, and enhance performance through manipulation of the duckweed microbiome. Despite challenges and knowledge gaps, there are now realistic opportunities to develop and operate high capacity, autonomous, controlled cultivation of duckweed under indoor conditions, for a broad range of purposes.
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, 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.
Rooftop farms can improve a building's thermal and energy performance, especially for uninsulated free-running buildings. The non-refurbished educational building stock lacks indoor comfort related to temperature and high CO2 concentration; and could benefit from the thermal insulation, food security and social cohesion provided by rooftop farms. However, to assess the adequacy of such strategies, building energy simulations need to include the thermal effect of plants. This study develops a novel co-simulation to leverage the transient flow exchange between crops and buildings by incorporating the plant's heat and mass balances in building simulation. This co-simulation allows an online closed-loop computation using Energy Plus for building energy modelling and MATLAB for crops modelling. The latter solves three agronomical sub-models: 1) crop's growth, 2) energy balance, and 3) net photosynthesis. This dynamic crop's growth function reflects how crops development affects heat, mass and CO2 flows. This co-simulation was first applied to assess the thermal coupling of three rooftop farm systems in two free-running archetype schools in Quito, Ecuador. The assessed rooftop farms were: edible green roofs, hydroponic rooftop greenhouses, and thermally integrated rooftop greenhouses. Results showed that rooftop farms are adequate to improve thermal comfort conditions and air quality in classrooms and diminish thermal demand. Integrated rooftop greenhouses achieve the best overall performance with a 42% decrement in thermal load, a 0.7 °C increment in indoor temperature, and a 40% reduction in hours exceeding CO2 concentration limits, despite a 2.94 kWh/m² rise in electricity demand.
Link for download: https://authors.elsevier.com/a/1ch233QCo9bJkP
Rooftop agriculture (RA) is a building-based form of urban agriculture that includes both protected and nonprotected farming practices, such as rooftop greenhouses as well as open-air rooftop gardens and farms. The use of underexploited urban spaces on buildings for farming purposes is considered a useful strategy for targeting global concerns (e.g., the limitations in food security and land access, impacts of climate change or social exclusion). While previous studies have addressed selected RA cases and the general worldwide dissemination of RA, a systematic evaluation integrating the constantly evolving sector and its diversity (both commercial and noncommercial) is currently lacking. Here, we provide an overview of the current status of RA based on a metadata analysis of 185 publicly accessible cases. This paper summarizes the global trends and spatial distribution of RA cases and presents their main features. The results present the global distribution of different RA types over time, their diverging farming purposes and further characteristics (such as farm sizes, building typologies, growing systems, products and reported yields, activities, implementation of resource-efficient practices, or economic and social activities). The results indicate an emphasis on RA cases in North America (44% of the analyzed cases) and show that RA practices are mainly represented by open-air farms and gardens (84%), as the growing sector of rooftop greenhouses is still relatively small. Similarly, commercial cases are scarce, with the majority of RA cases targeting social-educational goals or the improvement of urban living quality. This tendency suggests a range of currently untapped business opportunities that, if developed, may contribute to the evolution of more sustainable and resilient city food systems providing fresh crops from the inner urban fabric. In conclusion, the research showed a rising global interest in RA, although stronger policy intervention is crucial to upscale RA practices to reach decisive environmental, economic and social benefits at the city level
The absorption air-conditioning system is a good choice for green buildings. However, much energy waste in regeneration phase limits the performance of the traditional system. To solve this problem, an electrode regeneration method is proposed by using capacitive deionization(CDI) technology to concentrate absorbent solution. Another key advantage of electrode regeneration is the energy recovery characteristic, which further improves the performance of the absorption air-conditioning system. A complete energy recovery includes energy storage and energy reuse. Previous studies has analyzed energy storage efficiency (stored energy/input energy) in different conditions. However, these studies lack reports on energy reuse. Therefore, this paper presents a direct energy reuse strategy for an absorption air-conditioning system with two CDI stacks connected in parallel. The discharging efficiency (reused energy/stored energy) is investigated. The higher discharging efficiency is achieved with more discharging times and lower charging voltage. Combining energy storage and energy reuse, the higher total energy recovery efficiency (reused energy/input energy) is achieved with high charging voltage. The system performance system based on an electrode regeneration method is analyzed. Up to 44% of the stored energy could be recovered and the performance is doubled to 1.87 in contrast with no energy recovery.
The decarbonisation of residential building stock in the UK requires accessible tools that can reliably and rapidly model residential building power demands as a function of multiple low carbon technologies and building control schemes. Whilst a variety of modelling tools exists, these platforms are either intended for expert analysts, are not suited to rapid simulation (and therefore cumbersome at stock modelling scale) or are not flexible enough to allow analysis of detailed active control schemes. This work builds on a previously developed dynamic domestic building modelling tool developed in MATLAB/Simulink environment and intended for rapid generation of electrified heat demand profiles in buildings. The number of parameter inputs and time-resource required to prepare EWASP tool is several order of magnitude smaller than an equivalent EnergyPlus model, computational efficiency of this tool as well as its prediction accuracy are benchmarked against an equivalent E+ model. The EWASP model required 13 times less parameter input, reducing analyst time requirement and human effort. Both models produced similar trends of loads against external climatic changes for a Passivhaus case-study fabric while overall EWASP generated smaller ASHP electrical loads (4.4 kWh·m 2 ·yr) than EnergyPlus model (5.8 kWh·m 2 ·yr) which will be examined in future works. EWASP tool can assist assessment of the impact of fabric or HVAC retrofit and design and control scenario in buildings on the local distribution network and wider power grid.
Purpose
Rooftop greenhouses (RTGs) are agricultural systems that can improve the food supply chain by producing vegetables in unused urban spaces. However, to date, environmental assessments of RTGs have only focused on specific crops, without considering the impacts resulting from seasonality, combinations of crops and nonoperational time. We analyze vegetable production in an RTG over 4 years to determine the crop combinations that minimize yearly environmental impacts while diversifying food supply.
