Thanks to the rapid progress in the embedded system/micro-controller and supervisory control and data acquisition (SCADA) technologies, several micro-controller-based modules are developed and presented in this paper for the purpose to monitor and control the electricity demand of the aggregated window/split air conditioners (ACs). With the abilities of collecting power consumption data, controlling the developed modules through the internet, and applying available demand control rules, the proposed demand control system can effectively regulate the aggregated window/split ACs to lower the peak demand, therefore to decrease the penalty fee of violating demand contract, as well as to save the electrical energy. Based on the testing on a university teaching building with 28 classrooms and 56 split ACs, only one developed microcontroller-based infrared remote control module (IR485/232 module with double infrared emitters) is needed for one classroom with 120 square meters to control two air conditioners in a non-invasive way, and one IR4851232 module costs less than $35. The proposed system with demand control can decrease the over-demand penalty about $7900, the energy bill about $6400, and the emission of carbon dioxide about 26,000 kg (CO2) a year. One IR485/232 module can save approximately $350 on electricity bill a year. The proposed system is more cost-effective than a ZigBee-based system because a ZigBee system needs a pair of ZigBee modules (one in the classroom and one in the hallway) and an additional ZigBee/Infrared converter module to control two ACs in one classroom. (C) 2014 Elsevier B.V. All rights reserved.