Tag Archives for " ventilation "

Hosting Responsibly

Hosting Responsibly

‘Tis the season for gathering together for celebrations!  More than a few years ago, “hosting responsibly” might be taken to mean monitoring alcohol consumption and driving.  Now, it also means providing good air quality where participants don’t need to worry about breathing in germs.  What a difference a few years (and a pandemic) makes!

In November 2022, in grocery stores, malls, airports and airplanes, masks and distancing are no longer mandatory.  There are also no mandatory distinctions between vaccinated and unvaccinated people.  I realize that although most places present as pre-pandemic, these norms can change at any time, and many people are still concerned about virus transmission and their health.  This elephant has been dressed up well, but he’s not going away, so it’s best to acknowledge him!

Letting your guests know about your preparations means letting them know you care, and make them even more eager to attend!  How can we get started?  Here are some questions for the host:

Is your home or gathering place well-ventilated? 

Here are a couple ways to tell:

  1. Do odors persist for hours if you don’t do anything to abate them?  This might be a little tricky to answer, because it’s definitely a good idea to use your kitchen exhaust fan while cooking, but if you clean up the food bits, wake up and can still smell last night’s dinner, there is likely a problem.
  2. Is the carbon dioxide level in your home below 1000ppm?  It’s really helpful (and surprising) to use a portable CO2 meter in your home and elsewhere.  It let me know that my house (built 1982 with building paper as the air barrier) is quite leaky at about 520-550 ppm CO2, but on the other hand, my parents’ house (renovated 2020) seems to be quite tight and in need of more ventilation (1500ppm)!  The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), which is the dominant organization in establishing proper building ventilation rates in the US,  is hesitant to use CO2 levels as an indication of proper ventilation in homes and businesses because of lack of research and a number of variables.  However it does state in a white paper on indoor CO2 levels
  • Indoor CO2 concentrations do not provide an overall indication of IAQ, but they can be a useful tool in IAQ assessments if users understand the limitations in these applications.
  • All else being equal, higher CO2 concentrations correspond to lower outdoor air ventilation rates and the potential for an increased risk of airborne transmission.
  • Rather than using indoor CO2 concentration as an indicator of desired ventilation rates, several analyses of airborne infection risk have used CO2 as an indicator of the “rebreathed fraction” of indoor air (the fraction of inhaled air that was exhaled by someone else in the space). (Yuck!)

So, although ASHRAE did not set these values (contrary to misquotes), the generally accepted values are consistent with these:

Source: Washington State University Extension Energy Program

So, if you take a reading on your CO2 meter and find that the difference between the indoors and outdoors is less than 650 ppm (which is normally about 1000 ppm indoors), your ventilation is “acceptable”.  Above that level, your guests will have complaints of fatigue, loss of focus and concentration, and an uncomfortable ‘stuffy’ feeling in the air, all of which indicates you are not getting enough fresh air. (Kaiterra.com)  Keep in mind that with more guests, more ventilation is necessary to keep the CO2 level down!  You can crack windows to add more ventilation.

Do you have active air purification?  If so, let them know!  Just as businesses are proud to advertise that they use HypoAir products to keep their clientele safe, don’t hesitate to let your guests know if you are using active air sanitation like the Whole Home Polar Ionizer, Air Angel or Germ Defenders.  In addition, a fresh furnace filter in a higher MERV rating and/or use of a standalone HEPA filter also increase the air quality. 

How about making your gathering indoor-outdoor?  If you have a patio or yard, string lights and a firepit or chiminea make for a cozy, festive ambiance!  In addition, the opening of doors when guests enter or exit adds fresh-air ventilation to your indoor space. If you decide to light a fire in the fireplace, cracking a window will help the fire burn better with less chance of backdrafting smoke into the room.

Have you thought about food and beverage service?

If we had a throw-away mentality before COVID-19, unfortunately the pandemic has only made it worse.  Restaurants have embraced using disposable food trays, utensils and drinking glasses for sanitation, however I suspect it is now more for convenience.  According to this 2020 study, the SARS-CoV-2 virus can remain viable on inert surfaces, with varying lengths of time depending on the surface: four hours on copper, 24 hours on cardboard, 48 hours on stainless steel and up to 72 hours on plastic.  With this evidence showing that cardboard and plastic are not anti-viral, you don’t have to follow suit with everyone else regarding what you serve on.  Instead of having a large trashbin in the center of the party (although some garbage is inevitable for sure), why not fill one side of the sink with soapy water, or leave a basin with soapy water, in which to submerge dishes?  I’ve always enjoyed using real dishes over plastic or paper, so if your gathering is smaller than your collection of plates, it’s not taboo to use china and stainless steel. Marking drinking glasses with a marker or tag ensures that everyone keeps their own!  You could even DIY inexpensive beverage glasses with your guests’ names as favors.  If you decide to go with single serve drinks, cans or bottles are still best marked to avoid confusion.

What’s more important, though, is how you serve.  It’s wise to designate 1 or 2 people as “servers” who can add helpings to individual plates in order to reduce handling of the serving utensils.  If “seconds” are available, it’s best to use additional clean plates to avoid contamination.  Wrap utensils in individual napkins pre-party so that no one has to dig through a bin to get their own.  

Set containers of hand sanitizer throughout your space, and most importantly at the food and drink service area.  

Have you made sure the bathroom is clean and inviting?

  • Provide antibacterial soap and individual paper hand towels
  • If you have a bathroom vent, consider installing a switch protector or sign so that it stays on throughout the party to keep the bathroom air fresh(er!)
  • Instead of buying deodorizers that can add toxic chemicals and VOCs to the air, re-package some TotalClean in a pretty glass bottle and label “air freshener”--it really deodorizes well!

Will you have chemically sensitive guests?

Ask guests to notify you if they have chemical allergies, so you can keep it scent-free if necessary.   If you've ever had a smell irritate your nose or even cause a headache, you have a inkling of what Multiple Chemical Sensitivity (MCS) sufferers go through.

  • It’s hard to pass up candles and sprays in holiday scents, but try to do it for the sake of your friends!
  • It’s also wise to use unscented, natural products like TotalClean to get a thorough clean on all surfaces without any scent.
  • Ask other guests to abstain from using scented personal items like perfume and deodorants.

Less Coffee, More Fresh Air!

Less Coffee, More Fresh Air!

At some point in most peoples’ lives, fatigue is a fact of daily life.  We can chalk it up to too much work and not enough sleep, or poor quality sleep, or a virus that seems to be “going around”.  But what if it could be as simple as not enough fresh air?  Simple…yet sometimes not easy to fix, when opening the windows lets in more harmful air than good.  Let’s dig into this “simple” cause…

Different regulations regarding ventilation have been around for a long time, way longer than the American Society for Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) published its first Standard 62 for ventilation. The first, ANSI/ASHRAE Standard 62-1973, Standards for Natural and Mechanical Ventilation, presented minimum and recommended ventilation rates for 266 applications and became the basis for most state codes.(ASHRAE.org)

This standard has been revised several times since 1973, and the current standard calls for homes to “receive 0.35 air changes per hour  but not less than 15 cubic feet of air per minute (cfm) per person.” (epa.gov)  Why?  According to Britannica.com, Clean, dry air consists primarily of nitrogen and oxygen—78 percent and 21 percent respectively, by volume. Without any other contaminants such as carbon monoxide (from combustion) or radon (from the earth) entering a building, humans change the composition because we take in oxygen and breathe out carbon dioxide.  Our lungs can still rebreathe this air “safely” until it decreases below 19.5% (OSHA threshold for oxygen in atmosphere), but increaseing levels of carbon dioxide (CO2) may cause occupants to grow drowsy, get headaches, or function at lower activity levels.  (healthybuildingscience.com)  What’s the threshold of CO2?  

  • NIOSH (National Institute for Occupational Safety and Health): 1,000 ppm (parts per million in air) are a marker suggesting inadequate ventilation.  

  • ASHRAE recommends that carbon dioxide levels not exceed 700 ppm above outdoor ambient levels.   (Normal range for outdoor levels are typically in the 350-450 ppm range). 

  • OSHA (the Occupational Safety and Health Administration) limits carbon dioxide concentration in the workplace to 5,000 ppm for prolonged periods, and 35,000 ppm for 15 minutes.  

Taking the most conservative route, 1000 ppm is only 0.1%.  Wow, it doesn’t take a lot of CO2 to make stale air!  If this is the gold standard, why are we suffering in stale air?   The answer is that  many places in the US do not require building permits in order to build or renovate a home.  For this reason, it’s up to the homeowner to know what is needed and make sure it’s installed.  If the HVAC technician does not design fresh air into the system, and the homeowner does not know about the need for it, the home won’t have it and the air will be stale.  Case in point: my 1982 home in the country.  It cools, heats, and circulates stale air.  

Take this tweet from Andrej Karpathy and Elon Musk, who know a bit about technology: 

And then the public chimed in: a Stanford professor used to take CO2 measurements in a lecture hall before packing 100+ students in for 1.5 hours, because some halls did not have enough ventilation to sustain deep thought!  Then a restaurant worker began to think, oh, so that’s maybe why I got dizzy sometimes during peak hours of a restaurant?  And another: his son used to wake up crying but since increasing ventilation in his room, the child sleeps a lot more peacefully.  

