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Rooftop plant factories: effects on energy use for heating, cooling and electric lighting

Zhang, Yizhi LU (2021) AEBM01 20211
Energy and Building Design
Department of Architecture and Built Environment
Abstract
Within the next thirty years, two thirds of the human population will live in a city. This growing urban population requires a major shift in the way we produce and distribute food, since industrial agriculture practices contribute to climate change, biodiversity losses, pollution of waterways, soil degradation, etc. Urban and peri-urban agriculture and forestry (UPAF) represent one of the strategies that can contribute to climate mitigation, adaptation and development. Amongst the urban farming (UF) systems, rooftop plant factories may provide part of the solution for vegetable and fruit production in the city, while solving current problems created by existing flat roofs and saving on arable land outside the city.

This thesis... (More)
Within the next thirty years, two thirds of the human population will live in a city. This growing urban population requires a major shift in the way we produce and distribute food, since industrial agriculture practices contribute to climate change, biodiversity losses, pollution of waterways, soil degradation, etc. Urban and peri-urban agriculture and forestry (UPAF) represent one of the strategies that can contribute to climate mitigation, adaptation and development. Amongst the urban farming (UF) systems, rooftop plant factories may provide part of the solution for vegetable and fruit production in the city, while solving current problems created by existing flat roofs and saving on arable land outside the city.

This thesis presents a study of rooftop greenhouse (RTG) located on a typical warehouse in Malmö, Sweden (lat. 55.6°N, long. 13.0°E). The goal of the study was to investigate the effect on energy use of building a greenhouse on the roof of an existing warehouse. The study was performed by dynamic energy simulations with the computer program IDA-ICE. The results show that adding the RTG on the warehouse reduces total energy use compared to greenhouse and warehouse as stand-alone structures. Furthermore, the results indicate that the glazing and shading solutions are important aspects determining the energy-efficiency of the integrated system. The energy use for electric lighting is also significantly reduced by the RTG compared to an indoor horizontal farm of similar size illuminated by LED lamps. The main conclusion is that RTGs offer a great potential for food production in the city with the additional benefit of reducing overall energy use of host building and greenhouse. RTGs are also more energy-efficient than indoor farms illuminated by LEDs, when considering all energy end-uses (heating, cooling, lighting, and ventilation). (Less)
Popular Abstract
Human beings are now confronted with the greatest challenge they have ever faced i.e. an increase in food production due population growth and an acceleration urbanization. Urban agriculture is one of the strategies to ensure food security in future urban settlements. Amongst the urban farming (UF) systems, rooftop greenhouses (RTGs) present one solution for growing vegetables and fruits in dense cities. RTGs can provide additional value in terms of energy savings both for the host building and the rooftop greenhouse itself, in addition to solving current problems created by flat roofs while saving on arable land outside the city.

This study investigates energy use for an existing warehouse retrofitted with a rooftop plant factory. The... (More)
Human beings are now confronted with the greatest challenge they have ever faced i.e. an increase in food production due population growth and an acceleration urbanization. Urban agriculture is one of the strategies to ensure food security in future urban settlements. Amongst the urban farming (UF) systems, rooftop greenhouses (RTGs) present one solution for growing vegetables and fruits in dense cities. RTGs can provide additional value in terms of energy savings both for the host building and the rooftop greenhouse itself, in addition to solving current problems created by flat roofs while saving on arable land outside the city.

This study investigates energy use for an existing warehouse retrofitted with a rooftop plant factory. The warehouse receives large amounts of solar radiation in the summer and thus has a high cooling load. In the winter, the warehouse loses heat through the roof, which translates into a heating demand. On the other hand, a greenhouse on the ground needs to be heated when outdoor temperatures are too low. Therefore, putting the greenhouse on the warehouse roof can be advantageous in terms of overall energy use since the greenhouse can be partly heated by heat losses from the host warehouse. In the summer, the RTG can provide shading to the warehouse, thus reducing its cooling demand. In this thesis, a RTG was added to a typical warehouse in Malmö, Sweden (lat. 55.6°N, long. 13.0°E), and energy demand of the combination of warehouse plus RTG was compared to each system as stand-along.

This study was carried out by using a dynamic energy simulation programme called IDA-ICE. A basic model of the host warehouse was built and validated. By altering parameters of RTG such as glazing materials for the roof and sidewalls, as well as shading devices, the impact of combining RTG and warehouse was studied.

The results show that the warehouse has a lower heating and cooling demand by 10.7 % and 6.8 % respectively when fitted with a RTG. On the other hand, the greenhouse has a 10.4 % lower heating demand and a 11.7 % lower cooling demand than the greenhouse on ground. Adding the RTG on the warehouse thus reduces total energy use compared to the greenhouse and warehouse as stand-alone structures. Furthermore, the results show that the glazing and shading solutions are important aspects determining the energy-efficiency of the integrated system. The main conclusion is that the integration of RTG and warehouse is beneficial in terms of overall energy efficiency. The combination of using high resistance glazing envelopes and an external shading system for the greenhouse can provide the greatest energy savings. The study also demonstrated that energy use for electric lighting is significantly reduced by the RTG compared to an indoor horizontal farm of similar size illuminated by LED lamps. (Less)
Please use this url to cite or link to this publication:
author
Zhang, Yizhi LU
supervisor
organization
course
AEBM01 20211
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Urban and peri-urban agriculture and forestry (UPAF), urban farming (UF), rooftop greenhouse (RTG), lighting, daylighting, energy conservation, roof, greenhouse, food, cities.
language
English
id
9050706
date added to LUP
2021-06-09 09:34:34
date last changed
2021-06-09 09:34:34
@misc{9050706,
  abstract     = {{Within the next thirty years, two thirds of the human population will live in a city. This growing urban population requires a major shift in the way we produce and distribute food, since industrial agriculture practices contribute to climate change, biodiversity losses, pollution of waterways, soil degradation, etc. Urban and peri-urban agriculture and forestry (UPAF) represent one of the strategies that can contribute to climate mitigation, adaptation and development. Amongst the urban farming (UF) systems, rooftop plant factories may provide part of the solution for vegetable and fruit production in the city, while solving current problems created by existing flat roofs and saving on arable land outside the city. 

This thesis presents a study of rooftop greenhouse (RTG) located on a typical warehouse in Malmö, Sweden (lat. 55.6°N, long. 13.0°E). The goal of the study was to investigate the effect on energy use of building a greenhouse on the roof of an existing warehouse. The study was performed by dynamic energy simulations with the computer program IDA-ICE. The results show that adding the RTG on the warehouse reduces total energy use compared to greenhouse and warehouse as stand-alone structures. Furthermore, the results indicate that the glazing and shading solutions are important aspects determining the energy-efficiency of the integrated system. The energy use for electric lighting is also significantly reduced by the RTG compared to an indoor horizontal farm of similar size illuminated by LED lamps. The main conclusion is that RTGs offer a great potential for food production in the city with the additional benefit of reducing overall energy use of host building and greenhouse. RTGs are also more energy-efficient than indoor farms illuminated by LEDs, when considering all energy end-uses (heating, cooling, lighting, and ventilation).}},
  author       = {{Zhang, Yizhi}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Rooftop plant factories: effects on energy use for heating, cooling and electric lighting}},
  year         = {{2021}},
}