It takes planning and analysis to create an indoor environment in which one can breathe easily. This neglected area of home design directly impacts our health and well being.
There are only three holes in the shell of Equinox House.
One hole, required by Illinois plumbing codes, is for the plumbing fixture vent. In many homes, poor design coordination of bathrooms, kitchen, laundry and other areas requiring plumbing results in multiple plumbing vents. Multiple plumbing vents result in poor energy performance, potential roof leaks, and additional construction cost.
The other two holes in Equinox House are for fresh air intake and stale air exhaust, shown in the attached photo.
Conventional homes rely of poor construction techniques to provide “fresh air” through cracks, voids, and separations in the building. Unfortunately, relying on imperfections in building construction for providing air is both expensive and unhealthy. Air paths through a building’s cracks are often moist regions, promoting the growth of molds, mildew and fungi. Additionally, the uncontrolled, unfiltered flow of air through a building’s cracks allows the passage of pollens, dirt and other allergens into the house. Finally, these uncontrolled air flow passageways are also used by rodents and insects that leave their wastes in these passageways. Hopefully, you find this quite disgusting and have altered your perception of the “fresh air” in homes.
So, how does Equinox House promote fresh air in the house? A super sealed house (see the feature section on infiltration) must provide fresh air in a purposeful manner. The attached Sketchup diagram shows how Equinox brings air into the house through the fresh air vent. The air is immediately passed through an air filter that is placed in a convenient location for the residents to change as needed.
A photo of the filter box shows the accumulation of a large amount of dirt and insects removed from the incoming air. The air flows through a well-sealed, insulated duct to the CERV (see section on Newell Instruments’ Conditioning Energy Recovery Ventilator and the Equinox Features section on conditioning) for cooling or heating as the season dictates. The fresh, conditioned air then flows to the living areas and bedrooms of the house. Simultaneously, stale air is removed from the bathrooms, laundry room and kitchen. This air is passed through the CERV system for energy recovery, if beneficial, and then exhausted from the house.
How do we know the ventilation system functions as designed? We have run extensive tests including tracer gas tests and compared them to our air exchange simulation model predictions. We follow the ASHRAE 62.2 standard for residential fresh air, a relatively new standard for homes.
The attached plot shows carbon dioxide and VOC data from Equinox House during a week in December.
The weekends (data at the beginning and end of the plot), when Equinox is mostly occupied, increase in carbon dioxide and volatile organic compound (VOC) levels. During the week with lower occupancy levels, carbon dioxide and VOC levels are reduced. Target levels of carbon dioxide are 1200ppm or less on average.
VOCs are a family of substances that come from a variety of sources. Some VOCs are linked to human respiration. In the attached figure, in which our VOC sensor is calibrated in terms of equivalent carbon dioxide ppm (parts per million) levels, the VOC levels mostly follow the carbon dioxide levels due to human respiration. The high VOC peaks that overshoot the carbon dioxide levels represent other activities that release or produce VOCs, such as cooking (yes, wonderful smells contain VOCs…not all VOCs are harmful, which is what makes this so complex) and candles (yes, candles are bad for you if burned excessively). Notice that when human activity is low during the week, the VOCs return to a base level of 400ppm (a level in which VOCs are equivalent to outdoor fresh air). This indicates that our interior selection of paints (a zero VOC paint), cabinetry (our custom Italian kitchen uses aluminum frame structure with a special low VOC particle board for door fronts), and floor surface (concrete with low VOC area rugs used sparingly) are not continuously generating significant levels of VOCs.
See Equinox blog posts related to Air Quality:
