Marks Supply
21
Sep/11

Relative Humidity

by ifutter under Uncategorized

When I was groing up in rural Ontario I used to marvel at the frost patterns that were made on our bedroom window on those cold February nights.  It wasn’t until years later that the terms Dew point, relative humidity, saturation temperature, enthalpy, wet bilb, dry bulb, sensible heat, latent heat or evpourative rate meant anything at all.  To-day all of these terms are found when studying psychometrics.  And this all come down to Humidity.

R.H. can be defined easiest by stating that it is the amount of moisture, as a percentage, that is currently in the air compared to what it could hold at a specific temperature. That is to say 20% RH @ 20C  is far less air bourne moisture than 20% RH at 30C. 

So, at what point does moisture collect on your windows in your house in the middle of the winter? Mmmm, that depends on the Dew Point.  Getting confused?

Let’s go at it like this; if your house is 24C and the outdoor temperature is -12C the glass in your windows could reach -6C, at that point the moisture in the air that is being held in suspension will condense against the cold glass as it cools. If a shower is turned on or food is being washed, boiled and prepared, then the moisture content of the air will increase (rise in RH) and more moisture will collect on the window. Soon the window becomes so wet that the condensation runs across the sill and down the wall to the floor. And the question becomes, How do you cope with it & control it?

With “Ventilation” ….. in any form, by any method available to you. The easiest way is to open a window about 1/2″ (1.26cm) as far away from an exhaust fan as possible and allow fresh cool air in. As the air warms it will expand and it’s RH will decrease allowing it to absorb more moisure as it makes its’ way across the house and out the exhaust fan to the outdoors.  And as new air comes in it carries out more moisture etc,etc and eventually your windows stop sweating and the RH in the entire house drops.

How much does this add to your fuel bill ?  30 x 1.08 x  77 x “fuel cost” (because nothing is free.) Can you minamize that expense? Yes.

With an HRV the calculated cost can be reduced as much as 80% or more.  And you can take that to the bank!

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3
Aug/11

Brownian Motion

by ifutter under Indoor Air Quality

　

With-in the realm of  air borne particles there are some LAWS that govern their creation, composition and modes of travel.This month we’re going to look at a phenomenon called BROWNIAN MOTION or “random walk”. Small airborne particles, some that never settle & others that settle out in minutes, have a random pattern of travel that they follow (randon walk). When minute particles such as mite carcases, smoke, viruses, bacteria etc are introduced into the environment they immediately begin to bang & bump & knock each other around as they are pushed by the natural air currents & convections with-in the space. Their direction changes constantly and hence the term “ramdom walk”. This, so far, is not amazing nor mystifying, but what is interesting is that all of these particles (whether solid or gas) will continue to bounce and vibrate with-in the confines of the space until the distance between each of them has equaled out. Something like the equalizing of pressure in a tire or a balloon. Imagine the shape a balloon might take if the air molecules inside the balloon did not follow this order and settled out where ever they chose within the balloon. So the dust that settles on furniture and glass surfaces does so evenly across the entire surface, the longer the particles remain air borne the more evenly they will settle on surfaces. The heavier particles (10 microns & up) settle more quickly and their “random walk” is much shorter and they therefore settle out closer to their source. The particles that do not settle out (constantly airborne) will continue their “random walk” until their spacing is perfectly balanced out. This can best be seen with some sort of smoke generator (incence etc.) The smoke particles seem to disappear but in fact they never leave the area. They just bounce around until their spacing is so great they are for all intent and purposes invisable. These particles can move through an environment on currents & eddys in the air and, will rise and fall with the warm & cold convections with-in a space. This explains why if a laser particle counter is taken into a confirned area the lower levels have a smaller count than do upper levels BUT the upper level particles are far more numerous and considerably smaller. This can also occur between floors as well as from floor to ceiling in the same space. Brownian Motion continues to work on these particles and as we move from room to room we redistribute the particles that will hence continue to “walk” to balance out their density. So the fish that you cook in the kitchen at six o’clock (even with the exhaust fan operating) will still be in your second floor bedroom at 10:00pm when you decide to turn in, and those particles will continue to move around in your “residential soup” until fresh air is added while the “stale” air is drawn away and the dillution of the particles leaves the space less contaminated. And even as that occurs the particles are moving with-in that space in a random pattern to “equalize” their density and maintain equal spacing.

