To Prevent IAQ Problems, Consider All Home Factors

[Guest guest]

http://www.achrnews.com/CDA/ArticleInformation/features/BNP__Features__Item/

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03/29/2002

To Prevent IAQ Problems, Consider All Home Factors

By Greg Mazurkiewicz / News and Legislation Editor. E-mail him at

gregmazurkiewicz@....

EAST LANSING, MI - Contractors must be relationship experts. But this is

more than customer relations. An hvac contractor must understand the

relationships in the home among heating and cooling equipment, ventilation

strategies, insulation systems, windows, and other factors to get a real

handle on how to maintain good indoor air quality (IAQ) and prevent

problems.

That was the message provided by Steve Easley, owner of S.C. Easley and

Associates, a Danville, CA-based construction consulting firm, in his

keynote speech called " Under-standing the House as a System " at the " Energy:

It's Not All You Save " conference.

A former professor of building construction and contracting at Purdue

University, Easley is co-host on the Discovery Channel's weekly program

" Holligan's Your New House " ; host of the upcoming " Bob Vila's

EnergyWise Home Project for the Internet " ; and spokesperson for the

California Energy Commission's Internet video training series on home energy

efficiency. This expert stresses the need to evaluate all the factors in a

house that impact IAQ.

He noted that some builders and contractors blame tight homes for increased

mold and other problems. But this is not true, he emphasized. You have to

consider the driving forces - the temperature differences and pressure

differences that cause air movement.

The factors that affect IAQ, stated Easley, are:

1. Ventilation rate;

2. Pollutant source strength;

3. Exposure time; and

4. Individual sensitivity.

" If you build homes that are leaky and drafty, it's not going to improve

IAQ, " he said. Air coming in through leaks brings in moisture, which causes

problems such as mold.

Proper air filtration is important, as well as keeping filters clean. The

most common service call for hvac equipment is for dirty filters, he

remarked. But the efficiency of common furnace filters is very low.

" Ninety-nine percent of particulates in the air are less than 1 micron in

size. "

Duct sealing should be done if excessive duct leakage is found. Too much

leakage in the basement ductwork below the living room floor, for example,

can cause the carpeting to act like an air filter, trapping a tremendous

amount of dirt.

PROPERLY INSULATED ENVELOPE

" Sixty to 80 percent of moisture problems are because of failure in the

exterior envelope " of the home, said Easley.

Reviewing the basics, he related that heat goes from warm to cold; moisture

goes from wetter to dryer. Anytime you see mold in a house, it's because of

thermal bridging, poor air circulation, and high moisture. If areas of a

home are left uninsulated, they will get colder and the relative humidity

will be higher. Thus, a corner of a ceiling that has no insulation will

attract moisture and you can have mold problems in that corner. If walls are

insulated, but there are gaps that are uninsulated, moisture buildup and

mold can develop.

Insulation needs to be carefully installed to avoid such problems.

A kraft-backed insulation for the walls is better in colder climates, he

said. A polyethylene vapor barrier can trap moisture in walls and cause

serious mold problems due to air conditioning in the summer. If thermal

bridging occurs and moisture gets in the drywall, it cannot escape.

" A polyethylene vapor barrier works fine for the heating season but not for

the cooling season, " Easley remarked. Wall systems should be as tight as

possible, but make the insulation breathable, he stated.

He recommended using Tyvek® house wrap on the outside of the structure. This

wrap has about 58% permeability, he said. It serves as an air barrier from

the outside but allows any water inside to evaporate out.

It's better to install wiring down the interior walls of the house, rather

than the exterior walls, to ensure better insulation, he added.

ENERGY EFFICIENCY

In a breakout session on energy efficiency issues, Easley provided a list of

common sense tips, including:

Provide adequate insulation.

Make sure insulation is properly installed.

Control air infiltration.

Properly size and install the hvac system.

Eliminate duct leakage.

Insulation needs to be installed correctly for maximum efficiency. " You can

have 63 to 65 percent energy reduction with improper insulation, " he pointed

out.

Leaving areas around ceiling lights in cathedral ceilings without

insulation, or leaving corners or areas around windows uninsulated, causes

energy loss. These cold spots can also breed mold problems, as mentioned

earlier.

He estimates that " 20 to 50 percent of hvac systems are oversized. " A load

calculation should be done to ensure proper sizing.

If there is ductwork in the attic, all leaks should very definitely be

sealed. " Leaky ducts in a hot attic can reduce the efficiency of a SEER 14

system down to SEER 10, " Easley said.

Publication date: 04/01/2002

Related Features

<snip> There are a lot of articles in the archives here - check them out.

[Guest guest]

I have not seen any indication of the use and practice or weep holes

typicaly required by the structural code on brick veneer. A path

where condensate is going to occur and seepage at the top of the wall

is to be provided to the outside at the edge of the sill. Condensate

overflow, as well as condensate is required is required to be

drained. Preferably to the outside. Over sizing the cooling capacity

so there are very short cooling cycles do not allow complete removal

of moisture before the temp drops,,,,,,,ie. cold wet air in the

house, rather than dry wet air. A good HYVAC engineer should measure

all of these.

