Monthly Archives: May 2013

Tools of the Trade IV

In our last post, we talked about using the Duct Blaster, for testing the duct work in our high-performance homes.

Duct Blaster

Duct Blaster

In this post, we’ll focus on the importance of providing proper mechanical ventilation in all homes and how we use “Tools of the Trade” to test the performance of ventilation systems in the new homes we build and in our remodeling work.

The Balometer is one of the “Tools of the Trade” that we use to test the performance of the mechanical ventilation equipment that we install in our high-performance homes.
tsi-alnor-ebt731-balometer-capture-hood

Balometer® instrument directly reads average air flow rate, either intake or outflow, at ceiling, wall or floor diffusers.

In use, air to be measured is directed past a manifold which senses flow at multiple points spread across a carefully sized area. The manifold is designed so that the air volume is sensed at either supply or return diffusers with equal accuracy.

In our quest to build increasingly tighter homes, we came to realize how critical it is that we take an active role in managing moisture vapor in our homes.

Heat recovery ventilators (HRV), bath fans and range hoods are key components used to help manage indoor-air quality by expelling moist, stale air.
Moisture is the cause of over 90% of building and building material failures. (ASHRAE)

Through our study of building science, we’ve come to realize that in the cold climate where we build, a one inch hole in the building envelope will attract 30 quarts of moisture during the course of one heating season.
When I first heard of this phenomena, I was shocked and thought that this couldn’t be true, but when you consider the fact that each occupant contributes 4 pints of moisture, per day, through breathing and perspiration, you start to get a clue.
When you take into account the moisture that your pets, plants and non-vented combustion appliances add to the equation, you get a sense of how this can have an impact.
Now, consider the additional 4 pints of moisture that each occupant contributes each day, by cooking and bathing and you can see how it’s easy to reach the 30 quart mark for a heating season.

Simply installing properly sized mechanical ventilation equipment isn’t good enough.

Balometer

Testing Bath Fan Flow Rate

We use the Balometer to test and verify the performance of each system installed.

We’ve seen far too many bath fans, in particular, that did not perform as specified. The builder may not have understood how to calculate the drop in flow rate that some ducting options contribute to. The distance from the fan and where exhaust exits the structure might not have been taken into consideration. The installer might have missed the fact that there was a screw holding the damper shut for shipping purposes and neglected to remove it.
The duct work could have too many turns or was crushed during the course of insulation work being performed. There are many factors that contribute to the performance of mechanical exhaust equipment.

At Great Lakes Carpentry, we don’t simply install any type of mechanical ventilation equipment and walk away.
We take mechanical exhaust ventilation into consideration during the design phase. We plan our path and calculate distance to where exhaust will terminate. We consider size of room, length and configuration of duct run and duct material and size, in order to properly size the exhaust equipment.

Testing Trumps Talk.

With so many ways for an installation to go wrong, testing is crucial.
By using “Tools of the Trade” to verify that all mechanical exhaust ventilation is properly installed and functioning as it should, we provide our clients with  added value and peace of mind in knowing that everything is operating and functioning as it should.

The final link in the chain is perhaps the weakest.
Too often, we’ve heard of complaints from homeowners about moisture problems in the bathroom and have come to find that the occupants aren’t turning the fans on when they enter the bathroom.We’ve worked to resolve this problem by providing our client’s with a homeowners operating manual.
We educate our clients on the necessity of using exhaust ventilation and in some instances we’ll install a delayed timer switch or linked the fan with the light switch, so it comes on by default when the light is switched on.

State building codes are legal minimums. Performance standards are mediocre and there is no testing required.

Great Lakes Carpentry is building next generation, homes for the future, now.
Now that you have a choice, the question becomes; Do you want your home to be built to minimums, with no accountability from your builder and no clue as to how efficient your building envelope, combustion appliances and ventilation equipment performs,  or would you prefer to build to higher standards of performance and accountability? The choice is yours.