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21
Apr/11

What is I.A.Q.?

by ifutter under Indoor Air Quality

For the past four & something years I’ve been babbling on about “IAQ”.  We’ve even had discussions and put the Marketing Group to work on “IAQ” material.  We have an “IAQ” link to our web site.  There is a seemingly endless supply of material on the internet aimed at “IAQ” education.  SO !  Turn to the person next to you right now, (yes right now) and ask them – What is I.A.Q.?  And you’ll probably get the answer, “Indoor Air Quality, of coarse”.  And what is Indoor Air Quality?

I penned the title of these articles “Dirty Little World” for two reasons.  With the advent of the electronics age the world is getting (should I say it!) more “little”.  Plus it’s a dirty place.  Back in the days when human kind was still running around in bear skins, eating berries, and roots,  and trying hard not to be eaten, there was an abundance of pollutants that have remained with us over the eons.  And all we do now is track them into our homes to mix with what we generate by ourselves.  But what in fact makes air quality good or poor? What makes air clean or dirty? What is Indoor Air Quality.?  To our ancestors in bear skins Air Quality was non-existent. Just being able to breathe made you one of the fortunate ones.  We graduated to caves, found fire, burnt whatever was available, began burning meat over the fire, and still didn’t care about pollution or plumbing, that was all part of “cave dwelling”. Then came the constructed dwelling place. But still no plumbing – I would imagine we didn’t care too much because it was the “norm”.  (And as one of my friends would say)  “ and here’s the Hook Baby”.  It was the “norm”.  So to-day with years of enlightenment, and learning how is it we still have a hard time defining Indoor Air Quality.   The U.S. Federal Standard  209E (1994) set out a “bench mark” Standard of 100,000 respirable particles per cubic foot.  So at 100,001 p/cu ft is your IAQ unacceptable? Or conversely at 99,999 is it clean?  If airborne particle matter is low but undetected contaminating gases are high is your air clean? So ( the Hook!) what is the norm?

In Encyclopedia language: Indoor Air Quality (IAQ) is a term referring to the air quality within or around buildings and structures, especially as it relates to the health and comfort of the building occupants. (IAQ can be affected by microbial mold, bacteria, gases, radon, VOC’s, particles, or any mass or energy stressor that can induce adverse health conditions.)  Determining IAQ then involves the collection of air samples, monitoring of human exposure, and inside air flow studies.

So IAQ is more than just clean air/dirty air.?   It is perhaps, “the active study and correction of adverse human health factors with in, but not confined to, an occupied building or area of a building, vehicle or confined space.” To some that could be high levels of formaldehyde gas, to others air borne particulate matter smaller than 0.30 microns, and still to others something as simple as high humidity.  For me it would be elevated levels of Ozone and dust.  The “norm” is not always normal.  As long as the human body can deal with the stressors & contaminates, then is the IAQ acceptable?, but when airborne stachybotrys mold spores put  a person in hospital (or worse), is it poor?   I would like to offer you this thought.  IAQ is part of the more broad spectrum of A.Q. (Air Quality) and is or will be a branch of the HVAC Industry by it’s own right, and those who embrace the need and develop the skills  now will be sought after for consultation and remediation, and this will only increase as energy costs rise and building construction becomes “tighter”.

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21
Mar/11

RADON – DANGER OR MYTH?

by ifutter under Indoor Air Quality

Radon was first discovered in 1899 by Pierre and Marie Curie, and is naturally produced by the decay of uranium & radium. Uranium has been part of our world since the earth was formed.

Radon is a difficult study. So here we are to-day with a colourless, odourless, naturally produced radioactive gas that if allowed to build high concentrations in our environments can cause lung cancer. And it’s not going away!

Radon is measured in Picocuries per litre (pCi/L) and presents no danger to life or tissue @ 0.35pCi/L. But when trapped in a building, levels as high as 20.0 pCi/L can occur and the constant  bombardment of healthy tissue by the alpha particles of radon can cause the cells to mutate into a cancerous state.

