The November 2017 CCSBP newsletter discussed the importance of creating a tight building envelope to improving energy efficiency, as well as methods for doing it. When homes are built tightly, however, it is also important that they are ventilated properly. As the saying goes, "Build tight, ventilate right!" If there is not enough air exchange with the outside, indoor air
can become polluted with radon, mold, combustion by-products and volatile organic compounds from building materials, furnishings and finishes. When these compounds accumulate, they can cause health problems. This newsletter will focus on why adequate ventilation is important and ways to achieve it.
There are a number of pollutant sources that can impact the indoor air quality in your home, and thus your health. There are also ways to mitigate these impacts, but adding some form of ventilation is generally necessary to create acceptable indoor air quality. Let's look at each of the pollutants and their mitigation methods before exploring ventilation strategies.
Whether you are burning wood in a wood stove, or natural gas in a furnace, there are combustion by-products that are of concern to indoor air quality. Smoke from wood burning can be a significant health hazard. Particulates smaller than 10 microns (PM10) pose a particular risk, as these particles can move far into the lungs, into the tiny air sacs called alveoli, where oxygen enters the blood, causing permanent lung damage or worsen conditions such as asthma, emphysema and
bronchitis. For more information on best practices for wood burning see our November 2016 newsletter.
Carbon monoxide (CO) is another combustion by-product of concern. It is a colorless, odorless, tasteless and toxic gas. Because it is impossible to see or smell, concentrations can build up without notice and kill home occupants. CO is emitted from gas stoves and smoking, and also when furnaces, gas water heaters, wood stoves and fireplaces back-draft into the home.
Back-drafting happens when venting from these appliances is stymied by a negative pressure created in the house by the use of exhaust fans in bathrooms and kitchens. Carbon monoxide detectors are now required by code, and should be installed on older homes that did not have this requirement when they were permitted. Another consideration with combustion appliances is providing adequate combustion air. A fresh air supply to furnaces, water heaters, woodstoves and fireplaces is now required by code, but older units may draw air for combustion from the surrounding environment. This depletes the oxygen in the home and also often doesn't provide enough air for complete combustion, thereby creating more combustion by-products and reducing efficiency. If you have an older model wood stove, consider upgrading to a new EPA-certified model; there is an Arizona state tax incentive of $500 that can help fund the upgrade!
Top right photo: Wood stove with fresh air supply at Sea Ranch Inspired, designed by Architectural Design Studio and built by Grey Dog Construction.
Lower right photo: Carbon monoxide detectors can be combined with smoke detectors, or stand-alone, like this one at the Johnson Ave. Cottages, designed and built by JKC, Inc.
Make sure your kitchen fan exhausts to the outside, like this one at the Linwood Contemporary Farm House, designed by Architectural Design Studio and built by Green Mountain Construction.
Cooking- Cooking is one of the largest sources of indoor air pollution in a home. Gas stoves produce combustion by-products including nitrogen dioxide, carbon monoxide, formaldehyde and particulate matter. The cooking of meats and oils produces acrolein, an irritant that was used as a nerve agent in World War I, as well as carbon monoxide and particulates. Cooking often creates nitrogen dioxide and acrolein concentrations that exceed EPA acute standards for outdoor air quality. The Ernest Orlando Lawrence Berkeley National Laboratory has been researching the impact of cooking on
indoor air quality (IAQ) as well as the effectiveness of range hoods, to determine the extent of the problem and solutions to it. Some of their findings:
Gas ranges give off more pollutants than electric ranges, due to combustion by-products, but electric ranges do give off particulate matter. Induction cooktops have the lowest impact on IAQ.
Recirculating fans trap grease, but are not effective at removing gases.
Exhaust devices often remove less than half of the pollutants emitted by burners. Efficiency is improved at higher speeds, but the noise at those levels makes their use unlikely.
Exhaust fans with capture hoods were more effective than flat ones.
Cooking on the back burner helps substantially with capture efficiency.
Exhaust fans are only used about 30% of the time.
Recommendations: install a range hood that vents outside and use it! Vent hoods that cover the stove area more completely and have capture hoods are preferable. While none of the range hoods they tested were particularly effective (and the ones that were more effective had higher flow rates and used more energy), even a moderate amount of success is helpful. Cook on a back burner when practical. See the article links in the Sources section of this newsletter for more information.
Consider installing a passive radon ventilation system like this one at High Caliber Construction's Pulse Home.
Radon is a colorless, tasteless and odorless gas that is radioactive. It occurs naturally where the radioactive metals uranium, thorium and radium are present in native rocks and soil in the environment. These metals break down to produce radon. Because radon comes naturally from
the earth, people are always exposed to it, but it can build up to dangerous levels inside homes, schools and other buildings when it is trapped inside. Radon can enter a building through cracks and gaps in the building envelope. Installing a passive radon ventilation system during new construction is fairly inexpensive and can reduce chances of a problem. For more information on radon and radon testing see our January 2017 newsletter.
Formaldehyde and VOCs-
Zero VOC interior paint as seen at the Ryan Historic Home Preservation project.
