Posts Tagged ‘indoor air quality’

Are summer allergies keeping you inside?

August 7, 2014


August is a rough month for summer allergies, especially those allergic to mold spores.   Peaking during hot and humid weather, mold spores are on the attack.  The best solution is to stay indoors when the count is very high.  The problem we all have though, is outdoor air gets into our homes with all of its allergens and pollutants.  The tricky thing is this isn’t always because a window or a door is open.  We at GreenHomes call it infiltration.  It’s a fancy word that basically means that the outdoor air flows into the house through openings, joints, and cracks in walls, floors, ceilings and around windows and doors.

When your house was built, holes were made for pipes and wires that may have never been sealed.  We know this because of what we do: home energy audits.  It is a comprehensive test that includes a focus on indoor air quality.  Because of this test, we can identify where air is coming into your home and seal it up.  This will keep that outdoor air where it belongs, outside, and possibly give  you some relief from all of that sneezing.

Share this post with family or a friend who are suffering from allergies.

Thanks for stopping by!


The Six P’s, and some more!

December 11, 2012

Some may have heard the expression before:  “Proper Planning Prevents Pretty Poor Performance” or possibly a less pleasant version, but I will leave that to your imagination.  Permutations previewed in this photo provide possibilities for a plethora of problems, primarily CO poisoning!

Please provide proper ventilation for atmospheric combustion equipment such as the water heater shown here. VLUU L200  / Samsung L200

VLUU L200  / Samsung L200This is common configuration for a water heater, drawing combustion air from its surroundings, but it can create problems!

Pressures in a house can change and affect equipment like this.  Our predecessors discovered that it was more pleasant when smoke from the fire went up the chimney.  It’s more than pleasant but imperative! 

This chimney shown is going downhill before it goes up, the primary problem! Our heating equipment needs to be vented properly or those gasses enter our homes.  Consider having your combustion equipment checked as part of a whole house assessment

Please, a plug, poke, or paltry plea, proper planning provides prime performance, and prevents poisoning (CO that is!).




Home as microbiology experiment? Moisture, keep it reasonable and stay safe

June 29, 2012

Candida albicans PHIL 3192 lores
There are many sources of moisture in the home.  Cooking, showering, houseplants, and people are some expected sources.  Crawlspaces and basements can add to the humidity as well. And no matter where it comes from, too much humidity can promote the growth of unwanted microbes, mold, mildew and bacteria.  It should be a healthy home, not a lab experiment.

Consider some steps to avoid high humidity in the home:

  • Gutters and good grading can help divert water away from the foundation.
  • Cover dirt floors in crawl spaces and basements with heavy duty plastic, it reduces odors and moisture
  • Ensure that clothes dryers are properly vented to the outdoors.
  • Use ventilation fans to remove moisture generated by showering, bathing, and cooking.
  • Reduce the number of plants in humid areas.
  • If you burn wood, don’t store it in the basement.
  • Do not open basement windows and doors in the summer to dry out the basement. This can make the problem worse by allowing moist outdoor air into your cool basement, causing increased condensation. Crawlspaces (and basements) may not need venting, sometimes it makes it worse. I’ve talked about this here

Most of the time we know we have too much moisture only after it’s too late.  Wet stains on walls and ceilings, rotten wood, condensation on the windows, and musty smells let us know something is wrong.  Clearly indoor air quality suffers, so it’s best to keep your eye out for trouble.   Suffer from allergies?  You might be creating an ideal situation for the growth of the bacteria and mold that cause them.  Our homes are made of mold food: wood, sheetrock, paper.  It should be a palace not a Petri dish!



Miracle Material and Alchemists Asset: A Modern Day Construction Curse?

February 23, 2012

 Asbestos has captured the attention of human kind for thousands of years.   In fact, the Greek physician Dioscorides noted in De Materia Medica that handkerchiefs made of asbestos were reused, cleaned by fire[i].   Maybe a fine way to prevent the spread of germs well before it was widely understood, but I can’t imagine they were good for anyone’s health.

