Co2 Controller

See I am not sure about the parts. I know I need the Co2 sensor. But am unsure which to use. I am located in Western NY. I don't have too large of a budget but I feel like this code may be simple. I'm not sure about using the existing temp code for the co2 one and adapting because the temperature sensor changes voltages and allowing me to do some math within my code to convert to degrees Fahrenheit.