Blower door test and natural ACH

[mont1230]

According to the 2009 IECC it is required to do the blower door test or visual inspection. When getting the results back for the blower door test it's always better than the 7 ACH, but the natural ACH is usually lower than the 0.35 minimum requirement. This causes a health issue for homeowners. By following the prescriptive method of the IECC every house natural ACH would fail. The result is that after the test fails it requires so much cfm of mechanical ventilation to run continuously. My thought is that by using this energy code we're supposed to be saving money, but end up spending more money. (I could get into more detail, but very lengthly) Your thoughts.

 

[mtlogcabin]

ACH, but the natural ACH is usually lower than the 0.35 minimum requirement

Please provide the year and code section. I can't find it in the IRC or IECC

By following the prescriptive method of the IECC every house natural ACH would fail.

R303.1 Habitable rooms.

All habitable rooms shall have an aggregate glazing area of not less than 8 percent of the floor area of such rooms. Natural ventilation shall be through windows, doors, louvers or other approved openings to the outdoor air. Such openings shall be provided with ready access or shall otherwise be readily controllable by the building occupants. The minimum openable area to the outdoors shall be 4 percent of the floor area being ventilated.

I don't see how a tight house and natural ventilation requirements are a problem.

 

[Moscow]

Mtlogcabin,

were they are getting it from is in the 2009 IECC table 405.5.2(1) under air exchange rate colum proposed design.

 

[Moscow]

mont1230,

From my understanding is you can not mix Ashrae standard with the IECC you can go with on or the other but you can't make sombody follow the IECC for one part of the ventilation and then the ASHRAE for the other.

Just my two cents (which is not worth much)

 

[KZQuixote]

Hi Mont1230,

I agree, any home with a decent house wrap job will fail the .35 Air Change Per Hour standard. When I asked the same question I was told that when provided by mechanical means the ventilation air will not be entering at trouble spots likely to cause other problems like condensation. I suppose if the air infiltrated around doors and windows condensation could be the result.

Bill

 

[mtlogcabin]

Moscow

Thanks you are correct section 405 is an alternative to the Prescriptive requirements of Section 4

401.2 Compliance.

Projects shall comply with Sections 401, 402.4, 402.5, and 403.1, 403.2.2, 403.2.3, and 403.3 through 403.9 (referred to as the mandatory provisions) and either:

1. Sections 402.1 through 402.3, 403.2.1 and 404.1 (prescriptive); or



2. Section 405 (performance).

 

[fatboy]

I don't have anything to contribute to the question, but I did want to jump in and say WELCOME mont1230, glad you found us, make sure and come back around.

 

[mont1230]

Sections out of the code

The 2009 IECC and 2009 IRC. Code section out of the 2009 IECC - 402.4.2.1 and table R405.5.2(1). 2009 IRC - section R303.1, Exception 1. Contractors use this exception in most cases.

Please provide the year and code section. I can't find it in the IRC or IECCR303.1 Habitable rooms.

All habitable rooms shall have an aggregate glazing area of not less than 8 percent of the floor area of such rooms. Natural ventilation shall be through windows, doors, louvers or other approved openings to the outdoor air. Such openings shall be provided with ready access or shall otherwise be readily controllable by the building occupants. The minimum openable area to the outdoors shall be 4 percent of the floor area being ventilated.

I don't see how a tight house and natural ventilation requirements are a problem.

 

[mont1230]

Thanks for your comment.

 

[mont1230]

When excepting the blower door test report, it will also show the natural ACH or you can easily do the calculation if you know your N-factor for your zone. What I figured out in this area for a one-story home you need to be in a range of 6.5 to 7 ACH for the blower door test and 5.25 to 7 ACH for a two-story in order for the natural ACH to be at 0.35 or better. As you can see the blower door test range is very limited. The report usually does the calculation for you to determine the amount of cfm that is needed and after trying to achieve that you have to run the blower door test again to make sure it passes. This is getting very costly and time consuming for contractors. Most of the time were finding out that the contractors are taking a 4" or 6" vent pipe directly to the furnace room and making up the cfm this way. I see some problems with this. Were either bringing in cold or hot air depending the time of year and spending more money for the furance to run. Secondly, most furances will not warranty this situation. Since this is a State law requirement which they adopted and the law that they wrote stictly does not allow you to amend anything to it. It is coming down to where they want ERV's or HRV's intalled in the houses. This might be practical in some areas, but 99% of our new construction do not have them. In my opinion were spending more money again and not saving energy.

According to the 2009 IECC it is required to do the blower door test or visual inspection. When getting the results back for the blower door test it's always better than the 7 ACH, but the natural ACH is usually lower than the 0.35 minimum requirement. This causes a health issue for homeowners. By following the prescriptive method of the IECC every house natural ACH would fail. The result is that after the test fails it requires so much cfm of mechanical ventilation to run continuously. My thought is that by using this energy code we're supposed to be saving money, but end up spending more money. (I could get into more detail, but very lengthly) Your thoughts.

