Relationship between indoor and outdoor temperature and humidity in a residential building in Central Europe

Abstract Relative humidity and temperature in indoor spaces are two important environmental factors that not only determine the behaviour and well-being of residents but also influence airborne transmission of diseases in closed spaces. Since outdoor values of these two variables are often more convenient to measure, they are commonly taken as a proxy for their indoor values; however, the correlation between them is not always straightforward. We explore the relationships between indoor and outdoor temperature and humidity in a residential building apartment in a temperate climate in Central Europe. Measurements performed over the period of one year allow for a detailed comparison and analysis of correlations between both daily averages as well as daily profiles of indoor and outdoor variables. The results of this study add further evidence to the observations that day-to-day variation in indoor temperature and relative humidity are not well-represented by outdoor measurements. This work also adds to the growing body of data on indoor environmental variables and should thus prove useful in studies aiming to determine the influence of relative humidity and temperature on indoor transmission of airborne diseases as well as in studies examining the influence of these two variables on the well-being of building residents.