Methods
The system under study consists of an integrated RTG (i-RTG) with a hydroponic system in Barcelona, in the Mediterranean region. By using life cycle assessment (LCA), we evaluate the environmental performance of 25 different crop cycles and 7 species cultivated during the period 2015–2018. Three functional units are used: 1 kg of edible fresh production, 1 unit of economic value (€) in the wholesale market and 1 kcal of nutritional value. The system boundaries consider two subsystems: infrastructure (greenhouse structure, rainwater harvesting system and auxiliary equipment) and operation (fertilizers and their emissions into water and substrate). In addition, we perform an eco-efficiency analysis, considering the carbon footprint of the crop cycles and their value at the wholesale market during their harvesting periods.
Results and discussion
Spring tomato cycles exert the lowest impacts in all categories, considering all three functional units, due to the high yields obtained. In contrast, spinach and arugula have the highest impacts. Regarding relative impact, the greenhouse structure presented a large impact, while fertilizer production had notable relative contributions in tomato cycles. Moreover, nitrogen and phosphorus emissions from fertigation are the main causes of freshwater and marine eutrophication. By combining the most eco-efficient cycles, we can see that growing two consecutive tomato cycles is the best alternative with the functional unit of yield (0.49 kg CO2 eq./kg), whereas a long spring tomato cycle combined with bean and lettuce cycles in the autumn/winter is the best scenario when using market (0.70 kg CO2 eq./€) and nutritional value (3.18·10−3 kg CO2/ kcal).
Conclusions
This study shows that increasing the diversity of the system leads to better environmental performance of greenhouse urban agriculture if suitable crops are selected for the autumn/winter season. The functional unit involving the economic value and the eco-efficiency analysis are useful to demonstrate the capability of the growing system to produce added-value vegetables under harsher conditions while categorizing and classifying the crops to select the most suitable combinations based on economic and environmental parameters.
Creating Urban Agriculture Systems offers you background, expertise, and inspiration for designing with urban agriculture. It shows you how to grow food in buildings and cities, operate growing systems, and integrate them with natural cycles and existing infrastructures. It teaches the essential environmental inputs and operational strategies of urban farms, and inspires community and design strategies for innovative operations and sustainable urban environments that produce fresh, local food.
Over 70 projects and sixteen in-depth case studies of productive, integrated systems, located in North America, Europe, and Asia are organized by their emphasis on nutrient, water, and energy management, farm operation, community integration, and design approaches so that you can see innovative strategies in action. Interviews with leading architecture firms including WORKac, Kiss + Cathcart, Weber Thompson, CJ Lim/Studio 8, and SOA Architects highlight the challenges and rewards you face when creating urban agriculture systems. Catalogs of growing and building systems, a glossary, bibliography, and abstracts will help you find information fast.
A historic and current perspective is offered of building climate and plant control techniques while also reporting the results of a survey that reveals more conventional control methods to still be preferred by industry-based practitioners. Specifically Artificial Neural Network and reinforcement and machine learning have seldom been taken up in practice by HVAC and BAS industries due to uncertainty, long training periods, and complexity in setting up and maintaining the system. Future buildings are expected to be responsive to other civic activities, namely power generation, storage and distribution and potentially even transport. Given that HVAC industry predominantly continues to deploy conventional techniques, future control solutions seem inevitably to be pioneered by the digital and information technology innovators. Conventional techniques such as PID and simpler computational methods which require no data-training are reported to continue to exist particularly on closed loop mechanical systems (hydronic or air-based) at plant level. Survey participants state that at and beyond building level, control and integration require software-intensive solutions to enable online data analytics, system and occupant feedback, diagnostics, renewable energy management but most urgently smart grid controls and forecasting. Most of these innovations are expected to come from sectors beyond the building automation industry.
Building-Integrated Agriculture (BIA) in urban areas is claimed to be environmentally sustainable vis-à-vis conventional commercial agriculture practices by reducing food miles, minimizing land and water use and improving yields. However, as it is operated in controlled indoor environments, BIA can be highly energy-intensive. In order to better understand the influence of local foodshed characteristics, climate conditions and farm properties on the environmental performance of BIA systems, this article applies a performance-based parametric simulation workflow for BIA that incorporates daylight, energy, crop growth and water models, to (a) Rooftop Greenhouse (RG) farms and (b) Shipping Container (SC) farms located in the cities of Lisbon, Singapore, Paris and New York. Results show that – while RG farms can significantly reduce GHG emissions under all the tested climates – SC farms may only have a positive overall environmental impact in megacities located in colder climates, that seasonally rely on long distance food imports.
The past decade has seen a renaissance of urban agriculture in the world's wealthy, northern cities. The practice of producing food in and around cities is championed as a method to reduce environmental impacts of urban food demands (reducing distance from farm to fork - ‘food miles’) whilst conferring a number of ancillary benefits to host cities (runoff attenuation, urban heat island mitigation) and ex-urban environments (carbon sequestration). Previous environmental assessments have found urban agriculture to be more sustainable than conventional agriculture when performed in mild climates, though opposite findings emerge when external energy inputs are significant. In this study we perform an environmental life cycle assessment of six urban farms in Boston, US producing lettuce and tomatoes, with conventional counterparts across six impact categories. Performance of urban agriculture was system dependent and no farm provided superior performance to conventional for all indicators. High-yield, heated, greenhouse production of tomatoes has potentially higher environmental burdens than conventional methods in terms of climate change (267–369%) and non-renewable resource depletion (108–239%), driven primarily by external energy inputs. Heated lettuce production systems showed similar trends. Low-tech, empty-lot farming appears to hold some advantages in terms of climate change burdens and resource use, though water and land usage was found to be elevated relative to conventional lettuce and tomatoes. Open rooftop farming apparently provides benefits if high yield crops (e.g. tomatoes) are cultivated, otherwise significant capital inputs detrimentally affect environmental performance. In general, the benefits of reduced food miles may be overwhelmed by energy inputs and inefficient use of production inputs. A comparison of urban agriculture and solar panels showed that the latter would confer greater benefits to mitigate climate change per unit area. Thus, urban agriculture may not be the optimal application of space in northern cities to improve urban environmental performance.
Every person physically consumes products made from biomass. Our lives are thus inextricably tied to the crisis facing global agricultural land and water supply. The design of truly sustainable cities must, therefore, incorporate a more comprehensive assessment of the energy, water and land consumed during food production, processing, storage, preparation, distribution and disposal. One way of doing this is building-integrated agriculture (BIA) – high-performance hydroponic farming systems located on and in buildings, using renewable, local sources of energy and water. Integrating farming into the built environment has the potential to significantly reduce fossil fuel consumption, improve urban ecology, enhance food safety and security, enrich the lives of city dwellers and conserve building energy. This chapter begins by providing an overview of global food system challenges. A detailed analysis of BIA follows, including technical descriptions of BIA systems, environmental performance, economic models, sustainability challenges and future trends.
