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1 Answer

Is a heat-pump water heater in Zone 7 worth it?

I'm currently designing a highly efficient 2 bedroom 1080 sqft house. Right now I am wondering if a heat pump water heater would pay itself off before it needs to be replaced. Also, the mechanical room would only be 3'6" x 7'6", not big enough size for manufactures recommendations of 10'x10'x10'

My question is how could I run the numbers to see if buying one is a good investment?

In Energy efficiency and durability | Asked By Matt Berger | Jul 15 15
4 Answers

Is humidity above 60% above grade as much a mold problem as basements?

For houses without A/C in the summer in humid areas why is not mold a big problem?

In Energy efficiency and durability | Asked By Alan B | Jul 15 15
2 Answers

How much is R-value reduced by screws/nails and other fasteners?

Plywood/OSB is installed with nails/screws, the same with foam board, siding, studs and many other components, has anyone done the math to figure out how much they reduce the insulating value (since they are usually metal).

I'd like to hope its almost zero, but data/calculations may show an appreciable effect?

In Energy efficiency and durability | Asked By Alan B | Jul 15 15
2 Answers

Is it cool to use butyl and acrylic tape together?

Have some tyvek flex tape, is there some chemical weirdness that might occur with say 3m all weather?

In General questions | Asked By kevin freeman | Jul 14 15
13 Answers

Should I correct the ductwork or the un-insulated walls or both?


We live in Hudson, Quebec between Montreal & Ottawa. My plan is to insulate walls of 2 rooms, from the inside, using 2" EPS Type I insulation, covered with a reflective vapor barrier directly on the existing drywall and 1" furring strips and 1/2 drywall. These rooms have 2 “exterior walls” each and tend to be more humid and cold than the other rooms.

In Energy efficiency and durability | Asked By domenic montagano | Jul 10 15
6 Answers

Are Duct Booster Fans Crazy? Or will they solve insufficient cooling air reaching 2nd floor?

2nd floor of my Kansas City 24yo home (bought 3 years ago) is consistently 6-12 degrees (F) warmer in summer than first floor. The problem I noticed from Day 1 is simply that the 2nd floor does not get enough air from the HVAC system. With the house fan on full blast, you can barely feel any air coming up through the floor registers in the bedrooms, while the registers downstairs are blasting out cold air.

In Mechanicals | Asked By Stuart Miller | Jul 14 15
1 Answer

New NBER paper shows Weatherization Assistance Program

Has anyone had a chance to check out this report?

The link is only to an executive summary, the article itself is gated. I have a full copy that I'm reading through now. If true, the -9.5% rate of return is really a bummer, and hopefully says more about some weaknesses in the DOE program than it does about EE work in general.

Any thoughts

In General questions | Asked By Ben Wilson | Jul 14 15
69 Answers

Attic is hot after closed-cell spray foam was installed

Finished attic with 4 foot knee wall , duct located in knee wall to support 2 floor,extremely hot, BASF spray tite 2 inches with spray foam wraped around rafter in knee wall but with Sheetrock on ceiling just 2 in foam In cavity . Suggestions to handle heat issue. Richmond Virginia all attic seal very well thinking heat coming from rafters under Sheetrock. Thermal convection coming from rafters. Worked done in the winter, crawl space also done, house built 1994 colonial 2 story with garage with room above with dormer. Also in crawl space does it really need supply vent and return vent

In GBA Pro help | Asked By Mark Hippchen | Jun 27 15
12 Answers

Failed double glass units...moving forward?


I have a large sunspace/sunroom that I'm renovating that was originally built in the late 70s. Basically the design is 3 walls of vertically-mounted glazing--specifically 24 34" x 76" double-glass factory-sealed units. We needed to re-do the framing, so we removed all 24 back in April. 16 of the 24 were still good; the rest had lost their seal over the years.

In Green building techniques | Asked By Colin Croft | Jul 13 15
6 Answers

Window head flashing

I am preparing to install some windows. If I want to do best practices - I am assuming I should have end dams fabricated into the window head flashing. My questions are -

1) what is the typical height of the end dam - i.e. a 1/4 inch?

2) how far over the corner of the window should the flashing extend on each side of the window?

Thanks for your help.


In General questions | Asked By Randy Mason | Jul 13 15
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