MALB_2014 with 1-21 Revisions

Normative Appendix B ANSI/AARST MALB-2014 with 1/21 Revisions B— Occupied Versus Unoccupied Concentrations 1 NORMATIVE APPENDIX B EVALUATION OF OCCUPIED VERSUS UNOCCUPIED CONCENTRATIONS When conducting an evaluation of occupied versus unoccupied radon concentrations as an additional line of evidence relative to mitigation decisions, the evaluation shall comply with requirements of this Appendix B. B-1.1 Measurement equipment or processes Devices, such as CRMs, or other testing processes that can accurately measure the difference between average radon concentrations during occupied compared to unoccupied conditions are required. B-1.2 Measurement duration Testing shall be conducted for durations of not less than 46 hours to achieve average concentrations at each location for at least two occupied days compared to two unoccupied nights, as proportional to the percentage of significantly occupied and unoccupied durations. B-1.3 Reporting the evaluation Reported measurements shall include: a) The average radon concentration for the full measurement period; b) One average derived from the combined averages of the occupied periods across a test duration; and c) A second average derived from the combined averages of the unoccupied periods across a test. B-1.4 Simulation Testing When unable to test under the normal occupied operating condition for the building or unique sector , testing to simulate those conditions is permitted. Simulations to evaluate occupied versus unoccupied influences on radon concentrations shall be conducted by manipulating HVAC controls to simulate various HVAC operating conditions. The procedure shall include provisions a), b) and c) of this Section B- 1.4 . a) The evaluation shall include: 1. Building operating conditions that simulate normal occupied operating conditions, in accordance with Section 2.7.4 , and 2. Conditions required regarding minimum outdoor air ventilation and variable air distribution, as applicable, in accordance with Section 4.2 ; b) Details that shall be recorded and provided in reports include: 1. HVAC control settings and duration of activation for each simulated condition, and 2. Radon concentration measurements associated with each simulated condition; and c) The simulation measurements shall be made in each operational mode of concern for durations that are compatible with: 1. HVAC system capacity to achieve dynamic equilibrium for radon concentrations in the building or unique sector , and 2. Measurement device capabilities to achieve statistically accurate measurements for the duration of each operating condition. Informative advisory — Simulations to evaluate occupied versus unoccupied radon concentrations should only be made in coordination with building staff responsible for HVAC operations.