I like saving energy mostly because I like saving money.  It's good to know that I can get a more comfortable home and save a ton of money on energy costs at the same time.  This part of the program teaches builders to build homes, which are many times more efficient than they are now.  They are taught to properly seal the envelope, locate heating and air units inside the building envelope for maximum efficiency, and stop the energy from leaking into or out of your home.  Where you put the windows makes a difference.  The kind of windows makes a difference.  Did you know that insulation works vastly better when it's sealed inside a wall cavity.  Did you know how many places this doesn't happen in the everyday world when nobody thinks about it?  Did you know that when you turn on your HVAC some of the rooms become pressurized and the air leaks out of your can lights, unsealed outlets, and plumbing penetrations like under the sink and behind the tub.  Builders enlist the aid of a trained energy rater who can identify problem areas, and analyze the performance of the home on the site before construction even begins.  Through a detailed plan analysis with my HVAC supplier we were able to determine that my heating equipment could be resized smaller. The theory was that I'd be able to afford the most energy efficient equipment available, because I'll only need half as much.  I could use some of that money to implement other areas of the program, like energy star appliances, or tankless water heating.  Well that was the theory. In practice, when you get into 16 SEER variable speed equipment the two ton unit isn't really any less expensive than the 3 ton unit.  Maybe that will change.  Anyway I got some great HVAC equipment that never seems to come on.  Well it comes on if the temperature goes below about 35 degrees but it doesn't run long.  I'm not complaining, though.

First you have to think about sealing the box.  It doesn’t matter how much insulation you have, if it’s not sealed it doesn’t work.  I’ll pause for effect, and so you can think about it.  Sealed on six sides is what I remember the instructor saying.  That’s the bottom at the shoe, the top at the plate, the sides by the studs, and the inside at the drywall, and the outside at the sheathing.  If you go in the attic and look at a knee wall and you can see the fiberglass guess what?  It’s not sealed.  As the air blows around in the attic it blows through the insulation and guess what?   If your can lights are vented to the attic and you pressurize the room with AC guess what?  If they cut square holes under the tub or under the lavatory to hook it up guess what?  If your ductwork kind of snakes it’s way into the attic from somewhere else that’s not good either.  And when I learned that 85% of ductwork leaks I realized why my power bills along with everyone else’s is way too high

Sealing the Box A quick over view of what I'm trying to accomplish here, and how I'm going about it.  What you're trying to do here is seal the inside up tight from the outside, remembering that if you get airflow through any of your insulated "boxes" they are going to not work properly.  Remember that fiberglass insulation works best when it's sealed up in a box. You have to be careful to look for the places where your fiberglass kraft paper might not get sealed up by the drywall, like tubs or prefab fireplace areas.  Also look for electical (can light) penetrations, and plumbing pipe penetrations, or those building projections that leave overhangs like bay windows and such.  I was able to luck into a design that sealed up my entire floor system from underneath, and was also able to completely conceal the insulation in the attic for extra performance.

sealing the box

In my new home I had a stairway designed to lead to an unfinished attic.  I realized that a good part of my attic was potentially sealed, and by changing the remaining area to 2x10’s and OSB I could seal the whole thing up tight. Where the stairway enters the attic space you can seal the insulation with some leftover thermo ply.  That seals up the insulation on six sides.

You want to make sure that the sheathing seals up the exterior.  This use of thermo-ply aligns the floors with the wall lengths easily because the material comes in 10’ lengths. You also can use housewrap, or zip board products to seal the box and create a proper drainage plane.

Behind the tub unit there’s an exposed air cavity not covered by drywall on the inside.  You can seal that up with the thermo ply and keep air from moving around in there.  Same goes for behind the firebox on an exterior wall.  Make sure to deal the joint between the bottom plate and the plywood floor.  You can use caulking, I also wrapped the outside of the joint.  We used foam inserts inside the headers to form a thermal break. There also techniques for properly flashing the windows to keep moisture from getting trapped in the wall.

Another concept that I wanted to employ was moving the HVAC and ductwork inside the envelope.  Not only does it prevent conditioned air from leaking into the attic, the units and ductwork are inside the conditioned space, not working in a hostile environment such as a 135-degree attic space.  You can do it other ways of course, like spray foaming the attic space to enclose the units, but I wanted to go green with more conventional methods.  My lower garage area already has to be sealed with fire-rated sheetrock for the cars anyway, and I already decked in the attic, so this configuration was the right one for me. 

HVAC inside the box Another technique I'm experimenting with is moving the whole HVAC system inside the building envelope.  Think about where your system and ductwork is now.  My old one was in the attic and in the summer it's 150 degrees up there.  My system has to work harder in a tough environment like that.  And if there are any leaks in the air supply system it will create a negative pressure inside the home.  Bad things can get sucked into my home, from the garage, or through leaks in the envelope.  That's why I'm trying to seal the units and the ductwork inside the thermal envelope. There are other ways to accomplish this, a popular way is to seal up the attic with spray foam and essentially move the building envelope to the outside of the attic.  But since I had the opportunity to seal up the underside also and stay with fiberglass which is cheaper I decided on this approach.

HVAC inside the box

Ductwork sealing is extremely important. If your supply leaks into an unheated area two things happen, you lose the conditioned air, and worse, you bring in humid unconditioned air from someplace else that you can’t control.  A wall leak, floor leak, a chimney pipe, or those can lights we talked about earlier.  The best, most energy efficient equipment available, is worthless when combined with a leaky envelope or a leaky duct system.  Design your system using Manual J for loads, Manual D for ductwork, and Manual S for equipment sizing. Mastic seals the ductwork against leaks.  Later we covered this duct to prevent dust and dirt from getting inside. Energy star windows:  Look for the Energy Star Label, Low E label, and these numbers on the label.  Remember to use fewer windows on the east and west sides, and try to get those overhangs over south facing windows.

Just one more thing before we leave this section, all of you know how bad fuel prices are now.  I don’t think electricity can be that far behind, especially if we have to build some more nuclear plants, and they ever figure out how to run cars off the stuff.  My electric used to scare the begeezes out of me, and make me do bad things like yell at the kids to turn off the lights, and sneak around and adjust the thermostat behind my poor wife.  It really shouldn’t have to be this way folks, not in America.  Spend some time on this section, and maybe you could cut your power bill in half or something, wouldn’t that be great?  Personally I’m looking forward to a little family harmony around my house.