The ICTA-ICP Rooftop Greenhouse Lab (RTG-Lab) is a research-oriented RTG situated in the UAB Campus (Bellaterra, Barcelona). In contrast to current RTGs, the RTG-Lab integrates energy, water and CO2 flows into the building's metabolism. This integrated RTG (i-RTG) is an eco-innovative concept that will enhance the sustainability of both systems involved while producing high-value crops and maintaining indoor comfort in buildings with lower energy inputs. The RTG-Lab, within the Fertilecity project, aims to demonstrate the feasibility of producing vegetables in i-RTGs in the Mediterranean context and to quantify the environmental and economic performance of the metabolic integration between the greenhouse and the building. To do that, experimental crops (lettuce and tomato) in soil-less culture systems (perlite) will start on Fall 2014. Preliminary data of the metabolic integration is described in this contribution. First, the residual heat from the building will be introduced in the greenhouse to maintain crop temperatures. Moreover, the 692
A large number of randomly interacting variables combine to dictate the energy performance of a building. Building energy simulation models attempt to capture these perturbations as accurately as possible. The prediction accuracy of building energy models can now be better examined given the widespread availability of environmental and energy monitoring equipment and reduced data storage costs. In this paper a set of two calibrated environmental sensors together with a weather station are deployed in a 5 storey office building to examine the accuracy of an EnergyPlus virtual building model. Using American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Guide 14 indices the model was calibrated to achieve Mean Bias Error (MBE) values within ±5% and Cumulative Variation of Root Mean Square Error (CV(RMSE)) values below 10%. The calibrated EnergyPlus model was able to predict annual hourly space air temperatures with an accuracy of ±1.5 °C for 99.5% and an accuracy of ±1 °C for 93.2% of the time.
Purpose Rooftop greenhouses (RTGs) are increasing as a new form of urban agriculture. Several environmental, economic, and social benefits have been attributed to the implementation of RTGs. However, the environmental burdens and economic costs of adapting greenhouse structures to the current building legislation were pointed out as a limitation of these systems in the literature. In this sense, this paper aims to analyse the environmental and economic performance of RTGs in Barcelona. Methods A real RTG project is here analysed and compared to an industrial greenhouse system (i.e. multi-tunnel), from a life cycle perspective. Life cycle assessment (LCA) and life cycle costing (LCC) methods are followed in the assessment. The analysis is divided into three parts that progressively expand the system boundaries: greenhouse structure (cradle-to-grave), at the production point (cradle-to-farm gate), and at the consumption point (cradle-to-consumer). The applied LCIA methods are the ReCiPe (hierarchical, midpoint) and the cumulative energy demand. A cost-benefit analysis (CBA) approach is considered in the LCC. For the horticultural activity, a crop yield of 25 kg · m−2 is assumed for the RTG reference scenario. However, sensitivity analyses regarding the crop yield are performed during the whole assessment. Results and discussion The greenhouse structure of an RTG has an environmental impact between 17 and 75 % higher and an economic cost 2.8 times higher than a multi-tunnel greenhouse. For the reference scenario (yield 25 kg · m−2), 1 kg of tomato produced in an RTG at the production point has a lower environmental impact (10–19 %) but a higher economic cost (24 %) than in a multi-tunnel system. At the consumption point, environmental savings are up to 42 % for local RTGs tomatoes, which are also 21 % cheaper than conventional tomatoes from multi-tunnel greenhouses in Almeria. However, the sensitivity assessment shows that the crop efficiency is determinant. Low yields can produce impacting and expensive vegetables, although integrated RTGs, which can take advantage from the residual energy from the building, can lead to low impacting and cheap local food products. Conclusions RTGs face law limitations that make the greenhouse structure less environmentally friendly and less economically competitive than current industrial greenhouses. However, as horticultural systems and local production systems, RTGs can become an environmentally friendly option to further develop urban agriculture. Besides, attention is paid to the crop yield and, thus, further developments on integrated RTGs and their potential increase in crop yields (i.e. exchange of heat and CO2 with the building) are of great interest.
The conventional agricultural tunnel greenhouse is highly widespread in Mediterranean countries, despite the shortcomings it presents, specifically the overheating during the day and the intense cooling at night. This can sometimes lead to an internal thermal inversion. The chapel-shaped glass greenhouse is relatively more efficient, but its evolution remains slow because of its investment cost and amortization. The objectives of the agricultural greenhouse are to create a microclimate that is favorable to the requirements and growth of plants from the surrounding climatic conditions and produce cheap off-season fruits, vegetables and flowers which must be highly available all along the year. The agricultural greenhouse is defined by its structural and functional architecture as well as by the optical, thermal and mechanical qualities of its wall and the accompanying technical support.
Innovative forms of green urban architecture aim to combine food, production, and design to produce food on a larger scale in and on buildings in urban areas. It includes rooftop gardens, rooftop greenhouses, indoor farms, and other building-related forms (defined as “ZFarming”). This study uses the framework of sustainability to understand the role of ZFarming in future urban food production and to review the major benefits and limitations. The results are based on an analysis of 96 documents published in accessible international resources. The analysis shows that ZFarming has multiple functions and produces a range of non-food and non-market goods that may have positive impacts on the urban setting. It promises environmental benefits resulting from the saving and recycling of resources and reduced food miles. Social advantages include improving community food security, the provision of educational facilities, linking consumers to food production, and serving as a design inspiration. In economic terms it provides potential public benefits and commodity outputs. However, managing ZFarming faces several challenges. For some applications, the required technologies are known but have not been used or combined in that way before; others will need entirely new materials or cultivation techniques. Further critical aspects are the problem of high investment costs, exclusionary effects, and a lack of acceptance. In conclusion, ZFarming is seen as an outside-the-box solution which has some potential in generating win–win scenarios in cities. Nevertheless, ZFarming practices are not in and of themselves sustainable and need to be managed properly.
