IEA_Radon_Reporter_January_2024r

18 | January 2024 RESEARCH At the 2022 International Radon and Vapor Intrusion Symposium in Bellevue, WA, Bill Brodhead and Omer Zeyrek delivered a presentation and later authored a proceedings paper titled “RADON IN CONCRETE PASSIVE VENTING MITIGATION.” The paper is focused on a study conducted on a six-story concrete condominium in Florida with identified radon levels ranging from 8-16 pCi/l and ventilation rates of 0.02-0.06 air changes per hour (ACH) of ventilation, considerably lower than ASHRAE recommendations of 0.35 ACH for residential homes. The study investigates the effectiveness of passive venting from the HVAC (Heating, Ventilation, and Air Conditioning) closet to the outside as a mitigation strategy. The research aims to determine the impact of introducing outdoor air on radon and humidity levels inside four condominium units, providing insights into the development of an efficient and cost-effective radon mitigation system. Diagnostic testing and system design were conducted at the condo to implement an effective radon mitigation system with cost reduction, minimal occupant disruption, and reduced noise. The testing occurred in March and April in 2022. The diagnostic procedures involved using RadonEye Pro monitors and EcoTrackers for radon and ventilation measurements, including temperature and humidity. Additional radon testing was performed in the underground garage and the main office. Outdoor air was introduced into units, allowing measurement of ventilation needs to reduce radon levels. Direct flux measurements on exposed floors were challenging due to tile coverings, but significant radon emanation was found at grout joints and electrical closets. While specific contributions from walls and concrete ceiling couldn’t be assessed, introducing outdoor air helped determine natural ventilation levels and additional ventilation requirements to meet EPA guidelines. Elevated radon levels are attributed to radon emanation from the concrete. Flux measurements over grout lines and bare concrete suggest significant radon emanation, reinforcing the hypothesis that concrete is the primary radon source. Ventilation tests, introducing 30-40 cubic feet per minute (CFM) of outdoor air, prove effective in reducing radon levels to within acceptable limits. The study emphasizes the importance of considering outdoor air introduction carefully to prevent potential issues like increased humidity and mold growth. In Florida, addressing elevated radon levels in multi- family buildings traditionally involves three methods. The first, Air to Air Exchanger, requires installing an energy recovery ventilator in each unit, posing challenges like space constraints, duct routing, noise, maintenance, and costs. Unsuitable for Condos due to limited space. The second, Whole Building Ventilation, requires rooftop units conditioning outdoor air for nine units, facing challenges like roof weight, power requirements, duct routing, and high costs. The third, Individual Vent Fan Installation, uses a 20- watt radon fan controlled by a timer but raises concerns about humidity and mold growth when the air handler is off. Condo challenges include limited HVAC closet space, requiring alternative installations. Challenges at the Condo include limited space in the HVAC closet, necessitating alternative installations with ductwork and power sources. The study also proposes a Passive Outdoor Air Venting method. This alternative method to address elevated radon levels involves utilizing the negative pressure generated by the HVAC closet’s air handler to introduce outdoor air into the unit. This setup capitalizes on the strong negative pressure induced by the HVAC unit, drawing outdoor air through a duct routed from the HVAC closet to the outside. The benefits include immediate conditioning of outdoor air by the running HVAC unit, minimizing excess humidity in the closet and reducing the risk of mold. Moreover, this approach eliminates the need for a dedicated closet radon fan and associated electrical wiring, reducing installation costs. However, the success of this passive air duct method depends on adjusting dampers and considering the run time of the HVAC unit. A simple test involving a four- inch PVC pipe demonstrated that 33 pascals of negative pressure can induce 100 CFM of airflow, equivalent to the capacity of a radon fan at full operation. The proposed passive duct, measuring 4x6 inches, would be installed across the backside ceiling of the storage closet, routed through the entrance hallway to the outside. Adjusting the amount of incoming air would require an adjustable grill inside the HVAC closet and potential modifications to the smoke detector placement. While this passive outdoor air venting method offers advantages such as minimized humidity buildup and reduced installationcosts, challengesmayarise inadjusting the system for optimal performance, including potential modifications to the smoke detector and considerations for the size of the return grill. The research concludes that passive venting can effectively reduce radon levels, offering benefits such as simplified installation and lower costs. The passive system utilizes negative pressure induced by the HVAC system, eliminating the need for additional radon fans and electrical Radon In Concrete Passive Venting Mitigation RESEARCH wiring. The authors recommend further research and testing to validate the success of this passive approach, emphasizing its potential for simplified, cost-effective, and occupant-friendly radon mitigation. The study recommends implementing the passive outdoor air venting approach, emphasizing its benefits in terms of simplicity, cost-effectiveness, and reduced impact on occupants. The research suggests adjusting the passive system with an adjustable damper and monitoring its effectiveness, with the possibility of incorporating a fan if needed in the future. Continuous research is encouraged to refine and optimize this passive venting strategy for wider application in mitigating radon in concrete- constructed buildings. The research draws on previous work by Bill Brodhead, highlighting the author’s expertise and contributions to the field of radon mitigation. Relevant references include studies on at-grade radon mitigation exhaust, whole-building ventilation in high-rise condominiums, and measurements of radon and thoron emanation from concrete and granite. These references provide a comprehensive background for the current study and contribute to the body of knowledge on effective radon mitigation strategies. Read the proceedings paper at: https://aarst.org/proceedings/2022/Brodhead_ RADON_IN_CONCRETE_PASSIVE_VENTING_ MITIGATION.pdf training@spruce.com | 800-767-3703 NEW COURSES! ENTRY LEVEL & CE HIGHER KNOWLEDGE LOWER COURSE FEES FIGURE (16) VENTILATION INCREASE TO UNIT K & UNIT L