Impact of Eco-Conscious Living Series: Indoor Air Quality
Just as you may think about the poor outdoor air quality on a smoky day or the smog that surrounds large cities, every building has its own body of air with varying degrees of quality and pollution that make up the indoor air quality (IAQ). IAQ is incredibly important for your own health and is, unfortunately, frequently under accounted for by mainstream building practices. It is, however, an attribute of eco-conscious building techniques for its impact on human and animal health, interlinked outcome of house longevity, and subsequent decrease in environmental footprint.
Taking a deeper dive into what IAQ actually is, IAQ can be anything from biological pollutants such as mold and mildew, bacteria, dust or pollen, to carbon monoxide or volatile organic compounds (VOC’s)5. Each pollutant effects humans, animals and the environment differently and the effects on humans can also vary depending on personal sensitivities. Exposure to just biological pollutant could lead to “skin irritation, sneezing, watery eyes, coughing, shortness of breath, dizziness, lethargy, fever, and digestive problems”1. Other pollutants, such as VOC’s, can cause more severe symptoms such as “eye, nose and throat irritation, headaches, loss of coordination and nausea, damage to liver, kidney and central nervous system,” with some VOC’s known or suspected to even cause cancer in humans or animals6. For information about all the individual indoor pollutants and their sources, visit https://www.epa.gov/indoor-air-quality-iaq/indoor-pollutants-and-sources.
Many of these pollutants are unavoidable as they can occur naturally, but we can take steps to reduce them to levels that will be less harmful or eliminate them almost entirely. If you hire TC Legend Homes, then before you even step into your house, we have already been working on increasing your home’s IAQ by using low toxicity products such as SIPs, low/zero VOC paints and finishes, low toxicity flooring and more. The SIPs we use eliminate the ozone depleting chemicals HCFCs and CFCs, as well as reduce moisture in between the walls that lead to mold growth.2 This, accompanied by the superior heating and ventilation installed, will set your home up for much healthier air. The next blog post in this series will discuss the details of ventilation and its impact.
Once moved into your new home, it is still important to take daily steps to maintain a healthier IAQ. Be sure to vacuum and dust regularly, clean fabric items frequently, reduce household clutter3, avoid harsh cleaning products, maintain a lower humidity level, repair leaks, run your exhaust fan during and after showering, maintain your ventilation system and change the filters frequently4.
Many eco-conscious building methods and results are interconnected, including IAQ, house longevity and environmental footprint. The nature of obtaining and maintaining good IAQ, means ensuring your home is being fixed of any issues which will result in the deterioration of your home and therefore cause indoor pollutants such as mold and mildew. Immediately fixing smaller issues that come up, like leaks or a filter in need of changing, will decrease the likelihood of the issues becoming so large that it is irreversible or will require more replacements to the system or surrounding area in the future. To this same note, upkeeping your home regularly and fixing issues as soon as they turn up, means using less resources in the long run, as replacement will be less frequent. As we know, using less resources helps to lower your overall carbon footprint. Moreover, maintaining good IAQ requires use of less toxic materials including those containing toxins and pollutants that are harmful to the environment such as greenhouse gases like VOCs or potent chemicals like pesticides. This in turn reduces the negative impact on the environment.
Taking all these steps to obtain and maintain your IAQ, will not only help you and your family’s health, but help reduce pollution outdoors and increase the longevity of your home.
Written by: Nicole Miller
1“Biological Pollutants’ Impact on Indoor Air Quality.” United States Environmental Protection Agency (EPA), EPA.gov, https://www.epa.gov/indoor-air-quality-iaq/biological-pollutants-impact-indoor-air-quality. 2/10/2022.
2“Building With Sips Creates Healthier, More Comfortable Interiors.” Insulspan, https://www.insulspan.com/advantages/health-comfort/. 3/2/2022.
3“Easy ways you can improve indoor air quality.” Harvard Health Publishing, Harvard Medical School, https://www.health.harvard.edu/staying-healthy/easy-ways-you-can-improve-indoor-air-quality. 2/10/2022.
