SGM-SF_2017with 12/20 Revisions

Non-ASD Methods 47 ANSI/AARST SGM-SF 2017 (with 1220 revisions) Soil Gas Mitigation Standards for Existing Homes 12.5 Indoor Air Dilution Note—By way of mechanical or passive ventilation components, the introduction of outdoor air to a building or airspace can, under certain conditions, be effective to dilute concentrated gases or vapors that may pose hazards to occupants as a result of soil gas entry into a building. There are also times when additional ventilation is desired for other purposes. Informative advisory —The high volumes of added outdoor air required to dilute radon gas andmany other gases or vapors to acceptable concentrations will often result in unacceptable energy penalties, especially when accounting for occupant comfort. As a stand-alone method, practicality increases for buildings with tight, energy-efficient construction. When Indoor Air Dilution is employed: 12.5.1 Capacity (dilution) Mechanical or passive components that are newly installed or augmented shall result in a configuration with adequate capacity to continually provide the required volume of dilution air needed to achieve desired goals for radon reduction. 12.5.2 Sources for air Sources for air delivered to the airspace being pressurized shall comply with Section 12.2 . 12.5.3 Coupled with pressurization Considerations shall be made during design with attempts to verify after installation the potential for positive pressure to result from the system to an extent that radon is transported to another airspace in accordance with Section 12.3.4 . 12.5.4 Prior to system installation or augmentations a) A Qualified Ventilation Technician shall employ pressure and airflowmeasurements as needed to evaluate system capacity requirements, energy penalties and feasibility for the design stipulated in Section 12.5.1 . Note—Blower door measurements during system design are recommended to quantify the capacity needs of the system; b) Sources for air to be delivered to the airspace shall be evaluated for viability of meeting requirements in Section 12.2 .; and c) Measurement procedures shall include an attempt to evaluate the potential for the system to change an airspace or portion of the building from negative to positive pressure. If this is found to occur, the requirements of Section 12.3.4 shall also apply. 12.5.5 After installation or augmentations a) A Qualified Ventilation Technician shall verify with pressure and airflow measurements that adequate capacity for required operating parameters stipulated in Section 12.5.1 were achieved. Thesemeasurements shall be recorded an reported in accordance with Section 10.1.1 and often include the system’s: total airflow in and total airflow out, temperature in and temperature out, air density, altitude and other operating parameters; b) Sources for air delivered to the airspace shall be verified for compliance with Section 12.2 .; and c) Measurement procedures shall include an attempt to verify if the system has changed an airspace or occupiable portion of the building from negative to positive pressure, whereby the requirements of Section 12.3.4 shall also apply; and 12.5.6 A long-term OM&M plan is required in accordance with Section 13.7 . 12.6 Soil Air Dilution Note—Inducing outdoor air ventilation in the gas permeable layer or airspace between occupiable spaces and the soil can, under certain conditions, be effective to dilute radon prior to entry. Examples include passive or mechanically vented crawl spaces or rooms. 12.6.1 Requirements for soil air dilution All designs and installations of mechanical systems that induce soil air dilution shall comply with all requirements for Section 12.4 (Indoor Air Dilution).