>

>

http://www.achrnews.com/CDA/ArticleInformation/features/BNP__Features_

_Item/

> 0,1338,74792,00.html

> 03/29/2002

>

> To Prevent IAQ Problems, Consider All Home Factors

> By Greg Mazurkiewicz / News and Legislation Editor. E-mail him at

> gregmazurkiewicz@a...

>

> EAST LANSING, MI - Contractors must be relationship experts. But

this is

> more than customer relations. An hvac contractor must understand the

> relationships in the home among heating and cooling equipment,

ventilation

> strategies, insulation systems, windows, and other factors to get a

real

> handle on how to maintain good indoor air quality (IAQ) and prevent

> problems.

> That was the message provided by Steve Easley, owner of S.C. Easley

and

> Associates, a Danville, CA-based construction consulting firm, in

his

> keynote speech called " Under-standing the House as a System " at

the " Energy:

> It's Not All You Save " conference.

>

> A former professor of building construction and contracting at

Purdue

> University, Easley is co-host on the Discovery Channel's weekly

program

> " Holligan's Your New House " ; host of the upcoming " Bob

Vila's

> EnergyWise Home Project for the Internet " ; and spokesperson for the

> California Energy Commission's Internet video training series on

home energy

> efficiency. This expert stresses the need to evaluate all the

factors in a

> house that impact IAQ.

>

> He noted that some builders and contractors blame tight homes for

increased

> mold and other problems. But this is not true, he emphasized. You

have to

> consider the driving forces - the temperature differences and

pressure

> differences that cause air movement.

>

> The factors that affect IAQ, stated Easley, are:

>

> 1. Ventilation rate;

> 2. Pollutant source strength;

> 3. Exposure time; and

> 4. Individual sensitivity.

>

> " If you build homes that are leaky and drafty, it's not going to

improve

> IAQ, " he said. Air coming in through leaks brings in moisture,

which causes

> problems such as mold.

>

> Proper air filtration is important, as well as keeping filters

clean. The

> most common service call for hvac equipment is for dirty filters, he

> remarked. But the efficiency of common furnace filters is very low.

> " Ninety-nine percent of particulates in the air are less than 1

micron in

> size. "

>

> Duct sealing should be done if excessive duct leakage is found. Too

much

> leakage in the basement ductwork below the living room floor, for

example,

> can cause the carpeting to act like an air filter, trapping a

tremendous

> amount of dirt.

>

> PROPERLY INSULATED ENVELOPE

> " Sixty to 80 percent of moisture problems are because of failure in

the

> exterior envelope " of the home, said Easley.

>

> Reviewing the basics, he related that heat goes from warm to cold;

moisture

> goes from wetter to dryer. Anytime you see mold in a house, it's

because of

> thermal bridging, poor air circulation, and high moisture. If areas

of a

> home are left uninsulated, they will get colder and the relative

humidity

> will be higher. Thus, a corner of a ceiling that has no insulation

will

> attract moisture and you can have mold problems in that corner. If

walls are

> insulated, but there are gaps that are uninsulated, moisture

buildup and

> mold can develop.

>

> Insulation needs to be carefully installed to avoid such problems.

>

> A kraft-backed insulation for the walls is better in colder

climates, he

> said. A polyethylene vapor barrier can trap moisture in walls and

cause

> serious mold problems due to air conditioning in the summer. If

thermal

> bridging occurs and moisture gets in the drywall, it cannot escape.

>

> " A polyethylene vapor barrier works fine for the heating season but

not for

> the cooling season, " Easley remarked. Wall systems should be as

tight as

> possible, but make the insulation breathable, he stated.

>

> He recommended using Tyvek® house wrap on the outside of the

structure. This

> wrap has about 58% permeability, he said. It serves as an air

barrier from

> the outside but allows any water inside to evaporate out.

>

> It's better to install wiring down the interior walls of the house,

rather

> than the exterior walls, to ensure better insulation, he added.

>

>

>

> ENERGY EFFICIENCY

> In a breakout session on energy efficiency issues, Easley provided

a list of

> common sense tips, including:

>

>

> Provide adequate insulation.

> Make sure insulation is properly installed.

> Control air infiltration.

> Properly size and install the hvac system.

> Eliminate duct leakage.

> Insulation needs to be installed correctly for maximum

efficiency. " You can

> have 63 to 65 percent energy reduction with improper insulation, "

he pointed

> out.

> Leaving areas around ceiling lights in cathedral ceilings without

> insulation, or leaving corners or areas around windows uninsulated,

causes

> energy loss. These cold spots can also breed mold problems, as

mentioned

> earlier.

>

> He estimates that " 20 to 50 percent of hvac systems are oversized. "

A load

> calculation should be done to ensure proper sizing.

>

> If there is ductwork in the attic, all leaks should very definitely

be

> sealed. " Leaky ducts in a hot attic can reduce the efficiency of a

SEER 14

> system down to SEER 10, " Easley said.

>

> Publication date: 04/01/2002

>

> Related Features

> <snip> There are a lot of articles in the archives here - check

them out.