Installation of an evaporatively cooled hydroponic greenhouse on the roof of building can yield net energy savings for the combined structure, when compared to conventional air conditioning, and can conserve space by adding productive capacity to the rooftop. The proposed system offers energy and water savings far exceeding the levels achieved by traditional green roofs, but re- quires circumstances that favor co-location of a techni- cally sophisticated agricultural facility with the building. Compared with field agriculture, the hydroponic culti - vation of crops in greenhouses sharply reduces water consumption, requires no pesticides, uses several times less land, and doubles the growth rate. Integration of hy- droponics into the built environment also sharply reduc- es the distance from farm to consumer, saving transport costs, reducing waste, and increasing product quality. A 120 m2 low-energy greenhouse was constructed in 2006 on a barge platform in the Hudson River Estuary, a temperate eastern North American climate. A staged cooling algorithm escalates from passive ventilation to active ventilation to evaporative cooling as a function of internal and external temperature. In a Mediterranean climate, a temperature differential as large as 15 C can be achieved by evaporative cooling in arid summer conditions. Placed on a building, the greenhouse could serve as a complete HVAC system, although higher air velocities will require customized design of building ventilation systems. A hypothetical 720 m2 building of two stories in a Mediterranean climate is analyzed using a highly simplified spreadsheet model. Results indicate that this building adds only 9% to the summer cooling load for a rooftop greenhouse of the same planform area. Required inputs include water (550 tons per year) and power for fans (23 MWh per year), but these inputs for the com- bined system are lower than the energy cost to cool the building alone using conventional air conditioning. For this purpose, it is assumed that the greenhouse is inde- pendently viable as an agricultural venture.
Urban agriculture systems, such as rooftop greenhouses, are attractive alternatives for mitigating the impacts of the extensive food supply chains that currently feed cities. In this study, we study the opportunity that nutrient recirculation offers to improve the environmental performance of agricultural systems. In particular, we analyze the environmental burdens of a hydroponic closed-loop production system that recovers nutrients and reduces water demand by recirculating the irrigation water leaching from the substrate bags along with nutrients that have not been assimilated by the plant. The closed-loop system is compared to a linear system in which there is no nutrient or water recovery. Based on two green bean crop cycles in a Mediterranean rooftop greenhouse, we analyze the yield, climatic variables and water and nutrient balances, and apply life cycle assessment (LCA) to study the environmental impacts.
The results of this study indicate that closed-loop systems save daily 40% of irrigation water and between 35 and 54% of nutrients. Moreover, leachate reuse leads to reduced eutrophication impacts, but it can entail nutrient deficiencies. However, implementing a closed-loop system requires additional infrastructure causing larger impacts than linear systems in terms of global warming and fossil resource scarcity. The results of the LCA were highly sensitive to the yield, the crop production period and the meteorological conditions. Based on these results, we design improved scenarios, providing recommendations for reducing the impacts of closed-loop systems for more sustainable cities.
Energy and environmental data is collected from 5 tower blocks each containing 90 apartments to create two representative calibrated energy models. Three towers (heated by individual natural gas boilers) characterise medium (137.3 kWh/m2/yr.) and two (heated by electrical night storage heaters) characterise low (75.4 kWh/m2/yr.) thermal demands when benchmarked against actual UK domestic portfolio. Across 2020-2040 time horizon, an uncertain landscape is presented by 12 fuel carbon intensity and 14 economic scenarios in order to examine building fabric upgrade, with or in conjunction with centralised CHP engines, GSHP and biomass boilers in the case study towers. Out of 18 retrofit options examined, 7 or 8 solutions (under annual fuel price rises of 2% or 5.2% respectively) can provide lifetime CO2e mitigation at unit costs that fall below the upper bounds of carbon capture and storage technologies (US111/tCO2e (in 2020), while deep retrofits (i.e. plant and fabric) require much more punishing carbon taxes with 2020 figures ranging from US1665/tCO2e.
The environment and energy consumption of indoor urban farms within the city’s infrastructure cannot at present be adequately simulated using typical building simulation models as they do not include the ability to simulate the potentially significant heat and mass transfer between plants and the internal air. On the other hand, tools developed for the simulation of climate-controlled greenhouses do not allow complex interactions with existing buildings and infrastructure. In this chapter, we present the development of an urban-integrated greenhouse model, with the ability to simulate the response of the indoor climate to crop growth. We validate the model against data from an urban farm 50 m underground. Applying an analysis of resource needs and availability through a numerical simulation model allows us to investigate mechanisms to optimise the environment and energy benefits of growing food within the city space.
Urban agriculture is of increasing interest for tackling a range of environmental and social issues of the current food systems. However, many questions remain unanswered regarding upscaling, the balancing of its multipurpose nature, and how it should be embedded into the broader urban system. This review looks at a breadth of novel insights that are indicative for sensible future development, including new possibilities for nutrient circularity, opportunities for increased sustainability and open questions regarding logistics and economics and development pathways. A thorough assessment of the existing self-sufficiency studies is provided to advance the debate on expected productivity, which is highly dependent on the intended outcomes and the choice of practices employed. Addressing resource circularity, decentralized anaerobic digestion and vermicomposting are presented as methods of utilizing organic waste in urban agriculture, in particular food and garden waste. Furthermore, critical aspects of sustainability are synthesized and promising developments, such as the co-location of micro-scale anaerobic digestion and greenhouses, are evaluated and research gaps regarding life cycle assessments and technical understanding identified. The review also identifies three aspects of urban agriculture upscaling that have not been well studied, namely logistics, economic performance and business models, and institutional and civil development. Finally, the realization of the transformative potential of urban agriculture based on industrial ecology and inclusive co-design is discussed.
Although evolutionary algorithms coupled with building simulation codes are often applied in academic research, this approach has a limited use for actual applications of building design due to the high number of expensive simulation runs. The use of a surrogate model can overcome this issue.
In the literature there are several functional approximation models that can emulate the building simulation during the optimization, thus increasing the process efficiency. However, there are no evidence-based studies comparing the performances of these methods for the building design optimization.
This study compares the efficiency, the efficacy and the quality of the Pareto solutions obtained by Polynomial, Kriging (GRFM), Radial-basis function networks (RBFN), Multivariate Adaptive Regression Splines (MARS) and support vector machines (SVM) functional approximations. The test bed of the comparison is the evaluation of the optimal refurbishment of three reference buildings for which the actual Pareto front is also obtained through a brute-force approach.
