## Duct Design 5 — Sizing the Ducts

Posted by Allison Bailes on June 9, 2017
To this point in our little series on duct design, we've been calculating intermediate quantitites: available static pressure, total effective length, and friction rate. Today we use all that to find out how big the ducts need to be. We're following the Manual D protocol for duct design, a standard...

## Duct Design 4 — Calculating Friction Rate

Posted by Allison Bailes on June 1, 2017
Today's installment in the duct design series is a simple one. It's just a straightforward calculation that gives us the design friction rate from the two quantities I discussed in my last two articles. In part 2, I told you about available static pressure (ASP). In part 3, I covered total...

## Duct Design 3 — Total Effective Length

Posted by Allison Bailes on May 30, 2017
Today we move another step down the road of duct design. I started the series with a look at the basic physics of air moving through ducts. The short version is that friction and turbulence in ducts results in pressure drops. Then in part 2 I covered available static pressure. The blower gives us a...

## Grading an Attempt to Get Ducts Inside Conditioned Space

Posted by Allison Bailes on September 7, 2016
There's a ton of new construction and remodeling going on in Atlanta. On a lot near where I live, a developer tore down the old house and is building two new ones. This weekend, I took the opportunity to check out their progress on the first one and saw the mechanical system roughed in on the first...

## The Evolution of Passive House in North America

Posted by Allison Bailes on July 1, 2016
In 2002, Katrin Klingenberg introduced the passivhaus program to North America when she built the Smith House in Urbana, Illinois. She had come to the US from Germany, where she studied architecture and got involved with passivhaus. But is this really where it all began?

## Design Flaws That Can Rot Your House

Posted by Allison Bailes on May 2, 2016
Most of the moisture management problems I've written about here are ones that occur because of poor installation. When builders don't integrate window flashing with the drainage plane, for example, water can find its way in and rot out the window framing. Sometimes, however, architects make it...
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## The Surprising Building Science History Behind the Revolving Door

Posted by Allison Bailes on January 29, 2016
Revolving doors have been around for a century and a half. You see them at the bottom of tall buildings, which tells you something right there. They weren't invented merely to function as a way to enter and exit these buildings. There's a building science reason behind their invention. In fact, the...
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## 10 Essential Steps to Building a Pretty Good House

Posted by Allison Bailes on August 24, 2015
My friends up in Maine came up with the concept of the Pretty Good House a few years ago, and I love the idea! Not everyone can or wants to build a LEED Platinum, Living Building Challenge, Passive House. But a lot of architects, builders, and homebuyers would like to design, build, and live in...

## 17 Reasons I Love Working with Buildings

Posted by Allison Bailes on June 29, 2015
Yesterday I had lunch with Robert Bean and Eric Griffin at the ASHRAE conference here in Atlanta. As we talked about how we got into the field of building science, I began thinking of the reasons I love doing what I do. My background is physics, and I really enjoyed teaching it when I was in...