In our last blog about indoor air quality (IAQ), we discussed what influences IAQ, what effects it has on humans and nature, and how to create healthier IAQ in your home.
As a recap, IAQ is measured by the quantity and type of pollutants in the air within a building. The pollutants that decrease the IAQ (make the quality worse) can be anything from biological pollutants such as mold and mildew, bacteria, dust or pollen, to carbon monoxide or volatile organic compounds (VOC’s)4. These pollutants can cause a wide variety of health problems for humans and animals, from mild skin irritations all the way to damaging internal organs and causing cancer.2,5
While ventilation is just one of the many factors that affect IAQ mentioned in our previous blog, it is a multifaceted topic and requires a deeper dive than we were able to give.
We’ve already established that healthy IAQ is important, but how does ventilation impact it and what are the current shortcomings of code-standard ventilation systems?
Firstly, IAQ can be 2-5 times more polluted than outdoor air quality6; therefore, it is vital to expel a greater quantity of indoor air and intake more outdoor air to increase a building’s overall IAQ.
However, not all ventilation systems are made equally. Often, with forced air-heating and traditional air-conditioning systems, the main method of ventilation is infiltration or purely natural ventilation (opening windows)3.
This is problematic, because there will not be a great enough flow of air to expel the polluted indoor air and the outdoor air comes into the building’s envelope untreated. While outdoor air is generally less polluted than indoor air, it would be counterproductive to bring in smoky, smoggy or pollen filled air, for example, and should still be filtered before entering the building.
When mechanical ventilation is installed in a simply code-standard building, the typical system must be manually turned on and off and doesn’t have the capacity for higher airflows or continual airflows. For this reason, conscious builders like TC Legend Homes go above and beyond the less-than-optimal code-standard systems and always uses a Heat Recovery Ventilator (HRV).
HRV units allow for continual filtered airflow. They are also capable of utilizing smart technology with sensors to detect CO2 and humidity within the house, allowing the system to automatically adjust air flow.
The humidity tracking and management is a huge advantage because it creates a more comfortable environment to people, pets and indoor plants alike and helps keep mold and mildew growth in check. On top of increasing airflow and managing humidity, the HRV also contains HEPA air filters to ensure the incoming air is stripped of as many pollutants as possible.
Of course, the extra benefit to these systems beyond increased IAQ is that they “recover up to 90% of the heat and contribute to an energy savings of up to 50%.”1
This means HRV systems save money by lowering the overall energy bill, as well as decrease the building’s carbon footprint by using energy more consciously resulting in less consumption of energy, fossil fuels and other precious materials.
In all, choosing the best ventilation system can mean creating a healthier home, as well as reducing your wasted energy consumption and having a lesser impact on the environment.
2“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.
5“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.
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.
TC Legend Homes – Bellevue Net Positive Energy Home
Located on a portion of a subdivided, family property, this 2,614 SqFt Bellevue, WA home is a beautifully built house that helps to foster multigenerational ties and community. With a 5-Star Built Green rating, EPA IndoorAir Plus certification, and a Net Zero Energy certification, this award-winning TC Legend home is an example of the influence and success of the Build Green program. With a specific focus on indoor air quality, this home employs a new ventilation and air filtration system, helping to make it a safe and comfortable environment for its occupants.
Built with passive and active solar needs in mind, the two-storey house faces south. Numerous triple glazed Vinvltek windows on the south side provide passive heating and light within the home. These windows and others throughout the house are coupled with white interior paint to help provide significant daylighting and reduce energy demand from the 100% LED home lighting. The home also employs a 12.87kW photovoltaic system, producing enough power to make the home net positive and power an electric vehicle. With a shell system constructed from 6.5” SIPs walls, 10.25” SIPs roof, 4” foam under the slab-on-grade, ICF form slab-edge stemwalls & U 0.18 average triple pane windows, this house has a tight envelope, helping to reduce energy consumption.
The three-bedroom, two bath house is meant to allow the occupants to age in place with the kitchen, main living space, a bedroom and bathroom, and ADA compliant doorways on the first floor. The state-of-the-art fresh air system includes a Zehnder 350 HRV, Zehnder Comfopost inline heating/ cooling coil, and HEPA air filtration system. This system allows for fresh, filtered air to enter the home throughout the day and to be increased when needed, such as when the kitchen hood fan is drawing smoke out of the kitchen during cooking. This fresh air system keeps the indoor air clean, reducing particulates in the air, even when the outdoor air quality is particularly poor such as during a summer forest fire.
Overall, this home is a comfortable, clean, and net positive building, allowing the homeowners to be happy, healthy, and confident in the knowledge that their home is serving their needs and protecting the environment in the process. The BuiltGreen Certificate of Merit and 5-Star rating this home received help to reinforce this knowledge due to the standard of excellence required of BuiltGreen certified homes.
Built Green highlights:
SITE & WATER
Long term erosion reduction strategies in place
Over 70% of building site left undisturbed with preservation of trees and native vegetation
Stormwater infiltration system catches all stormwater from the site and the uphill grandparents house, mitigating flow
Approx. 50% of the lot is turf grass
Watersense certified fixtures and low flow fixtures and toilets
Rainwater collection ready
Net-Positive Home with a HERS score of -22 and extra power to serve an electric vehicle
12.87 kW roof PV array
Substantial envelope insulation lowers heating requirement: R-30 walls, R-49 roof, R-20 under slab, R-24 slab-edge, average U-0.18 windows
Triple-paned Vinyltek Windows with u-values from 0.15-0.22
Passive Heating Design strategies utilized
Chiltrix Air-to-Water Heat Pump for heating and domestic hot water with COP of 3.92
AeroBarrier air sealing and blower door results of 0.47 ACH50
100% LED lighting
All Energy Star certified appliances
Energy Star certified
DOE Zero-Energy Ready certified
HEALTH & INDOOR AIR QUALITY
Indoor AirPLUS certified
Solid wood cabinets with Low-VOC finish
All Low-VOC paints, adhesives, and sealants
No gas-burning appliances in house
HEPA Air Filtration System
Zehnder HRV with ComfoPost
Graphite SIPS for exterior walls and ceilings
ICF foundation walls
85%+ of waste recycled
Locally produced lumber, SIPs, concrete, cabinets, doors, and siding
Exterior cedar posts constructed form telephone pole MFG waste
Leftover materials moved to next job
Solid wood, domestically grown interior doors and trim
Locally produced Vinlytek windows
Location: Bellevue, WA Star Level: 5-Star, Net Zero Energy Label Checklist: Single Family/Townhome New Construction Verifier: Ecoe Company
Site and Water: 109 Energy Efficiency: 239 Health and Indoor Air Quality: 126 Materials Efficiency: 109 Total Score: 629