Tiny Houses and Indoor Air Quality Part 1

Guest Post by J C Sherrill

I am a heating and cooling contractor in North Carolina and have been following the Tiny House Blog for a few years. I have some concerns with a small indoor air space and I would like to share some information and offer some guidance to help improve your indoor air quality. The information contained could save someone’s life.

When people breathe, cook, or take showers it adds moisture to the indoor air. Small indoor air spaces can become problems from indoor pollutants and moisture. Moisture is measured as RH/relative humidity. Moisture in the air is not usually a problem in a home but when you shrink the air space and have the same volume of moisture content it can make matters much worse than you would have in a larger home where the indoor air could be better diluted by having a greater volume of air space. Going to the restroom could also become an odor problem when your entire home is only as big as some bathrooms.

Ways to improve your indoor air quality:

Ventilation is one way to improve the indoor air. Windows are passive where fans are mechanical and require power. Source containment is another. A good example would be a full floor to ceiling shower door vs. a shower curtain. No indoor plants, the dirt in the pot may also contain mold. Do not cook inside or use a microwave and an electric burner whenever possible. Use an outdoor grill for most cooking. Place a lid on your pots while cooking. Do not burn oil lamps or candles. Candles produce tremendous amounts of soot.

Another problem with tiny homes is that they are mostly built outside any building code inspection requirements and by amateurs. Tiny homes are situated for off grid or partially off grid when it comes to heating and cooking. This is usually taken care of by using LP Gas. LP gas is heavier than air. If you were to have a gas leak it can displace the air you breathe and cause death. Unvented gas appliances use the same air/oxygen; you need to breath inside the small space. Unvented LP gas appliances also add about one gallon of water to the air for every 100K Btu’s of heat produced.

Jay Shafer uses a small Newport boat heater in his tiny houses and it is vented. Good for Jay. It also brings in its own combustion air from outside so you do not need to open a window. This way the gas heater is not competing for the same air/oxygen; you need to breath inside the small space and the products of combustion are vented outside of the living space.

Most Radiant, Big Buddy and Little Buddy style heaters are not vented. Yes some of these have a low oxygen sensor but I would not trust my life inside of a confined space with one. Some of you may be saying: They wouldn’t sell them if it wasn’t safe or I have done this before and that this guy doesn’t know what he is talking about. Can we agree that Carbon Monoxide / CO is an odorless colorless gas and that it is a poison that can put you to sleep? Now just how much of a dose Carbon Monoxide and low oxygen can you stand? CO affects the young an elderly differently.

Do not place your family in danger of this deadly and silent killer.

Although I do not live full time in a tiny house I have a Big Buddy heater for winter emergencies; I would never go to bed with it on. I would crack a window about an inch or two for combustion air in an emergency situation.

LP Gas, Smoke and Carbon Monoxide alarms:

Carbon Monoxide/CO is produced when combustion occurs. If you are all electric CO is not a problem. If you burn fuel oil, gas or wood inside of your home, get a CO alarm preferably with a digital readout. Get one that will operate with a battery or 115v and battery backup. CO alarms have a recommended life of only 7 years. The new ones will chirp at their end of life cycle. If yours is old replace it. (The date should be on it or call the manufacture and ask). If you can’t find a combo unit you may need to purchase all 3 LP Gas, Smoke and Carbon Monoxide alarms to get complete coverage.


Cooking with Gas.

LP gas releases moisture when it burns. Unvented LP gas appliances add about one gallon of water to the air for every 100K Btu’s of heat produced. LP gas will compete for the same air/oxygen; you need to breath to support the flame. Coleman style camp ovens and cook grills are usually not rated for indoor use. Read and follow the instructions and keep a fire extinguisher handy.

Gas hot water heater.

Non-vented, point of use hot water heaters are great for off grid living. I bought one from E-bay for a little over $100.00 it works great. I have seen a You-Tube video where one was in use inside of the small cabin. I would recommend placing this and showering in an outside enclosure. Bring it in after use in the winter to protect it from freezing.

Moisture, mold and mildew:

Mold will not grow if the humidity stays below 60% RH. Off grid this may be a problem due to not having enough power for an A/C unit to control the humidity inside of the space. Mold grows on almost anything. Mold and dust mites need moisture to feed. Moisture is what we can control to prevent mold.