 

[conarb]

Mont230:

This whole sealing up of buildings and then pumping outside air into them has gotten so absurd it's ridiculous, around here people are turning the fans off because they either don't like the feeling of having them running, or don't want to pay the additional expense of having them running. When the fan industry (lead by Panasonic) was promoting this at our Building Standards hearings the Berkeley Lawrence Laboratories presented a paper opposing it on the basis that fan technology wasn't efficient enough and recommended delay until the technology advanced far enough, Building Standards approved the requirements anyway on the basis of a Panasonic study showing that people don't open windows anymore, what they failed to realize is that people don't run fans either, or disconnect them if they are wired to run full time or on a time clock as required. An important sidebar explanation to our Energy ode:

As houses have been tightened upover the last twenty years due to

energy cost concerns and the use of

large sheet goods and housewrap,

what used to be normal infiltration and

exfiltration has been significantly

reduced. In the meantime, we have

introduced thousands of chemicals

into our houses through building

materials, cleaners, finishes,

packaging, furniture, carpets, clothing

and other products. The California

Standards have always assumed

adequate indoor air quality would be

provided by a combination of

infiltration and natural ventilation and

that home occupants would open

windows as necessary to make up

any short fall in infiltration. However,

Commission sponsored research on

houses built under the 2001

Standards has revealed lower than

expected overall ventilation rates,

higher than expected indoor

concentration of chemicals such as

formaldehyde and many occupants

who do not open windows regularly for

ventilation. The 2008 update includes

mandatory mechanical ventilation

intended to improve indoor air quality

in homes with low infiltration and

natural ventilation rates.

 

[Wooly]

There are energy savings to be had even if you do bring air back in. The biggest benefits are sustainability. The less energy the home uses the less drying potential it has the greater risk for mold and rot. If we tighten the home up and have proper air exchange we can control that. Note the word control. If you just leave a house leaky there is no control of air movement and warm moist air can go places where it condenses and causes problems. So really it no longer is a matter of leakage but leakage control. Mechanical ventilation can be harnessed, mother nature can not. As you know, there is nothing "natural" about the natural rate of infiltration. Tighter homes encourage getting combustion appliances out of the home as well as get us to think about IAQ. I reach my rubber glove through the case and give you a hearty wave. ;-)

 

[conarb]

Wooly:

You can't tell me that in a moderate climate like mine where I seldom run either air conditioning or heating that running fans 24/7 is going to save energy. I hate fans running and at times have to go into one of those commercial buildings without windows from the 80s that have constantly running fans, I had to go into the DMV last year to renew my drivers' license, during the wait I moved several times to get away from the blowing air, I belonged to a gym 20 years ago, women were turning fans on and we men were turning them off, a friend left and I asked him why, he stated: "One word - Fans". Now they are going to make us put them in homes, I never put fans in baths preferring windows or operable skylights (unless it's a first floor powder room with no ability to use either), now they are required, most people never use them anyway, Panasonic's study showing that people don't open windows like they used to is probably correct, but they open windows more than they run fans, and windows don't use any energy to operate.

I see this as the fan industry taking a page from the fire sprinkler industry's book, mandating their products through code, and it's now apparent that simple fans aren't going to work, it's going to take expensive ERVs or HRVs.

 

[mont1230]

Conarb:

I agree with you last statement. Houses are getting so expensive and adding ERV's or HRV's is only using more energy and not saving energy. The 2009 IECC is not the clearest on finding the requirements for ventilation and when you do find it doesn't give you enough information. Every house here in our area would require ERV's or HRV's but the contractor is opting out to use a 4" or 6" supply vent directed to the furnace. Most furnace manufactures don't warranty this. Their doing this because they're savings $1000's. I feel that the furnace manufactures should get on board on improving the level to meet all aspects of this energy code. Every 3 years were driving cost on these new homes and of course the Building Safety is getting the heat.

 

[Wooly]

Conarb,

You have a fan on your furnace (air handle etc.). Bringing in outside air could be as simple as adding a duct from the outside, through a filter to the return air plenum. When the air handler runs air is drawn in. Yes, you would want to adjust that to outside conditions. No need to pull in excess moisture at times. This method works great in heating climates where condensation builds up on the windows. Agreed, many moderate climes receive little benefit from this but then again they are not the ones we are concerned with in regards to energy efficiency. Another fan you have, or should have is above your cooking appliance. You do want to remove that moisture and in some case smoke out of the house don't you? If you are using sealed combustion units or all electric for space & water heating the amount of air needed is greatly reduced and easy to satisfy.

 

[Robert Ellenberg]

This is a subject I have read and studied quite a bit over the past several years. Building Science Corp. does a lot of research on the subject and has published quite a few papers on it. They study and write of the benefits of using an ERV or HRV but they also promote simply introducing fresh air in a controlled method with a device like the Air Cycler. Here is one of their research papers on why the ventilation is important and doing it with an damper controlled vent.

http://www.buildingscience.com/documents/information-sheets/information-sheet-ventilation-system?searchterm=Air+Distribution+Fan+and