Stepwise verification of functions and energy use for central residential AHU in apartment buildings

In Sweden, central air handling units (AHUs) with plate heat exchangers are often used in energy-efficient airtight multi-family buildings to reduce maintenance points, improve operation, and low risk for odour spreading. New energy-efficient buildings often use around 50 % more heat energy than calculated, and desired. This is often due to insufficient procedures and analyses at initial stages of the building process and design. This paper highlights the importance of a well-adjusted and functioning AHU in energy efficient multi-family buildings, to obtain low energy use for the AHU and the multi-family building. In initial stages, operating conditions (pressures, flows, temperatures, etcetera) are assumed for the first calculations of AHU and building energy calculations. These conditions change during the construction process, but there is often a lack of updating for these calculations with changing conditions as the building process progress. This means that system selection and design will not be optimal in the finished multi-family building due to changes during the project. So, there is a need to work with stepwise verification of functions and energy use for AHU to reduce the risk of these and similar deviations in the finished multi-family building.