A/C units and dehumidifiers control moisture. A/C units will also cool the space while dehumidifiers will usually heat up the space. Do not leave any wood exposed to water or steam in the shower or sink backsplash area or anywhere wood will stay wet to prevent mold an mildew.

This information is provided to keep you and your family safe inside your home no matter how small. If you don’t believe me do a Google search, educate yourself, seek professional help if you need it and improve your indoor air quality.

What you do not want is to become sick or die from Carbon Monoxide poisoning or form condensation inside your living space or between the walls. Moisture + cellulose products = mold food. Look for part II How heat moves, Insulation, Radiant and Vapor Barriers

© 2011 J C Sherrill III Reproduction without permission prohibited.

63 thoughts on “Tiny Houses and Indoor Air Quality Part 1”

  1. This is an important consideration. We had a large camping event here in Arizona in Feburary some years ago. One man asphyxiated when a camp size LP gas container leaked in his tent and a couple did so as well from running a propane heater inside a rather large tent. I rail on everyone each year to look at those propane heaters…its says “DO NOT USE INDOORS”. There was also an incident in Arizona where a couple inside a truck camper shell who burned candles and used up all the oxygen and died.

  2. Very valuable information. Your pointing to items that are okay to use rather than just saying what not to use is very helpful. Thank you!

  3. Very good advice.

    About the moisture situation- Those of us who live in cool, moist areas can actually heat our houses by running the dehumidifier instead of the heater. The electricity used does two things at the same time. That saves energy. The same thing can be said for getting heat from light bulbs turned on when you are home.

  4. Excellent post! Tiny Homers often seem to get caught up in the iconoclasm of escaping building codes that they might overlook the codes that are there for a good reason. Thanks for reminding all of us.

  5. I would disagree on the “no indoor plants”. They contribute to indoor air quality and shouldn’t be a mold problem when they’re watered correctly (let them dry out a bit in between watering). Treehugger featured an article about NASA’s air-filtering house plants a while back.

    • I agree with you Cheryl. I have read about some research done in office buildings with no access to outdoor air. They showed that 4 areca palms, 1 money plant, and 6 mother-in-law tongue plants will put back the oxygen in the air for each person if in a small enclosed area. The money plant is also known to take toxins such as formaldahyde out of the air. These plants all do best when allowed to dry out between watering, so they shouldn’t contribute much to mold issues if watered correctly and help with the oxygen content in the air, especially if the house needs to be closed up in the winter like the office buildings they were tested in. (They will take up a little space, but I have these in my apartment and they could be placed strategically around a tiny house without it feeling too cluttered.

      Personally, I like to get a little fresh air in the house, even in the colder months. I know this is contrary to energy conservation, but I figure a little air exchange every so often is a good trade off paired with good passive solar heating.

      • Plants only produce oxygen when given enough light. They also produce carbon dioxide at night. The biofiltration aspect of plants is often attributed to the microorganisms associated with the roots and soil, rather than the plant itself…

        see Wood et al. 2002. Potted-plant/growth media interactions and capacities for removal of volatiles from indoor air, Journal of horticultural science & biotechnology, vol. 77, no1, pp. 120-129

  6. Great subject matter and very important considerations for tiny houses. Are there any solutions that will allow for indoor showering/cooking? Like some sort of roof vent with a fan that will recycle the air?

    I’ve all wondered about the safety of the heaters that Shafer uses… so those things are 100% good to go?

  7. I’m also curious about indoor cooking. I prefer cooking over a flame to an electric stove. Are small apartment sized propane stoves or rv propane stoves vented? I would think that the rv propane stoves that are put in “certified” RV’s should be okay. It’s pretty hard to only cook and shower outside when in a cold climate, I would think that using proper venting and fans in the bathroom and over the stove should solve the problems you talk about. I would love if you could talk more about how to build these solutions in to the tiny homes.
    Thank you for the post!

    • RV cooking stoves are not vented, but often have a vented hood fan over them. In houses or RVs, having the hood vent fan running during cooking or baking with gas is recommended.

    • Residential stoves are usually set for a higher out put at the burner

      This is for a residential GE LP Stove

      All-Purpose Burner 9100 BTU/150F degree simmer
      High Output Burner 11000 BTU/150F degree simmer
      Power Boil Burner 15,000 BTU/180F degree

      RV Stoves are set at a lower output The one I found had a high-output of
      9,000 BTU front burner and two 6,500 BTU rear burners.

