The CO2 recorder TR-76Ui three-channel data logger simultaneously measures and records CO2 concentration, temperature, and humidity. The unit has a CO2 range up to 5,000 ppm and a capacity to store up to 8,000 data sets. The supplied software enables the user to download data recorded by the data logger to a PC via USB connection, whereby data from all three channels can be simultaneously viewed in graph or table form. By using a handheld data collector TR-57DCi with graphical display, it is possible to collect recorded data from the TR-76Ui via infrared communication and immediately check the collected data on the spot. For monitoring in locations where electrical outlets are not available, this unit can also measure and record when operating under battery power. The product is a package that includes the data logger unit, sensors, USB cable, batteries, and software.