3 ms·

Indoor air pollution from gas combustion appliances can actually be worse in newer homes because they are so much less leaky (and by consequence more efficient)

by danans 4y ago

Indoor air pollution from gas combustion appliances can actually be worse in newer homes because they are so much less leaky (and by consequence more efficient) than older homes. New building codes call for mechanical ventilation, but not nearly enough to compensate for the byproducts of combustion appliances or other sources of indoor air pollution. The best solution (an airtight house with 24/7 whole house mechanical ventilation with heat/humidity recovery) is sadly still the stuff of high end green homes. If you cook with a gas stove, you should open windows and run your extractor fan at max when cooking.

aclatuts 4y ago
Some higher end homes have a make up air system for venting a stove top in air tight houses, but it is so expensive.
- ed25519FUUU 4y ago
  Are you describing something different than the overhead fan equipped above the gas range in most new homes?
  - danans 4y ago
    They are describing a system that automatically creates a path for replacement air when the overhead extractor fan turns on, which is also achievable by opening a window. Absent replacement air, stove extractor fans (like any extractor fans) cause an airtight house to experience negative pressure and reduce the effectiveness of the fans.
- thinkcontext 4y ago
  I believe you are referring to a Heat or Energy Recovery Ventilator (HRV or ERV). In the absence of a range hood they would be better than nothing. But they aren't designed for the large volume of air changes that cooking requires.
bgentry 4y ago
I have a new house (built in 2020) and it did come with an inefficient, underpowered mechanical ventilation intake that just pulled outside air directly into the home. Given the house is in Austin, Texas where the weather outside rarely matches the conditions inside, this results in a lot of cooling or heating loss, as well as losing the humidity conditioning of the indoor air. It's no wonder that I regularly hear locals advising folks to simply turn off the mechanical ventilator; bringing in hot, humid summer air or cold, dry winter air is not good, even if the fresh air is. That's why shortly after moving in, I had the garbage ventilator replaced with an ERV. Based on my research I selected a Renewaire EV-Premium L, a variable speed unit which does up to 280 CFM. That's a ton of fresh air, even for a 4300 sqft house. But importantly it preserves some of the temperature and humidity when exchanging the air, so it's a lot more efficient than a plain mechanical ventilator. I have it wired into my Ecobee thermostat. It runs at its configurable low speed 24/7, and the Ecobee puts it in boost mode (full output) for 10-15 minutes per hour. This setup did cost some money of course, but the $2000 cost was pretty minor in the context of a new home. With this setup, we never see a buildup of CO2, VOCs, etc indoors. Definitely worth it when we're both working from home and spending most of our time there. And although we have a gas cooktop, I never see any indoor air quality issues so long as we're running the hood while cooking. I hope indoor air quality becomes a bigger priority for homes, offices, and schools. The building codes in this area haven't yet caught up to the need for improved ventilation to account for how much better sealed up modern buildings are.
- alliao 4y ago
  is it humid where you are? I'd love to have ERV but I'm in Auckland, NZ where dew point is bit of an issue and house sized dehumidifier isn't common as weather's temperate and heatpump only really caught on in the last decade or so. central air not common.
  - bgentry 4y ago
    Yes, Austin is quite humid relative to most of the US, though not quite as humid as along the gulf coast (i.e. Houston or New Orleans). The ERV was easy to tap into our existing central air system (which is where the crappy ventilator was connected) but if you don't have central air then it's going to be challenging to ensure quality air throughout your home.
alliao 4y ago
i've really come full circle on the whole housing thing. At first I hated leaky old buildings, looked into passivehaus standard etc, wanting to minimising all air leakage. then I read about the NYC's oversized steam powered heater that allowed you to open windows during winter to achieve proper air change per hour during Spanish flu. Later on I looked into ERV systems for ventilation, which threw me down path of looking at dew point as when introducing a lot of outside air, humidity becomes an issue. now I'm convinced plenty of older buildings actually considered a lot of these things, I saw many cottages in NZ angled properly to receive the ideal amount of solar gains in different seasons which naturally ventilated and are pleasing to be in. very rare, but they do exist, and as result only a very small heatpump is required to minimally push the comfort envelope one way or another. I guess what I am saying is don't fight the nature if you can, and architecture it properly. failing that, airtight + mechanical ventilation is going to be expensive and probably impossible to hit good air quality (6ACH+)...
- danans 4y ago
  > then I read about the NYC's oversized steam powered heater that allowed you to open windows during winter to achieve proper air change per hour during Spanish flu. > I guess what I am saying is don't fight the nature if you can, and architecture it properly. Oversized steam heaters are exactly fighting nature, are they not? Really, every building system is a fight against nature. The idea is to exploit properties of materials and the forces of nature when you can to get closer to whatever your chosen optimum is without having to fight nature so hard. It's not even that hard build to near PassivHaus standards for airtightness these days with regular materials (I did it). It does take an intention to focus on airtightness, which most production builders don't have. > failing that, airtight + mechanical ventilation is going to be expensive and probably impossible to hit good air quality (6ACH+)... 3ACH is plenty for good indoor air quality. I got close to that once with a whole house ventilating fan that cost $300. HRV/ERV are more expensive, but they also do heat recovery and air filtration, and provide consistent air quality everywhere.