      Lower BTU output = less CO. I’d like for you to find your RV or camper’s owners manual on line or call them and ask for one owners manual for every brand of gas appliance you have.

      See what they recommend. Then use your head.

  8. Ok, I knew I’d get beat up on the plant and indoor cooking issue. If you don’t spill water on your floor and have clean soil you may get away with a few indoor plants. Keep an eye on your homes RH with a meter you want it to be less than 60% if it goes up to the point you start forming condensation inside you will now have a tiny green house and will be providing much need moisture for mold and mildew. If you see mildew or condensation on the glass you will be entering the food zone for indoor mold growth.

    Now you know why I didn’t mention smoking inside or furry or feathery pets.
    We all have our vices.

    I once had a lady that allowed her cat to crawl inside her return air duct. She had a bowl of cat food inside of the return duct behind the air filter. She was complaining of mold issues and allergies.

    For some of us it is obvious.
    Stay safe folks.

    • I am extremely sensitive and cannot handle any mold. I have seen mold grow in dirt on dry cactus. The mold spores can be in the dirt before the plant is put in the pot. It doesn’t have to be caused by the watering. It won’t die simply because it dries. If anything…it is worse. Dry mold floats through the air and spreads.

      Everyone should have a CO monitor. It’s easy to think you’ll know but you would be surprised. I almost died from carbon monoxide. My dog did die from the complications. There was a leak in the gas line under the house. Didn’t matter that the gas heater wasn’t being used. I kept calling the company and was ignored. I had 3 firemen stand in my living room….say that they smelled gas…and go down the street looking for it. They then concluded that it was from a neighbor’s septic. Even when I went to the hospital and I had bright red knees (dead giveaway), they would not listen to me and as such I wasn’t treated properly for what had happened.

  9. Please address the additional safety/health issues involved in living in an Airstream trailer (older model). I assume everything you say applies but wonder if additional moisture might be an issue due to the fact that metal condenses moisture even more? Also, many people choose to live in Airstreams or similar trailers due to multiple chemical sensitivities and this is another thing that should be written about, as many building materials are particularly toxic, and it would be REALLY good to talk about this. Anyone?

  10. It would be a simple fix to install a heat recovery ventilator (HRV)that is hooked up to a humidity switch – if the RH gets too high, the HRV is triggered letting moist warm air exhaust and cooler fresh/dry air in while exchanging the heat on the way out. Similarly, a gas cooking appliance could be coupled to the HRV as well so that when cooking occurs, the same exchange takes place.

    • Please be patient with my ignorant question, but can the system you talk about be installed without ducted heating and cooling? For instance, if I choose electric heat, can this system be installed?

  11. Rats. An outside shower and cooking outside sound not so fun for the long term. With good ventilation how small can a place be make cooking inside ok?

  12. Great post. I have been interested in and reading about tiny homes for some time and have always marveled at the lack of attention to this important topic. It seems to me that the addition of a small HRV/ERV (heat-recovery ventilator / energy-recovery ventilator) should be of paramount importance to those who make their home in small, well-insulated and well-air-sealed spaces.

    • You can even make your own fuel & Moonshine.

      The ATF would like to come and find you if you did. You would need a federal permit to stay inside of the law to make your own. A man near me was on the news a while ago he was the only man in Eastern NC with the permit to make alcohol fuel.

      Alcohol burns with a blue flame and is visible in the dark. You can’t see the flames burning during the day.

      Stay safe.

  13. What is the fresh air exchange rate needed per person occupying the tiny home? How many cfm of fresh air to square footage of the tiny home? Size of fresh air vents? What are the best locations for fresh air vents? Is there a different fresh air vent sizes between powered and passive? Is there a way to have a passive exhaust vent? Your article was very good but lacking specifics.

    • “Your article was very good but lacking specifics.”

      I don’t want to come across as a wise guy.

      Just don’t burn any fuels that have open flames inside a tiny box where you live.

      It produces CO and is bad for your health and may kill you.

      I hope you get that you can Cook, heat and burn fuels with open flames and vent your tiny house with all of the fans or passive venting (windows) you would like but you then are living with the products of combustion where your home has now become the inside the chimney.

      How much CO can you stand?

      Not where I’d be living.

