Comments on: A Sticky Psychrometric Situation: Wet Bulb Temperature

By: Allison Bailes

Allison Bailes — Wed, 26 Aug 2015 14:30:38 +0000

James, that’s an easy one. It
James, that’s an easy one. It’s coming from outdoors, where the humidity is. The vinyl wallpaper is a vapor barrier so it doesn’t let the wall dry to the inside. The water vapor from outdoors gets stuck and causes the problems you’re seeing.

This has been a problem with hotels in humid climates especially because they like install bathroom ventilation that depressurizes the walls in the building, helping to suck in even more humid air.

If you want to understand the details of why the water vapor is condensing, see this article:

What Happens When You Put a Plastic Vapor Barrier in Your Wall?
http://energyvanguard.com/blog-building-science-HERS-BPI/bid/75130/What-Happens-When-You-Put-a-Plastic-Vapor-Barrier-in-Your-Wall

By: James Hinkle

James Hinkle — Wed, 26 Aug 2015 03:19:12 +0000

We have a bldg. in Lockhart
We have a bldg. in Lockhart Texas Zone two and it is a new bldg. finished in March 2015 and we have wet walls behind vinyl wall paper, it has tyveck commercial wrap on exterior. The walls behind the vinyl has Mold ,but above vinyl paper has not , where is this moisture coming from Thanks

By: Dale Sherman

Dale Sherman — Tue, 07 Jul 2015 20:12:15 +0000

Syracuse, NY: 12 noon, 82&
Syracuse, NY: 12 noon, 82°F, Humidity 73%↑, Wetbulb 75°F, Dew Point: 72°F.

By: Armando

Armando — Tue, 07 Jul 2015 18:28:26 +0000

Plano, TX: 9:25 AM, 81.9&
Plano, TX: 9:25 AM, 81.9°F, Humidity 77%↓, Wetbulb 76.3°F, Dew Point: 73.9°F↑

By: Curt Kinder

Curt Kinder — Tue, 07 Jul 2015 18:07:50 +0000

In evaluating humidity /
In evaluating humidity / discomfort I think in terms of dewpoint since that figure is regularly reported at National Weather Service stations. It runs steadily in the high 60s low 70s all summer in north Florida. In another (non-HVAC / building science) role I routinely wear body armor while operating a center console boat. A cooling technique I use while underway at 20-25 mph is to alternately allow air to pass under the armor via my collar cooling the wet cotton tee shirt beneath and then let the cooled shirt back in contact with skin. Repeating this every few seconds by hunching shoulders back and forth really helps stay cool.