The results show that the MARS method outperforms the other surrogate models both in terms of efficiency and effectiveness, and also by assessing the quality of the Pareto front.
In today's growing cities, where land is an expensive commodity and direct exposure to sunlight is a valuable asset, rooftops constitute vast underexploited areas. Particularly with growing urban environmental concerns, the potential of transforming these areas into productive spaces-either for food cultivation or energy generation-has emerged as a viable option in recent years. Both food production and energy generation have benefits in the urban environment. Rooftop farming is an environmentally and economically sustainable way of exploiting urban rooftops, reducing "food miles" and providing local jobs, while roof-integrated solar photovoltaic (PV) modules provide clean energy, are increasingly cost-effective, and offer job opportunities. In both cases, a rooftop network of production could directly supply a portion of a necessary resource-either food or electricity-to the local community while concurrently reducing the burden on the environment. To provide a basis for comparing the implementation of these productive uses of rooftops in Mediterranean cities, this article applies a Cost-Benefit Analysis (CBA) to a mixed-use neighborhood located in Lisbon to assess the following uses: (1) open-air rooftop farming on intensive green roofs; (2) food production in low-tech unconditioned Rooftop Greenhouse (RG) farms; (3) Controlled-Environment Agriculture (CEA) in high-tech RG farms; and (4) solar PV energy generation. Relative costs, cost-saving benefits and added value of these four alternative productive uses of rooftops were modeled over 50 years and deducted from present value, considering two levels of analysis: (a) effects directly incurred by the operator of the systems; and (b) societal effects on the local community. To the authors' knowledge, this is the first comprehensive comparison of rooftop PV versus rooftop farming technologies. The results have shown food production to be more beneficial than energy generation, for both the owner of the system and the local community, under the modeled conditions and given the selected items of comparison. In particular, the results show that rooftop greenhouse farming can provide significant benefits over rooftop green roof and solar PV systems when assessed from a holistic perspective that accounts for impacts on both the operator and the local community.
Urban farming, especially on rooftops, is a popular and growing topic in both the media and the scientific literature, providing a genuine opportunity to meet some of the challenges linked to urban development worldwide. However, relatively little attention has been paid to date to the growing medium of green roofs, i.e., Technosols. A better understanding of the influence of Technosols and the link with ecosystem services is required in order to maximize the environmental benefits of urban rooftop farming. Between March 2013 and March 2015, a pilot project called T4P (Parisian Productive rooftoP, Pilot Experiment) was conducted on the rooftop of AgroParisTech University. Urban organic waste was used, and results were compared with those obtained using a commercial potting soil, based on yield and trace metal concentrations, substrate characterization, and the amount of leaching. An assessment of the ecosystem services expected from the Technosols was undertaken in terms of the output of food (food production and quality), regulation of water runoff (quantity and quality), and the recycling of organic waste. Indicators of these ecosystem services (e.g., yield, annual loss of mass of mineral nitrogen) were identified, measured, and compared with reference cases (asphalt roof, green roof, and cropland). Measured yields were almost equivalent to those obtained from horticultural sources in the same area, and the Technosols also retained 74–84% of the incoming rainfall water. This is the first quantitative analysis of ecosystem services delivered by urban garden rooftops developed on organic wastes, and demonstrates their multifunctional character, as well as allowing the identification of trade-offs. An ecosystem services approach is proposed for the design of soil-based green infrastructure of this kind and more generally for the design of sustainable urban agriculture.
A comprehensive systems approach is essential for effective decision making with regard to global sustainability, since industrial, social, and ecological systems are closely linked. Despite efforts to reduce unsustainability, global resource consumption continues to grow. There is an urgent need for a better understanding of the dynamic, adaptive behavior of complex systems and their resilience in the face of disruptions, recognizing that steady-state sustainability models are simplistic. However, assessing the broad impacts of policy and technology choices is a formidable challenge, as exemplified in life-cycle analysis of the implications of alternative energy and mobility technologies. A number of research groups are using dynamic modeling techniques, including biocomplexity, system dynamics, and thermodynamic analysis, to investigate the impacts on ecological and human systems of major shifts such as climate change and the associated policy and technology responses. These techniques can yield at least a partial understanding of dynamic system behavior, enabling a more integrated approach to systems analysis, beneficial intervention, and improvement of resilience. Recommendations are provided for continued research to achieve progress in the dynamic modeling and sustainable management of complex systems.
Building-integrated rooftop greenhouse (i-RTG) agriculture has intensified in recent years, due to the growing interest in the development of new agricultural spaces and in the promotion of food self-sufficiency in urban areas. This paper provides a first assessment of the indoor dynamics of bioaerosols in an i-RTG, with the aim of evaluating biological air quality in a tomato greenhouse near Barcelona. It evaluates the greenhouse workers' exposure to airborne pollen and fungal spores in order to prevent allergy problems associated with occupational tasks. Moreover, it evaluates whether the quality of the hot air accumulated in the i-RTG is adequate for recirculation to heat the building.
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The concept of regenerative cities is seeking to address the relationship between cities and their hinterland, and beyond that with the more distant territories that supply them with water, food, timber and other vital resources. We need to re-enrich the landscapes on which cities depend, and this includes measures to increase their capacity to absorb carbon emissions. Creating a restorative relationship between cities, their local hinterland and the world beyond, means harnessing new opportunities in financial, technology, policy and business practice. This text argues that the established horizon of urban ecology should be expanded to include all the territories involved in sustaining urban systems. Urban regeneration thus takes on the meaning of eco-regeneration.
Understanding of environmental factors affecting various aspects of plant growth and development is crucial in plant factories' design and operation. This chapter first defines vegetative growth (shoots and root growth) and then discusses the typical abiotic environmental factors (temperature, light intensity, light quality, photoperiod, humidity, carbon dioxide concentration, air current speed, and nutrient and root-zone environment) affecting plant growth and development. Then transpiration and translocation of sugar are briefly described using the general physiological understanding of water potential and the sink–source relationship.
