Développement d'une approche d'estimation de l'impact des plantes sur les charges d'un espace d'agriculture intégrée au bâtiment

Abstract

Protected urban agriculture is a viable alternative to intensive agriculture, which, in cold climates, makes it possible to maintain local crop production throughout the year. This includes installing a high-tech agriculture system within a building-integrated agriculture space (BIAs) such as a vertically stacked hydroponic system under artificial lighting. This type of system requires a fully controlled environment where indoor environmental conditions (temperature, humidity, lighting intensity, CO2 concentration), that enhances agricultural productivity, are maintained with the use of heating, ventilation and air conditioning systems (HVAC) and other systems. In order to be able to maintain these conditions at all time, the HVAC systems must be properly sized based on the maximum loads. These loads are calculated according to the rules of the art for internal gains defined subjectively by the designer and according to hypotheses and simplifications. However, the integration of sensible and latent heat fluxes, induced by plants, into load calculations is sparsely detailed and the sensible and latent thermal impacts induced by plants are usually neglected. The main objective of this thesis consists of developing an approach to estimate the impact of plants on the loads of a BIAs. To do so, the impact of plants on the loads is assessed first using an exploratory parametric study. Then, a second parametric study is completed to assess the impact of the plants on peak loads according to the design parameters. The chosen approach is to complete both studies subsequently using TRNSYS 18, a transient energy simulation software, in which the BIAs, located within a building in cold climate, is modeled. Using this model, loads without considering the impact of plants, which is the reference case, can be assessed. Then, by coupling a plants (tomatoes or lettuces) thermal model to the building model, loads considering the impact of plants can be assessed. The first study showed that the impact of plants on loads is significant for a specific case of BIAs. The results made it possible to identify the suitable plants heat fluxes to be considered to estimate peak loads for the design conditions. The second study assessed the impact of plants on the peak loads of a general case of BIAs for various parameters generally specified by the growers. The results showed that the estimated impact of plants on the sensible heating and latent cooling peak loads is significant. Indeed, when twelve shelves of lettuce under artificial lighting are stacked and grown according to a diversified stage’s growth method, the estimated sensible heating load is 3.7 to 4.1 times greater and the latent cooling are 1.7to 6.5 times greater than the reference values, depending on indoor air conditions (temperature/relative humidity of 19°C /80% vs. 24°C /70%). For a single-stage growth method, the loads obtained are 13.7 to 15.7 times greater for the sensible heating load and 9.4 to 19.5 times larger for the latent cooling load than the reference values. Finally, sensible and latent heat fluxes of lettuce are proposed which could be used in load calculations.

Date	28 Jan 2019
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Danielle Monfet (Supervisor)