      Folks educate yourself about CO.


      • Sorry, my comment and questions were not intended to offend. Your post was very clear and to the point, Carbon Monoxide is very dangerous and because of your post I will installing a Carbon Monoxide/smoke alarm. In my 160 sq ft little house on wheels I am presently building I will only have one source of Carbon Monoxide a propane stove/oven with a range hood vented outside. I don’t plan on using it much, I prefer to cook out side when I can or on the wood stove when I am heating. I also will have a 50 cfm bathroom exhaust fan and a 50 cfm exhaust fan over the desk. For my wood stove I plan to use outside combustion air, less efficient but a lot safer. Then there is the factor of the number of oxygen consuming occupants. My tiny house can sleep three adults comfortably. My question is what size fresh air intake vents do I need and preferred locations? Thank you

        • No offence taken and I hope that any of my responses are likewise.

          My Grand Daddy would say “Live Learn Die and Forget it all”

          This must have been a saying before the internet and CO alarms.

          I’d just hope I can pass some of my knowledge along so those reading and that can think through this information and gain the skills necessary to safely live their dream.

          If you are reading and following this post please don’t ever think It’s OK or they wouldn’t be selling and installing gas appliances inside RV’s.

          Don’t depend on the guy at Wal-Mart, the RV place, Home Depot or the government to take care of this for you. Learn the facts about CO for your own safety.

          Before you get upset over any of my statements realize that my only intent is to not get you or any of your family members sick or killed!

          The first part of RV is Recreational. Recreational use is not full time. These fall under a different set of codes that is much more relaxed than residential construction that is for full time use. Refer to the statement above if this has hit a nerve.

          RV furnaces and hot water heaters have a heat exchanger (the combustion flame is taken place inside a box with a vent out the side of the RV) it is OK to use this type of heat since it is vented. You still should use a CO alarm just in case of a malfunction of the venting or a crack in the heat exchanger, etc. in getting the products of combustion away from the living space. Always follow the instructions and operational manual.

          If you open a window to bring in outside air with the furnace or generator exhaust in the side of the RV while it is running, you take a risk that the wind could blow it right back in on you.
          How much air exchange is needed? If you had a tiny living space 8 wide x 9.5 tall x 16 long = 1216 Cu ft. of space

          If we were to bring in 15 CFM (Cubic feet per minute) per person you would have 900 CFH (Cubic feet per hour) 15 CFM x 60 minutes in an hour = 900 CFH)

          15 CFM / CF of air exchange in 1 hour for 1 person. Or .74 air changes per hour per person.
          How would you measure this? I don’t know of an easy way. 15 CFM is a nominal amount. 15 CFM per person may be an awful lot if you lived in a cold climate. Also in a cold climate the furnace would be running for longer periods and producing more CO. I’d open a window (an inch or 2) away from and not near any type of vented or gas appliance chimney exhaust or muffler from a generator to bring in some air.

          Fans rob your tiny home of power. The air outside may be much more humid, hotter or cooler than you desire to bring in for 15 CFM a person.

          ERV and HRV units exchange the air like a fan only they keep some of the indoor temperature from going out the window so to speak. They will not clean up the air you bring in from outside other than what an air filter can collect.

          Learn what you can and act on your knowledge. Hermit DeLuxe I’m glad you are getting a CO alarm.

  14. You can find SAFE Direct Vent (uses outside air for combustion and sends combustion gasses outside) thru Northern tool for 1/3 of the price of the Newport (the Newport is a great heater ) and all the advantages except seeing the fire. I have used 3 in Tiny(128 sq.ft.) and Small( 256 sq.ft.& 270 sq.ft.) Cabins in Northern New York. I rent 2 of these all year and of course use carbon monoxide and smoke detectors in them.

    • Lee, I’m curious which units from Northern you’ve been using. I’m looking at the Newport P12000 which I found in line today for 765 including shipping and the HouseWarmer 18000 BTU unit which is 535 with shipping. I’m really temptes to spend the extra 200+ for the looks of the Newport considering I’ll be living here for a while. I’m also in Florida, but from Upstate so I know the cold….here it’s mostly a few days not months. Please share your thoughts, thanks

  15. Another good reason to not cook too much inside a tiny space is that all your cloth items start to smell like the food after a while. Some things aren’t a problem but some odours can really linger. It may not be much of a safety issue but sometimes it can affect your work or social life. You get so used to it you don’t notice but other people definitely do.

