The influence of possible definitions of a reference environment to determine the exergy of air in buildings

This paper critically analyses the influence of possible definitions of the standard state of air to determine the exergy of air in buildings. Three different contributions are considered related to differences in temperature, pressure, and humidity of air inside and outside the building envelope. The possibility to calculate the exergy of air in buildings, based on only one or two of these contributions, for example expressed by a characteristic air temperature and/or air as dry air, is explored for three different locations on earth. These values are compared to those calculated using hourly statistical climate data during one year.