Évaluation des impacts énergétiques et environnementaux de différents modes d'agriculture urbaine en environnement contrôlé

Abstract

Urban densification, increasing food demand, food accessibility, community empowerment, promotion of local economy, transport reduction or environmental footprint reduction are many reasons that explain the growing interest in urban agriculture. In Quebec’s climate, year-round productions are done in controlled spaces. Many types of agricultural controlled spaces can be integrated into a city: traditional greenhouses on ground, rooftop greenhouses, or even building integrated agricultural spaces (BIAs) like vertically stacked hydroponic production. However, potential impacts of these kind of productions vary greatly and are not well known. Also, there is a lack of data for the analysis of these productions. Considering the need to reduce the environmental footprint of food production, it is important to quantify the potential impacts of these new types of production. The main objective of this thesis is to quantify potential environmental impacts of different urban agriculture production in controlled environment in the Quebec’s energetic context. To do so, four scenarios are compared using environmental life cycle assessment (LCA) methodology: (1) a traditional greenhouse on ground, (2) a rooftop greenhouse, (3) a BIAs with natural and artificial lighting, (4) a BIAs with artificial lighting only, that are either gas heated for the greenhouses or cooled using electric systems for the BIAs. Since there is little to no data available on the energetic consumption of these scenarios, building performance simulation (BPS) tools are used to create an energetic model of each scenario. The calibration of a greenhouse is also completed to reinforce the trust in the plant heat gains model and the estimated energetic consumption to maintain culture conditions (temperature and humidity). The calibrated model allowed the analysis of some energy-saving measures. Among the tested measures, the energy savings vary between 5% and 30%, with the insulation of the North wall having the shortest payback (between 9 and 16 years with 3.36$/GJ). Regarding the LCA results, they tend to indicate that no scenario performs better in every environmental impact category. The rooftop greenhouse and the BIAs with natural lighting have generally lesser impacts than the other two scenarios. The global warming potential score varies between 0.62 and 2.79 kg CO2 eq for all scenarios. The sensitivity analysis tends to indicate that lighting type and transport distances do not affect the general trends in results. However, a change in the energy source can have great impacts on the results. In Quebec, in order to reduce the environmental footprint of food production, priority should be set to promote renewable energy use like maximising the natural lighting when possible and using electricity for heating.

Date	15 Jul 2019
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Danielle Monfet (Supervisor) & Annie Levasseur (Co-supervisor)