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19 Answers

Are "Energy Nerds" in agreement on this?

"PV's are cheap enough now to remove the need to super insulated houses"

Asked By tech1234 | Apr 19 18
3 Answers

Mini-split energy usage

I thought I would offer some energy usage I had this winter with my Mitsubishi mini-split. Some info

Units: Mitsubishi MSZ-FH12NA H2i and MZ-FH15NA H2i heat pumps.
Location: Just North of NYC
99% outdoor temp - 12 degrees F
Heat load - 26,000 BTU

Month Degree Days KWh KWh/Degree day
Apr 12, 2018 824 997 1.20
Mar 14, 2018 817 978 1.19
Feb 12, 2018 1035 1450 1.40
Jan 11, 2018 1248 1773 1.42
Dec 11, 2017 751 870 1.15

Asked By WPmichael | Apr 20 18
22 Answers

Roof underlayment for vented roof with standing-seam metal roofing

Im nearing the end of construction of a high efficiency timber frame hybrid house I'm building for my self and have a low slope roof question that I would like some opinions on. Roof pitch is 1.5/12 (7 degrees)

Our main roof structure consists of timber rafters, 20" I-joists, dense pack cellulose, 1/2" plywood sheathing taped to the walls as air barrier. We drilled holes all over the roof to dense pack the cellulose from above (as our interior finish was installed on top of the timber beams as soon as they were installed.

Asked By Scott Benson Climate Zone 7A | Apr 9 18
0 Answers

Foundation Waterproofing & Insulation Treatment

My new home design has an 8' basement and an attached garage with a 4' foundation. Is the garage foundation poured at the same time as the house or separately? On the basement foundation walls I'm planning to use spray-on waterproofing, board insulation, and a dimple mat. I'm not sure how to treat the vertical edge condition where those materials would start/stop. I used Sketchup to help myself visualize what's happening. Do basement exterior materials wrap under the garage footings and continue along the basement under the garage slab?

Asked By Bryanw511 | Apr 20 18
9 Answers

Furr-UP instead of furr-down to include ducts in the envelope?

Hi all,

I'm building a new home in south Louisiana and I've been lurking here for a few week soaking up some energy efficiency building techniques.

One of the biggest points I see on here is to include the HVAC system in the insulation envelope. But, that isn't standard practice in Louisiana for new construction ( as in, NO ONE does it in my area). I get the deer-in-the headlights when I even mention a closet unit with ducts installed in furr downs. This also goes for Framers and Home Designers

Asked By Jiggernaut | Apr 18 18
3 Answers

Open cell vs closed cell in a basement?

Hi All!
I am looking to insulate the basements worth of band joists in Northern Vermont (climate zone 6A). There's a couple different things going on here and I want to be sure I'm not goofing it up.

Asked By David Bailey | Apr 19 18
2 Answers

After the fact roof air sealing

Hello all,

Asked By Randy Williams | Apr 20 18
12 Answers

Wall assembly for an old church in Vermont

A client has an old un-insulated church in Central Vermont. She want to insulate the whole thing and turn it into a house. The builder wants to do this wall- assembly. I am concerned about dew point issues and trapped moisture. The walls are currently 2x5 studs with no insulation. Thoughts?

Asked By Robert Swinburne | Apr 18 18
11 Answers

Minisplit for a small room

I'm considering a mini-split install in our house. I'm in Austin TX, so it's a climate that requires significant cooling. I have calculated loads and I have questions about what happens if one has a mini-split running in a low load room. It's a child's bedroom and the doors are closed all night.

The room has internal walls on 3 sides and just one 3x5 window. Currently the load calc shows it at about 3300 BTU (of course that is at design temperatures of nearly 100°F and 72°F inside).

Asked By James Howison | Apr 18 18
5 Answers

Frustrated with local HVAC contractors - should I outsource the design?

Hi everyone. We're building a pretty large house here in the SF Bay Area, and having a devil of a time trying to find an HVAC contractor who'll actually design things using calcs and not eyeballing it. When I finally got one to do a manual J, he had to quit the program due to a family member with a terminal illness.

Asked By mike myers | Apr 18 18
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