Urban agriculture appears to be a means to combat the environmental pressure of increasing urbanization and food demand. However, there is hitherto limited knowledge of the efficiency and scaling up of practices of urban farming. Here, we review the claims on urban agriculture’s comparative performance relative to conventional food production. Our main findings are as follows: (1) benefits, such as reduced embodied greenhouse gases, urban heat island reduction, and storm water mitigation, have strong support in current literature. (2) Other benefits such as food waste minimization and ecological footprint reduction require further exploration. (3) Urban agriculture benefits to both food supply chains and urban ecosystems vary considerably with system type. To facilitate the comparison of urban agriculture systems we propose a classification based on (1) conditioning of the growing space and (2) the level of integration with buildings. Lastly, we compare the predicted environmental performance of the four main types of urban agriculture that arise through the application of the taxonomy. The findings show how taxonomy can aid future research on the intersection of urban food production and the larger material and energy regimes of cities (the “urban metabolism”).
Saving energy in greenhouses is an important issue for growers. Here, we present a method to minimize the total energy that is required to heat and cool a greenhouse. Using this method, the grower can define bounds for temperature, humidity, CO2 concentration, and the maximum amount of CO2 available. Given these settings, optimal control techniques can be used to minimize energy input. To do this, an existing greenhouse climate model for temperature and humidity was expanded to include a CO2 balance. Heating, cooling, the amount of natural ventilation, and the injection of industrial CO2 were used as control variables.
Standard optimization settings were defined in order to compare the grower’s strategy with the optimal solution. This optimization resulted in a theoretical 47% reduction in heating, 15% reduction in cooling, and 10% reduction in CO2 injection for the year 2012. The optimal control does not need to maintain a minimum pipe temperature, in contrast to current practice. When the minimum pipe temperature strategy of the grower was implemented, heating and CO2 were reduced by 28% and 10% respectively.
We also analyzed the effect of different bounds on optimal energy input. We found that as more freedom is given to the climate variables, the higher the potential energy savings. However, in practice the grower is in charge of defining the bounds. Thus, the potential energy savings critically depend on the choice of these bounds. This effect was analyzed by varying the bounds. However, because the effect can be demonstrated to the grower, the outcome has value to the grower with respect to decision making, an option that is not currently available in practice today.
Between 1998 and 2003, the company Ecofys from Utrecht developed and tested a new concept of an integrated climate and energy system that permits permanently closing the ventilation windows of a greenhouse. The technical concept consists of a combined heat and power unit, heat pump, underground (aquifer) seasonal energy storage as well as daytime storage, air treatment units, and air distribution ducts. Active air circulation is one of the key elements for controlling the climate (T, RH, CO2) at crop level. This paper discusses the technical aspects and the results of a trial using a fully closed 1400 m2 demonstration greenhouse for tomato production. Results showed: 1) reduction in primary energy (fossil fuel) use of 20 and 35% respectively for an "island" closed greenhouse and a closed-conventional combination greenhouse, 2) increase in tomato yield of 20%, 3) an 80% reduction in chemical crop protection, and 4) a 50% reduction in use of irrigation water. The energy efficiency was improved by 50%. Finally, some preliminary environmental data will be shown for the first 14,000 m2 of closed greenhouse installed at a commercial greenhouse operation. The concept of a fully closed greenhouse will be discussed in relation to sustainable greenhouse production.
This review summarizes and organizes the literature on life cycle assessment (LCA), life cycle energy analysis (LCEA) and life cycle cost analysis (LCCA) studies carried out for environmental evaluation of buildings and building related industry and sector (including construction products, construction systems, buildings, and civil engineering constructions). The review shows that most LCA and LCEA are carried out in what is shown as "exemplary buildings", that is, buildings that have been designed and constructed as low energy buildings, but there are very few studies on "traditional buildings", that is, buildings such as those mostly found in our cities. Similarly, most studies are carried out in urban areas, while rural areas are not well represented in the literature. Finally, studies are not equally distributed around the world.
The primary objective of a greenhouse is to produce good plant-growth conditions such as temperature and humidity. One of the hot issues for the greenhouse is to provide an appropriate heating system which can achieve favorable temperature condition and save energy. In this study, the performance of a ground-coupled multi-heat pump system for the greenhouse heating was investigated. The ground-coupled multi-heat pump system was composed of GLHX (ground loop heat exchanger) and multi-heat pump unit which had one outdoor unit and two or more indoor units. The temperature distribution within the greenhouse using the ground-coupled multi-heat pump system was represented relatively uniform comparing to when the conventional heating system and GCHP system were adopted, because the capacity of each indoor unit could be changed linearly according to the variation of load. The temperature difference between the maximum and minimum temperatures and the standard deviation of inside temperature for the greenhouse were 2.1 degrees C and 1.2 degrees C, respectively. It is necessary to develop the multi-heat pump unit which can be operated with high performance at relatively low temperature setting conditions. The system COP of the ground-coupled multi-heat pump unit decreased greatly at part load condition due to relatively high power consumption of the ground circulation pump. Therefore, it is suggested that a control algorithm of the ground circulation flow rate has to be developed to maximize energy saving by applying the ground-coupled multi-heat pump system to the greenhouse.
This paper provides a review on three streams of life cycle studies that have been frequently applied to evaluate the environmental impacts of building construction with a major focus on whether they can be used for decision making. The three streams are Life Cycle Assessment (LCA), Life Cycle Energy Assessment (LCEA) and Life Cycle Carbon Emissions Assessment (LCCO2A). They were compared against their evaluation objectives, methodologies, and findings. Although they share similar objectives in evaluating the environmental impacts over the life cycle of building construction, they show some differences in the major focuses of evaluation and methodologies employed. Generally, it has been revealed that quite consistent results can be derived from the three streams with regard to the relative contribution of different phases of life cycle. However, discrepancies occur among the findings obtained from the three streams when different compositions of fuel mixes are used in power generation, or when the overall impacts are not contributed mostly by greenhouse gases emissions. The use of different functional units in different studies also makes it difficult to compare results with benchmarks or results from previous studies. Besides, there are drawbacks in boundary scoping, methodology framework, data inventory and practices which impair their usefulness as a decision making support tool for sustainable building designs.
This paper presents an experimental analysis to investigate the performance of a novel mixed mode solar greenhouse dryer with forced convection which was used to dry red pepper and sultana grape. The drier consisted of a flat plate solar collector and a chapel-shaped greenhouse. The drying rate in the solar greenhouse dryer could be much higher than that for the open air sun drying. The present drying system practically shortens the drying time of red pepper and grape by 7 and 17 h respectively. The experimental drying curves show only the falling rate period. The payback period of the dryer was found to be 1.6 years, much less than the estimated life of the system (20 years).
