Assasment of Outside Air Supply for Split AC system - Part A: Affordable Instrument

Split Air Conditioner(AC) is a very popular cooling system not only for residential spaces but also commercial spaces.. Typically the split AC units are installed without adding any supply of outside air. While the supply of outside air is unregulated for residential spaces, the commercial spaces do have a ventilation requirement. The elimination of outside air supply is usually justified by a myth that the space is leaky enough that the infiltration can provide the ventilation requirement. This study aims at debunking the myth by presenting measurement data on the infiltration rate for air conditioned spaces. The measurement method used in this study is the tracer gas method with the CO2 is used as the tracer gas. This paper focuses at the development of an affordable instrument. The primary component of the instrument is the CO2 sensor that will trace the concentration of CO2 in the room. This paper shows how the components are assembled, tested and calibrated. The final product is about four times cheaper than the instrument available in the market. This paper also presents one measurement result that shows a very low infiltration rate for a space equipped with a split AC unit.