Let’s talk home ventilation and indoor air quality, Hearth.com style.

[Newbie78]

I would rather my house just breathe naturally through some leakage, than to have a super tight house.

I don't even want a vapour barrier. My building science from the late 70's, early 80's was all about sealing stuff up with a continuous, interior, impermeable barrier. After many years I realized it is all hogwash and plastic, glue board junk.

currently, the science is all about controls and crutches to correct too-tight sealing. Ridiculous.


toxic.

 

[EbS-P]

Yeah that's what I meant by pricey. Not worth it for the average homeowner application unless you absolutely love to play with this stuff.

Yes But if you have a new new house that gets a sub 2.0 AHC 50 blower door test you need fresh air. Your choices are an expensive ERV or an even more expensive ventilating dehumidifier and both would have the same control issues.

Why can’t ecobee have some block level programming in their app? Nothing that could damage equipment just read value and if then statements that turn equipment on and off like you could while standing at the unit.

I have my old battery thermostat. I’m half tempted to get a 24v transformer and wire the fan wire in parallel to turn on the blower when when the temps get below my set point.

 

[gthomas785]

The HVAC industry particularly in the US is 100% reactive. They will only develop a new product or feature when sales of their current products are either banned by code or tail off due to lack of demand. As you correctly noted the new houses are having ventilation problems which the general public is completely unaware of and even building trades are only starting to get a handle on it. It will be a while before the available solutions catch up. And I agree with you it's maddening since the capability already exists.

I personally have not had to worry about mechanical ventilation because my house leaks like a screen door, but if I were in your situation I would not hesitate to cobble together a homemade set of analog controls to monitor co2 and humidity. Set the CO2 sensor to control the outdoor air damper, dehumidifier based on humidity, and a pair of relays to call for fan whenever the air damper or humidifier is on. From what I could tell of your setup the heat/AC could then be totally independent and you just need to grab the G wire for ventilation. And forget the Ecobee, it's not like you'd really need to adjust the setpoints that much once you get them dialed in.

 

[EbS-P]

I think I have all new penetrations sealed up. Hvac contractor left huge gaps. Like two cans of foam big. Rim joists insulated and sealed on 25% of the perimeter. I will seal off woodstove flues this week.

We are now waking up to 950 ppm CO2 levels. Occupied with everyone home 750-850 ppm.

So at what regular occurring CO2 level would you start exploring ventilation?

 

[EbS-P]

My newest revelation is that manual J should include latent heat load of 200-800 btus per hour (depending on what the people are doing). So for our 7 member household that’s over 30 pints a day. I don’t know if that includes cooking and bathing (I don’t think it does. I think the load would be the same for a commercial space)

The point is, it is substantial. That’s 1/3 the capacity of my dehumidifier. And to be realistic it’s about 1/2 of what it is actually running at.

I’m running about 8 cycles per day. AC is not really at all.

 

[EbS-P]

Data
I have co2 data in a csv I need to look at when life slows down.

 

[Nate R]

So at what regular occurring CO2 level would you start exploring ventilation?

I've seen somewhere between 1000 and 1200 ppm referenced.
Where is the CO2 monitor?

 

[ABMax24]

Data
I have co2 data in a csv I need to look at when life slows down.

View attachment 314224 View attachment 314225 View attachment 314226 View attachment 314227

Don't waste your time, there is no CO2 sensor in the Ecobee, it just infers CO2 concentrations based upon the PM/VOC sensor in the unit.

 

[EbS-P]

I've seen somewhere between 1000 and 1200 ppm referenced.
Where is the CO2 monitor?

The eco bee measures VOCs and based on occupancy calculates CO2. It’s in the hallway next to the bedrooms. I also have. 60$ air quality meter in the dining room. They seem to correlate but are not calibrated.

Don't waste your time, there is no CO2 sensor in the Ecobee, it just infers CO2 concentrations based upon the PM/VOC sensor in the unit.

