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4 Answers

ERV-Minisplit combo vs. Magic Box

We are conducting a deep energy retrofit on our two unit building (each unit 1,500 sf) in Chicago (zone 5a). I am pretty much done with the first floor and chose the ERV-Minisplit combo to primarily address our ventilation needs, cooling needs and summer dehumidification. And it appears to work well (Recoupaerator and one 12,000 Btu Fujitsu Minisplit): Winter time humidity around 40%, summer time humidity around 55%.

In Energy efficiency and durability | Asked By Marcus de la fleur | Jul 26 16
7 Answers

Off-grid weather station to measure build site conditions

I've purchased vacant land in hilly terrain and will be building a residence and workshop next summer.
I'd like to setup a solar or battery powered weather station to learn more about the microclimate.

Knowing, e.g., typical temperature and humidity swings on the site will help me answer questions like: "how much insulation does the workshop need to prevent condensation / rust on tools?"

Does anyone know of an off-the-shelf battery or solar powered weather station that can measure temperature, humidity, and wind speed?

In Green products and materials | Asked By Kevin Lynagh | Jul 26 16
62 Answers

Questioning my logic...GSHP, ASHP, radiant?

I'm in the planning/almost ready to break ground stage of a new home and I'm beginning to question my sanity when it comes to figuring out the right approach for heating & cooling.

The home is:
North end of Climate Zone 5
Main Floor: 1700 sq ft + 1000 sq ft garage, vaulted ceilings through much of it
2nd Floor: 1100 sq ft (2 bedrooms, 2 baths, living room) primarily over the garage
Basement: 1700 sq ft, partial walkout + 1000 sq ft shop under the garage (separated from the rest of the basement)

Walls: R30+ (2x6, 2" XPS outside, 2lb SPF for sealing + 1/2lb SPF for cavity fill)

In Mechanicals | Asked By Dave De C | Jul 16 16
4 Answers

Fiberglass batts in a cathedral ceiling?

Hi Martin,
I've been reading the GBA web site and have subscribed to the Fine Homebuilding magazine for several years but this is my first venture into the "green expert" arena. I could ask much but will try to narrow my questions to the two below.
My wife and I are building a small, hopefully energy efficient week-end/retirement home located approximately 50 miles east of Erie PA. Though the maps indicate Zone 5, having grown up there and experienced the winter lake effects, I'm considering it Zone 6.

In GBA Pro help | Asked By Michael Watson | Jul 26 16
10 Answers

Bowed gable-end truss

Today we got 18/19 trusses set and somewhat braced, more to go on bracing.

The problem we ran into is that the gable and would meet the wall in the middle, but both ends were off the walls. The walls are straight and flat.

I pulled the gable down and snapped a chalk line along the bottom of the bottom chord, and found that the center was lower than the ends by a good 3/4".

Having never set a pre-buiilt gable truss, I would think that it would be nearly impossible to load the top chord enough during installation to push the bow out.

In General questions | Asked By Mike M | Jul 24 16
9 Answers

How should I heat my water?

Hi there. I'm just starting a major renovation of a two story studio space attached to our detached garage to be used as a studio and sometimes guest house. We're adding water and septic to the house, and I'm looking for ideas on the best way to get hot water. We'll only have a single bathroom with shower, and a small wet bar sink on the same wall as the bathroom, so there are no long pipe runs. Usage will be infrequent but once in a while fairly aggressive if we have guests there who need to take multiple back-to-back showers.

In Mechanicals | Asked By Curtis M | Jul 17 16
70 Answers

Why haven't steel-framed homes become more popular?

I am in the planning phase of building a home in the NJ-NY area, Climate zone 5. As I investigate my options; SIPS, double wall stick 2x4 wood, 2x6 wood, ICFs, CMU, Larsen trusses, etc.. and the myriad of permutations to insulate each one (spray foam, cellulose, hybrid batt & flash, exterior rigid foam/iso panels, etc....) I came across STEEL. My goal is as high R-value as I can get within reason $$, with hope of upwards of R-30 final values. That said, I need some objective input.

In Green building techniques | Asked By Sal Lombardo | Dec 27 12
6 Answers

Air space required for GE Geospring hybrid electric heat-pump water heater?

I'm interested in going to a heat pump water heater and looking at the GEH50DFEJSR geospring model. I see in the manual it says it needs a 10×10x7 room or louvre door or duct kit. I'm curious if a vented pass thru to a larger room works the same? Kinda like a cold air return. The room is 8x5.5x8 and would rather not put a louvre door up. Any recommendations? Anything else I should know before purchase?

Thanks so much!

In General questions | Asked By Stephen Audretch | Jul 24 16
3 Answers

Open-cell foam and airtightness

I've seen reports from the foam manufacturers touting how much better the foam is than fiberglass of the same R value. They're essentially using the improved airtightness of the foam to show better performance compared to fiberglass with no air barrier. I can see it's mostly BS. I am wondering if you have a proper air barrier if open cell foam can measurably increase the air tightness of the structure?

In Green products and materials | Asked By Brad H | Jul 25 16
6 Answers

Preferred underlayment under metal on unvented roof?

Hi Everyone,
Need to make a final decision on which underlayment to use under a metal roof on an unvented roof system. The roof is currently built as follows: Beams on 5' centers; 1 1/2' T&G decking; 3/8" plywood diaphragm - seams taped; with TriBuilt granulated self adhering underlayment on top of the plywood.

Next I'll be screwing down 5 1/2"RayCore SIPS panels over heated space and framing boxes over the eaves covering everything with 5/8" CDX. Still looking at metal roof products but am zeroing in on a high seam (1 3/4") snap lock system. Roof pitch is 2/12.

In General questions | Asked By Robert McKee | Jul 23 16
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