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Can Occupants Be Trusted to Control Their Home’s Ventilation System?

Ventilation Eco Touch Controller Fantech

ventilation eco touch controller fantechOne of the points of contention in the great ventilation debate is whether a home’s occupants should control their own ventilation systems. The issue came up again in my article last week, Does a Gas Furnace Dry Out the Air in Your Home? I wrote that occupants should have control of their ventilation system and experiment with the rate to help prevent drying out the air by diluting it with too much cold, dry outdoor air. Paul Raymer, a friend and member of the ASHRAE 62.2 committee, then questioned me on that:

One of the points of contention in the great ventilation debate is whether a home’s occupants should control their own ventilation systems. The issue came up again in my article last week, Does a Gas Furnace Dry Out the Air in Your Home? I wrote that occupants should have control of their ventilation system and experiment with the rate to help prevent drying out the air by diluting it with too much cold, dry outdoor air. Paul Raymer, a friend and member of the ASHRAE 62.2 committee, then questioned me on that:

“We can make ventilation system controls that do pretty much anything like vary the rate automatically in response to other factors, but what would those factors be and would anyone be willing to pay for such controls? Do you know of any data that would tell us the percentage of impact from the mechanical ventilation on the RH in the house?”

The issue first came up in this blog about a year ago, though, when Michael Blasnik wrote in one of his comments on my article about blower doors and mechanical ventilation:

“I’m also surprised how you (and Joe) are so adamant about mechanical ventilation but then think we can rely on occupants to set their own ventilation rates. That would be a good idea if radon, asbestos, CO, and other pollutants were all smelly — but they aren’t.”

The Joe he referenced is of course Joseph Lstiburek, PhD, PE. He and Michael went back and forth in what was probably the best comment debate ever hosted by this blog. In one of Joe’s comments, he wrote:

“In our experience, the occupant is more intelligent on setting acceptable ventilation rates specific to them than the members of the ASHRAE 62 committees.”

Then, last summer I interviewed Paul Francisco, chair of the ASHRAE 62.2 committee, and he told me:

“I don’t believe homeowners should have no control. I also think that homeowners can’t detect a lot of potential indoor air quality hazards and they’re not knowledgeable enough to know what levels of ventilation they need at any particular time.”

The heart of the issue is the same one that has Joe riled up enough to create his own ventilation standard: What ventilation rates should we recommend for homes? Joe has been giving talks about the issue over the past year and says the rates we recommend are based on research about odor control. Dr. Max Sherman of LBNL sees things differently, and I’ll come back to the question of optimal ventilation rates in another article.

Today, though, I want to throw the question of occupant control out to our readers. Can occupants be trusted to control their own ventilation rates? If they adjust the rate based on their own experience of odors and relative humidity in the home, are they endangering their health. Besides odor and RH, what other factors are important? Tell me what you think.


N.B. If you’re going to the ACI National conference in Detroit this year, I’ll be a moderator of a panel on this topic: The Ventilation Standard Debate – Real Housewives of 62.2. Duncan Prahl of IBACOS put it together and is the other moderator. The panelists will include Joe Lstiburek, Michael Lubliner, Don Stevens, and more. You really don’t want to miss it!


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ASHRAE 62.2 Committee Chair Predicts Confusion & Frustration from BSC-01

A Blower Door Can’t Tell You How Much Mechanical Ventilation You Need

Interview with Dr. Joe Lstiburek — The Ventilation Debate Continues

This Post Has 22 Comments

  1. Unfortunately people just
    Unfortunately people just come in all types.  
    I’ve had some people who wouldn’t even remember to turn their ERV on without reminding. And I had some people who do want to play around with it, but mostly as relates to getting optimal RH levels. The second camp is made up of those pesky engineer types, and are probably the minority.  
    In both cases though, selling ventilation to begin with was not all that easy, because you selling a system protecting against largely unseen dangers. What exactly ARE the health issues associated with long-term living in a very air-tight house? I don’t really know, honestly, but I imagine they are of the long-term and chronic type rather than the acute and noticeable type. If people have a hard time even understanding why they need this thing to begin with, I suspect that more will fall into the camp of forgetting about their ventilation system altogether. I don’t know if the answer is to completely take control away from even the forgetters, though, so much as it is to push harder to get ventilation out there as a concept, and into that list of things you deal with when living in houses.

