Abstract
A Java class library was developed to construct a Ubiquitous Environment Control System (UECS), and the developed system was used to control the environment in a greenhouse using information communication. The library was able to implement the UECS communication protocol, so a developer could write a program without referring to the complicated communication protocol. Specifically, we created a program for operating a ventilation fan using data on air temperature that was received automatically via a local area network. In this case, only 45 lines of programming were needed, just 3.6% of the the number that would be needed to create an equivalent program without the library. Java programs can run on a variety of platforms, so the scope of the library’s application is wide. In addition, both the development of UECS devices and construction of UECS systems will be facilitated through the use of this library.