6“Volatile Organic Compounds’ Impact on Indoor Air Quality.” United States Environmental Protection Agency (EPA), EPA.gov, https://www.epa.gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality. 2/10/2022.
SIPs are wall, roof (and sometimes floor) panels. Fabricated from a slab of foam sandwiched between two plywood sheets. Actually, it’s not ply it’s OSB (oriented strand board).
The sandwich-panels can be up to 24’x8’ and are made in the SIPs factory, in our case Premiere-SIPs in Puyallup. The doors and windows are cut-out in the factory, a stack of pre-fabricated house panels are loaded onto a trailer and arrives on-site where the SIPs are assembled… a bit like Legos.
Because TC Legend Builds affordable Net Zero energy houses, we use our crew to assemble the wall panels, man-handling them into place, but a crane can be used for walls. We do use the crane to set to thicker, heavier roof panels.
Our goal with SIPs panels is to create a continuous foam box, surrounding the inside of the home. When you remember that there’s 4” foam under the concrete slab, the 6” foam walls and 10” foam roof trap all the heat inside the house.
The ‘S” in ‘SIP’ stands for structural and the panel-system carries the load of the house, floors and roof, and does not need the sticks of vertical lumber you see in the walls of a conventionally framed house.
How are SIP panels joined? We’ll use the walls as an example:
The SIPs panels typically have the interior foam held-back to form a 1.5” gap at the panel edges. Two panels are joined by setting a ‘spline’ into the recessed gap on one panel, then sliding the second panel over the spline, nailing the connecting spline in place through all four edges. Splines can be made of 2×6 lumber (L-spline), foam mini-SIPs (called S-splines), or an insulated TJI spline (called an I-spline).
Because a 2×6 lumber splines touches both the warm inside of the house wall, and the cold exterior of the house wall, they are said to cold-bridge. A cold-bridge creates a poorly insulated pathway for the warm inside energy to travel to the cold exterior. There a many cold-bridges in conventional framing and that’s why we don’t do it. We aim to minimize L-splines as they have an insulating value of R7.8, compared to R29 for our Neopor graphite foam 6.5” Premiere SIPs wall panels.
Last week the TC Legend Homes crew finished off the SIPs roof structure on the Lake Stevens house.
On average we take about (2) days to assemble the 1st floor SIP wall panels. We build the 2nd floor-level TJI and sheeting floor system over the succeeding (2) days. The upper level walls take a day or so, and then it’s roof-day!
On roof-day the crane arrives early, and the roof panels are rigged, swung up, and screwed in-place by Ted and Norm. The crew have pre-assembled the boundary supports, so we don’t use more crane time and belch more diesel than necessary. The boundary support is a continuous 2×10 that seats into the 1.5” perimeter recess & connects together the outside edge of the roof panels.
SIPs are very fast to assemble and incur almost no waste material onsite because everything arrives pre-cut. Most excess off-cut foam is recycled back into the process during factory fabrication and the Premiere software nests the required panel shapes for maximum efficiency, making Premiere more streamlined, more profitable and more environmentally responsible.
Air sealing is very, very important for energy efficiency.
Imagine a fast, cold wind blowing over the building and all the warm air streaming out through the construction cracks. The Lake Stevens house is modeled to need a maximum of 12,500Btu/ hour to heat in midwinter, if we air-sealed the envelope to 0.6 air-changes per hour. (Note: (1) air-change-per hour assumes the entire volume of the house has the air replaced once within (1) hour).
If we air-sealed the Lake Stevens house to 5.0 air changes per hour, code minimum, we’d need 19,000Btu/h of heating for midwinter! So you can see that air sealing to reduce the air-changes per hour can give over 35% reduction in heating load.
SIPs are a pre-sealed sandwich, and compared to typical construction there are far fewer construction-joints in a SIPs building due to the large SIPs panel size. The standard SIPs assembly process includes installing beads of specialist mastic to air-seal and adhere the panels to each-other. SIPs have a measurable dollar advantage with that high level of pre-sealing and easy panel-to-panel air sealing. Meaning you can buy and run a smaller heat pump. And we haven’t yet examined the standard R29 insulation in the equivalent 2×6 wall!