So if you want to measure your air, lethargy, unclear thinking and headaches don’t have to be part of your day!  There are lots of CO2 monitors on the market, with most starting about $65-70.   This monitor by INKBIRDPLUS shows temperature, humidity and CO2, and also allows you to customize an alarm for different levels of CO2 (they recommend normal (400-700 ppm), warning (700-1500 ppm), and dangerous (1500-5000 ppm)).  

Can you imagine measuring the CO2 while sitting in a conference room or in a lecture hall?  With such technology at your fingertips, there’s no reason to be ashamed to say “I need a break”.   Your brain and body will thank you!

Photo by Call Me Fred on Unsplash

Getting the Basement Dried Out

Getting the Basement Dried Out

In our post on how the basement affects our whole home’s air quality, we discussed how mold and mildew form and are sustained in the basement.  Active water leaks (flowing down the walls and pooled on the floor) are not required to make the basement a musty place.  Here are some sources of moisture coming into the basement:

  • Concrete is not a moisture barrier on its own!  Water will permeate concrete walls and floors and simply evaporate, increasing humidity.  
  • Open or broken windows allow moist air from the outside to come in and upon encountering cool walls and surfaces in the basement, condensation will form or just increase relative humidity in the air.  
  • Air leaks around windows, entry doors, unsealed wall penetrations and penetrations into the first floor above allow air to come in, in an uncontrolled way. 

Ideally the basement is inside your building envelope, whether you decide to finish it or not.  This is because it can be a suitable place for mechanical systems like HVAC air handlers and furnaces, hot water heaters, and also for storage.  To house these systems, however, the basement needs to be dry, with good air quality.  We argue that the basement air quality needs to be as good as any other floor in the home, because it will mingle with the atmosphere of the rest of your home!  There will be small leaks in the basement ceiling that make it permeable to the rest of your home.

The way to control humidity is to control:

  • Water flow into the space,
  • Airflow into the space, and
  • Air circulation within the space.

Let’s tackle each problem individually.

Water flow into the basement

Water flowing down walls in streams and puddling on the floor is a major problem– in this case, it is like living above a lake!  It will be difficult to “dehumidify” the air when open water is present, because the water will be continually vaporizing into the air as fast as a dehumidifier can take it out.  Although many basements exist like this, walls and storage of home goods in such environments can accumulate mildew rapidly.  Painting on a “waterproofing coating” will usually just act as a band-aid, because the pressure behind the wall, forcing it into your basement (called hydrostatic pressure) will eventually break through the paint and even degrade the foundation if it’s not drained away properly using interior and/or exterior drains. (basement waterproofing)  It’s best to contract several reputable basement remediation contractors in order to get their recommendations and quotes on stopping the inflow of water.  

If the water is only causing dampness on the walls but not visible condensation, then it’s possible to allow the walls to continually “dry” to the inside by doing the following:

  • Cracks and damage to the walls need to be repaired first.
  • Install rigid foam board with a “perm” rating of 1 or greater.  This allows the moisture to move through the foam and dry out, but still insulate the basement for greater thermal comfort and avoid condensation on the cold wall. Keep the foam insulation up about an inch from the floor to allow any condensation to drain.  If desired, the walls can be framed with treated wood to hang drywall inside.  An excellent cutaway diagram of the installation can be found here (page 24). Below is a picture of rigid foam board insulation from the same document (page 32).
  • An alternative to applying rigid foam board is to paint concrete walls with a waterproofer such as UGL’s Extreme Latex Masonry Waterproofer.  This product has a perm rating of less than 1 (according to this manufacturer’s video), so it is vapor semi-impermeable, but it does not have any insulating properties, like the foam board, so the walls will still be cold to the touch and allow condensation if the air inside is too warm and humid.  
  • Use dehumidification to dry things out.  
  • Decrease relative humidity by increasing the temperature slightly (the dehumidifier may raise the temperature a few degrees, but if not, you can add a small heater).
  • Increase circulation with fans so that air is evenly dehumidified.