by danans 4y ago

aclatuts 4y ago

Some higher end homes have a make up air system for venting a stove top in air tight houses, but it is so expensive.

ed25519FUUU 4y ago
Are you describing something different than the overhead fan equipped above the gas range in most new homes?
- danans 4y ago
  They are describing a system that automatically creates a path for replacement air when the overhead extractor fan turns on, which is also achievable by opening a window. Absent replacement air, stove extractor fans (like any extractor fans) cause an airtight house to experience negative pressure and reduce the effectiveness of the fans.
thinkcontext 4y ago
I believe you are referring to a Heat or Energy Recovery Ventilator (HRV or ERV). In the absence of a range hood they would be better than nothing. But they aren't designed for the large volume of air changes that cooking requires.

bgentry 4y ago

I have a new house (built in 2020) and it did come with an inefficient, underpowered mechanical ventilation intake that just pulled outside air directly into the home. Given the house is in Austin, Texas where the weather outside rarely matches the conditions inside, this results in a lot of cooling or heating loss, as well as losing the humidity conditioning of the indoor air. It's no wonder that I regularly hear locals advising folks to simply turn off the mechanical ventilator; bringing in hot, humid summer air or cold, dry winter air is not good, even if the fresh air is. That's why shortly after moving in, I had the garbage ventilator replaced with an ERV. Based on my research I selected a Renewaire EV-Premium L, a variable speed unit which does up to 280 CFM. That's a ton of fresh air, even for a 4300 sqft house. But importantly it preserves some of the temperature and humidity when exchanging the air, so it's a lot more efficient than a plain mechanical ventilator. I have it wired into my Ecobee thermostat. It runs at its configurable low speed 24/7, and the Ecobee puts it in boost mode (full output) for 10-15 minutes per hour. This setup did cost some money of course, but the $2000 cost was pretty minor in the context of a new home. With this setup, we never see a buildup of CO2, VOCs, etc indoors. Definitely worth it when we're both working from home and spending most of our time there. And although we have a gas cooktop, I never see any indoor air quality issues so long as we're running the hood while cooking. I hope indoor air quality becomes a bigger priority for homes, offices, and schools. The building codes in this area haven't yet caught up to the need for improved ventilation to account for how much better sealed up modern buildings are.

alliao 4y ago
is it humid where you are? I'd love to have ERV but I'm in Auckland, NZ where dew point is bit of an issue and house sized dehumidifier isn't common as weather's temperate and heatpump only really caught on in the last decade or so. central air not common.
- bgentry 4y ago
  Yes, Austin is quite humid relative to most of the US, though not quite as humid as along the gulf coast (i.e. Houston or New Orleans). The ERV was easy to tap into our existing central air system (which is where the crappy ventilator was connected) but if you don't have central air then it's going to be challenging to ensure quality air throughout your home.

alliao 4y ago

i've really come full circle on the whole housing thing. At first I hated leaky old buildings, looked into passivehaus standard etc, wanting to minimising all air leakage. then I read about the NYC's oversized steam powered heater that allowed you to open windows during winter to achieve proper air change per hour during Spanish flu. Later on I looked into ERV systems for ventilation, which threw me down path of looking at dew point as when introducing a lot of outside air, humidity becomes an issue. now I'm convinced plenty of older buildings actually considered a lot of these things, I saw many cottages in NZ angled properly to receive the ideal amount of solar gains in different seasons which naturally ventilated and are pleasing to be in. very rare, but they do exist, and as result only a very small heatpump is required to minimally push the comfort envelope one way or another. I guess what I am saying is don't fight the nature if you can, and architecture it properly. failing that, airtight + mechanical ventilation is going to be expensive and probably impossible to hit good air quality (6ACH+)...

danans 4y ago
> then I read about the NYC's oversized steam powered heater that allowed you to open windows during winter to achieve proper air change per hour during Spanish flu. > I guess what I am saying is don't fight the nature if you can, and architecture it properly. Oversized steam heaters are exactly fighting nature, are they not? Really, every building system is a fight against nature. The idea is to exploit properties of materials and the forces of nature when you can to get closer to whatever your chosen optimum is without having to fight nature so hard. It's not even that hard build to near PassivHaus standards for airtightness these days with regular materials (I did it). It does take an intention to focus on airtightness, which most production builders don't have. > failing that, airtight + mechanical ventilation is going to be expensive and probably impossible to hit good air quality (6ACH+)... 3ACH is plenty for good indoor air quality. I got close to that once with a whole house ventilating fan that cost $300. HRV/ERV are more expensive, but they also do heat recovery and air filtration, and provide consistent air quality everywhere.