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10 Answers

Air-source heat pump for heating, cooling, and domestic hot water

We are working on a net zero project here in Dauphin, MB (Western Manitoba) and are interested in reducing our annual electrical usage (thereby minimizing the size of our required PV system to achieve net zero 'status'). I have been encouraged by our energy modeller to consider a cold climate air source heat pump for space heating and cooling. I am seeking to know if a practical solution exists to use air source heat pump technology for space heating, cooling AND domestic hot water with a single outdoor unit.

The annual usage is estimated as follows:

Space Heating 2100 kWh

In Mechanicals | Asked By Eric Bjornson | Aug 31 17
5 Answers

Sizing a furnace

I was reading an article about HVAC sizing with Manual J & D.

Here is my question:

If you have data for an existing home -- heating-only therms, furnace run-time (from smart thermostat), HDD, etc for the coldest days of the year for multiple years -- can you calculate furnace sizing in a different way?

In Mechanicals | Asked By mtaylor12345 | Sep 12 17
4 Answers

Sub-slab insulation

I was planning on using 4" of Type II EPS covered with 10 mil Stego under my slab and 2.5" of EPS on the basement walls. I spoke with my concrete guy today and he told me they have been using this product:

In Energy efficiency and durability | Asked By Jonathan Lawrence CZ 4A New Jersey | Sep 13 17
2 Answers

How much do oil-based stains affect vapor permability?

Hi guys,

I stained my siding recently (bevel siding) with oil based stain.

Since my house is built fairly vapor open, I am curious how much oil stains will affect the vapor permability of the building's envelope and ability to breath?

I am guessing it leaves the wood still semi vapor permeable because almost every house has paint/stain.

How do you guys approach this when building a vapor open house? Even if it makes it vapor closed, I do have 1/2" furring strips behind my siding, so would that be suffecient to allow vapor to escape from the house?

In Energy efficiency and durability | Asked By MichaelBa | Sep 13 17
6 Answers

Vapor barrier

I have read that with me putting two layers of 1 1/2 inch foil-faced rigid foam with staggered joints on the outside walls, I don't put a vapor barrier on the inside.

Now on my low-slope roof, I have 2x12 rafters. Starting at the top, I have:

15 lb. felt paper-
ice shield over the full roof-
1/2 inch plywood sheathing-
1 5/8 inch air space to vent-
1 inch foil-faced rigid foam, caulked at the edges-
1 1/2 inch foil-faced rigid foam, caulked, with staggered joints-
2 inch foil-faced rigid foam, caulked, with staggered joints-
5 1/2 inch Roxul insulation.

In Green products and materials | Asked By Gary Ovens | Sep 13 17
3 Answers

Insulating at the ridge

We finished framing the roof and are getting ready to start sheathing tomorrow. I have a structural ridge (7 x 20 LVL) over a cathedral ceiling and a non-structural ridge (1 3/4 x 11 7/8) with collar ties over the rest of the roof. The roof assembly calls for 5/8" gypsum, Siga Majrex vapor control membrane, 2x10 rafters packed with DPC, 5/8" Zip sheathing, 5 1/2 ThermaCal1 nail base panel (4" of polyiso with a vent channel on top) and shingles (probably cedar).

In Energy efficiency and durability | Asked By Jonathan Lawrence CZ 4A New Jersey | Sep 4 17
4 Answers

Wait to air seal until after blower door test?

I’ve been waiting for cooler weather (in zone 5A) before scheduling an energy audit that includes a blower door test with infrared camera. But now in early fall/late summer is a comfortable time to venture into the attic. Is there any reason to wait until the energy audit to work on obvious air sealing improvements? The only thing that I can really think of is that we might miss out on some potential credits for improvements if our “Before” results limit our improvements.

In Energy efficiency and durability | Asked By andrew c | Sep 13 17
4 Answers

Should I use EPS/XPS or spray foam to insulate basement walls with a brick texture?

I am looking to add a few bedrooms and a bathroom to my walkout basement. It has poured concrete walls on 3 sides, but the poured concrete has a brick pattern / texture to it complete with simulated mortar joints. Since this is an uneven surface, I am wondering if EPS/XPS is an option or if I have to go with spray foam insulation to fill all the voids?

In Energy efficiency and durability | Asked By Macrocks | Jul 18 17
2 Answers

(MA-specific) How to get clawfoot tub installed in NEW construction

We are about to pour slab-on-grade here in Massachusetts. Under-slab plumbing is done. Our hope is to reuse an old antique clawfoot tub in our new construction. *Reusing* old, instead of buying new, seems very 'green' to us, hence this inquiry at GBA.

MA has an 'approved plumbing list' for all fixtures. If it not on the list, then it is not permitted for installation. So far as I can tell, I don't think the AHJ can override it, but perhaps there is some slack.Until I am more sure of my options I do not want to have a discussion with the plumbing inspector office.

In Building Code Questions | Asked By Kenneth Gartner | Sep 13 17
1 Answer

Double vs Tri Pane Marvin Windows

I have a window quote for several windows. Going with Marvin Integrity. Contemplating an option for TriPane Low E2/Low E1 w/ Argon. Ufactor drops from 0.28 with the double pane to 0.19 with the TriPane, and SHGC drops as well from 0.45 to 0.25. Windows will be on the NW and NE sides of my house.
Price premium for TriPane is >25% ($267 increase), so needless to say the energy payback is long long term (if at all).

In General questions | Asked By Pete Marthaler - Zone 7 | Sep 13 17
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