Some notes on Vapor Permeability: A material’s permeability is measured in units called perms, which assess how much moisture can pass through a barrier in a 24-hour period according to standardized industry tests. Materials are separated into four general classes based on their permeance:

  • Vapor impermeable: 0.1 perms or less

  • Vapor semi-impermeable: 1.0 perms or less and greater than 0.1 perm

  • Vapor semi-permeable: 10 perms or less and greater than 1.0 perm

  • Vapor permeable: greater than 10 perms

Materials with lower perm ratings are better at stopping the movement of water vapor. If the perm rating is low enough, the material is a vapor retarder. If it’s really low, it is a vapor barrier. (Barricade Building Products)


Air flow into the basement

Sometimes it’s difficult to know what to do: open the windows or not?  Many reputable websites advocate “airing out the basement” (such as thisoldhouse.com), and we at HypoAir always advocate for ventilation to dilute stale air, but here’s the problem: when you don’t know the dewpoint of the air coming in or leaking in, it can cause major mold problems in the basement!  Dewpoint is the controlling factor of whether fresh-air ventilation alone can prevent mold.  As we wrote in another post

The best way to explain this (per this great article) is to find out the dewpoints of the indoor and outdoor conditions.  If the outdoor dewpoint is lower, you can ventilate with fresh air and still dry out your house!  For example on July 26, 2002, here are the conditions inside and outside my house (a relatively “dry” hot day outside!):

Inside: 76 deg F, 67% humidity = 63 deg F dewpoint (check out this easy calculator on dpcalc.org)

Outside: 91 deg F, 54% humidity = 72 deg F dewpoint (dpcalc.org)

See, in this case even though the relative humidity outdoors is lower, if I open my windows, that hot air coming inside would be cooled and relative humidity would increase, working against my humidity goals.

In the case of the basement, the air temperature could easily be lower, like 68 deg F.  If you cool 91 deg air with 54% relative humidity down to 68 degrees, water vapor in the air is going to condense, making your humidity problem worse!   Therefore we want to control all sources of air inflow and only let in drier air for ventilation.  Here is a diagram showing the problem of leaving windows open, and how to solve it:

source: bayareaunderpinning.com

  1. Close windows, block off vents, and seal the window frames with caulk, spray foam or adhesive tape made for the purpose.  Make sure exterior doors have weatherstripping. 

  2. Check for unsealed penetrations in the walls.  If you have to use a flashlight and look behind appliances such as water heaters or furnaces, be prepared with gloves and pest spray to get it done!  The best sealant for wall penetrations in the basement would be sprayfoam, because it conforms to the shape of the hole.  You may want to shove in a wad of steel wool first, because it deters animals from chewing through the foam and re-opening the hole.

  3. Look up–check the ceiling.  If there is a false ceiling in the basement, you may need to remove ceiling tiles and/or insulation in order to see the underside of the subfloor, but this is where big problems can hide!  The photo below shows the underside of a tub.  Plumbers often cut BIG holes to make their jobs easier, but this can really hurt air quality when these holes let lots of moldy air up (if there’s a negative pressure generated in the space above, this is easily done with a bathroom vent fan), or warm air down (if you are using any type of air extractor in the basement).  It’s best to seal big holes like this one by framing in a box to the surrounding joists, and using spray foam to seal the resulting cracks and holes.  It’s not recommended to insulate the ceiling of the basement (see this definitive guide, page 25) to try to separate it from the rest of the building, as this will only cause more mold problems in the basement.

Source: energyvanguard.com

Where does fresh-air ventilation come from if you’ve sealed outside access off?  According to energyvanguard.com, there are 6 ways to supply fresh air to your home in a humid climate, and for the purpose of a basement that is outside the building envelope, only one makes sense since you’re probably already using a dehumidifier: a fresh air fan that purposely pulls in outside air.  Here are some options to make it happen: 

  • Air King’s QUFresh, 120 cfm, $413 at ecomfort.com
  • Broan’s FreshIn, 180 cfm, $239 at sylvane.com
  • ACInfinity’s AIRTITAN T3 6-In Ventilation Fan, 120 cfm, $69.99, sylvane.com

The AirTitan is a good option where windows are available, because it can be retrofitted to fit in an open window more easily than the other ducted models.  Each of these models have temperature and humidity settings you can adjust so that the fan will only operate when it meets those specifications.  These may need to be set higher in hot and humid climates, but the dehumidifier should be able to handle moderate inflows of fresh air.  When you control the airflow into the basement, you can control the humidity.

And finally, Air Circulation Within the Space

Your basement may be one wide-open area, or several rooms separated by walls and doors, but in each case, good air quality requires that air is moving constantly.  Here are some tips to get the best circulation:

  • Leave doors within the basement open as much as possible
  • Leave dedicated fans running all the time.  Floor fans work great for this purpose, as you can move them around/adjust direction and speeds until you find the optimum circulation.
  • Move boxes and furnishings away from walls and up from floors so that air will circulate to dry them.  Don’t stack boxes to the ceiling.  Separate boxes by several inches to get air moving between them. 
  • Remember, the less absorbent material stored in a non-conditioned space, the better (less cardboard, less fabric, and less wood).

I hope these suggestions help you to dry out your basement so that your whole-house air quality improves, from the ground up!