Development of a Natural Soil Depressurization System Sizing Tool

Abstract

Abstract This paper presents a summary of the main developments and results achieved in the frame-work of the French research project called EVAL-SDS. This project aims to analyse the performance of Natural, i.e. without use of fan for extraction, Soil Depressurization Systems (NSDS) to protect the built indoor environment from soil gaseous pollutant (Radon, Volatile Organic Compounds…). In this paper, the aeraulic performance of NSDS is studied i.e. its capacity to extract air from the ground to protect building’s occupants. To this end, we first performed measurements of airflow rates extracted by a NSDS integrated in a test-house during one year. Those data include various weather conditions (stack effect, wind) for several key parameters (wind extractor type, slab air permeability and basement pressure). Then, a dedicated calculation tool has been developed and validated against the experimental results. This numerical model has been used to evaluate the NSDS performance in France for different building heights and ventilation systems. The results show that NSDS succeed in creating a negative pressure under the building slab most of the time and that the extracted airflow rates can be enhanced by better design of wind extractor, association with mechanical insufflating ventilation system and thermal transfer from the building during the heating season.