The location of an asset can be determined in three dimensions using pressure data from reference sensors in combination with conventional two-dimensional location technology, such as GPA or TDOA. In a building, reference sensors are distributed on multiple floors and transmit accurate pressure readings to a receiver. The asset also has a pressure sensing element and transmits the pressure at its location to the receiver. The asset pressure value is compared with the reference pressure sensor values to determine the floor in a building on which the asset is located. Thus, the combination of accurate two-dimensional location technology and pressure sensors can accurately determine the location of an asset in three dimensions.