Radon occurs all over North America from the coal mines of the eastern U.S. to the Canadian Shield, from the coal producing Canadian Provinces to the areas of bed rock where uranium sits and decays. Radon usually dissipates harmlessly into the atmosphere but can also “migrate” below the earth’s surface and find its way into buildings via cracked foundations, open sump pits, foundation joints, poor seals, etc. Oddly enough — control of radon gas in an internal environment is simple. Ventilate. The most effective method is:

  • to place a duct inlet below the foundation floor level of the building (seal the joint at the floor)
  • Lead the duct to the atmosphere and
  • have an inline fan (Fantech FR110) that is energized 24/7, thus creating a negative pressure below the floor level & drawing off the gas before it can penetrate the cracks & joints.

One other method is to install an HRV (Fantech SHR/VHR) at a slight positive pressure imbalance thus creating a positive pressure with-in the building & “holding the gas back” so it cannot enter. Either way, sealing of all the building joints below grade is most important. Testing for Radon is a simple method and there is tons of information on the internet at www.radondetect.ca. This could be a huge opportunity to boost sales in a tough economy.

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1
Mar/11

OXYGEN FOR YOUR HEALTH

by ifutter under Indoor Air Quality

I have been under a reasonable amount of stress lately, (let’s face it, who hasn’t) and in evaluating what was needed to control or at least minimize it and its effects, it occurred to me that to think clearly on the subject the #1 requirement should be a reasonably oxygenated brain. Sounds kind of silly doesn’t it?

Actually not! If you consider that the average work place is designed on “Exhaust Ventilation” (which is a ventilation system based on exhaust fans sucking out enough air to allow the influx of an equivalent amount of fresh oxygenated air to infiltrate the building — right!) then it’s not too far of a stretch to realize that a BRAIN with a build up of CARBON DIOXDE does not function as it should.

  • Does not make decisions as it should,
  • does not evaluate criteria as it should,
  • does not reason as it should, and
  • just basically wants to go to sleep instead of being used.

So after being subjected to poorly oxygenated air for 6 – 7 hours of the day, by 3 pm the brain starts getting groggy and can’t seem to “think” its way out of the stressful situations at work. (That’s me!) So why does the Ventilation Guide allow for “Exhaust Only Ventilation”? It worked back when it was designed because buildings were as loose as, “a clap board driving shed built for three horses and a couple of surreys.” To-day, even the “loose” buildings are tight enough to retard the progression of an exhaust only system. The stress just seems to overwhelm you around 2:30 – 3 o’clock in the afternoon. So why don’t we just open a window or “boot-up” the Economizer?

Eee—Gads, man, that costs money. But guess what! So does a bunch of stressed out, confused, dopey, tired CO2 laden brains. Not to mention (watch how this ties in!) the negative pressure in the building will aid in the increase of subsoil Radon entering the building structure from cracks, joints and fissures in the foundation floor & walls.

So I head outside & get a good dose of fresh air and feel refreshed and ready to take on the rest of the day – and you know what? Those “stressful” little things just seem to fall into place, just as they should. So you head home at the end of the day, plant your seat and your feet, relax – eat a good meal, collapse in front of the tube, and begin to breathe the CO2 laden air that has plagued your house since four weeks before the advent of the New Year. And on we go.

The cost to reheat just 20 cfm of fresh air brought into your dwelling is equal to 20 x 70 (air temp difference) x 1.08 (correction factor to standard air density) x the cost of N.G. /per cubic foot.

  • 20 cubic feet of fresh air @ 0 ° F would require 20 x 70 x 1.08 = 1540 BTU of heat to bring it to 70 °F

Since we are introducing a small amount of fresh air into a much larger amount of existing warm air, the actual load on a heating system or dwelling is almost negligible. A four inch (4”) intake pipe ducted into the farthest end of the return air (as far from the air handler as possible) will allow enough fresh air into the building to offset the buildup of gases (methane is also a big one). It can have a manual adjustment damper in it to control the incoming cold air during extreme cold weather. It will also help dry the interior air by lowering the RH.

So I’m asked, “Does this not go against everything you preach about HRVs and ventilation?” To some extent yes, BUT – it’s also a low cost practical solution to an age old problem. Fresh air for Health, Welfare & oxygen for that lump of grey matter stuck in the top of our heads. Breathe deep & keep it working to the max.

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