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5 Answers

Should you insulate the exterior of a house with rigid insulation if you have spray foam inside?

A customer of mine wants rigid foam on the outside of his house to stop thermal bridging, and then wants to have either open or closed-cell foam blown in the interior.

I was wondering if that would be a bad situation for the OSB trapped between the two. What would be good ok around?

In Energy efficiency and durability | Asked By Jed Koljonen | Jun 12 12
23 Answers

HVAC Recommendations and Costs for a tight well insulated home

We are at the stage of determining the HVAC system for our new near passive home 2 story home (Upstate NY zone 5a). The Manual J run by my builder (total heating load ~14,000, cooling ~20,000) is attached along with the floor plans. We do not want a visible unit in the main living area. We are concerned about getting even heating and cooling in the master suite and upstairs where noise transmission is an issue (we both work from home). Backup heat will be with a wood stove but the building inspector will probably want another source if we use a heat pump.

In Mechanicals | Asked By Elizabeth Kormos | Jun 3 12
7 Answers

Thermal/Ignition barrier options?

I am looking for the best option for an ignition or thermal barrier to apply over open cell spray foam insulation in roof rafters.

My understanding is ICC code requires a minimum ignition barrier on open cell spray foam in roof rafters when the attic space functions as a usable space. I.e. – storage, air handling systems, etc.

In Energy efficiency and durability | Asked By Mark Lancaster | Jun 8 12
2 Answers

Rainscreen detail with brick mould window

I'm getting ready to reinstall the windows on my exterior foam retrofit project. I installed two 1" layers of PolyIso foam. I plan to side the house with Hardi Lap siding. I had planned on using a rainscreen between the PolyIso (foil surface is my WRB, all seams taped for each layer). I'm hung up on how to install the windows. They are brick mould Marvin casement windows that were on the house prior. I am installing new PVC brick mould and PVC stool to the windows before re-installation. How do I incorporate the rainscreen into the window installation?

In Green building techniques | Asked By Kacey Zach | Jun 11 12
2 Answers

Why is a well air sealed house with exhaust ventilation more energy efficient than a average house?

I believe it but its hard to explain. Are there studies and reports on the subject? I live in zone 4 NW California not real cold but lots of cool nights.

In Energy efficiency and durability | Asked By larry ogden | Jun 11 12
1 Answer

Windows and insulation

A portion of my bedroom ceiling is vaulted into a dormer. The dormer window is energy efficient (low e, etc). The window faces east and when the sun shines the vaulted area is noticeably warmer.

I want to try and insulate the window further. Would a film help, and if so would the film need to be rated by any specific industry standard? I have seen several stained glass films, but don't know if they would help with energy efficiency. Or, would a honeycomb shade work?

In Energy efficiency and durability | Asked By Chris Johnston | Jun 11 12
2 Answers

Window options - large picture window

We are building a new home in the Omaha, NE area and have a number of windows on the north side of the house. We are planning to use triple-pane IGU's from Cardinal in fiberglass frames from Inline (window units will be assembled locally).

In Energy efficiency and durability | Asked By Dave W | Apr 13 12
1 Answer

Should we insulate under a slab even in an unconditioned space?

We have a +/- 3,000 sq. ft. maintenance building we are designing which is mostly unconditioned space on a concrete slab (there are a couple offices in one area). The primary goal of the slab is to provide a durable and flat work surface for relatively precise vehicle and equipment maintenance. There is always the chance that the building could be re-purposed in the future and insulated and conditioned. We are in climate zone 4. Is the slab less prone to cracking if we install +/- 2" continuous insulation underneath? or even just 2" at perimeter?

In Energy efficiency and durability | Asked By Duncan McPherson | Jun 11 12
4 Answers

Good plan for a minisplit?

So I previously was ruling out a minisplit for the new home. However I notice Mitsubishi released a new single-head Hyper Heat unit that is now 21 kbtu instead of just the 9 k and 12 k. I think this opens up the discussion again.

Zone 6, 7200 HDD, design temp of -13. First floor footprint is about 1650 sqft. There is a full basement, with most of it finished. Total heat load for main floor and basement is 21k and 14k cooling.

In Mechanicals | Asked By Jesse Lizer | Jun 8 12
3 Answers

If you're interested in ASHRAE 62.2 and existing buildings, you should check out this email string

At ACI this year, I had the pleasure of meeting many members of a group known as the Trainers Consortium. Following a recent conference call, which I was unable to attend, an amazing email string appeared in my inbox. Barely able to keep up with the conversation, I felt that it deserved broader distribution as it covered some very important and interesting (at least to us geeks) topics. I have assembled the content and posted it on my website. Please enjoy the conversation an add your own thoughts.

In Energy efficiency and durability | Asked By Carl Seville | Jun 8 12
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