Comments on: Questions on Building a Passive House in a Humid Climate

By: Dale N Bickenbach

Dale N Bickenbach — Tue, 10 May 2016 21:30:45 +0000

The discussion session was
The discussion session was possibly the best part. Without the engineer's daughter none of this would have happened. Canadians are American's too. I was surprised and delighted by the number of people from outside the local area. Now, we need to build and have actual people live in houses in humid climates as well as more build everywhere.

By: Sergey Belov

Sergey Belov — Mon, 09 May 2016 20:22:56 +0000

Allison, would it be possible
Allison, would it be possible to see a set of notes or video from the panel discussion? Wish I could attend but currently out of state. Also do you have any recommendation on a good source of information for designing to passive house standards in humid climates? Many thanks

By: Howard Katzman

Howard Katzman — Sat, 07 May 2016 05:28:46 +0000

What about using a dessicant
What about using a dessicant wheel system like what is used in commercial buildings? Don't they use less energy to remove the humidity?

By: c-a-l

c-a-l — Sat, 07 May 2016 04:52:52 +0000

I'd like to understand
I'd like to understand solutions that meet both the passive house/tight house needs in a hot-humid climate (need for dehumidification, often need for heat, low energy use so ductless preferred, etc.) while also addressing the aesthetic desires of the typical homeowner. Mini-splits are a tough sell and usually a no-sell.

By: Charlie Conger

Charlie Conger — Sat, 07 May 2016 03:14:48 +0000

True and good points. I like
True and good points. I like mini splits but they are not easy to to find in the hot humid gulf coast of the US. Then again passive home don't work well here.

By: Clive

Clive — Sat, 07 May 2016 00:14:24 +0000

I agree — products like the
I agree — products like the Ultraire range should always be considered. The only proviso is that they require ducting / forced air distribution and smaller footprint PH residential builds might not want to specify this. It will always be difficult to get a forced air system to be as efficient as the best of the mini splits and if you’re aiming for the lowest energy consumption per sq. ft. (regardless of air tightness) the mini split(s) might get selected for their heating performance, thus ruling out the presence of duct runs — and Ultraire or similar.

By: Curt Kinder

Curt Kinder — Fri, 06 May 2016 23:14:52 +0000

In reply to John Semmelhack. Good point about sensible
Good point about sensible heat ratio relative to efficiency of HPWH. In Florida the prevalence of 68F/50% RH indoor are is rare...75 / 55 is common much of the year. Both my HPWHs used to fill a 5 gallon bucket fairly regularly depending on time of year until I got 'round to running drain lines into a utility sink.

By: John McMurtry

John McMurtry — Fri, 06 May 2016 22:20:17 +0000

After reading all of the
After reading all of the comments on attic fans I still feel that I have something to contribute.
The ceiling in the second floor of my condo got very warm in the summertime. The association had brilliantly re-shingled with darker shingles and we could immediately feel the difference. I complained, and the roofer said that it wouldn’t make any difference… The roof was properly vented with screened eve vents and six eyebrows. There was also had 8 inches of insulation in the attic. So I measured the temperature of the inside ceiling at 3 o’clock in the afternoon. I than installed a fan that forced air out of one of the large eyebrows. I then measured the temp again, in the same place at the same time, same weather, a day later. The ceiling was 30 degrees F cooler and the upstairs was very noticeably cooler all day and night. I suggest that the heat from the hot air in the attic was being conducted through the insulation and the ceiling (obviously). Do the experiment. Insulation will conduct heat. It slows down conduction but does not stop it. It is pure physics; If one side of the insulation is hotter than the other, heat will flow in an attempt to cause both sides to have the same temperature. Insulation is actually better at blocking radiation than it is a blocking conduction even though blocking conduction is it supposed purpose. And why in the heck anyone would use dark shingles in California is beyond me. If you want the best results use white shingles, or better yet silver, or even better yet, cover the whole roof with solar panels… The idea that conduction is unimportant in energy transfer from attic into living space is easily proven to be false. Again; don’t just talk about it, do the experiment. The structure of the radiative surfaces has a great deal to do with how easily heat moves from one environment to another.

By: Allison Bailes

Allison Bailes — Fri, 06 May 2016 22:14:27 +0000

Yes, indeed, Charlie. That's
Yes, indeed, Charlie. That's exactly the one I was thinking about when I mentioned split-system dehumidifiers.

By: Charlie Conger

Charlie Conger — Fri, 06 May 2016 21:10:08 +0000

How about something like the
How about something like the SD12 from Ultra aire. It is like a mini split with a huge dehumidification capacity on a small, about 1/4 ton sensible capacity. Very efficient too.
http://www.ultra-aire.com/products/dehumidifiers/ultra-aire-sd12