Testing – Is It For the Birds??

We make mistakes (I’m sure some of you are saying ‘damn right you do’).  We’re only human.

Our new homes are LEED certified under the LEED for Homes program that is administered by the US Green Building Council.  We’re up to about six LEED certified homes now, with several more in the pipeline.  It’s a rigorous and time-consuming process, but we believe it has benefits for our customers.

This bird’s nest is an example of why we think LEED is a good idea.

The “old school” way of building a home is to guestimate, use rules of thumbs, etc.  Some homes are still built this way.

A new approach to building a home is to design certain key elements of the home such as HVAC and ventilation with sophisticated modeling software.  It’s not a perfect approach because you can’t model every last aspect of a house, but it does result in a home that performs better and is more efficient.  And if you have problems it gives you some troubleshooting information.

The best approach to building a home is to design and verify.  This is where LEED comes in, and this is why we have a photo of a birds nest.

LEED (and Energy Star (all of our new homes are also Energy Star certified)) requires that several aspects of a home are verified and tested.  This testing confirms that the home is performing as designed.

One of the required tests involves measuring the amount of air that is exhausted by the bath fans.  The exhaust rate is measured in CFMs (cubic feet per minute).  Bath fans in moist areas such as bathrooms are required to exhaust a minimum of 50 CFM of air.

At a recently completed home our Energy Rater tested the bath fans as part of the final Energy Star/LEED testing.  One bath fan was only pulling 36 CFM, which was surprising because it was an 80 CFM fan with a very short duct run to the outside.  We knew we had a problem.

Our HVAC contractor went outside and removed the vent cover and looked inside.  He then stuck his arm in and soon started to pull out pieces of hay, then more pieces, and finally a complete birds nest.  Clearly this was the cause of the low CFM reading.

Between the time we installed the bath fan on rough in and ran the duct to the outside, and the time we installed the vent cover on final trim out, a bird had decided this looked like a good place to build a nest (we didn’t find any babies in the nest, so maybe the bird had abandoned the idea, or maybe they all hatched and flew away to live happily ever after).  The bird was not concerned about the Energy Star or LEED certification of the home.

As a result of this testing, we found out the cause of the problem, but we also learned that going forward we need to crimp the duct at the end so that birds don’t get in and build nests.

We’ll still make mistakes in the future, but our commitment to the LEED and Energy Star programs will help us to prevent some of the mistakes and catch others.

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