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In an effort to fully assess a home with an indoor air quality complaint we feel it is best to measure the homes basic indoor environmental conditions.  These include the temperature, humidity, airborne particulates, formaldehyde, carbon dioxide, and volatile organic compounds.  For these measurements we use handheld monitors to obtain onsite real time measurements.  The measurements may also include additional components such as carbon monoxide, combustion gas, ozone, and refrigerants.  These measurements are also collected onsite real time to establish the actual conditions of the home. 

We begin our assessment by first measuring the home with the HVAC off for a few hours measure the above indoor environmental conditions with the home at rest and then we turn the HVAC on and let the system fully condition the home for a minimum of 45 minute and remeasure with the home while active.

In a properly functioning home, that meets the ASHRAE ventilation rate and properly sized mechanical equipment; the active indoor environmental conditions should be less than at rest indoor environmental conditions of the home.  The air handler while running will easily reduce the temperature; in addition, if properly sized, the air handler will easily reduce the indoor humidity.  It’s easy to see how conditioning (cooling or heating) the indoor air has a measurable and direct impact on the temperature and humidity of the indoor environment. 

This is also true when it comes to all other indoor environmental conditions that we measure, airborne particulates, volatile organic compounds, etc….  So, it stands to reason that if any of these indoor environmental conditions remain unchanged or become elevated, we have identified an action item or an area in need of improvement.

If the home does not meet the minimum ventilation rate, we know that it’s very likely that we’ll see either no change or a rise in the measured conditions within a home.  The issues become even clearer when there’s an outdoor air supply that is not properly installed.  For example, if the outdoor air supply is not pre-filtered, dehumidified, or dampered these two issues can easily elevate the indoor particulate levels or indoor humidity to the point of occupant complaint.

So, for us the measurement and documentation of the indoor environmental conditions is the most important aspect of our “initial” diagnostic assessment. The collection of these indoor environmental conditions and the comparing of the “at rest” levels to the “active” levels is where we can begin to establish and identify any areas of concern or issues within the home.  We often find that the home performs beautifully when active and all measured conditions with the home at rest began within the acceptable range and were further reduced when active.  In these homes the ventilation system is working well and may require no changes. 

With the collected data we can help our clients improve their indoor air quality and validate those improvements by remeasuring the home or office.

Presented by: John Lapotaire & Lydia Lapotaire