Don't Forget The Fresh Air
Here we go again. Higher energy prices, Government, Utility and
Manufacturer rebate programs have homeowners back on the renovation
path. However, in all the frenzy of insulating, sealing, new windows,
doors, furnaces all in an effort to reduce those high-energy bills,
many failed to address their indoor air quality (IAQ). Up until
now, that is. Now that cold weather has arrived, so too has moisture
on the windows, mould on the walls, stuffy stale air, cooking
odours, etc.
What happened? Quite simply, many people forgot the need for fresh
air. They tightened their home to save energy but failed to recognize
the need to control the indoor pollutant levels that we generate
in our daily lives. What happens when pollutant levels rise is
we get what is commonly termed Sick Building Syndrome (SBS). SBS
is a growing problem in new and renovated buildings. Occupants
experience acute health effects that appear to be linked to the
time spent in the building, with no significant illness or cause
being identified. SBS is usually caused by inadequate ventilation,
chemical contaminants, and biological contaminants. SBS can result
in headache, dry cough, dizziness, nausea, fatigue, difficulty
concentrating and eye, nose, or throat irritation. And with most
people spending 90% of their day indoors the indoor environmental
risks are high.
Identifying the Common Pollutants
According to the Environmental Protection Agency (EPA), the five
most common pollutants and their effects are:
- Ground -level ozone: Created by a chemical
reaction between nitrogen oxides, volatile organic compounds
(VOC's) and sunlight, it can travel long distances. Prolonged
exposure can cause permanent lung damage. Lesser exposure lengths
can cause wheezing, coughing, aggravated asthma, and reduced
lung capacity.
- Particulate matter: Describes particles in
the air such as dust, dirt, soot, and smoke. These can lead
to chronic bronchitis, painful breathing, and premature death.
- Carbon Monoxide (CO): According to the EPA,
78% of CO levels come from on-road vehicles, airplanes, and
construction machinery. This pollutant can damage central nervous
systems, cause respiratory issues, and contribute negatively
to those with pre-existing heart problems.
- Nitrogen dioxide: This is a reactive gas
formed when fuel is burned at high temperatures that can cause
acid rain, smog, and water quality deterioration. Exposure leads
to damaged lung tissue, emphysema, and bronchitis. It also aggravates
existing heart conditions.
- Sulphur dioxide: The most common of the sulphur oxide gases, this gas occurs when coal and oil are burned; when gasoline is extracted from oil; and when metals are extracted from ore. Short-term exposure can cause temporary breathing difficulty for asthma sufferers. Long-term exposure at high levels has a tendency to cause respiratory illness and aggravate existing heart conditions.
Know the Basics
Homeowners need to follow the basics in achieving better IAQ.
- Source Control - this is not always easy to accomplish
and many times, some but not all the sources can be eliminated.
- Get rid of the family cat or dog - not likely to happen, if you want to remain married.
- Seal off the kid's bedrooms - even if a child has asthma this is not likely to happen either, when do a kids close doors
- Get rid of carpets and upholstery - somewhat possible, not inexpensive, but often these are major contributors to poor IAQ
- Disconnect water lines to the house - not practical, but the source of water leakage from water lines or seepage into the home is a huge contributor to poor IAQ
- Sanitize the home weekly - not practical, but good housekeeping, removal of outer footwear, etc goes a long way to improving IAQ
When dealing with source control we need to first identify all potential areas or products that may be creating or contributing to the problem(s). Canada Mortgage and Housing Corporation (CMHC) has a booklet titled, "The Clean Air Guide" (NHA 6695). This guide was developed to assist homeowners and IAQ professionals identify pollutant sources by conducting a thorough whole house assessment. Many times plants, fish tanks, paint storage, chemical cleaners, laundry products, etc are contributing factors that can be easily reduced, if not eliminated. Or something as simple as operation of an existing exhaust fan(s) while cooking or doing craftwork, which brings us to ventilation.
- Ventilation - Many times homeowners do not
make proper use of bathroom fans or kitchen fans due to noise
or water leaking around the grilles on the ceiling when in use.
Of course this should not happen, if it does, it's due to an
improperly installed fan or a fan that is in need of an upgrade.
Newer fans as so quiet that they are available now in 1 and
1.5 sonnes (ultra quiet).
