Sump effectiveness was analysed in two locations: underneath the basement, which involved cutting openings into the foundation, ground storey and roof slabs, and outside the basement walls, which entailed digging a pit alongside the building exterior. The effectiveness of both sumps was likewise tested with passive and forced ventilation methods.
The systems proved to be highly efficient, lowering radon levels by 91–99 % , except in the solution involving passive ventilation and the outside sump, where radon levels were reduced by 53–55 % . At wind speeds of over 8 m/s, however, passive ventilation across an outside sump lowered radon levels by 95 % due to a Venturi effect induced drop in pressure.