The acronym VOC stands for "volatile organic compounds," a large group of chemicals that are found in many products we use in building, furnishing and finishing a house. These products turn into vapor easily and thus "off-gas" into the indoor air from the products they originate from. Buying products that are "low" or "zero" VOCs will reduce the amount of toxic chemicals in your
environment. You can also look for the GreenGuard Gold certification label, a program that ensures that products are acceptable for use in schools and healthcare facilities where sensitive individuals may reside. Another useful label references CARB compliance. The California Air Resources Board has a stringent emission standard for formaldehyde in composite wood products.
VOCs can also come from cleansers, air fresheners and other household products. You can find "safer" products at EPA's Safer Choice website.
GreenGuard Gold label on batt insulation used at the West Street Cottages, designed by Sunteriors and built by AHC Construction.
Mold and Microbial Contaminants-
A large body of research has indicated that dampness and mold in homes contributes to an wide array of health problems. That list includes asthma, respiratory infections, bronchitis and eczema. Ventilation is important both in the prevention of mold and microbial growth, as well as in alleviating the build-up of these organisms in the air. Understanding the flow of air in a building is important for managing moisture, and must be considered when implementing ventilation strategies. Moisture management will be the subject of a future CCSBP newsletter.
Ventilation- When the building industry began building homes more tightly to improve energy efficiency, there was a concern about how to ensure adequate ventilation. In 2003, the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) developed a ventilation standard, specifying the amount of air flow needed to create acceptable air quality. This gave building code developers a tool to use to ensure adequate ventilation while requiring a tighter envelope for new homes. ASHRAE Standard 62.2 "Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings", includes the determination that a home's living area should be ventilated at a CFM rate determined by adding 3% of the conditioned space floor area to 7.5 times the number of bedrooms plus one [formula: vent CFM = 0.03A + 7.5 (# bedrooms + 1)] as published by ASHRAE 62.2 in 2013. In a tight home, mechanical ventilation is necessary to achieve this ventilation rate.
There are three basic strategies for ventilation. They are natural ventilation, spot, and whole house ventilation.
Homes have been ventilated naturally throughout history. Opening windows and doors provides fresh air to a home and air can naturally infiltrate through cracks and crevices in the building envelope with no help from mechanical systems. The advantage of this approach is that no energy is used to achieve it, and it is not dependent on a mechanical system which can fail. The drawbacks are that in cold months, when windows are closed, there may not be enough air exchange to ensure a healthy environment. Also, if the gaps in the home that the air is infiltrating from are in crawl spaces, it may have significant levels of mold, radon or other contaminants.
Opening windows is one way to naturally ventilate a house. This is the Wachowski Residence, designed and built by Scott and Darcy Wachowski with Matt Robinson and Western Strawbale Builders.
Spot ventilation is used to remove pollutants at the source. Examples include bathroom fans that remove moisture and odors, and kitchen fans that exhaust combustion and cooking by-products. In order for this strategy to work, the fans must be used! For bathrooms, the fan can be connected to the light switch, or a humidity/motion detector can be installed to ensure that moisture doesn't build up and cause problems. Installing a kitchen fan with a noise rating of one sone or less will make the likelihood of fan usage greater.
This bathroom fan is tied to the light switch to ensure moisture removal at the West Street Cottages, designed by Sunteriors and built by AHC Construction.
Whole House Ventilation-
This is the inside of a Panasonic ERV as seen at the Eden Project, designed and built by Ezra Builders LLC.
Energy Recovery Ventilation-
There are four approaches to whole house ventilation. The first is energy recovery ventilation. Energy Recovery Ventilators (ERVs) and Heat Recovery Ventilators (HRVs) use heat exchange technology to transfer heat from outgoing stale air to incoming fresh air, thereby reducing heat lost to ventilation. ERVs also transfer humidity, so choosing one over the other necessitates deciding if this is beneficial or not. In Flagstaff it is important to choose a cold-weather model so that the unit doesn't freeze.
A second way to achieve whole house ventilation is through a balanced approach, where fresh air is provided at essentially the same level as the exhausting of stale air. This approach was used at the Four Square Historic Project. Good Oak Construction worked with E3 Energy LLC to balance the fresh air brought in to the return line of the furnace with an equal amount of air taken out with the timer-activated bathroom fan.
Exhaust and Supply Whole House Ventilation-
Other approaches to whole house ventilation include exhaust and supply approaches, which are not as common as the other two methods. These involve using a center fan to either exhaust or supply air from the building. As you can see in the diagram below, both of these strategies create a pressure variation from the inside to the outside of a home. Using an exhaust only system creates a negative pressure inside the house while a supply system creates a positive pressure. It is important when using these systems to understand the implications of this to moisture management and air quality. Moisture can be driven into the wall cavity with positive pressure and radon and other pollutants can be drawn into the home from crawl spaces or other contaminated areas with negative pressure. For the pros and cons of each kind of system see this DOE website.
