Did anyone get to go to this? I'd never heard of the White River Group or Sierra Club. My Landscape Design for Energy Efficiency is a big burning bush against the west side of our house. It's too big even though I've pruned it aggresively several times. Every year I say I need to cut it down but it keeps the garage so much cooler with no sun coming in the west windows so I've left it there. It definitely makes a difference.

To elaborate on thermal bridging since it was brought up again... there are several ways to calculate it, but to keep it as simple as possible, here is how it affects your total wall's insulation. First thing, if you put in r20 rated insulation product, you are certainly not getting an r20 wall for cavity walls. Other products such as ICF and SIPs (some SIPs even have thermal bridges) are nearly thermal bridge free and have what is called continuous insulation. My home is an ICF house from the footings to the roof, and there are no thermal bridges anywhere until the roof line. This gives me an r28 continuous insulation. However with wood frame structures, you have a framing reduction to take into account. Most new homes, studs, heads and plates take up anywhere from 18-25% of the wall area. (lets keep the numbers whole and rounded for easy math) Say you select blown fiberglass in a 2x6 wall, gives you roughly r20. You have 1000sqft of wall surface. That r20 is only for the stud bays, and every 16" roughly you only have an r1 due to the stud (framing factor) So you have 800 sqft of wall at r20 and 200 sqft of wall at r1. . Your "r20" wall is performing at an r16 on average with the studs acting like heat sinks. Add just 1" of XPS foam to the exterior (r5). Your r20 turns into r25, and your r1 turns into r6. Now 200 sqft of your wall is an r6 vs an r1 and reduces the heat sink effect.The materials to add that 1" XPS would be roughly 500-600 for that 1000 sqft wall. The upgrade from blown fiberglass to open cell foam is typically more than that. For adding exterior foam, details are pretty simply up to about 1.5" thick. After that, the details change and become more costly. Luckily for you, in zone 4. 1.5 is about as thick as you need to go. 1" would be a good start, and your details really do not change. I have detailed 1" foam and windows 1 of 2 ways. Either install the sheathing and foam and then the window. Or with 1" foam, most window flanges are 1 1/8"+ wide, so you can install the window and then install the foam. This gives them about 1/8"+ lap for a caulk joint for trim to hide the foam. The trim stands proud of the window with this detail obviously. 1.5" adds another step. I like to detail a frame out around the windows and butt the foam into it. So frame the wall as normal, install sheathing, then rip a 2x4 in half to give them 1.5x1.75 furring to frame out around the window RO. Install the foam, butt into the furring around the window, and then set the window, nailing into the furring. Everything planes out, and quite simple. Obviously this can also be done with 1" foam too, its just not necessary. There are lots of details floating around out there. Check out green building advisor as well. You can also checkout my blog for more details and nerdy building information. Again, a very untechincal explaination, but you get the idea hopefully. Here is a link that might be useful: home building blog

You have to research what works and what doesn't in your geographical area. Online articles and research studies that generalize dont take into consideration different zones and what is efficient and operable there. Some folks take this as gold and dont look into what goes in their area and often times it gets them in trouble. What works in your area most often times is a different animal in other areas.

While burning natural gas (i.e., methane, a greenhouse gas) does produce less carbon dioxide than burning coal, it's been argued that during the production and distribution of natural gas, more carbon emissions are released into the environment, overall, than coal. Needless to say, the validity of the claims behind the eco-friendliness of natural gas, hydraulic fracturing ("fracking"), and fossil fuels in general, remain highly controversial. That said, in more practical terms, residential energy rates for natural gas will typically be significantly lower than for electricity (however it's been generated). In major metropolitan areas such as Los Angeles, this cost difference is huge, making the choice of a gas dryer an easy decision (providing you have gas in your home, and are able to properly vent the dryer). For whatever reason, so-called, "Energy Guides" (the ubiquitous yellow stickers found on most appliances) aren't published for either gas or electric dryers, making direct comparions near-impossible. Modern front-loading washers are pretty miserly on both electricity and water usage, and the minute differences in efficiencies between brands should be negligible. This post was edited by studio460 on Tue, Jul 16, 13 at 6:45