Right but it’s better than nothing and agrees with what I’m seeing on a separate meter.

 

[Poindexter]

Steep learning curve for me this summer. The Poindexters are relocating to a 2015 build apartment with HRV and no wood stove. Once we are done downsizing, everything left behind in the big (1980 build) house goes to the dump, the trades come in, the high maintenance behemoth goes on the market.

Home technology hasn't progressed perhaps quite as competitively as automobiles, but consider for instance a 1980 Chevy Corvette vs a Y2K Corvette, vs 2020. We Poindexters are just done trying to make a silk purse out of a sow's ear with the 1980 build.

I am coming down on the side of modularity. There are some pretty good standalone dehumidifiers out there. I can think of a couple units I have seen lately that can fit through a crawlspace trapdoor (unboxed) nominal maybe 14x18x30 inches. About $300. I actually started shopping for accurate hygrometers today, but the dehumidifier units I am familiar with do well enough compared to the instrumentation I have, judging by the lack of rust on the edges of my woodworking tools.

It is nice to have everything all in one system. Like a giant diesel pusher class A RV riding around with a rock and roll band inside. But when you need a brake job, wouldn't you rather have a big crew cab from a major mfr, and a fifth wheel RV? Or your AC is acting up. I have never seen a pick up truck big enough to haul man and wife and 7 kids while towing a fifth wheel RV, but the fact remains it is easier and cheaper to service a common dually (Ford/Chevy/Dodge) truck than a niche Winnebago.

I am currently pointing at a pretty good house with OAK/woodstove/chimney for the really cold weather, and some kind of heat pump system for the shoulders that can do reasonable cooling in the summer. The heatpump area is not in sharp focus. I am planning on a bunch of solar panels. I think it will be less fussy, in a new build, to have the HRV/ERV system just move air with separate systems for heating, cooling and dehumidification. With all of those stand alone, I don't need one HVAC tech certified in everything with a firm grip on my short hairs. I can call almost anyone to work on the individual systems.

So far the HRV system we have rented is catching about 2/3 of incoming PM2.5 when it is running, with visible wild fire smoke in the outdoor ambient air. The HRV will probably do much better at filtering incoming air when the outdoor air is cleaner. I am keeping (have already kept) my existing indoor filter boxes for re-scrub the air inside the house between HRV cycles.

I do despise concealed duct work. If ducts are behind drywall they won't/ don't get cleaned. After we finish downsizing and sell the behemoth, and buy a lot, and build on it, the new house will have exposed ductwork for the ERV that is aesthetically pleasing in the house, but can be easily taken down and hosed out in the driveway as well. The idea of exposed duct work is an issue for Mrs. Poindexter, but the idea of decades of accumulated dust in the ductwork is an issue for Mr. Poindexter. We shall find a middle ground.

 

[gthomas785]

Why do you feel the need to clean ductwork? I have never cleaned my ducts and when I took a section apart to reconfigure it was clean as a whistle inside. A tight fitting filter on the return should be all you need.

 

[EbS-P]

Steep learning curve for me this summer. The Poindexters are relocating to a 2015 build apartment with HRV and no wood stove. Once we are done downsizing, everything left behind in the big (1980 build) house goes to the dump, the trades come in, the high maintenance behemoth goes on the market.

Home technology hasn't progressed perhaps quite as competitively as automobiles, but consider for instance a 1980 Chevy Corvette vs a Y2K Corvette, vs 2020. We Poindexters are just done trying to make a silk purse out of a sow's ear with the 1980 build.

I am coming down on the side of modularity. There are some pretty good standalone dehumidifiers out there. I can think of a couple units I have seen lately that can fit through a crawlspace trapdoor (unboxed) nominal maybe 14x18x30 inches. About $300. I actually started shopping for accurate hygrometers today, but the dehumidifier units I am familiar with do well enough compared to the instrumentation I have, judging by the lack of rust on the edges of my woodworking tools.

