Q&A: A Forum for Green Building Experts and Beginners

[Click map to enlarge]

Please register for a free account or sign in to ask and answer green building questions. The usual rules of courtesy apply: 1. Be nice. 2. If you can't be nice, be polite. 3. If you can't be nice or polite — well, please be brief. To attach a photo or illustration: Under the box labeled "More explanation," look for the words "File attachments." Click that, and you should be able to attach a photo. Thanks for joining the conversation!

8 Answers

I am having trouble calculating water heater recovery efficiency.
Specifically, I do not know how to calculate or determine RE for a 90 or 95% Thermal Efficiency gas storage tank water heater, examples Vertex 100k unit or State GP 650 76k or 100k unit.
Since these units are over 75k BTU input, they are classified as commercial water heaters, do not have energy factors specified by law, and I am now simply trying to learn how to calculate their recovery efficiency RE.
Any help would be greatly appreciated.

In Energy efficiency and durability | Asked By Andrew Dunn | Nov 5 11
3 Answers

Can anyone refer me to a "primer" for how to best vent and insulate the "vaulted" ceiling of a hipped-roof loft room? I have three major questions: venting a hipped roof, insulation type, and vapor barrier.
I'm turning an unconditioned attic into livable space, as a part of a complete cottage remodel (strip interior to studs and start over). The roof I'm working with is long-hipped (longer than wide), with a ridge along the center. There will be kneewalls and built-in closets/drawers.

In Energy efficiency and durability | Asked By Anita Brosius-Scott | Nov 11 11
1 Answer

I’m in marine climate, 4-C, a couple of miles from Puget Sound in Washington.
So far I have osb sheathing over 2x6 studs at 24” OC. My plan: one inch of rigid EPS (the white stuff mostly due to lower cost) with foil backing (towards the inside to reflect heat back?), tape and seal with flashing and screen to keep bugs from making new home, then 1x4 furring strips to create rain screen channel and boost R factor. I have one gable end without OSB so would have to extend EPS or fur out the plane two inches after covering with asphalt felt.
Sound like a good plan?

In Energy efficiency and durability | Asked By Bjorn Benson | Nov 11 11
2 Answers

After two long power outages here in NJ, I'm looking at putting an insert in my existing fireplace as an alternative to being dependent on oil and the grid.

One manufacturer, Avalon, boasts inserts whose efficiency and emissions are very close to those of their free-standing stoves. Are inserts a good idea? Are they really comparable to stoves? Does their reliance on electric fans to circulate the hot air mean that they can't actually be used in a power outage?

In GBA Pro help | Asked By Gary Hemminger | Nov 11 11
6 Answers

My house is one story, 24x48, with 2x6 walls and 2x8 floor joists.
It sits on 3' posts with an open crawl space.
The location is western Arkansas.

The wall sheathing is Zip panels; vinyl siding will be applied directly over the Zip panels. The drywall is not installed yet on the walls.

The subfloor is Avantech T&G. OSB will cover the bottom of the floor joists.

Roxul batts for the walls and floor will cost $2,200 just for the Roxul (with me doing the installation).

A company will blow cellulose in the walls and floor for $1,150.

In General questions | Asked By Jim Wright | Nov 9 11
9 Answers

This year’s World Energy Outlook is now out.

From the press release

“The world is locking itself into an unsustainable energy future which would have far-reaching consequences, IEA warns in its latest World Energy Outlook”

Or as the the Guardian newspaper put it…

“World headed for irreversible climate change in five years, IEA warns.” (link)

In Energy efficiency and durability | Asked By Andrew Henry | Nov 10 11
3 Answers

I recently stumbled on this video.....
No snappy vests... but still a very interesting perspective from Ireland
nice mock-ups too

In PassivHaus | Asked By John Brooks | Nov 5 11
13 Answers

We are in the planning stages of a super-insulated house that we hope to building in the coming year. I'm having trouble deciding what type of range we should get. Electric is out of the question because of its lack of efficiency and inconvenience. Propane has always been my preferred choice for cooking, but I don't understand how to provide adequate make-up air for a gas range in a tight house.

In Green building techniques | Asked By Randy George | Nov 8 11
1 Answer

On November 8, 2011, Steven Ziessler, the president of Guardian Building Products, sent Allison Bailes a letter. In that letter, Ziessler told Bailes, "I apologize."

More information on the Guardian apology can be found in several new paragraphs added to the end of the GBA news report on the Guardian-versus-Bailes affair: Guardian Fiberglass Threatens Blogger With Legal Action.

GBA applauds Guardian's wise move. Congratulations, Allison.

In General questions | Asked By Martin Holladay | Nov 8 11
8 Answers

I'm back after having met with the architect and asked about the soffit venting.

In Energy efficiency and durability | Asked By Sean McLoughlin | Nov 7 11
Register for a free account and join the conversation

Get a free account and join the conversation!
Become a GBA PRO!