  16. It certainly isn’t my intent to sound argumentative, but recreational vehicles have been around for years. I’m sure it has likely happened, but I’ve never heard of anyone dying from CO2 poisoning and almost every RV since the ’40’s has had factory installed heating, cooking and water heating units. I am 100% in agreement for the concern and everyone should be wary but to cook outdoors? Is that not just a little bit over-kill? I prefer a flame to electric as well and I’ve never had a moisture problem from gas.
    I will say the points about the shower are spot on and I have experienced that first-hand. I especially liked this guys comments about place the shower outside. What could be more romantic than an outdoor shower? And, yes, a campground I stayed in once had outdoor (enclosed) showers and it was wonderful to take a hot shower while looking up at the moon. So, in planning my “perfect place” I plan to incorporate that idea into my plans. As for the tankless water heater being brought inside to prevent freezing, many models are designed to be mounted on the outside of the home so even in extreme weather conditions they won’t freeze because of the pilot. Remember, living off grid, a piezoelectric ignitor is not really feasible. With a pilot standing inside the water heater, it won’t freeze. Just my comments and I know everyone won’t agree.

  17. Hi J C,
    I think your article is excellent, helpful, and very informative! Too many people die needlessly every year from improper use of small heaters, stoves, and gas lamps.
    We heat our 128 sq ft two level micro home/studio with a 1500 watt ceramic cube heater (cost $29.95) by running it no more than 15 minutes per hour. It’s hard to beat the cube heater for economy in smaller spaces. I am in favor of using an air quality sensor and a reliable source of venting including an outside air source for any type of combustion heater. Personally I prefer to sleep with a window in the room cracked.
    I’m looking forward to your next article.
    Walt Barrett

    • I was looking at some of the wood stove imitation electric heaters myself. If my place is small, I shouldn’t need to run it more than a few minutes at a time. Thanks for the idea.

      • An oil filled electric radiator is a great little heater, nice and quiet, no fan to drive you bonkers. They tuck away neatly when not needed and are fairly cheap to buy and operate.

  18. All electric just ain’t going to happen. I can site an inspected and recertified 100+ gallon propane tank at the 2 or 3 places I might take the tiny house I am slowly planning. I’ll be bringing my own electricity to two of those places. I look forward to additional content on this subject. I am, however, a huge fan of CO2 monitors and I make a pest of myself about this to friends and families. A dear friend of mine in college nearly lost her life, as did her three kids to a combination of maintenance issues on a house next to the one I’d previously lived in, and built by the same contractor. They’d been getting ill for a long time, and attributing it to other things. They were discovered by neighbors passed out, or passing out while trying to leave the house. Keep in mind this was a house built in the mid-1980s a decade before they moved in with then modern, all electric appliances. It scared me.

    This was reinforced by my experience living in a condo near the Astrodome. No, my condo was okay, but I paid special attention to the dome during the huge Houston Livestock Show and Rodeo, as did all people living near there during the month of the Rodeo — traffic. During the three years I lived there, there were at least three incidents of CO2 poisoning in RVs and stock/living combos for people working the event. Two resulted in fatalities. All three of these RVs – trailers were modern, and well appointed. So Randy, it does happen with some regularity, we just don’t hear about it much.

  19. I am extremely sensitive and cannot handle any mold. I have seen mold grow in dirt on dry cactus. The mold spores can be in the dirt before the plant is put in the pot. It doesn’t have to be caused by the watering. It won’t die simply because it dries. If anything…it is worse. Dry mold floats through the air and spreads. No plant removes mold in the air. Here is the solution however, for those not so sensitive (from Debra Lynn Dadd’s site):

    “…house plants that can help clean the air (from the NASA study). When searching this site, I read that some were concerned about mold in the plant soil becoming its own air contaminant. In my research, I found a replication study of the original NASA study that stated that you should use “[s]everal centimeters of small washed gravel … to cover the surface of pot plants when large numbers of plants are kept in the home … to reduce the exposed area of damp potting soil which encourages the growth of molds (fungi)” (Houseplants, Indoor Air Pollutants, and Allergic Reactions by Wolverton, 1986, abstract and p. 7). Although, people with allergies would probably want to do this with all plants, regardless of the number, and would probably want to start with only one or two.”

