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

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40 Answers
Higher solar heating fractions???

I find it hard to believe that with today's building and insulating technologies, that most or even all of a home's space and hot water heating can not be provided by solar... I realize that the issues of heat storage and controlling the release of this heat need to be dealt with. I am intrigued by Robert Starr's (www.radiantsolar.com) ideas for an insulated earth bed storage system. Read the DOE's report on this system...they seem to be rather enthusiastic. (note that it was done in the 80's).

In Mechanicals | Asked By Garth Sproule | Sep 28 09
5 Answers
Locking two buildings together; old, and new build

Full circle? We are looking, again, at adding on instead of building new. I'd appreciate any links to prior discussions on this issue, here or other sites, books, etc. PROBLEM: How do you lock a new and an old foundation/footer together? Presently, we have a 2-story, daylight basement, stick. We are considering adding two stories on the daylight end, essentially just expanding horizontally. This will get everything my wife wants on one floor and leave a huge dungeon for me.

In Mechanicals | Asked By John Klingel | May 21 10
1 Answer
What should I do to help overall energy efficiency to an old building?

I am working with a 2-story commercial building with a restaurant being operated on the main floor and a large unused/un-finished upper level. The windows on the upper level have been replaced recently. There is insulation covering about 25% of the floor area on the upper level. What can be done on the upper level to achieve greater energy efficiency in the building overall?

In Energy efficiency and durability | Asked By Greg Nissen | May 24 10
13 Answers
Windows and low-e coating

I have always understood that low-e windows worked in cold climates when you had the low-e on the exterior side of the pane closest to the interior (surface 3) and vv for hot climates (surface 2). This is stated pretty clearly in the book Residential Energy, for example, which most energy auditors use to train from, and I just checked with the DOE website and they say the same thing.

In GBA Pro help | Asked By Amanda Evans | Oct 25 09
2 Answers
New Office Remodel = poorly insulated??

A year and a half ago, I purchased a 35 y.o. building, gutted and remodeled the entire structure for a new professional office (dental). The original walls, sub-floors, foundation and half the roof were retained. Everything else was built new: insulation, electrical, mechanical, water/sewer, etc.

In General questions | Asked By Geoff Sheen | May 23 10
20 Answers
Thermal bridging with spray foam insulation

If you have 2x12 rafters and are installing approximately 5 inches of foam do you need to encase the rafters in foam to prevent heat loss through the top of the 1 1/2" of rafter? Or is the heat loss so insignificant that totally encasing the rafter in foam would prove to be unnecessary?

Gary

In Energy efficiency and durability | Asked By gary | May 4 10
4 Answers
To Vent or Not to Vent?

I will be building a new home in Vermont this summer and I was planning on installing a vented cathedral ceiling and insulating it with dense pack cellulose. I recently spoke with an insulation sub-contractor and he explained to me that if the R-value is above 60, then there is no need to vent the roof. In fact, his company guarantees my roof performance. I was under the impression that venting was the only way to go. Which method is better?

In Energy efficiency and durability | Asked By Graham Mink | May 21 10
1 Answer
Membrain or vapor retarding primer in attic?

I have a 1911 brick farmhouse in Racine, WI (20 miles south of Milwaukee) in which I insulated the attic with 6" of Icynene open cell spray foam, sprayed right to the underside of the roof deck (no air vents). Most of the perimeter of the roof is sloped approximately 45 degrees, but the center section of the roof is flat. Because of varying differences in roof joist thickness and overall inadequate depth for the foam, I decided to "sister" 2x4s to the sides of the roof joists to increase the cavity depth to a uniform 6". An added benefit to this is that it created a thermal break.

In General questions | Asked By Darin Weisensel | May 21 10
8 Answers
Electrical Wiring

I am wiring a double electric oven that is equipped with 10 guage wire factory installed. The spec plate indicates it is rated at 7800 watts. Can I use 10 guage wire to run 240 v wiring to the electrical box. My electrical book says I need to use 8 guage - isn't that overkill since the stove only has 10 guage?

In Mechanicals | Asked By Kellye | May 19 10
1 Answer
What kind of preparation is needed to install a tub surround in my basement?

My basement walls are foam concrete block that have seams every 16" for nailing into and we are putting a bathtub with a tub surround in. Plumbing was prepared for when we laid the basement floor, but we are not sure how to properly put the tub surround up against the wall. Right now we just have a layer of drywall against it-our plan originally didn't include the tub. The longest part of the tub will be back up against the basement wall as well as the short wall that doesn't have the plumbing.

In Project management | Asked By Laurie Voss | May 19 10
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