  2. This is an important debate
    This is an important debate to have, but it seems to me that we’re missing an ingredient: clear, easy-to-understand IAQ info. that’s available to the homeowner. Think about how cars have evolved so that you get a dashboard alert when tire pressure is low. In order to finally and totally cede ventilation control to homeowners, we need to develop new technology that measures and displays key IAQ indicators. I envision a digital display (or smartphone ap) that graphically shows a green-orange-red gradation of radon, particulates and other IAQ variables, with accompanying mitigation information related to ventilation adjustment. Back to the car analogy: You see the icon; you know what to do. In 10 years, this technology will probably be required on all Passive houses.

  3. Leigha D.:
    Leigha D.: I agree that we need to “get ventilation out there as a concept, and into that list of things you deal with when living in houses.” 
    Steve C.: A simple timer control, where you set the number of minutes the system runs each hour, should work for the lowest-tech occupants. A more complex one, like the Fantech controller shown above, should satisfy those who want more options. 
    Paul A.: Yes, education is a huge part of it. 
    Tim S.: Absolutely! We need more “clear, easy-to-understand IAQ info. that’s available to the homeowner.” 

  4. To answer this question, it
    To answer this question, it would be helpful for us to take a step back and look outside our field. Let’s look at cars. Given how dangerous cars can be, one could argue that we shouldn’t entrust control of vehicles to humans who can make judgement errors, get distracted, or operate the vehicle impaired, leading to deathly results. But of course, we the people would not accept Laws (or standards) that took away our ability to control our own vehicles. Instead we continue to develop a combination of technology, laws, and education that continually drive down the negative outcomes that still result from poor operation of vehicles. So, let’s think about IAQ and ventilation in this light. Can we all accept that a knowledgable, skilled occupant can operate a ventilation system more effectively than a committee? If you didn’t answer yes to that one, you’re a hopeless curmudgeon. For the rest of us, let’s focus on improving the Technology, the Rules (i.e., standards), and the Education such that home ventilation will be operated as safely as possible for the benefit of the occupants, without removing all control from the occupants. Conceptually, it’s that easy. In practice there are some devilish details. But, seriously, do any of us think ventilation issues are any more complicated than automobile safety? In fact it’s way simpler, and the stakes are not as severe. We can do this – but not if we try to do it all through the standard alone or through automated technology without user input. Both approaches are doomed to failure. Let’s use this as the foundation of our debate, and not waste time arguing which part of solution is better.

  5. Steve B:
    Steve B: There’s only so much we as professionals can do. As Eric wrote below your comment, we trust people to drive cars, and the consequences of that can be much more severe. 
    Eric W.: Hear, hear! Look for an article soon about your Experts’ Session presentation last month. 

  6. Steve Jobs famously said,
    Steve Jobs famously said, “Our customers don’t know what they want until we tell them,” (or words to that effect). Arrogant? Sure, but frighteningly correct. 
    If you don’t know what the technology has to offer, how can you be expected to make a rational judgement? If home occupants don’t understand IAQ issues, how can they be expected to make reasonable choices? 
    We need good systems set up by knowledgeable people, with occupants given the information required to use the system properly. But occupants must have the ultimate control. (In the car analogies mentioned earlier, think of automotive stability control: designed to prevent certain serious accidents, but the driver can turn it off — for good or ill!)

  7. I agree with David G the most
    I agree with David G the most. Set it at a minimum level, then give homeowners the ability to increase the speed when they feel they need it. This covers the people who don’t care and the people who do – doing no harm. 
    As far as RH goes, with a communicating thermostat like an Ecobee, it will automatically manage humidity and, in the case of an Ecobee, do datalogging so you can see how well it actually manages it so you can make adjustments, if necessary. If the base level ventilation rate is too high for the humidifier to keep up, back it off a little, or vice versa. A little continuous commissioning can go a long way, HVAC contractors could do it at their AC and furnace tuneup calls.

