We provide indoor air quality testing services throughout the Puget Sound area. In the case study below, you can see how we designed some specific VOC testing for residential clients in Gig Harbor. If you feel that you have particular indoor air quality testing needs, feel free to call and discuss how we may be able to test and inspect your home or office
The client has requested testing in the home to determine if high levels of xylenes are present. This testing was prompted by blood testing results in her young son.
Once on-site the clients raised concerns in regards to highway exhaust contaminants that may be concentrated near the home during periods of localized convergence zones.
The subject property is a 2,300 square foot single-family home that was originally built in 2003. The home has a full basement that is currently being partially finished.
- Based on the data gathered by testing, hazardous levels of xylenes are unlikely to be present in the ambient air within the home during the normal course of occupancy.
- The home’s natural ventilation is likely sufficient to prevent gross indoor air quality concerns, but improvements to the ventilation and environmental conditions can be made.
- The basement must be clearly defined as either conditioned space or unconditioned space and ventilation, sealed, and insulated accordingly.
- The home’s heating system is currently filtered by a Honeywell electro-static unit. These units may generate ozone gas and are not recommended. The electro-static core should be removed and an appropriately sized 4” pleated filter installed in the existing filter box. The client’s may also wish to utilize a carbon filter to further decrease chemicals in the air, although these are not necessary for the average home or average occupant.
- The client’s questions in regards to outdoor pollutants could not be addressed at the time of inspection, but furnace filter upgrades may decrease particulates if they are an issue.
LIVING SPACE VENTILATION
The living space in the home is currently ventilated by:
One exhaust fan with 2 vents in the master bathroom.
Flow from vent above the toilet are measured at 100CFM
Flow above tub not measured (duct not fully connected to sheet-rock) but assumed to be 100+ CFM
One exhaust fan with vents in the hall bathroom and laundry room
Flow from laundry vent measured at 30CFM
Flow from Upper level hall bathroom measured at 128 CFM
One standard exhaust fan in the ½ bathroom
Flow measured at 84 CFM.
Insufficient ventilation in the living space of the home can lead to a buildup of humidity (contributing to mold growth in the living space and attic space), a buildup of miscellaneous building pollutants (such as VOC’s from cleaners, fragrances, cosmetics, and building materials), and is significant contributing factor to a wide range of indoor air quality concerns.
Recommended Ventilation Rates:
As per 2013 ASHRAE 62.2 (these requirements are in excess of Washington State’s most current building codes, but Hawk Environmental Services prefers a more liberal ventilation plan)
|Number of Bedrooms|
Environmental data evaluation:
- Temperature: The temperatures throughout the heated spaces of the home appear consistent and no dramatic fluctuations that may impact indoor air quality were noted.
- Humidity: The humidity levels in the heated spaces of the home are within normal limits and should not precipitate any indoor air quality concerns.
- Carbon Monoxide: Carbon monoxide was not detected in any tested areas
- Carbon Dioxide: The carbon dioxide levels in the home exceeded 800 ppm in select areas, but do not exceed 1,000 ppm in any tested areas. This suggests that minor improvements to the home’s ventilation may be beneficial to indoor air quality.
- Total VOC’s: The total VOC levels measured in the home did not exceed 500 ppb (as per isobutylene), but the levels may be decreased by 25-50% by implementing improvements to ventilation. This may not be noticeable by the average occupant, but sensitive individuals may experience some beneficial effects.
- Xylenes (as corrected via RAE systems correction chart for 1,2-Dimethylbenzene): The correction factor of 0.46 was applied to the total VOC levels measured in each area of the home. These levels assume worst-case scenario, in that all measured VOC’s were 2,xylene. The NIOSH recommended exposure level for this chemical is 100 parts per million which is approximately 1,000 times higher that the readings noted in the ambient air in the home. Based on this information, hazardous levels of xylenes were not present in the home at the time of inspection.
Recommended ventilation improvements:
Although no current system for constant or periodic mechanical ventilation is in place in the home, the natural building leakage at the time of inspection is likely sufficient to create a rate of air exchange great enough to mitigate average amounts of CO2, VOC’s, and humidity. The levels of air leakage will likely fluctuate with temperature and climate conditions, and an adjustable mechanical system to create ventilation should be put into place. Below are some of the most common options for residential ventilation.
The total air exchange volume that can be achieved by the currently installed exhaust fans is 442 CFM, while the desired volume is 105 CFM. If these fans are to be used to create the recommended ventilation, each fan must be run for no fewer than 5.75 hours per day.
Hire a licensed contractor to install a fresh-air intake and/or heat recovery ventilator on the existing HVAC system, that can be tuned and set to achieve the desired air exchange volume listed above.
If an HRV is chosen, the clients may wish to investigate the Life-Breath 205MAX, as Hawk Environmental Services has had very good experiences with this unit, and it should be both sufficiently sized and sufficiently adjustable to allow for a wide range of ventilation levels.
All ceilings and exterior walls in the home were scanned with an infrared camera.
No evidence of obvious water intrusion, as inspected with the infrared camera was noted at the time of inspection.
Additional Areas of Concern:
The basement is currently undergoing a remodeling effort and an appropriate heating and ventilation plan should be enacted in the newly finished spaces.
This space may be heated via electric wall units or other thermostatically controlled devices.
This space may be easily ventilated via the installation of a Panasonic Whisper Green 80CFM exhaust fan in the bathroom. This fan may be set to run at 30 CFM constant-flow, which will provide sufficient negative pressure ventilation for up to 650 square feet of living space with an 8′ ceiling height.
The remainder of the basement will likely remain unfinished and should be properly separated from the conditioned spaces above and ventilated to the exterior.
All accessible gaps and penetrations between the unfinished areas of the basement and the living space should be sealed with expandable foam sealant or another appropriate material.
If the unfinished areas of the basement are to be ventilated passively, vents should be installed at a quantity of 1 square foot (net-free area) of venting per 300 square feet of basement foot-print.
If the unfinished areas of the basement are to be mechanically ventilated to the exterior, the flow rating of the exhaust system should be equivalent to 0.35 air changes per hour = (volume/60) x 0.35.
Solvent and chemical storage:
A large quantity of adhesives, solvents, and other standard household products were observed in the basement. The VOC meter (ppbrae plus) was used to measure the off-gassing of these products into the ambient air. Total VOC levels approximately 12” away from solvent containers were consistent with the ambient levels noted in the chart above. When the meter’s probe was placed approximately 1-2” from the solvent container’s cap VOC levels were measure in excess of 15 parts per million. This information suggests that minor quantities of solvent gases are exiting the storage containers, but that the quantities involved are unlikely to become a health hazard when diluted into the ambient air.
The most conservative approach to the storage of solvents and other household chemicals would be to place them in a well-ventilated area, outside of the conditioned environment. If the basement areas are ventilated as per the standards above the materials will not need to be relocated.
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