Greenhouse environment control technologies for improving the sustainability of food production

Protected cultivation, especially in Asia, is operated at a small scale (<0.1 ha) using a relatively low-cost structure. This type of operation is a low-input, low-output system with low resource use efficiency, while larger industrial operations (>1 ha) with high-input, high-output systems that adopt modern high technologies have increased in number during the past few decades. In contrast, technology-intensive indoor agriculture operations (i.e., plant factories with artificial lighting or PFALs) in urban/suburban areas are steadily increasing in number. Such operations are a potential driving force for the development of resource-efficient technology to enhance the sustainability of both small- And large-scale protected cultivation. This paper focuses on recently developed controlled-environment technologies for these contrasting but technologically complementary applications. We discuss: A) low-cost intelligent environment controllers suitable for small-scale greenhouses; B) the concept and methodology of variable rate control; and C) closed plant production system (CPPS) and PFALs. Topic A includes intelligent controllers that can be used independently at a cost of around 100 Euro, and can also be used as a distributed environmental controller connected with an integrative environment control system for a large-scale greenhouse. Examples include controllers for: 1) null balance CO² enrichment; 2) variable-rate fogging; and 3) multi-purpose heat pumps.