Blog Post

Green Building Priority #3 – Ensure a Healthy Indoor Environment

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. Click on image to enlarge.

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

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).


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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).

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. Click on image to enlarge.

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 entry¬ways. 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 materi¬als 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, bisphe¬nol-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 connec¬tions 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, 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.

Published November 2, 2010

(2010, November 2). Green Building Priority #3 – Ensure a Healthy Indoor Environment. Retrieved from–-ensure-healthy-indoor-environment

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November 2, 2010 - 5:38 am

Dear Alex, Don't forget that electromagnetic fields are the greatest form of pollution on Earth, said in 2000 Dr Robert O. Becker, twice nominated for the Nobel Prize in medicine. The World Health Organization admits (at least low-cost or no-cost) precautionary measures are warranted. The Electric Power Research Institute recognizes contact current may be a cause of leukemia (, many Canadian parents want schools to unplug WiFi because they say it makes their children sick, and electric fields increase the risk of infection: ''Measurements of small air ion concentrations, electrostatic potential and AC electric field strengths were taken in an office setting to investigate the link between electric fields and charged molecule and particle concentrations in individual microenvironments. The results obtained indicate that the electromagnetic environments individuals can be exposed to whilst indoors can often bear little resemblance to those experienced outdoors in nature, and that many individuals may spend large periods of their time in ‘‘Faraday cage’’-like conditions exposed to inappropriate levels and types of electric fields that can reduce localised concentrations of biologically essential and microbiocidal small air ions. Such conditions may escalate their risk of infection from airborne contaminants, including microbes, whilst increasing localised surface contamination. The degree of ‘‘electro-pollution’’ that individuals are exposed to was shown to be influenced by the type of microenvironment they occupy, with it being possible for very different types of microenvironment to exist within the same room. It is suggested that adopting suitable electromagnetic hygiene/productivity guidelines that seek to replicate the beneficial effects created by natural environments may greatly mitigate such problems.'' Source: Atmospheric Environment 41 (2007) 5224–5235 The effects of electric fields on charged molecules and particles in individual microenvironments K.S. Jamiesona,??, H.M. ApSimona, S.S. Jamiesona, J.N.B. Bella, M.G. Yostb aCentre for Environmental Policy, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, UK bDepartment of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Box 357234, Seattle, WA 98040, USA Best regards, André

November 5, 2010 - 7:58 am


This is a very good point--one that we have made frequently in Environmental Building News. See, for example, this BackPage Primer:

To illustrate the problem that exists with these definitions, I was at an AIA trade show a few years ago and asked a manufacturer of concrete sealants if they offered any "green" alternatives to standard solvent-based products. He said (and I paraphrase), "yes, but our green, zero-VOC product, which we make to satisfy the demand for zero-VOC products, is actually worse, because we use the VOC-exempt solvent methyl chloride." I couldn't believe that! Methyl chloride is far more dangerous than simply hydrocarbon VOCs, but it doesn't meet EPA's VOC definition.

Unfortunately, while the VOC definitions were created to address outdoor air pollution and smog generation, they remain our only widely available proxy for chemical emissions in buildings. So they are likely to continue to be used as a metric in efforts to create healthy indoor environments. I and many others in the green building community would love to see a better metric for the safety of chemicals, but until that exists I'm afraid we will continue to consider VOC emissions in evaluating chemicals.

What are you suggesting as an alternative, Andy?

November 5, 2010 - 7:27 am


The EPA definition of a VOC is any carbon-based molecule that readily vaporizes at room temperature, that could react with nitrogen and UV to create low-level smog. Nowhere in that definition does it elude to human health. Yet, you and the other leaders of the green building movement continue to propagate the idea that VOC's in paint need to be avoided to improve the health of the human indoor occupants.