    • That’s interesting. Thank you for sharing. I always put the gravel in the bottom for good drainage, but will now put some on top as well.

      This has been a great post. I thank everyone for their contributions, it will help me choose carefully with how to handle daily living needs.

  20. Very sound advise, I learned a long time ago from a building inspector who’s motto was “More Air”….and he was so right.
    In reality especially in a Tiny Home does a cracked window or two improve air quality but it also improves heating efficiency and overall feel as it helps to circulate the air and lessen hot and cold pockets.

  21. All of this is important information I have wondered about for a long time. Jay only hints about these issues (exhaust fan in loft) in his book. I noticed in one video I saw somewhere he had what looked like plexiglass/plastic sliding panels in the bath to protect wood on an outside wall/window. I don’t know if he ever answers questions about air quality/RH at workshops since I have yet to attend. He must have some thoughts since he lived in one for several years. His examples pics show propane cook tops.
    I know the answers are not simple since there are at least a couple different camps debating here, on or off-grid part-time if not permanently. I want off-grid solutions but limit the amount of “roughing it” I must endure. Aesthetics aside electric is fine for water, heat and cooking on-grid. Off-grid is not very feasible. You need to many Btu’s.
    Another issue is location. I see so much about how well ones live off the grid in SoCal, Arizona, Texas, Florida and points south. I appreciate those examples but Mother Nature is a boost in those climates. Anyone living in the Northeast, Upper Great Plain and Upper Midwest as I do (and wish to continue to) knows nature is less of an ally.
    Another issue is politics/cost. Many want to be “Green” and/or frugal and thus super insulate (encapsulate) their tiny house. That causes the “breathing issue” of these homes. A person with a tiny log house in Alaska probably doesn’t have to worry because the chinking/caulking still allows for a lot of “breathing”. If one is heating/ cooking with wood it keeps the RH low. Fuel is probably plentiful/cheap and I probably don’t want to know what one does about showering.
    Basically I want it all. Shower, cook, and heat inside in the upper US. I want to be able to do so off-grid at least part of the time (even in winter months) which probably means via a flame. I am willing to incur some cost but I am not wealthy.
    If NSAA and the Soviets can put astronauts in a space station for months at a time safely there has to be some knowledge out there about these issues. They probably don’t cook or at least not by flame. I realize their solutions are big bucks but where are the “Tang” level solutions for us here on Earth. Must be some lower cost knowledge/solutions they possess useful for our less hostile environments that at least provide practical improvements for small house dwellers. Just have to find it.

    • Joe

      Part II, may help provide a little more information with some of your questions about cold climates and insulation.

      A good understanding of the properties of air is a huge help as well as knowing how heat moves.

      Stay tuned and look for the part II next week.

      I’d like to thank everyone for contributing to this important topic. Folks please continue learning about vent-less VS. vented appliances.
      Then please when you need to speak up and pass on your knowledge of the safety factors when using stoves, heaters, fuels, Liquefied Gas / LP gas and the dangers of Carbon Monoxide poisoning inside any confined space or a home.

      You may just save someone’s life.

  22. I’ve lived in a now-63-year-old, 576 square foot house for 17 years, and find this information VERY useful. Much of it is also consistent with my experience….moisture, mold (I suspect, not only from plants but from my dirt crawlspace below). Boil a pot for spaghetti and every window is steamy (I have issues with grease, too, and have learned the ‘cover the pot’ trick.

    I’ve wondered about air quality from my (vented) water heater, which does have a pilot light running all the time…my gas furnace and drier are ignition driven. My windows are original to the house and drafty, so that’s always eases my mind a bit, but if I should replace the windows…? Looking forward to the insulation

    • http://www.advancedenergy.org/buildings/knowledge_library/crawl_spaces/pdfs/Closed%20Crawl%20Spaces_An%20Introduction%20for%20the%20Southeast.pdf

      Copy and paste this for more than you may want to know on installing a sealed crawl space.

      I have done several sealed crawl spaces. It is a lot of work, more so if it is low.

      I’m glad I did it. It lowered the RH inside and cut down on musty smells after hard rains. My wood floors would cup under my bed. (CLUE; If you ever see this you may have a crawl space moisture problem)

      You may also want to look up Basement systems. They will want to send a guy out if you request a information. It is free quote.

