The life cycle costs of indoor climate systems in dwellings and offices taking into account system choice, airflow rate, health and productivity

The life cycle cost (LCC) of the heating, cooling and ventilation system was simulated for a typical cell office building, multi-family dwelling and detached house. Different ventilations systems were simulated resulting in different heating and cooling system designs. A health-related cost dependent on the airflow rate which was based on recent studies was added to the LCC for the dwellings as well as a productivity cost for the office building. An optimal airflow rate can be found depending on the assumed size of the health or productivity-related cost. The results for the office building indicate that a much higher outdoor supply airflow rate at presence, as well as a cooling system, is appropriate from a LCC perspective even if the influence on the human being still should be taken with precaution. With that higher airflow rate, the results show that there is a clear benefit with variable airflow rate ventilation systems. For dwellings, there is also a clear benefit from higher airflow rates even if the optimal airflow rate in the presented examples was not much higher than common requirements. Furthermore, it is not well known or defined how to valuate that possible influence. Despite this, this study is the demonstration of a method which can be used to optimize airflow rates in buildings if the influence and costs on human health related to the airflow rate is known.