It is nice to have everything all in one system. Like a giant diesel pusher class A RV riding around with a rock and roll band inside. But when you need a brake job, wouldn't you rather have a big crew cab from a major mfr, and a fifth wheel RV? Or your AC is acting up. I have never seen a pick up truck big enough to haul man and wife and 7 kids while towing a fifth wheel RV, but the fact remains it is easier and cheaper to service a common dually (Ford/Chevy/Dodge) truck than a niche Winnebago.

I am currently pointing at a pretty good house with OAK/woodstove/chimney for the really cold weather, and some kind of heat pump system for the shoulders that can do reasonable cooling in the summer. The heatpump area is not in sharp focus. I am planning on a bunch of solar panels. I think it will be less fussy, in a new build, to have the HRV/ERV system just move air with separate systems for heating, cooling and dehumidification. With all of those stand alone, I don't need one HVAC tech certified in everything with a firm grip on my short hairs. I can call almost anyone to work on the individual systems.

So far the HRV system we have rented is catching about 2/3 of incoming PM2.5 when it is running, with visible wild fire smoke in the outdoor ambient air. The HRV will probably do much better at filtering incoming air when the outdoor air is cleaner. I am keeping (have already kept) my existing indoor filter boxes for re-scrub the air inside the house between HRV cycles.

I do despise concealed duct work. If ducts are behind drywall they won't/ don't get cleaned. After we finish downsizing and sell the behemoth, and buy a lot, and build on it, the new house will have exposed ductwork for the ERV that is aesthetically pleasing in the house, but can be easily taken down and hosed out in the driveway as well. The idea of exposed duct work is an issue for Mrs. Poindexter, but the idea of decades of accumulated dust in the ductwork is an issue for Mr. Poindexter. We shall find a middle ground.

After removing 50 year old duct work I don’t think exposed ductwork would be needed. Using rigid so it all could be cleaned once a decade might be a good choice.

But designing to heat with wood means your layout will easily circulate the conditioned air. Do you even need ducting? Why not just use a multi head mini split for heating and cooling?

The dehumidifier is nice when it’s ducted so one room doesn’t get all the hot air. I don’t have a good sense of how much a dehumidifier would run in your climate. Individual through wall room vents might be worth looking into.

I agree separate systems is easier. No good controller/thermostat exists that can do temp humidity and ventilation. I’d seriously look into a CO2 controller for ventilation. Why run it if you don’t need it. does it need to be variable speed?

 

[Poindexter]

I looked at CO2 detection technology today, reliable will not be cheap.

I wonder if accurate temp/RH readings both indoors and outdoors at the same time can be useful enough?

Every time an organism exhales, a little water vapor and a little CO2 comes out. Certainly a crock of home fermenting sauerkraut could run up the CO2 level without adding much to the humidity, or opening up can after can of sugary soda pop.

If I can buy enough solar panels I am willing to take all the heating BTUs out of the heat pump system. Now is a great time for me to stop humping 6-8 cords of wood every year. If I can drop that down to 1-2 cords I will be greatly relieved.

I am going to start with decent to good quality instrumentation for water. I do want to keep my shop space ten degrees above dewpoint so my tools don't rust. The current interior space, without AC, will need both humidification and dehumidification seasonally.

Besides HVAC, I like to think about HVAC-C. In my mind 'ventilation' is intentional exchange of air between indoors and outdoors. Circulation, again to me, is moving the air inside the house around, without it taking a detour through the back garden.

 

[EbS-P]

I looked at CO2 detection technology today, reliable will not be cheap.

I wonder if accurate temp/RH readings both indoors and outdoors at the same time can be useful enough?

Every time an organism exhales, a little water vapor and a little CO2 comes out. Certainly a crock of home fermenting sauerkraut could run up the CO2 level without adding much to the humidity, or opening up can after can of sugary soda pop.

If I can buy enough solar panels I am willing to take all the heating BTUs out of the heat pump system. Now is a great time for me to stop humping 6-8 cords of wood every year. If I can drop that down to 1-2 cords I will be greatly relieved.

