Speaker
Description
This report analyzes the main design criteria for achieving low indoor radon concentration levels both in new constructions and in existing buildings that are part of the historical heritage of our cities. Although achieving low indoor concentrations in new buildings is relatively straightforward with good foundation insulation and the avoidance of emitting materials in the construction envelope, remediation of existing buildings becomes much more challenging. Italian constructions, in fact, differ significantly from those in other European countries, and the techniques described in foreign design manuals can only be partially utilized. A rigorous technical approach is therefore absolutely necessary and desirable. In the historical centers of many Italian cities, the building envelope is made of lapideous or semi- lapideous materials from local quarries that are highly emitting, whose contribution cannot be underestimated; hence, a technique for evaluating the exhalation rates from construction materials widely used by the author in preliminary investigations for the design of radon remediation works is described. All these criteria must be considered in the initial phase of building design to meet the recommendations of the World Health Organization and the standards for implementing Directive 59/2013, which in Italy has been transposed by Legislative Decree 101/2020. For new constructions, we can identify three design criteria assuming the use of non-emitting materials in the construction of the building:
1. Establish a barrier to radon gas rising;
2. Depressurize the sub-foundation;
3. Dilute indoor air with external air using heat recovery systems.
These criteria will be used partially or in combination with each other depending on the area risk characteristics calculated based on Soil Radon and permeability
For existing buildings, in addition to the 3 criteria already mentioned, a 4th is added related to the evaluation of exhalation rates from the construction materials used to create the building envelope.
When utilized, these criteria can prevent radon infiltration and lower the concentration of radon in indoor air. Radon can cause lung cancer, and it is not known if there is a safe lower limit for humans; therefore, it is important to reduce the indoor radon concentration as much as possible. Air rising from the ground is the main source of radon indoor, but the contribution of the materials making up the building envelope cannot be underestimated in the design of remediation works for existing homes.
Keywords - Radon, natural radiation, barrier, material exhalation, ventilation, HRV (Heat Recovery Ventilation).