Adding trace amounts of Ti (0.01–0.02 wt.%) significantly changed the volume fraction, morphology and size of the β phase in the microstructure of as-cast AZ61 alloy, despite its effect on grain size and texture being small, and strongly affected the corrosion properties of the alloy. The addition of 0.01 wt.% Ti drastically increased the corrosion rate in sodium chloride solution due to breaking up of the semi-continuous β phase, which destroyed the barrier effect of the β phase against corrosion attack. The addition of a larger amount of Ti (0.02 wt.%) also increased the corrosion rate, but the AZ61 alloy with 0.02 wt.% Ti exhibited a much better corrosion resistance than the AZ61 alloy with 0.01 wt.% Ti. This was because adding 0.02 wt.% Ti greatly decreased the volume fraction and size of the β phase, which reduced the galvanic corrosion effect. The current results suggest that a proper control of trace amounts of Ti has a potential to improve the corrosion properties of cast Mg–Al alloys by modifying the microstructure of the β phase.
A simulating model was used to simulate and improve the thermal performance of solar greenhouses. Simulations with the weather conditions of Xuzhou, Jiangsu Province show that the greenhouse with clay brick wall (0.6 m thick) insulated with polystyrene boards (0.1 m) and the greenhouse with soil wall (3 m thick) perform better than the one with hollow concrete block wall (0.6 m thick). The lowest air temperature increases with thermal resistance and thermal inertia index of north wall. The thermal performance of the solar greenhouse with hollow concrete block wall can be improved by increasing the density and reducing the thermal conductivity of north wall. The soil wall can be conceptually divided into three layers from inside to outside: energy-storing layer, thermal stable layer, and thermal insulating layer. Thermal stable layer shrinks with the reduction of the size of north wall and it would disappear when the wall is reduced to a certain size. A trapezoidal soil wall with a top of 0.5 m and a base of 1.7 m appears to be a proper design if the air temperature is to be maintained above 10 °C under the weather conditions of Xuzhou, Jiangsu Province of China.
A computational fluid dynamics (CFD) model for simulating greenhouse night-time climate and condensation is presented. The model was applied to a four-span plastic covered greenhouse. Film condensation was simulated by applying a user defined function (UDF) added to the commercial CFD package. The CFD model was verified by comparing CFD predictions with experimental measurements. The effect of cover temperature on greenhouse humidity was then determined by the CFD model and compared to experimental results. Root mean square values for the differences between the CFD and experimental values of internal temperature and humidity showed there was good agreement between. The results showed the importance of heat transfer losses by radiation, particularly for low values of soil heat flux (SHF). They also showed the roof was the coolest surface in the greenhouse, and therefore the sink for the water vapour produced by the crop. For each configuration (SHF 10, 25, 50 and 100W m(-2) and equivalent sky temperature 263 K, 273 K and 276 K), the condensation rate curves and relative humidity (RH) evolution are presented. It was observed that all the condensation rate curves had the same characteristic shape and could be represented by a single logistic function. The response of the CFD model to a step-change in the water vapour source (night-time transpiration from the crop) was then analysed. It was observed that the model predicted the same steady-state temperature, RH and condensation rate independent of the time when the water vapour source was enabled. The CFD condensation model is intended to be used for the design of strategies for humidity control, particularly in unheated greenhouses.
Planted roofs contribute positively to the improvement of the thermal performance of a building. They block solar radiation, and reduce daily temperature variations and thermal ranges between winter and summer. In this paper, a calculation has been done, using a stationary method, in order to determine the thermal behaviour of the planted roof and the way it influences the thermal protection of the building, in accordance with Greek climatic conditions. Planted roof elements with different heights of plants and different drainage layers are calculated and a comparison between a bare roof and a planted roof is made. All sections are calculated with and without thermal insulation. The results are illustrated in figures, in which the temperature of the layers of the planted roof is presented for both winter and summer. The planted roof contributes to the thermal protection of a building, but does not replace the thermal insulation layer.
The closed greenhouse is an innovative concept in sustainable energy management. In principle, it is designed to maximize the utilization of solar energy through the seasonal storage. In a fully closed greenhouse, there is not any ventilation window. Therefore, the excess sensible and latent heat must be removed, and can be stored using seasonal and/or daily thermal storage technology. This stored excess heat can then be utilized later in order to satisfy the thermal load of the greenhouse. Thermal energy storage (TES) system should be designed based on the heating and cooling load in each specific case. Underground thermal energy storage (UTES) is most commonly chosen as seasonal storage. In addition, a stratified chilled water (SCW) storage or a phase change material (PCM) storage could be utilized as short term storage system in order to cover the daily demands and peak loads. In this paper, a qualitative economical assessment of the concept is presented. Here, a borehole thermal energy storage (BTES) system is considered as the seasonal storage, with a PCM or a SCW daily storage system to manage the peak load. A BTES primarily stores low temperature heat such that a heat pump would be needed to supply the heat at a suitable temperature.A theoretical model has been developed using TRNSYS to carry out the energy analysis. From the economical feasibility assessment, the results show that the concept has the potential of becoming cost effective. The major investment for the closed greenhouse concept could be paid within 7–8 years with the savings in auxiliary fossil fuel considering the seasonal TES systems. However, the payback time may be reduced to 5 years if the base load is chosen as the design load instead of the peak load. In this case, a short-term TES needs to be added in order to cover the hourly peak loads.
Botrytis cinerea is the causal agent of grey mould disease which is one of the most important diseases affecting tomato crops in unheated greenhouses. Nocturnal ventilation is a technique that can be used to reduce relative humidity inside unheated greenhouses. The main objectives of this research were to investigate the effect of ventilation management on the environmental conditions and on the Disease Severity, to develop and validate a model which could predict Disease Severity and to present a warning system.Experiments were conducted in two plastic greenhouses. Two natural ventilation treatments were randomly assigned to the greenhouses. One was nocturnal ventilation (NV), with the vents open during the day and night, while the other was classical ventilation (CV), in which the vents were open during the day and closed during the night.A tomato crop was grown directly in the soil between the end of February and the end of July during two crop seasons. Climatic data were measured with three meteorological stations, averaged and recorded on an hourly basis. The number of diseased leaflets were counted and removed from the greenhouse.In the NV greenhouse a significant reduction of air humidity and disease appearance was observed. A warning system was developed and can be a useful tool for helping to decide on appropriate actions and the correct timing to avoid conditions that favour disease development. For a more practical application, disease risk levels were defined as a function of the duration of periods with RH > 90%.
