In light of the recent Lumber Liquidators controversy, buyers are demanding homes that won’t make them sick. This means that builders, who are pushing to make their homes energy-efficient and airtight, must be extremely careful about the products and materials they use. It’s the Catch 22 of energy-efficient construction: Well-sealed buildings can trap in toxic chemicals, mold, pollen, and other irritants.
The first thing builders should be aware of is asking manufacturers the composition of their materials. Asking for transparency may have the single greatest impact on the health of homes across the country. As more manufacturers voluntarily disclose what is in their products, their competitors will have to follow suit. There are programs such as the Declare label by the International Living Future Institute that offer manufacturers low-cost ways to certify their products with a third-party label.
At my Chicago-area home building company, Evolutionary Home Builders, we apply quality control through extensive performance, health, and building science testing to ensure all projects are third-party certified to programs such as LEED and Passive House. We spec products (other than framing lumber) that have specific indoor air quality testing certification through programs like GreenGuard and Declare.
While these certifications assure us that the products we’re using are made to a higher level of health, specification of the right materials is only one step in our game plan to ensure good indoor air quality. It takes a range of building science-based strategies—from proper ventilation and moisture control to radon mitigation and conscientious construction practices--to make sure a home is healthy. Here is our checklist:
1. Conduct a third-party laboratory certified indoor air quality test. Testing for the indoor air quality by using a professional third party lab will give you a performance metric to compare and improve homes. Consider testing for formaldehyde, tVOC, particulates, and mold.
2. Keep air changes to a minimum. Ensure that the home is built to perform at least less than 1.5 ACH@50 Pascal. (Click here for more on air change calculation.) We like to build to the Passive House required .6 AHC@50, but 1.5 is a good goal to shoot for if you are just starting to measure this metric. Having a tighter envelope prevents dust, insects, and airborne particulate from entering the dark, drafty corners of most homes.
3. Provide balanced and distributed energy (or heat) recovery ventilation. Installing a balanced ventilation system with MERV filtration is critical for superior comfort and air quality. This makes certain there is no pressure imbalance in the house. For example, an exhaust-only ventilation plan requires bringing in the makeup air somewhere. If it's a tight home, you know it’s not evenly distributed or filtered correctly. Additionally, having your ventilation system distributed throughout the home will ensure that fresh air gets to all the places you would want it to, like above your beds.
4. Make sure walls are modeled using the WUFI tool to guarantee proper dry out potential. WUFI is a hydrothermal modeling tool that models your exact building assembly with all of the layers to your exact climate. It runs a multi-year model that shows if there is a risk of condensation in your wall and assesses the potential for mold growth. Condensation within your wall is moisture, and moisture leads to building failure.
5. Install carbon monoxide detectors on every floor and within 15 feet from all bedrooms. An odorless, fatal gas, carbon monoxide is obviously important to monitor in the home, and installing detectors correctly will ensure there is never a dangerous level.
6. Install a radon vent below the basement slab that vents through the roof. A passive radon vent installed through the roof is cheap and easy. We takes it a step further and also run in a junction box next to the pipe in the attic in case a homeowner needs or wants to add an exhaust fan to make it an active radon mitigation system.
7. Work to eliminate condensation, which can lead to mold growth. A third of the home’s R-value should be installed outside the air barrier to ensure any condensing surfaces in the wall assembly are eliminated. This is a good rule of thumb for colder climates zones and WUFI is a great tool to double check that the system is working properly. The exterior insulation will warm the exterior sheathing so that the inside face of the sheathing does not become a condensing surface.
8. Take photos of all wall cavities prior to insulation.Transparency is critical to maintain a customer's trust knowing you stand firmly behind your product. I always shake my head when we remodel a home and find garbage and sawdust piles inside the wall cavities, which guarantee dirty, dusty homes. Taking images reinforces that you take pride in the cleanliness of your homes, and also gives your clients exact locations of all mechanical systems and studs. This information is key for hanging pictures and for future remodels.
9. Flash exterior penetrations, windows, and roof to help move bulk water away from the home. Unfortunately, American homeowners have become accustomed to leaky windows and roofs, and that needs to change. If exterior water is finding its way into your homes, it cannot be considered a healthy home.
What are some ways you ensure buildings are constructed with assured high indoor air quality?
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