Building design approach in stack effect calculation for complex cases. Multi-instrumental solution

Winter external infiltration in mid-rise and high-rise buildings demands high attention during the building design process in locations with heating degree-days (HDD) of more than 4000 at 18°C. Depending on the type of façade system and insulation in use, exfiltration losses could account for 7% to 45% of the total heat loss from the building envelope. Considering this fact, there is a need to design a more accurate method to calculate infiltration losses, differing from the widely used rule of thumb of 0.1 cfm per sq. ft. of building envelope.

The main reason for exfiltration in mid-rise and high-rise buildings is the stack effect. The calculation of the stack effect can be done in several ways. The most precise method is a heat-conjugated CFD-coupled calculation and a network model of the whole building. CFD calculation is more precise and can show room-level features, but it requires significantly more execution time and cannot be scaled to the whole-building level.

Network models, on the other hand, do not provide a highly accurate description of real airflow processes in a room, but they require much fewer computing resources, which allows for the analysis of a large number of design solutions and measures to minimize the stack effect, selecting the most optimal ones for implementation in the project design within a short period of time. The main purpose of our study is to find an approach to calculate the exact value of infiltration at the design stage by combining both of these tools.

When designing and assessing buildings to evaluate the stack effect, it is often not possible to obtain initial data for the doors and fenestrations being installed. During the design process, we developed a method for assessing the characteristics of a multi-zone model under conditions of limited initial data and plan to verify it using CFD and real experimental data.