We are identifying innovative products to bring in representatives for, and we are also interested in innovative systems, designs and methods that speakers would like to highlight in break-out sessions we will be holding. Please send us your ideas for products you'd like to learn more about or spread the word about, or systems, designs and methods that you would like to give a presentation about or learn more about.
We will be keeping you posted about the event and the "Applied Sustainable Building Innovations" student poster competition in upcoming newsletters and on Facebook as it comes together. For more information see our website.
Free Home Energy Efficiency Workshop
February 6th, 6-7 pm
East Flagstaff Library, 3000 N. Fourth St.
House too cold? At this workshop, a licensed contractor from Cozyhome will demonstrate ways to make simple energy efficiency upgrades, weatherize your home and save money on your utility bills. You will receive a free home energy efficiency kit to help you get started.
Please join us for this one-hour workshop at the East Flagstaff Library. Workshops and materials are provided free of charge on a first come, first served basis.
The American Solar Energy Society is hiring a Sales and Development Professional to help grow our non-profit organization through large donor development, grants/institutional sponsorship, new program development/sponsorship ad sales for our printed and online publications, and sponsorships for our annual National Solar Conference and National Solar Tour.
This is a unique opportunity to work for an organization that is leading the charge to 100% renewable energy. Working for ASES means knowing you are doing good for our country, economy, and environment. Compensation is commission only to start and then is negotiableas results are demonstrated. Commission is based on gross sales of magazine and digital advertisements, sponsorships, or other revenue generating programs driven by the sales professional.
This position requests an average of a minimum of 20 hours/week, remote work, and enables work on your own schedule. The position is supported by the full time executive director, the volunteer board, and volunteer fundraising committee. ASES is a progressive organization and is always looking for it's talented people to bring new ideas and new energy to our programs. If you are ready for a challenge and want to help fight for renewable energy, come join ASES.
ASES asks that candidates be willing to balance their sales activities with a mix of large donor asks and a series of magazine ad/conference sponsorship sales. This mix of proven smaller revenue transactions with big "home run" opportunities ensures ASES of growth and stability.
A qualified candidate will have a proven history of success in sales, preferred experience in magazine ad sales, and a familiarity with non-profit organizations and the renewable energy and sustainability landscape. Familiarity with ASES is a plus.
February 10th, 10AM-12PM
Join Willow Bend and the Arboretum at Flagstaff for a unique workshop that’s all about Mushrooms! Kris Haskins, Director of Research at the Arboretum will introduce attendees to mushroom biology and diversity, and teach how to use dichotomous keys, a common identification tool, to identify mushrooms.
Cost is $15 for the general public or $10 for Willow Bend and Arboretum members.
Workshop is open to all but designed for adults and children ages 10 and over. Secure your spot by signing up online or calling our office (928) 779-1745.
Beginning Gardeners Workshop
presented by Roots Micro Farm
When: February - May, Wednesdays 6:30-7:30
Where: ROC Yoga Studio
Cost: $10 per class or $95 for all 11 courses
Our beginning gardeners workshop series will be a great time for the new grower to learn simple, organic gardening techniques. We will have guest speakers, local farm visits, and educational materials that will connect you to Flagstaff’s growing community.
Email email@example.com to reserve your spot.
February 3rd, 9AM-1PM
Join Willow Bend for a hands-on interactive event celebrating winter! Winter stories and games, snow experiments and displays, winter art, and more! Special guest Catherine Esquivel will be sharing traditional Diné winter stories during two sessions, 10:00-10:30AM and 12:00-12:30PM. Make snow art, learn about animal winter adaptations, hands-on experiments and more. No need to RSVP.
The Kahtoola Uphill is a fun, family-friendly annual mountain race designed to encourage human-powered movement and a fundraiser for Friends of Camp Colton. Join us as we celebrate our 11th year! New this year, kids 12 and under race for free with a registered adult. Participate as a racer, volunteer, Champ for Camp fundraiser, and/or purchase a Golden Ticket or raffle tickets (purchase tickets and sign up to be Champ for Camp at http://champforcamp.com/). With the Flagstaff Subaru Fun Climb, Loven Contacting Midway Climb, and the Lumberyard Brewery Agassiz Climb, our race courses range from fun to challenging with something for everyone. Racers, supporters, and spectators enjoy food and festivities at the Arizona Snowbowl Hart Prairie Lodge.
Speaker: Mary Estes of Norris Design, PLA, SITES-AP, LEED® AP. With a background in both landscape architecture and architecture, Mary's career has been dedicated to design excellence and the advancement of artful, relevant responses to a variety of project types.
Continuing education credit: 1 GBCI CE, 1 AIA LU and 1 LA CES hour pending
The Flagstaff Mountain Film Festival highlights a collection of the most inspiring and thought-provoking social, environmental, outdoor-adventure and indigenous films from around the world. Primarily screened at the historic Orpheum Theater, each unique session promises to expose new points of view with many of the filmmakers present to discuss their filmmaking process.
Program will be released 2 weeks before the festival.
The City of Flagstaff is hiring a grant specialist. For a job description and more information see the City's website.
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