 The material is fireproof, strong, flexible, and is an all natural mineral mined from the earth.  Easy to see why it has captured the attention of so many including medieval alchemists who suggested the fibers came from hairs of fire resistant salamanders!   It was with the growth of industry that the use of asbestos really took off, and took a toll on us all. 

I do not wish to entirely vilify the material; it is still used and necessary in many applications in industry. But since the construction boom after World War II, its widespread use in products in our homes as well as the misunderstanding of the dangers behind the material, a costly toll has been paid.  What is clear is that the material has been used in many things from ceiling tiles, shingles, floor tiles, loose insulation, and pipe insulation.  The question is what do we do with it now we better understand the inherent dangers and realize it exists in many forms in our homes?  We will look into this more in the coming weeks stay tuned!



 Tremolite image used with permission from Asbestorama on flickr.

[i] James E Alleman and Brooke T. Mossman, Asbestos Revisited in Scientific American, July 1997

Which end is up? Either way breathe easy.

March 23, 2011


From zimbio

For being the foundation of the house it is surprising how basements and crawlspaces can be ignored.   Whether a dirt root cellar, basement or crawlspace these sub surface spaces can be a big headache to us. For some it’s not the Robin that is the harbinger of spring but the song of the sump pump humming and gurgling as the snow melts.   Or maybe it’s the beginning of the long run of the dehumidifier and the utility bill to match.

Mike brought up odor and air quality issues such as mold and mildew related to spaces that the team at Energy Efficient Solutions, a GreenHomes America location in Yorktown, Virginia sees, and the same issues that happen there happen on the west coast and the northeast. 

As homeowners we too often come to accept the problems in our house as just the way it is or hope they will go away.   We take care of our roofs and siding to keep the water out.  These underground spaces ought to be treated with the same importance.  Air sealing like we recommend for attics can help a lot down below as well.  You can flip the house upside down and treat it the same way.  We need something to keep the water out and drain it away, insulation and good solid air barrier between the living space and the outside. 

 Either way you look at the house, there is an optimum relative humidity for healthy air inside.   Higher (and lower) ranges are ones ripe for growth of bacteria viruses, fungi and mold.  Lower and we get to be too uncomfortable and suffer from the effects.

There is a sweet spot right down the middle.  Preventing big moisture issues is important for our well being.  Because they are out of sight down below doesn’t mean they should be ignored.  Make sure any contractor who does work on your home understands this and how it relates to the work they’re doing.  If not, you could be headed for trouble.

McKinsey EE Report on Comfort and IAQ

August 3, 2009

Whew—tons of good stuff in here.  I do talk a lot about energy, but it’s not just energy.  In fact, many of our customers are more interested in comfort and health and safety.

Thus it’s reassuring to see this mentioned on page 13 of the report

Impact on comfort and health.  Energy efficiency upgrades, including proper insulation and sealing against air infiltration [emphasis added], can address a number of common residential problems, such as drafty rooms, cold floors in the winter, damp basements, dry air, musty odors, and mold.  Because people spend up to 90 percent of their time indoors, many of these issues can lead to health risks, contributing to chronic allergies and asthma, as well as periodic illness.  Sick building syndrome (SBS), which is associated with poor indoor air quality, can manifest itself in building occupants as irritation of the eyes, nose, throat, or skin, as well as other ailments.  Flaws in HVAC systems, emissions from some types of building materials, volatile organic compounds used indoors, and inadequate exhaust systems may be contributing factors.  Severe problems with heating or cooling systems, for example, can result in dangerous concentrations of carbon monoxide or radon gas.  Air and duct sealing and periodic maintenance of HVAC equipment can mitigate a number of these risks.  While quantifying the impact of higher air quality on health is difficult, research suggests that the benefits are significant.  Improved indoor air quality can reduce symptoms of SBS by 20 to 50 percent, asthma by 8 to 25 percent, and other respiratory illnesses by 26 to 76 percent.

Right on!


“Scorched Air” Furnaces—They don’t have to be that way

January 9, 2009

You may have heard it before—“I heat with scorched air.”  Forced air heating has a bad name.  From the (purported) dryness it creates and the blasts of hot air and temperature swings to the noisy fan motor and banging in the ductwork.  The reality is that is what many people experience with forced air heat. 