If you’d like to learn more about home performance testing, exhaust ventilation, high-performance home building or building science, contact us. We love to talk about this stuff!

Please stay tuned for our next post, where we’ll talk about the Psychometric Calculator, how we use it to determine the dew point and how that relates to you and your home.

Great Lakes Carpentry is “Building Today for a Greener Tomorrow”

Tools of the Trade Part III

Our previous post focused on the infrared thermal imaging scanner that we use to detect air infiltration into new and existing homes.

Infrared Scanner

Infrared Scanner

In this post we’ll focus on another of the diagnostic tools of the trade that we use to verify supply and return-air efficiencies in forced-air heating/cooling systems.

We use the Minneapolis Duct Blaster to perform a “Total Leakage Test” of the duct system.

Duct Blaster

Duct Blaster

The Duct Blaster is a device that uses pressure testing to find the amount and location of air leakage in a duct system.
To do the test, we seal all outlets except for one on the return side of the system. This is the side that returns stale air to the furnace to be reconditioned. The Duct Blaster is connected to this return-air opening and then turned on to blow air into the ducts. The air goes through the return ducts to the air handler and then through the supply ducts. If the duct system is very tight, it doesn’t take much airflow through the fan to pressurize the ducts. If you have a big leak, like a disconnected plenum or duct, it will be next to impossible to pressurize the ducts adequately.  This would be like trying to pump air into a tire that has a big hole in it.

The process yields quantitative results because testing requires two pressure measurements: one inside the ducts and the other inside the fan. The first allows the tester to compare results from different systems by always pressurizing to the same level. The second measures the airflow in the fan when that level is reached. As mentioned above, tight ducts means low airflow, and leaky ducts require lots of airflow.

Pressurizing only the ducts determines the total leakage. That includes the air that escapes into the conditioned space and the air that leaks to the outside of the building envelope (i.e., the attic or crawl space). The latter is the most important part because you derive no benefit from it. To separate it from the total leakage, we pressurize the house to the same level as the ducts by using the Blower Door. Then, when the Duct Blaster brings the ducts up to the required pressure, none will leak to the inside of the house because it’s at the same pressure as the ducts. The fan only has to blow enough air in to make up for the leakage to the outside, and that’s the amount that’s important.

This is a picture of the blower door ready for use.

This is a picture of the blower door ready for use.

In a tight air distribution system, the leakage to the outside (in cubic feet per minute, or cfm) will be 5% or less of the square footage of the home. Most new installations start at about 15% to 20%, and go downhill from there. At those rates, a third of the heating and cooling bills could be a direct result of duct leakage.

After performing a Duct Blaster test to determine the amount and locations of air and duct leakage, we seal up the leaks that we find. Upon completion the house and/or duct system will perform better, and your heating and cooing bill will be lower.

You can follow this link to a you tube video part 1 of 4 videos.
http://www.youtube.com/watch?v=sk-A08zsguE

As they say at Focus on Energy, “Testing Trumps Talk” and we couldn’t agree more.
By testing and  verifying the tightness of the building envelope and the duct systems in our high-performance homes, we are able to identify any deficiencies and take corrective measures.

Lower operating costs, greater comfort, safety, durability and higher resale values are just a few of the benefits realized by implementing building science principles and best practices into the homes that we build.

By testing, inspecting, and documenting the quality of work, we bring a higher level of added value and peace of mind for our clients.

The Duct Blaster is another diagnostic tool of the trade that helps us in delivering the added value that is built-in to our high-performance homes and remodel projects.

If you’d like to learn more about how we can provide added value to your new home or remodel, please visit our website and contact us.
http://www.greatlakescarpentry.com

In our next post, we’ll talk about mechanical ventilation, exhaust equipment and the diagnostic tools of the trade that we use to verify performance and efficiency of this critical component of the high-performance homes we build.

Great Lakes Carpentry is “Building Today for a Greener Tomorrow.”