Purpose of the work
It is easier for large buildings to meet the requirements of airtight construction than for small buildings since the proportion of internal air volume to envelope area is more favorable. In large buildings, typical leakages,also found in single-family homes, bear a higher risk. The lift and driving forces for leakage flows are stronger. In addition, building components and connections prone to risk take up a larger area in the respective clusters of rooms or apartments. Besides the leakages in the building envelope, internal leakages are also important. In small buildings they are of less importance, but in large buildings they are to be avoided for purposes of soundproofing and fire protection. The question as to whether the measurement of individual sections/apartments of a building allows for deriving statements on the airtightness of the building as a whole is also of interest.
Method of approach
Guard-zone measurements of individual apartment units or clusters of rooms as well as conventional pressure differential measurements were carried out consecutively in a series of apartment buildings (V > 2 000 m³, WE ≥ 10), . Comparing the two testing series, the airflow determined can be separated into that of leakages in the building envelope and of internal leakages. A statistical analysis of the results shows a connection to different building components and joints and thus a system behind the distribution of leakages in the building envelope and internal partition areas.
Content of the presentation
The presentation provides the first results from the current testing series together with the measured objects and the metrological methods. It also elaborates on the limitations of the method of approach, as well as obstacles in preparation, measurement, and evaluation. It concludes with recommendations for comparable measurements and a discussion of outstanding points.
Results and assessment
There is a system to the distribution of leakages in the building envelope with a significant accumulation in roof and floor areas. With regard to internal leakages, there are no available results that could be generalized. However, in particular when it comes to the calculation of infiltration, it may make sense to review the general distribution of the leakage flow. It would, for example, be possible to distribute the air flow based on the envelope area (air permeability at 50 Pa) q50 to the part of the envelope area of the individual zone that is in contact with outside air.
A review of the blanket infiltration approach is recommended. Some preliminary work for a reviewed draft of the German and European Industrial Standard DIN EN 12831 Heating Systems in Buildings – Method for Calculating the Standard Heating Load has already been done. The standard is currently being reviewed at European (it goes by PR EN 12831-1:2014- 11) and ISO level. A checklist or leaflet with recommendations from the FLIB (Association for Airtightness in the Building Industry) for the measurement of large buildings, including the general procedure and complementing recommendations makes sense to facilitate the testing of large buildings. Further measurements are necessary in order to be better able to evaluate the distribution of internal leak.
For more information, please contact the reference author at: Andreas.Kaschuba-Holtgrave@t-online.de