We're talking about building a green house, not a greenhouse. According to the National Building Museum these are the 5 principles of building a green house:

Let's look at each one of these in building a green house...

1.Optimizing use of the sun.

In the northern climates it's a sheer waste of resources NOT to take advantage of the warming rays of the winter sun. It's my belief that most builders don't think about this because they're constructing their house during the warmer summer months and don't readily think about what it's going to take to heat the house in the winter.

Building in southern latitudes has just the opposite problem. Trying to shade from the intense sun in the summer to help reduce cooling costs. I haven't studied this one (as I live in Wisconsin), but I'd venture to guess that shading windows with wide overhangs would go a long way to reducing that solar gain.

Tradition is also a big stumbling block in getting folks to think about house orientation to the sun. Because fossil fuel heating options have generally been cheap, or at least affordable, most people think heating their home in the winter will be "budgetable".

If potential home buyers really aren't asking questions about how a house is oriented to the sun, then builders will keep on doing what they've always been doing. Which is not being too keen to put extra money into a spec home for energy conserving features.

But, orienting to the sun is so simple it should be a no-brainer. With the small house I built there are 2 6' x 4' windows and 2 2' x 4' windows in the main living area (there's a vaulted ceiling), plus 2 4' x 2.5' windows in the exposed basement wall below, on the large south face of the house. And there are 3 very tiny windows on the north face. East and west faces have an average amount of window space.

I didn't, however, orient the long axis parallel to the imaginary east-west line. If you're thinking about a design that incorporates many interesting gables and dormers, and is basically a squarish (as seen from above) design, then there's really no long axis to worry about. You're primary focus will be the size and positioning of windows. Oh yeah, and maybe you'll want to consider where the "front" of the house is in relation to the street-- but, that's really a style issue ;).

The reason for positioning a house with the long axis parallel to an east-west line is to take advantage of more hours in the day to absorb that solar radiation. Also, if you're thinking of adding solar panels of some kind (PV or water) the large face of the roof that faces south is a great mounting place for those panels. Although some of the newer remote PV solar tracking panels are pretty cool, in which case you don't want to attach them to the fixed surface of a roof.

2. Improving indoor air quality.

Not really sure why this is on the list for building a green house. Maybe from the standpoint of choosing building materials that are free of formaldehyde and other nasty chemicals. Building materials in general are getting better about using glues and adhesives that don't degrade or off-gas harmful chemicals, but there's still a lot out there that use the old adhesive formulas.

Your bigger lumber yards that have a high turn over of product are your best bet for finding the newer, cleaner, engineer woods on hand. If you don't find what you're looking for you can always have green building products special ordered.

Particleboard, plywood, and MDF (or medium density fiberboard) are some of the engineered lumber products that use bonding glues to keep the particles together. These products use a fair amount of urea resin to bind them into sheets, which eventually transforms into gaseous formaldehyde. OSB (or oriented strand board) tends not to have as much of an off-gassing problem as the other engineered wood products.

Carpeting and vinyl flooring are some of the worst offenders in this regard. Traditional manufacturing of these products require a lot of petroleum, and they off-gas VOCs (volatile organic compounds) as they age. Wool carpeting and real linoleum are better choices.

Even though carpeting can be recycled and made from renewable and green materials, it still can harbor natural elements that can adversely affect indoor air quality. Primarily mold, dust mites, and pet dander. If you've ever pulled up old carpeting you've seen all the grunge that filters down through the carpet and pad onto the subfloor. This is dirt that will never be cleaned out by any super rug cleaner. Think of this before you install carpeting.

If you're looking at dealing with bad indoor air quality in the house you're currently in, then it's time to look at a really good air filter. Preferably one that goes on the ductwork of your heating/AC system. That way the whole air space on a house can be drawn through the filter and cleaned more efficiently.

Looking At "Being Green" In A New Light

Little House on a
Small Planet

Contains many examples of people and families that are succeeding at living small.

Shay Salomon says in Little House On A Small Planet:

I'm already starting to look at my building itch in a new way! No matter how "green" or "ecological" a new small home is, or remodeling project or addition, it will always use more resources than simply not building.

A simple, yet profound, thought.