While VOC's can be hazardous to humans, that is not always the case. Peel the skin off of an orange and you are releasing 850 g/l of VOC's into the air. Squeeze toothpaste onto a brush and you are releasing unknown quantities of VOC's from the propylene glycol (which is an FDA approved good-grade additive). It is also true that not all hazards in paint are classified as VOC's. When the EPA wrote the VOC regs, they gave specific exemption to a certain class of carbon-based solvents that didn't react to create smog. Ammonia, acetone, butyl acetate, as examples. While these solvents technically are VOC's, they do not have to be listed as such on an MSDS. Then, add in the fungicides, chemical masking agents and formaldehyde precursors, which do not have to be listed because they either make up less than one percent of the volume or they are part of a "proprietary blend", and you've got a product that is likely to be very harmful to humans but technically zero VOC.

If folks in the green building industry really want to help create healthy homes, then the discussion needs to change. VOC's are only regulated by the EPA because of outdoor air pollution. They're not addressing the 86,000 chemicals used in the production of building materials, in which we know the toxic effects of about 3% of those. Please, stop promoting the herd mentality of VOC's and start focusing on the real hazards in building materials.

I look forward to your response.

November 5, 2010 - 9:52 am

Alex, by telling that story you are doing exactly what I advocate. I am first of all in favor of education instead of regulation. Regulation arises out of the shorthand "all voc's are bad" formulation, and like most shorthands makes people think they are doing something when in fact they often wind up ignoring more serious problems. I can't tell you how many people we work with that have been persuaded to buy a mainstream company's zero voc paint and come to see us because something in it is making them sick. Here's a verbatim letter we received the other day (with the manufacturer's name redacted, but it's clear from photos you use that you know who they are):

"We have a problem with an odour from a new application of a zero VOC paint (____ from __________). They tried sealing it with [their] primer and then finishing with their _____ product but the odour from the [zero voc paint] application returned."

We provided this customer with a solution using Safecoat paints and all is now well, but what's surprising is how often we encounter this same situation, where people have been misled by a big company into thinking that the zero voc paint they use is healthy, as opposed to just not containing smog-forming ingredients. This is a direct result of the past few years' efforts to find a "villain" in voc's, as opposed to making appropriate differentiations. Here's another example: we work with a company that historically made a fantastic low voc paint, reasonably priced and uniformly tolerated even by people with allergies and chemical sensitivities. Although it contained some voc's, they were not toxic and the product was extremely environmentally responsible. But because people have had it so drummed into their heads by a superficial environmental media that "all voc's are bad", the company ultimately decided that it could no longer offer the low voc product, and had to focus on zero voc. Their zvoc products are still health based and are in fact the best zero voc paints we've tested, but by virtue of not being able to use the cheap ingredients the other non-health focused zero voc products do, they are more expensive. Had there been more effort to differentiate between voc's as opposed to universal condemnation, people would still have this more reasonably priced, healthy alternative.

The need for "metrics" is partially what drives this, and therefore creates these types of problems (which you so aptly illustrate in your post). I'm not sure this is soluble in terms of creating another "metric". Perhaps that demand for black and white is the problem in a world where there's still plenty of gray.

November 5, 2010 - 9:49 am

Just to be clear, BuildingGreen's GreenSpec team uses a wide range of measures to assess potential indoor environmental hazards from products - VOC and otherwise. Section 01350, described in the article Alex referenced, is more advanced than the EPA definition, by basing considerations of VOCs on health-based CRELs, and this measure is increasingly available for products. Paint and other wet applied products are tricky to test though (see, and this is where the EPA VOC method may still be of use. There is also plenty of work to further improve the situation, including Greenguard's new standard in development - though it's yet to be seen where that will go.

I guess to me the best metric would be one with an emissions component based on CRELs (including an expansion of the CREL list into semi-volatiles and other concerns) and a composition component based on absence of constituents with specific hazardous chemical properties, not the chemicals themselves, as the only way to get out of the substitution trap -- but that's not a ready drop in replacement for something like the VOC metric for paints at this point.