The objective of this research is to simulate the effects of vertical greenery systems on the temperature and energy consumption of buildings. Firstly, it involves performing TAS simulations to determine their effects on thermal comfort and energy consumption. It is found that 100% greenery coverage from vertical greenery systems is effective in lowering the mean radiant temperature of a glass facade building. Furthermore, to lower the energy cooling load significantly, the shading coefficient of plant species has to be low. Secondly, a thermal calculation of the envelope thermal transfer value (ETTV) to obtain their effects on the thermal performance of building envelope is performed. Results show a linear correlation between shading coefficient and leaf area index where a lower shading coefficient leads to a greater thermal insulation. 50% greenery coverage from vertical greenery systems and a shading coefficient of 0.041 reduce the ETTV of a glass facade building by 40.68%. Lastly, vertical greenery systems in mitigating the UHI effect within an estate is simulated using STEVE model. The increase of greenery coverage from vertical greenery systems is most significantly felt with a drop in the minimum estate air temperature throughout a large region of the estate.
Greening the building envelope focusing on green façades with vegetation is a good example of a new construction practice. Plants and partly growing materials in case of living wall systems (LWS) have a number of functions that are beneficial, for example: increasing the biodiversity and ecological value, mitigation of urban heat island effect, outdoor and indoor comfort, insulating properties, improvement of air quality and of the social and psychological well being of city dwellers.This paper discusses a comparative life cycle analysis (LCA) situated in The Netherlands for: a conventional built up European brick façade, a façade greened directly, a façade greened indirectly (supported by a steel mesh), a façade covered with a living wall system based on planter boxes and a façade covered with a living wall system based on felt layers. Beside the environmental benefits of the above described greening systems, it is eventually not clear if these systems are sustainable, due to the materials used, maintenance, nutrients and water needed.A LCA is used to analyze the similarity and differences in the environmental impacts in relation with benefits estimated for two climate types for building energy saving (reduction of electrical energy used for building cooling and heating).
In view of recent studies of the historical development and current status of industrial symbiosis (IS), life cycle assessment (LCA) is proposed as a general framework for quantifying the environmental performance of by‐product exchange. Recent guidelines for LCA (International Reference Life Cycle Data System [ILCD] guidelines) are applied to answer the main research questions in the IS literature reviewed. A typology of five main research questions is proposed: (1) analysis, (2) improvement, and (3) expansion of existing systems; (4) design of new eco‐industrial parks, and (5) restructuring of circular economies. The LCA guidelines were found useful in framing the question and choosing an appropriate reference case for comparison. The selection of a correct reference case reduces the risk of overestimating the benefits of by‐product exchange. In the analysis of existing systems, environmentally extended input‐output analysis (EEIOA) can be used to streamline the analysis and provide an industry average baseline for comparison. However, when large‐scale changes are applied to the system, more sophisticated tools are necessary for assessment of the consequences, from market analysis to general equilibrium modeling and future scenario work. Such a rigorous application of systems analysis was not found in the current IS literature, but would benefit the field substantially, especially when the environmental impact of large‐scale economic changes is analyzed.
Urban environment quality is worsening every year. It is a fact that the urban air temperature is gradually rising in all cities and some effective measures are needed to mitigate it. Planting of vegetation is one of the main strategies to mitigate the urban heat island (UHI) effect. Large urban parks can extend positive effects to the surrounding built environment. National University of Singapore (NUS) complex can be considered as a “city” on a smaller scale. The greenery along Kent Ridge Road seems like a “rural” area, with a cooler ambient temperature. Some methodologies were employed in this study, such as satellite image, field measurement and computer simulations. The satellite image was used to identify the “hot” and “cool” spots in NUS environment. Field measurement was used to get the real temperature distribution across the campus and finally, computer simulation was used to predict some scenarios of different conditions. The result shows that buildings near or surrounded by greenery have lower ambient temperature than the ones away from the greenery and it is an effective way to lower the ambient temperature. The TAS simulation results also show that a rooftop garden has the potential of cooling energy savings for NUS buildings.
Green roofs have several environmental benefits, such as improving building energy efficiency. The present paper provides a comprehensive study of the impact of a green roof on building energy performance. A model of green roof thermal behavior was coupled with a building code to allow the evaluation of green roof foliage and soil surface temperatures. Simulations were conducted for a single-family house with conventional and green roofs in a temperate French climate. In the summer, the fluctuation amplitude of the roof slab temperature was found to be reduced by 30 °C due to the green roof. The heat flux through the roof was also evaluated. In the summer, the roof passive cooling effect was three times more efficient with the green roof. In the winter, the green roof reduced roof heat losses during cold days; however, it increased these losses during sunny days. The impact of the green roof on indoor air temperature and cooling and heating demand was analyzed. With a green roof, the summer indoor air temperature was decreased by 2 °C, and the annual energy demand was reduced by 6%. The present study shows that the thermal impact of green roofs is not functionally proportional to the leaf area index parameter. It also shows the high dependency of this impact on the roof insulation. Finally, the simulations suggest that green roofs are thermally beneficial for hot, temperate, and cold European climates.
Due to growing concerns over climate change and rising energy costs, energy efficiency in industrial applications and use of renewable energy sources for energy supply have gained growing importance. Furthermore the potential for the recovery of low grade waste heat has become a subject of a multitude of scientific and industrial studies.
Commercial greenhouses are often seen as the optimum heat dump for very low grade waste heat. Availability, temperature levels and fluctuations in the availability of heat necessitate a very different approach towards production planning as compared to traditional systems where energy supply is adapted to production demand and not converse.
In the study presented here, a commercial ornamental plant nursery that switched its heat source from natural gas to utilizing the waste heat of a nearby commercial CHP system in 2007 was analyzed. During the study, the differences between production planning and temperature regimes before and after switching to waste were compared.
The results of the study undertaken show that greenhouses present a good opportunity for the use of the low grade waste heat but that production needs to be planned very carefully to enable the production high quality plants and that traditional cultivation planning is unsuitable for such approaches.