I am going to start with decent to good quality instrumentation for water. I do want to keep my shop space ten degrees above dewpoint so my tools don't rust. The current interior space, without AC, will need both humidification and dehumidification seasonally.

Besides HVAC, I like to think about HVAC-C. In my mind 'ventilation' is intentional exchange of air between indoors and outdoors. Circulation, again to me, is moving the air inside the house around, without it taking a detour through the back garden.

I’m not completely sold on expensive CO2 monitoring to control ventilation. Once you understand how your home works I think simple time scheduling and occupancy monitoring can do. Pretty good.

Your new place will be tight ventilation will be needed. Is it 50 cfm? Maybe 10 minutes per hour? I think that is easy enough to figure out in the first year living there as long as you have a way to monitor CO2. (Data logging would be nice). Temperature and humidity are easy enough to control inside with a simple thermostat and or the built hygrometers on dehu units. Don’t see a need to complicate things unless you want to.

All the thinking, planning, research and designing are useless unless you find the right contractors. The attention to detail to get a house built to 1 ahc50 or below, I don’t think is profitable for many. And once that’s achieved getting any hvac contractor to do an unbiased load calc and actual trust the numbers it’s spits out… good luck.

I could see a wood furnace working well with the ducted heatpump. Add a whole house dehumidifier annd humidifier and HPHWH. It’s going to be a very complex duct design.

 

[Poindexter]

I did find a pleasant surprise on Amazon just now. It has a Plantronics 5003 particle counter on it, I am very happy with those. I am sure each unit has a life cycle and when mine start disagreeing with each other I will probably bring in this new thing that also has on it a Sense Air S8, for NDIR CO2 detection. You too can internet search on SAS8 'problems and reviews' to draw your own conclusions.

On the four particle counters like this I do own, I find the temp/ humidity sensors never have agreed with each other.

And I found my psychrometer.

Amazon product ASIN B0BWQ2TPM5
Amazon product ASIN B003NV6PXY

 

[Poindexter]

I’m not completely sold on expensive CO2 monitoring to control ventilation. Once you understand how your home works I think simple time scheduling and occupancy monitoring can do. Pretty good.

I fully agree with this. I went a little bananas, taping particle counters to the walls and so on while I was figuring out how the air in the big old house circulated, but I found one sensor for particles on the table beside my easy chair in front of the wood stove gave me, on that floorplan, a pretty good idea of whole house particles.

For temp/humidity I used a system of four sensors, three in battery operated remotes and one in the home station. I have two remotes in the crawlspace, one near the dehumidifier and one near where the water supply comes up out of the ground into the crawlspace. I can tell at a glance when it is time to go to the crawlspace and empty the dehumidifier bucket. And I have stopped worrying about freeze up down there. I ended up pulling all the rim joist insulation because it was mold metropolis. That is actually when the dehumidifier went in. I am sure my fuel bill went up a little bit, but the crawlspace sections of hotwater baseboard heat (with no fin pipe down there ) kept the crawlspace temp up in the +50s F even in deep winter.

 

[Poindexter]

We are now waking up to 950 ppm CO2 levels. Occupied with everyone home 750-850 ppm.

So at what regular occurring CO2 level would you start exploring ventilation?

As quoted by Washington State University, ASHRAE, the same HVAC industry group that came up that MERV rating system for furnace filters, suggests at or below 1000ppm in schools, and at or below 800 ppm in offices.

I found another page at the Minnesota DoHealth, also referencing ASHRAE, calling for 15 cfm per person in a classroom and 17 cfm per minute in an office "that should keep CO2 concentrations under 1000ppm." In all other workplaces Minnesota requires 15 cfm per person.

MN DoH also says "Occupants may experience health effects in areas with elevated levels of CO2, but these are usually found to be caused by other substances that are also increasing because of inadequate ventilation.

