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Energy Solutions

Green Building Priority #3 – Ensure a Healthy Indoor Environment

Number 3 on my list of the top-10 green building priorities is to ensure that the houses we build or renovate are healthy.

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Use low- or zero-VOC paints and finishes, such as this zero-VOC Natura paint, to help maintain a healthy indoor environment. Photo: Benjamin Moore.
Image Credit: Benjamin Moore
Use low- or zero-VOC paints and finishes, such as this zero-VOC Natura paint, to help maintain a healthy indoor environment. Photo: Benjamin Moore.
Image Credit: Benjamin Moore
Maintaining a healthy indoor environment is partly about controlling moisture. The Delta Dry rainscreen system keeps moisture away from the wall cavity and allows sheathing to dry out if it gets wet. Photo: Cosella-Dörken Products, Inc.
Image Credit: Cosella-Dörken Products, Inc.

A green home should be a healthy home. It shouldn’t grow mold, mildew, and dust mites. It shouldn’t introduce significant quantities of volatile organic compounds (VOCs) or other hazardous chemicals into the indoor environment. It should have plenty of fresh air for its occupants.

Beyond keeping homeowners healthy, a well-designed green home can go even further with measures to ease stress and enhance a sense of wellbeing.

A few specific strategies for ensuring a healthy indoor environment are described below:

Deal with moisture

Moisture getting into homes—or not being able to get out—is probably the number-one cause of health problems in homes today. Standing water, dampness, and high humidity result in mold and mildew growth, dust mites, and other problems. Strategies for keeping water out include deep roof overhangs, surface grade sloping away from the house, and proper flashing around windows, doors, and other penetrations.

Strategies to get rid of moisture include installation of quiet bath fans that will actually get used (automated controls for bath fans are even better), kitchen range-hood fans that exhaust to the outdoors, rainscreen detailing on walls to allow trapped moisture to escape, and soffit and ridge vents in the attic (unvented “hot” roofs can also work, as long as the roof system is extremely well-sealed).

Various “operation and maintenance” measures are also very important in dealing with moisture: fixing roof leaks that are found, fixing plumbing leaks, never drying firewood in the basement, always operating fans when showering, and avoiding too many indoor plants (especially in the summer when relative humidity levels are high).

Keep pollutants out

One of the easiest ways to cut down on pollutants and moisture being tracked into a building is to install track-off mats for entryways. In commercial buildings, track-off mats are often designed with grates and drainage outside, then a coarse mat to remove soil and particles, and finally a softer mat that dries shoes as you scuff across it. In homes, a place to remove shoes and a no-shoes policy is a great way to keep pollutants out and reduce cleaning needs.

Avoid VOCs

Specify zero-VOC or low-VOC paints, sealants, and other materials with chemical constituents. With recent advances in finishes and adhesives, for most applications there is no longer a compromise in performance or durability when selecting low-VOC products.

Avoid hazardous chemicals and components

A wide range of chemicals are introduced into our homes through building materials, furnishings, and other products. Hazards we should try to avoid include brominated or chlorinated flame retardants, bisphenol-A or BPA (used in epoxies and polycarbonate plastics), phthalate plasticizers (used mostly in flexible vinyl or PVC), and formaldehyde. It’s a good idea to invest in learning about these hazards and working to select products that are free of them. Try to avoid insulation materials that include brominated flame retardants, for example, and cabinets made with particleboard or medium-density fiberboard (MDF) that contains urea-formaldehyde binders.

Provide fresh air

Mechanical ventilation is needed to deliver fresh air throughout a house. The old argument that we shouldn’t tighten up our homes too much, because we won’t get enough fresh air doesn’t make sense. When we depend on air leakage for fresh air, we only get fresh air when there’s a pressure difference driving air exchange in a house: that could be wind or very cold temperatures that create a stack effect. In the swing seasons (spring and fall) and in milder climates air leakage doesn’t cut it. With mechanical ventilation, we can control how much air we introduce, where it comes from, where it is delivered, and from where we exhaust the stale indoor air.

The best ventilation system is a “balanced” system with separate fans for exhaust and supply with ducting. In cold climates, it makes sense to run these air streams past each other using a air-to-air heat exchanger or heat-recovery ventilator, so that most of the heat from the outgoing indoor air is transferred to the incoming fresh air.

Provide for psychological health

Delivering daylighting and connections to the outdoors can help to maintain psychological health. A growing body of research is showing that in offices, these features boost worker productivity, in hospitals they speed recovery from illness or operations, and in schools they improve learning. The idea of design features that connect us with nature is referred to as “biophilic design” (biophilia is the innate affinity humans have for nature). This is a way to make an ordinary home a great home.

My top-10 list of green building priorities so far:

#3. Ensure a healthy indoor environment

#4. Reduce the need for driving

#5. Build smaller and optimize materials use

#6. Ensure durability and reuse existing buildings

#7. Protect and restore the site

#8. Use green materials

#9. Create resilient, climate-adapted buildings

#10. Make it easy for homeowners to be green

In addition to this Energy Solutions blog, Alex writes the weekly blog Alex’s Cool Product of the Week on, which profiles an interesting new green building product each week. You can sign up to receive notices of these blogs by e-mail—enter your e-mail address in the upper right corner of any blog page.

Alex is founder of BuildingGreen, LLC and executive editor of Environmental Building News. To keep up with his latest articles and musings, you can sign up for his Twitter feed.


  1. Tanya Shively | | #1

    maintaining good indoor air quality is so critical
    I absolutely agree with you on this one, Alex. Indoor air quality is actually my primary concern - probably due to growing up with a father who suffers from severe asthma. I love how finishes can now be truly zero-VOC and still durable and beautiful.
    My favorite is the paint from Benjamin Moore - have used it for clients and reviewed it on my blog:
    Live plants placed in every room is a great place to start, too. Easy, quick and relatively inexpensive way to make your home more inviting and healthier!

  2. pNJRiLZxNH | | #2

    Tight House Vs. Spot ventilation, Range Hood Fan, and Dryer
    In an effort to control my indoor air quality, I have a very tight house with a balanced HRV....but during Spot ventilation and clothes drying, I have negative pressure. Does the electric dryer incurr an energy penalty trying to dry clothes? Is the bath fan working to get the moisture out? I guess I'm a bit confused as to where the air comes from to evacuate the spot ventilation spaces when my house tested at .13 ACH... and is the unintended consequences poor spot ventilation.

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