Ventilation in Humid Climates
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- čas přidán 5. 09. 2024
- Bryan talks a bit about outdoor air and why ventilation is an important but delicate subject in residential homes in humid climates.
Ventilation can refer to the process of bringing air in or exhausting it from a building. Bath fans and kitchen hoods are ubiquitous and can expel indoor air, but bringing in outdoor air effectively requires a bit more planning and care.
Bringing outdoor air into the home helps dilute harmful substances inside homes, including volatile organic compounds (VOCs) from cleaners, flooring, paints, and furniture. Outdoor air also dilutes carbon dioxide, which humans and pets exhale naturally (though house plants can also help control indoor carbon dioxide content). Ventilation also helps keep our indoor environments pretty close to the outdoor environment (given that the outdoor air environment is healthy and free of smog, smoke, etc.).
However, when we bring outdoor air inside, we need to watch out for the relative humidity. When the outdoor relative humidity is high, then the outdoor dew point is also high. Bringing that air into a cooler space will wring that excess moisture out of the air and make it "rain" all over the surfaces in the home, leading to insect problems and microbial growth. Older Floridian homes ("Cracker" houses) were designed before A/C was widespread, and many of these homes were "loose" with large breezeways and windows that were meant to be left open on hot days. Houses nowadays are much tighter, and VOCs and carbon dioxide can exist in much higher concentrations indoors.
ASHRAE Standard 62.2 requires buildings to bring in outdoor air to dilute and purify indoor air. However, Florida's high dew points present a challenge for bringing in outdoor air. Since the outdoor dew points are high, we often need to rely on filtering and dehumidifying outdoor air via a ventilating dehumidifier. A filter alone is not good enough to remove harmful spores and particulates from the air. ERVs and HRVs tend to work well in other parts of the country but have their limitations in humid climates. Ventilating dehumidifiers tend to be among the most practical solutions for tight homes in humid climates.
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Good video Bryan
Thank you for the video. I am living in Portugal. I have a very old apartment. No tight seal… wood windows on stone and plaster window sills. The humidity levels outside in the winter here are around 80-90%, and temps are in the 40s at night and the 60s in the day. There is mold growing on my cloths and walls.
Can I have a Zoom call with you? I need to know if a dehumidifier would be helpful (remember, no tight seal in this place), or if a portable convection heater would be good… or both.
Bryan's floridian dew point battle continues.
We use a ventalation Hoeywell dehumidifier with a honeywell 8000 tstat and a two stage zoned furnace at the company Im at in SC. We alsonhave high humidity and dew point temps
The company I work for does a lot of new construction & most of the builders are Energy Star which requires fresh air. We vent the fresh air pipe into the return (before) now most of our installs are into a coffin box. The fresh air essentially gets conditioned before it goes into the home. We are using a Honeywell controller which requires the tech to input home size, amount of bedrooms & com desired. We were wiring them up to only let in fresh air if the system had a call (heating/cooling). Then Energy Star said no that's not correct it needs to bring in fresh air even if theirs not a demand. I'm sure you can figure what happened then! (Tampa Bay area) What are your thoughts on this? We basically now just wait until 30 days after homeowner is in home & wire it to only bring in fresh air if theirs a heating/cooling call.
So, how about my condo here in Florida 14th floor. If I am going to be away for 90 days, should I leave my window cracked?
Is it possible to be cold and humid at the same time?
I'm not that smart with the topic but the basic is yes, but colder air hold less moisture than hot air due to it being more compact or whatever, so a 100% humid cold day wont feel as bad as a 100% humid hot day since cold air hold less
Very pertinent information. I sure hope everybody appreciates the amount of time you put into trial and error, research and true testing. I sure do. Keep up the great work!
You can be at 100% humidity at every temperature as a graph of dew point. A given volume holds less and less H2O at 100% relative humidity as you drop the temperature. Wind chill effect on skin can depend on the individual. Pretty much has Zee Dic said.
It's 6:am and my home is 69 degrees inside right now its going to be 107 where in live in Southern California today and it was 106 yesterday and never did I turn on my AC not even for a minute. Our humidity outside is 17% and my Bonair 5900 evaporative cooler is blowing like an AC. As long as some fool doesn't spark a brush fire we won't need to use our AC. Thats a 36 degree temperature swing without useing AC.
Why haven’t someone come up with pulsing the air handler’s heat strips to allow long run times to reduce humidity in the home? The ultimate whole home dehumidifying solution, and no extra unit needed.
Bryant Evolution extreme systems do have this ability but that wont bring in fresh air in a controlled way like a dehumidifier will.
@@synackack evolution extreme and infinity 26 (and 19, for that matter) will ramp down the compressor for better dehumidification but they won’t run electric heat for dehumidification purposes
I guess I need to throw away my pleather couch.