Passive House Design: Energy-Efficient Doors

| 1/27/2011 1:05:41 PM

Mark A. Miller is a practicing architect/builder/developer living in Chicago who designs projects around the country. His studio, Mark A. Miller Architects + Builders, designs and builds high-performing, energy-efficient homes that speak to the soul. Mark recently co-founded the Passive House Alliance Chicago and is lecturing about the Passive House standard throughout the Midwest. You can learn more about his unique approach to designing thoughtful homes at his websites: Zen + Architecture and Passive House Midwest. 

I wanted to start to go through some of the techniques that help one achieve the Passive House standard. We spoke last time about the air tightness, and I wanted to continue this discussion a little further into one element in particular, a weak link in our wall system, that is our entry doors.

I recently moved our family into an older home on the northwest side of Chicago. The front door was similar to most American front doors, about 1 3/4-inches thick, little to no insulation, and minimal attempts at weather stripping. We noticed right away that a huge amount of cold winter air was coming inside our heated space, as there wasn’t much of door sweep. So, being the energy-efficiency nut I am, I went down to the local hardware store to see what I could buy, off the shelf, to improve my situation.

I found a insulating product called “Twin Draft Guard,” which is designed for folks in this unfortunate situation like myself.  It’s basically a long sock with two long compartments connected by about three inches of material.  The idea is to insert a one-inch diameter tube of foam in each compartment and slide this under your door.  Each tube of foam is to nestle up on either side of the door and seal any gaps between the door and the threshold. Well, be careful here. Out of the box this product does not work. Most doors are 1 3/4-inches thick, and the material between the two tubes of foam is 3 inches. That leaves 1 1/4-inches of space that doesn't allow the tubes to nestle up to the door and stop air from pushing in.

My letter is on its way to this product manufacturer, but I was able to fix the product. I happened to have some foam “Backer Rod” left over from my handy “City of Chicago Home Weatherization Kit” I was fortunate to get at my kid’s school’s holiday fair. I added a length of 3/4-inch diameter backer rod to each sleeve, which forced the foam tubes closer to the door, and hey hey, it now works fairly well. 

OK so what have learned here?  The state of doors in this country are quite poor in meeting the energy efficiency desires of today’s green community. Let’s take a quick look at what the German building products companies are producing to give us a little benchmark comparison of how much room there is for improvement regarding this item.