A Highrise Hotel Window Head Scratcher
The ASHRAE conference and AHR Expo were in Atlanta last week. Because I live here, I didn't have to stay in a hotel but a lot of people I know came to town and did stay in hotels. One of…
The Energy Vanguard Blog
Defogging Your Car Windshield with Psychrometrics
A lot of people don't understand the best way to defog their car windshield in wet, cool weather. About 30 years ago, I was on a group trip on a hired shuttle bus. The outdoor temperature was probably in the…
Do High-MERV Filters Always Reduce Air Flow?
Over the past few months, I've taken a look at some critical issues for indoor air quality. Starting with the issue of how much time we spend indoors, I then wrote about kitchen ventilation, the panoply of indoor air pollutants,…
Does Fiberglass Attic Insulation Really Lose R-Value?
When you get into the world of building science, it's inevitable that you'll hear about the study that proved fiberglass insulation loses half its R-value because of convection within the insulation. Or it could be you're a homeowner who's been…
Looking Back & Looking Forward in the New Year
Welcome to another January, this time in the year 2019. The month, of course, is named after the Roman god Janus, who has two faces, one looking backward, one forward. Because, you know, to really know where you're going, you…
A Birthday, a Report, and a Prize
Happy birthday to Willis Carrier! He invented modern air conditioning and changed the world. In his quest for a device to control humidity in the Sackett-Wilhelms Lithographing & Publishing Company in Brooklyn, New York, he invented a device that changed…
The Unintended Consequences of High-MERV Filters
What is a hair's breadth? A strand of the finest human hair is about 20 micrometers (also called microns) in diameter. Take a piece and slice it in half. Then take one of those halves and slice it in half…
The Demon in My Ducts
KERKLUNK!I instantly spring up in my bed at the loud noise. "What the heck was that?!" I don't know but it seemed to have come out of the heating vent on the wall above my dresser.I'd been lying quietly in bed…
What Happens to Air Flow in Ducts When Size Changes?
As we continue our study of indoor air quality and filtration, we now come back to duct design. Today's lesson is on an interesting bit of physics that applies to anything that flows. It could be heat or particles or…
7 Reasons Your Filter Isn’t Improving Your Indoor Air Quality
Indoor air quality (IAQ) researchers have established that little bitty invisible pieces of stuff that float around in the air are bad for human health. Of course, being scientists, they don't call it little bitty invisible pieces of stuff. They…