  8. We absolutely have to trust
    We absolutely have to trust homeowners. We (?) must provide tools and feedback to allow the control, and the best goal would be to then create automated (easy to use and monitor) control systems that manage reasonable strategies.  
    If the homeowner wants to bypass, or deactivate the sytem, then it’s their right to do so. The question now is, does the control system provide a comfort level that the owner will use, and trust it? On/Off is probably too simple and does not provide any performance feedback to let the owner know even IF the system is working.

  9. My thought; install a control
    My thought; install a control that the owner can access, but not too easily [up high, behind some ducts :)]. And include an easily seen disclaimer to let them know if the setting is changed they assume all responsibility for problems. I’m remembering the home where the owners allowed mold to grow until the home had to be burned down, then blamed the builder. I agree that most owners won’t know or care about the reason for, operation or control of the ventilation system, but will turn it off to save on the utility bill. I get a lot of, “We have to make the house tight, then ruin it by pulling in outside air anyhow.” Unfortunately I don’t see the large majority of home buyers, so there’s no opportunity to have the proper discussion.

  10. Absolutely not! This is not
    Absolutely not! This is not an arbitrary comfort issue (like room temperature), this is ventilation to promote a healthy environment. First order of business – define what a healthy environment is. And, oh by the way, this is not new science. How long have submarines been in operation? How long have modern mining operations been in operation? What about the decades of study and application from NASA? The answer (and probably the solutions) are already old tech. Looks more like politics than science at work in residential air quality.

  11. If the ventilation system is
    If the ventilation system is dumber than me, then I need control to partly work around its dumbness. When I take a shower I turn on my dumb extractor fan that is too dumb to realize that I’m taking a shower. I didn’t realize that was controversial. 
    If the ventilation system is smarter than me, then I don’t need control, and I won’t use it if I have it. 
    A fixed rate ventilation system is dumber than me. Neither of us can smell radon, but at least I can smell methane.

  12. No we can’t be trusted to
    No we can’t be trusted to manage when we don’t have measurement. Seems absurd to suggest this is anything but the best of a bunch of bad choices.  
    But until we have control systems that MEASURE and respond (such as this vent hood, I think the occupants need to have range of control or they will be inclined to simply shut ventilation off.

  13. Customers that care enough
    Customers that care enough about IAQ to pay to have ventilation controls installed are typically capable of operating them properly. IAQ controls are still rare in OKC, less than 1 in 100 homes have them installed. The 1 out of 100 has a simple fan cycler control with an outdoor intake. I’ve NEVER seen an HRV installed in the 100’s of homes I’ve been in.

  14. Occupants can control their
    Occupants can control their ventilation system, if it is designed and built smartly. Filter change alerts, outdoor pollution shutoff, variable rate based on numerous inputs (including occupant), and VOC sensors. 
    I was building a ventilation control system (VentWright) that measured outdoor temperature, humidity, wind speed, and had an occupancy count dial next to the thermostat. The occupant sets the dial up or down based on the number of people in the home, and could program a setback for “0” occupants when folks go to work. The control system would reduce mechanical ventilation if infiltration increased due to wind or delta-T, a much needed control in older existing homes. Then I came across LBL’s RIVEC ventilation control system. Seems they’re all over this concept with a provisional patent. So I guess I can only use my system for my own home. When can I buy a RIVEC system?

  15. I think we need to give
    I think we need to give occupants control. If we do not they will do other things to regain control. Some of their interventions will be energy intensive. Others will be just plain dangerous. 
    I recently audited an apartment complex with timed light switches hooked to the exhaust fans. So people were not using the light. They were using table lamps in the bathroom to take shows and baths with. 
    Perhaps the choice should not be a Black and White: ON / OFF. 
    I have 3 modes on my ERV. OFF / ON and when the air handler runs. I’m considering adding some type of timer to the ON and the air handler modes. The timers I’ve looked at to this point are not user friendly. They are set and forget, never change them again. 
    I wonder if NEST will add a controller for MV some day?