      The guys at Advanced Energy are the gold standard for modern building science. Have a building science question do a search at their site.

      Windows are expensive I need mine replaced, I have single pane with storm. I would be better off with insulated drapes and a good caulk and paint job.

      For now I am only dreaming of doing the paint job.

  23. Good article. I notice this issue is overlooked in a LOT of the builds I see. I’m currently working up the plans for my own tiny home. I plan on using the vented Dickenson 9500 but wall unit for heat to prevent excess moisture buildup and to ease any issues with carbon monoxide and oxygen depletion. As for the space station and NASA vis-a-vis the mold issue on the space station? You better do some research before giving NASA too much credit here. There’s been panels, etc removed (IIRC) that were found to be hiding huge stashes of molds, etc. From what I’ve read the whole dam thing smells like monkey butt now. I plan on also incorporating the smallest 5000 btu air conditioner I can find into the build for both moisture and temperature control. In theory, even a small unit should handle the interior space of a well insulated tiny home. Wish me luck. I’d also be curious if anybody knows of an ‘active’ system of air handling for these tiny homes? Something with sensors and relays that can auto-adjust air quality ‘on the fly’. I know they have these types of air handling systems in large buildings. I don’t know if it would even be a factor in something so small as a tiny house, but on the other hand, I can’t help but wonder if perhaps a tiny home isn’t exactly the kind of airtight environment these types of systems are built for? Enjoy.

  24. Great discussions. I am planning a tiny house build here in Montana. I also am in the HVAC business. Not that I’m always right but I have some plans. We do not have much for humidity problems outside here, but new homes are a bugger. We install lots of HRV s here in the tight homes. They work great, bring in fresh air while warming it up first and exhausting stale, moist yucky air. We use mostly the Venmar and the Lifebreath. We have been real happy installing both. These can be set on a timer to run let’s say 10 or 20 minutes an hour. Can run when manually switched on. They can have a humidistat so also humidity triggers them to come on. The draw back is power consumption and the cost. These on the low end are $ 1200 or so.
    One system we installed worked on motion. So when you entered the shower for instance the system ran for 20 minutes.
    My utility closet will be air tight to the inside and outside with a small combustion air intake for my small tankless water heater.
    Broan makes some good inline duct fans. I will design in 3, 4 inch ducts to my utility closet. This is helped by my 2×6 walls and framing; cold up here. Oh yes fantech makes some better ones but are pricey. So one inlet goes over toilet n shower, one will go to my small hood over my LP gas range, one will go in the middle highest point I can get in the ceiling just below attic. I think I will design that the inline fan sits in my little air tight utility closet. Air tight also keeps the noise down. Inline fans are much quiter and do not have to be in the living space. The controls can be as simple as a manual dial timer, 1 – 20 minute for example. The fan can also be hooked to a humidistat. Most likely will have timer over my range and one by the shower. Yes efficiency is affected but always have fresh air. This would be one fan, in a sound proofed spot that will pull air from 3 places. The same amount of air pulled out has to be replaced. So my vent to the outside will be small and strategectly placed; possible behind my Kimberly wood stove. Lots of Dead Beatle killed wood everywhere, might as well burn it. If done right you will not here this running. So once in a while will have to be sure it’s pulling air. You need the broan with multi ports to pull from more than one space. Usually has a 6″ exhaust port to go to the outside with a small hood or vent cap on the exterior. The interior at least the ones I’m looking at are 4″ and can take up to 4 inlets. Lots more to it all but I’m tired of typing. Another thing, Mitsubishi this year launched a 30 SEER heat pump air conditioner. Very low amps needed. They come in 9,000, 12,000 and 15,000 btu s . We can heat with this for less than 1/2 the cost of propane here in Montana anyway. In 13 years we have installed over 450 of these. Look close at these. Might be worth the extra 2 solar panels and extra battery to run this once in a while on electricity. Plus will have ac and heat. These shut off at 14 below zero, but hey need other heat anyway. Very quiet and a perfect fit high up on the high wall. Also AC’s are great moister extractors, so really this one unit serves so many purposes.
    Oh yes the Kimberly stove pulls in air from outside for combustion.
    Every house needs at least 2 Carbon Monoxide alarms…I don’t care how new or old the house. Dead and buried is expensive too…


Leave a Comment