Evaluation method for leakage characteristics of building envelope openings in multi-family dwellings

The leakage characteristics (relationship between air flow rate and pressure difference) of rooms and buildings were compared with measurements from leakage modeling of the constituent openings. Rooms and buildings can be considered as networks of openings that can be combined either in series or in parallel. An exponential equation, commonly known as the power law, has often been used for building envelope openings. The parallel combination model consists of combination of openings in parallel by (long) narrow openings at low Reynolds numbers (e.g. adventitious openings - cracks in walls, etc.) and (short) large openings (e.g. purpose provided openings - air inlet, etc.). The parallel combination model has precision equivalent to that of the power law, and indication of the crack opening ratio of openings of building envelope is possible. New buildings and retrofitted buildings have high crack opening ratios, and the leakage characteristics are similar to those of narrow openings.