- Dilute contaminants - by exhausting air from a home air can be made up through a passive fresh air intake that will introduce air to dilute airborne pollutants
- Bio-aerosols - these are mould spores, viruses and bacteria, (pollutants) which, is why we need to maintain proper levels of humidity by proper use of source exhaust fans
- Odours - these can come from people, carpets, pets, plants, and moulds by effective source exhaust fans
- CO2 - this has long been used an indicator of good or poor IAQ, high CO2 levels make you lethargic, to low CO2 means you are over ventilating, wasting energy
Ventilation can be passive or mechanical and since our goal is to increase our buildings efficiency, we will discuss mechanical ventilation. By installing a Heat Recovery Ventilator (HRV) or Energy Recovery Ventilator (ERV) we can control the air exchange within the building envelope to .3 air changes per hour (ACH). This rate will provide a fixed amount of stale polluted exhaust air from the building while at the same time introducing or replacing an equal amount of fresh clean air back into the building. The term used to explain this is called "balanced flow ventilation", because it's neither positive nor negative. HRV's and ERV's should be installed in all new and renovated homes.
- Filtration - A standard furnace air filter
removes particulate from the air in the 10.0 - 5.0-micron size
(1 micron = 1/25,000th of an inch). However these only account
for about .18% of the particles that we breathe, 1.32% are mid
size, and 98.5% are sub microscopic.
To further make removal of particulate from the air even more difficult an average 2600 sq. ft. home only passes the air through the filter four times a day, when it should pass it through a filter 10 times a day. This is because most homes do not operate the furnace fan continuously.
When it comes to filter selection homeowners must use caution and do their homework. A couple newer terms that are getting a great deal of attention are Minimum Effectiveness Reporting Valve (MERV) and High Efficiency Particulate Arrestance (HEPA). MERV is the Industry's newest standard that allows homeowners to know if the air filter is effective at removal of particulate and what size of particulate it is effective at removing. HEPA is the highest quality air filter delivering at a minimum 99.97% of all particulate in the .3-micron size.
- Trap contaminants - Some air filters that
can be purchased have very high MERV ratings. Caution needs
to be exercised because they can often be too restrictive for
use on many furnaces. Some of the problems that can be experiences
are increased energy use, decreased air flow, motor failure,
and overheating of the heat exchanger eventually leading to
premature failure.
Make certain the filter you choose will work with the furnace that you have. Just because it's the right size and will fit doesn't mean it can be used. MERV 10 rated filters as an example can be 1" thick or 5" thick, the difference is the restrictiveness of the filter to airflow and higher frequency of replacement. Most high end trade filters installed by contractors require replacement annually and pose no affect on equipment components or performance.
HEPA air filters are different and must be installed in a by-pass configuration (parallel to the furnace) this due to the highly restrictive nature of the filter. Most HEPA air filters are minimum MERV 16 and as a rule filters rated higher than MERV 10 should not be used in-line on residential furnaces. Many companies claim and advertise "HEPA like" air filters. These are not HEPA. Remember, do your homework, look at initial filter costs, life-cycle costs (frequency of replacement) and ease of maintenance.
- HRV's & ERV's - the ever-changing design,
features and ease of operation and maintenance has come a long
way. Integrated HRV with electric furnaces such a Nutech's "Clean
Air Furnace" allow for one piece of equipment in a small footprint
to heat, cool, filter and ventilate the home.
- HEPA's - the 99.97%HEPA air filters now available
in whole house or portable models make for affordable high-quality
air filtration with ease of installation and maintenance. Americare's
complete line of HEPA's do have an option for installation of
a VOC cartridge.
- Particle counters - the handheld particle
counters have now found there way down into the residential
HVAC marketplace and homeowners can now have IAQ professionals
test up .3, .5. 2.0, 3.0 and 5.0 micron sized particles within
minutes in your home. It can also be used to verify a filters
true performance.
- Humidifiers - believe it or not, even with
tight home and ventilation systems many times there is a requirement
to add humidity. Desert Spring has an excellent unit that requires
very little maintenance that when fitted with an auto flush
feature that can be programmed to flush the reservoir every
so many hours.
- Ultra Violet (UV) lights - used to sterilize,
eliminate and prevent microbial growth such as mould spores,
viruses, and bacteria, breaking down their DNA protecting the
inside ducted systems used to convey air through the building.
Lennox presently claims to have the highest intensity UV light
on the market, designed to reduce bioaerosols by 50% in less
than one hour.
- Digital thermostats - temperature is also in the mix when we talk IAQ because if temperature is not properly controlled, humidity and particulate matter with vary. As such, Honeywell's newest Vision Pro 8000 series touch screen offers the most precise temperature control with features such as reminders to change the filter, replace the UV lamp, clean the humidifier and service the HRV/ERV. In addition, to auto changeover from heating to cooling and vice-versa.
In Summary
Many things have been discussed that affect indoor IAQ, some you
will be able to address on your own by using and following the
information and checklists in the CMHC "Clean Air Guide." There
will also be many of you who will need further assistance, seek
out a company that has taken training through CMHC's Indoor Air
Quality courses, who have a minimum of 10 years experience specializing
in residential IAQ.