But it doesn’t have to be that way.  The right variable speed furnace and good insulation, air-sealing, and duct-sealing can virtually get rid of these issues. 


Skip ahead it you want the solution.  I am going to walk through some of the problems and their causes, first.


First is sizing, and the are two parts to this.  Your furnace and system needs to be designed to keep you warm on the coldest day of the year.  (Geek speak:  we actually target a size that will hold your thermostat set point 98% of the time—but without getting too technical, you should be good 100% of the time.)  Older furnaces and even many new furnaces sold today are “single speed”.  This means they are pumping out enough heat to keep you warm on the coldest night every time they turn on. 


Think about that in terms of driving through town in your car.  What if every time you stepped on the gas, you had to floor it to get to 80 mph.  No feathering allowed.  No easing off for different situations like a short block, pulling into a parking space, etc.  You either had the pedal to the metal or you had the brake on.  The ride would no doubt be thrilling!  But you’d probably be overshooting stop signs quite a bit.  Wearing out break pads.  (And probably getting a lot of tickets.)  That’s what’s going on with a single stage furnace.  If you need a few BTUs (read: a very small unit of heat) or 100,000 BTUs, the furnace would churn out the same thing.  This means that on all but the coldest of days, the furnace is cranking out more heat than you need.  And like the car racing to a stop sign, it doesn’t stop exactly where you want it. It overshoots the thermostat setting, and you get too warm.  Then the temperature cools back down, and you do it again.


This can be fixed with multi-stage, variable speed furnaces.  These furnaces ratchet down the output when less heat is needed, just as you might not hit stomp on the gas if a stop sign was only 15 yards away.  When coupled with an efficient (ECM) fan motor, these furnaces can also have a big impact on the electricity you use in the winter.  As an added bonus, these motors, especially at low speeds, tend to be much quieter that the monsters going full blast all of the time.


Dryness is another factor.  In simple terms (that the physicists won’t like because I’m over simplifying a bit), how much moisture the air can hold is a function of the  temperature.  The warmer the air, the more moisture it can hold.  And for a give volume of air and water in the air, as the temperature goes up, the “relative humidity” or “RH” goes down.  So a temperature swinging up and down can give you an RH that swings up and down, increasing a sense of dryness.


That’s not the big cause of dryness in your home in the winter, though.  Air leaks are.  As air leaks out of your house (see my previous post on insulating)

the moisture in the air escapes with it.  And it is replaced by cold and very dry air from the outside.  This goes on 24/7 during the winter, the leakier the house, the worse the problem.  Then, add to this the fact that many ducts which move your heated air (and cooled air in the summer) are also very leaky and dump a lot of that air directly outside.  Just like leaks in the rest of your house, the more that goes out, the more cold dry air gets sucked in.  This is really what dries out your house.


You actually generate, by breathing, perspiring, showering, cooking, watering plants, etc, more moisture than you need in your home.  Most people don’t need humidifiers.  In fact humidifiers, especially if not rigorously maintained, can actually create problems.  If you seal up the major leaks, you’ll not only reduce drafts and be more comfortable and save on your energy bills, but you also won’t have to deal with super-dry air in your home.  You’ll want to provide adequate ventilation to provide some outdoor air and make sure you don’t have too much moisture, but it’s better to be able to control this rather than letting the wind and temperature decide for you.


The bottom line, whatever type of system you use, forced air, water, or even wood, isn’t as important as how your whole house is operating and how your heating system is integrated into the house.  For maximum comfort and efficiency with a forced air system, remember this:


  • Make sure your house is well-sealed and well-insulated.  A good contractor can verify this for you using a blower door and infrared camera.
  • Make sure your ducts are also well sealed.
  • Used an efficient (95% or better AFUE)–multi-stage furnace with a variable speed ECM motor.  Have your furnace professionally maintained at least once per year.  (See Patrick Herbert give an intro to furnaces.)
  • Make sure your house has adequate ventilation and use bath and kitchen exhaust fans to remove excess moisture at the source.

In a well-built or well-improved house, forced air can be a great heating system.  (Hot water systems can be great, too—but you still want to insulate and air-seal properly!)



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