  16. We can be moderately
    We can be moderately successful in making a mechanical device do what is needed. Homo Sapiens is not a mechanical device, and getting them to do anything in particular is much more difficult and less successful. Automobiles have way more things that are not under our control than are under our control based on many years of development. hydraulic brakes, collapsible steering columns, suspension systems that are well behaved, air bags, etc. etc.

  17. Y’all should be talking to
    Y’all should be talking to Google. Larry and Sergey just bought Nest: show them a market, tell them what you want (all good ideas above). I bet Nest will respond, or maybe it’s already being designed.

  18. I like the comparison to a
    I like the comparison to a operating a car. 
    What is necessary for anyone to operate ventilation is a good controller, one with at least some idiot lights. After all the homeowner is the one observing the control.  
    The question is how many types of sensors does a control need & are they even available in a form to integrate into a controller. 
    The answer is, the number of pollutants which appear to be present on an ongoing basis. 
    Since temperature & humidity impact things the controller should work with heat/cooling. 
    I like the comparison to a operating a car. 
    What is necessary for anyone to operate ventilation is a good controller, one with at least some idiot lights. After all the homeowner is the one observing the controls. 
    So now it should monitor not only air temp & humidity but the interior & possibly exterior wall/mass temps. 
    Ideally it would monitor several places in the house. 
    Well this bad boy is going to have some cost, no? 
    I’m ready to take my cut! 
    The alternative is to start identifying & eliminating materials & substances used in homes that are significantly polluting the air, in other words, just smarten up!

  19. Yes, we need measurement and
    Yes, we need measurement and control for IAQ. 
    The controls can have scientifically derived maximums, just like a space heating thermostat has a (pipe freezing) minimum of 45F. 
    With this “set and forget” control logic, ASHRAE 62.2 is moot and can be ignored. The “great ventilation debate” will be over.

  20. Too many geeks in this
    Too many geeks in this discussion. We love you and need you but we expect your job is keep our home life simple. We have enough entertainment, computers, appliances, etc with controls to maintain.  
    Complicated electronic systems affects just about all trades and professions. When they walk through the door at night they want simplicity, rest, relaxation, uncomplicated and pleasure. The systems need to meet their needs. It is the industry’s purpose to develop such systems.  
    A good example is the Prius with simple controls and informative monitors. Sophisticated, safe and user friendly, but controlling in some areas. And I do not like the safety belt the first few blocks, annoying but it can be tuned out.

  21. In my house built in 2012
    In my house built in 2012 (Seattle area) the biggest problem with the ventilation is that it brings in cold air in the winter and hot air in the summer because it uses the furnace fan. The second problem is in the winter the humidity is very low. If a homeowner has the kitchen hood on and some bathroom fans on for a while the RH will drop noticeably (from 45% down to 28%). A homeowner should be able to turn off the ventilation if it’s blowing cold air on a 35 deg F day or if the RH is already low. The ventilation sounds good in theory, but in practice it’s a loud energy hog that causes uncomfortable temperatures, uncomfortable humidity levels, and it’s a nuisance. I’d rather turn it off year round, live with low ventilation rate (though I’d argue that the kitchen and bathroom fans provide more than adequate ventilation) in the winter and open the windows during the summer. What if I had a window open or I was moving furniture and the door was open for a long time? I think Joe is right, until you can prove with scientific data that certain ventilation rates are necessary you can’t scare homeowners to turn ventilation fans back on.  
    The End

  22. Dorel: Just turn the
    Dorel: Just turn the ventilation off. There is a switch required for you to do that. When your window sashes rot, and/or you grow a mold farm, and/or you get lots of critters, and/or occupants start to have respiratory problems, then turn it back on. Or, you could install a less-than-the-cheapest ventilation system. You get just what you pay for, no more.

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