I found a page at Yale.edu citing "three recent studies (circa 2015)' have documented subtle declines in thinking ability when CO2 increased to 1000ppm.

OSHA 04-01-2016 calls for enough ventilation to keep indoor CO2 levels below 1000 ppm.

Illinois Do Public Health calls for CO2 to be maintained below 800ppm.

Clearly less is better, but some is inevitable. I did not see a CDC page. The various pages I did cite claimed outdoor CO2 levels are between 300ppm and 450ppm, so monitoring what your outdoor CO2 level actually is periodically is probably prudent.

 

[Poindexter]

It is starting to look to me, thanks to @EbS-P , that CO2 is a good thing to monitor and control for the health of the people in the building, while the Pretty Good House people make a compelling case in their book that controlling water is fundamental to the health of the building with the people in it.

I learned something today.

 

[Poindexter]

Your new place will be tight ventilation will be needed. Is it 50 cfm? Maybe 10 minutes per hour? I think that is easy enough to figure out in the first year living there as long as you have a way to monitor CO2. (Data logging would be nice). Temperature and humidity are easy enough to control inside with a simple thermostat and or the built hygrometers on dehu units. Don’t see a need to complicate things unless you want to.

I don't want to derail your thread, but I do want to answer your question. The new place is tight. The old place was not tight.

For overall total indoor air quality I was, in the old place, battling both outside air and the building itself. In the new apartment, the building is on my team, we are working together to battle the outside air and water for our mutual wellbeing.

As of today, I don't even have a picture of the MFR label on the HRV unit in my phone to look up later. I took two pickup loads of junk to the dump out of the old place today, we got 387 gallons of oil delivered to the old place today on autofill, blah, blah. Downsizing is a cold hearted witch, but also quite freeing when the time comes.

I do think the built in hygro on my existing standalone dehu is good enough. The HRV in the apartment is very simple. It is either off or on. There are two intakes, one each in kitchen and bath. There are two outlets, one in the bedroom and one in the living room.

I am going to obsess on the dewpoint in the shop space where my razor sharp and rust free handtools live. Whatever cudgel setting on the hygro in the dehu makes me happy is the one I will use.

I am going to sign back in to Amazon to order a CO2 monitor now. I am thinking less than 800ppm CO2 is the green zone, 800-1000 ppm is the yellow zone, and >1000ppm CO2 is the red zone.

 

[EbS-P]

I looked at CO2 detection technology today, reliable will not be cheap.

I wonder if accurate temp/RH readings both indoors and outdoors at the same time can be useful enough?

Every time an organism exhales, a little water vapor and a little CO2 comes out. Certainly a crock of home fermenting sauerkraut could run up the CO2 level without adding much to the humidity, or opening up can after can of sugary soda pop.

If I can buy enough solar panels I am willing to take all the heating BTUs out of the heat pump system. Now is a great time for me to stop humping 6-8 cords of wood every year. If I can drop that down to 1-2 cords I will be greatly relieved.

I am going to start with decent to good quality instrumentation for water. I do want to keep my shop space ten degrees above dewpoint so my tools don't rust. The current interior space, without AC, will need both humidification and dehumidification seasonally.

Besides HVAC, I like to think about HVAC-C. In my mind 'ventilation' is intentional exchange of air between indoors and outdoors. Circulation, again to me, is moving the air inside the house around, without it taking a detour through the back garden.

I do think the circulation helps lower CO2 levels one experiences (not necessarily measurable unless you have personal CO2 monitor). Levels build when the the occupants are stationary for periods of time. Moving all the air around, stirring it up lead to a more even mixture, lowering what you are likely to experience.

I really think everything you are wanting is best served by ducted system (Or systems). Zoning a single system is a compromise. Two floors two systems. A mechanical chase connecting all the conditioned spaces is a good idea (conditioned crawl space to second floor)

 

[stovexxx]

2 air intakes with external, possibly with diameter adjustable could guarantee continuous air exchange, certainly always monitor initially.