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!


37 Answers

Solar thermal systems for heating water

Jin this is for you and Richard

Let's run the costs and the systems through the paces

so far I hear $16,000 for a Caleffi system and maybe that for labor? $32,000
saves $500 a year

CO2 production unknown to manufacture
Very little CO2 to run the ECM circulators

There are much less costly systems

NYSERDA here in NY is unveiling a new program this January
Will post more about it when they tell us more

Jin, Richard, others... what say you all

Asked By aj builder, Upstate NY Zone 6a | Dec 15 14
21 Answers

Foam-free builds

All the talk about sub-slab foam levels has me thinking. What floor systems easily allow foam free construction? Pier construction immediately comes to mind, but beyond that?

Asked By Malcolm Taylor | Oct 4 14
7 Answers

Meanwhile at BSC ... PHIUS draft standard

Not sure it was linked here .....
But it might interest some of us that missed the hint from PHIUS or PHAUS

http://www.buildingscience.com/documents/bareports/ba-1405-draft-climate...

BA-1405: Climate-Specific Passive Building Standards

Draft paper from PHIUS and BSC .

Still reading and learning, interesting stuff.

Might we discuss the proposed standard now ? :)

Asked By Jin Kazama | Dec 12 14
22 Answers

B&G's low flow Vario ECM circulator - stupid efficient pumps

http://bellgossett.com/pumps-circulators/small-circulation-pumps-booster...

What I discovered as a result of the research stimulated by this GBA dialogue is that my circulator controlled hydronic heating will not work with a smart pump like the Alpha, Bumble B or the new Taco model.

Asked By flitch plate | Dec 16 14
6 Answers

Retrofit insulation of an exterior wall

I want to insulate my exterior wall and have the room gutted. I am in the Poconos of Pennsylvania and in Zone #5 I believe. I have 2x6 walls with Tyvek wrap, OSB siding and vinyl siding. The walls had R-19 faced fiberglass batts that were installed poorly. Currently all of the wall cavities and studs are exposed and are in perfect condition. The studs, tyvek and insulation have absolutely no moisture issues at all. They look like the day they were installed 22 years ago. I want to insulate but have questions about vapor issues. I sealed the rim joist with closed cell spray foam.

Asked By John Divincenzo | Dec 17 14
7 Answers

Housewrap under vinyl siding

Ok, I'm getting educated and made some decisions. To recap, I'm residing with vinyl after stripping down to plywood sheathing (1/2" plywood over 2x4 studs, fiberglass batt, poly vapor barrier, sheetrock, zone 5). I've decided to go with 3/4" rigid foam over the plywood and under the vinyl which is R3 and very water vapor permeable. Can only fit 3/4" thickness insulation board (long story). Probably going to use Progressive Foam HalfBack H2O with water management system (grooves toward sheathing to drain any leaked in water). Want to add house wrap (Tyvek or Typar).

Asked By george baloga | Dec 17 14
9 Answers

Woodstoves: does efficient burning depend on size?

We are in the market for a new, non-catalytic woodstove. We understand that a non-cat stove needs a minimum temperature of around 500° for an efficient secondary burn. Question: Does attaining that 500° depend on the size of the stove at all? Or will the same quantity of wood produce the same burn temperature regardless of firebox size? (I know, dry, seasoned hardwood, etc.)

Asked By Patricia Appelbaum | Dec 17 14
29 Answers

Any experience with an unheated (but insulated) slab as a finished floor? Will it be uncomfortably cold?

We are building a 1000 s.f. single-story home in Northwestern Ontario (climate zone 7) on a very tight budget. It will be well-insulated (walls R-40, roof R-60), and have triple-glazed windows, etc. An energy efficiency consultant calculated our heat loss as 16,800 Btu/hr at -32.8 F. The foundation is a short ICF stem wall with a 4" concrete slab (R-20 insulation underneath). Heating will be accomplished with the combination of a high-efficiency woodstove and electric baseboard, and we might add a mini-split down the road.

Asked By Beth Turner | Dec 11 14
14 Answers

Unfinished basement, Cgi 5 gas boiler, Z vent. The outside air is making the basement cold. Can it be louvered?

Hi all,

So Ive just finished sealing the rim joist with 2" XPS (Dow Blue board) and spray foam, sealed the perimeter between the walls and floor with silicone, installed a air tight sump lid but was still getting drafts.

So Ive tracked it back to the Z vent for our CGi5 boiler, it seems the air is coming in through the z vent and back that way. It has the Z Vent termination cap on outside but was wondering if it could use a metal louver on the outside so when the boiler isnt firing it the drafts stay outside?

Asked By Darren Finch | Dec 16 14
6 Answers

Foam insulation and vented attic

I am in the process of buying a house with open cell spray foam on the attic roof. The vents were left open for gas combusting furnaces. We are in Austin, Tx.
My budget to address the problem if there is one should be enough to cover any number of scenarios.

Asked By Heidi Hicks | Dec 16 14
Register for a free account and join the conversation


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