Construction

Historically, people used whatever material was available locally to build with, and the style of construction was adapted somewhat to the climate. Modern construction methods, and cheap transportation has eliminated both of these aspects, at least in the US. While these traditional building methods have much merit, they were mostly far from ideal, and so a compromise of new and old makes a better building.

No matter how a house is built, the building must accomplish three things:

Hold itself and the contents of the house up.
Each story needs to hold up everything above it, all of the buildings contents and its occupants, and any snow load on the roof. It also needs to hold up when all the occupants are dancing, when the wind is blowing and during earthquakes.
Keep the weather out: it provides a continuous barrier between inside and out.
It also has to keep the indoors in, since most building will be using energy to modify the indoor temperature. The type and size of the barrier depends on climate: How much it has to keep out the weather depends on climate: in a tropical climate you may only need to keep out the rain, in the desert only the hot or cold, but in most climates you want to keep out both.
Adequately deal with moisture movement, which generally means there is both a moisture and air barrier, and often some way for the interior to dry out.
This is to prevent mold.

Building From the Ground Up

Buildings have three components: structure (that forms the space), weatherization (that keep the temperature reasonable and the rain out), and finish materials. Depending on the building system, each function can be accomplished by separate materials or multiple functions can be accomplished with one material. Construction is simplified when one material does multiple functions, but the properties of materials (strength, water resistance, heat resistance) often make this difficult or impossible.

Envelope

Although we think of foundations, walls and roofs as separate things and in fact build them separately, these component go on to combine with insulation, air barriers etc to form a complete envelope, ie effectively an unbroken membrane around all six sides of the building that control water and heat movement. Of course, this membrane will not be perfect: first because we have to get in and out of the building, and second, because we'll be building the membrane in pieces, but still the goal will be to make it as good as you reasonably can. In designing the structure, we must not only account for where the insulation goes, but we must have a plan for how air sealing will be done, and how we'll control water entry, and how we'll deal with moisture movement.

The net result is that after weatherization, one should be able to trace a nearly continuous line of the barrier around the building in any direction, including underneath. This barrier is one that resists water entry, resists heat movement, and controls vapor movement in all directions.

Structure

There are many ways to build a building, and which way you choose will depend on your climate, availability of materials and personal preferences. Most houses in the US are build from a single wall wood frame, and most of them are inadequately insulated as well as sometimes having other problems. Wood frame construction has a large infrastructure of suppliers and labor who knows how to build frame walls, but that doesn't mean its necessarily the best choice for all climates.

Each of these building techniques has its own user groups and cheerleaders, and each group will claim their building technique is better than everyone else's. Needless to say, they're all wrong, because each has its own unique set of tradeoffs. In considering each of the techniques, you need to not only evaluate their relative merit, but to figure out whether you can find the materials and expertise to build in that style. If you live in an areas with building codes, you may also find the building department not especially open to alternative construction techniques they are not familiar with. Although not insurmountable (patience and charm help), it can add a significant burden to the construction process. A place to look for help is the Northwest Ecobuilding Guild's Code Innovations database.

The following discussion, a building is broken down into three components: floor, walls and roof because they are each fundamentally different. There are many more options for walls than there are for floors and roofs, and this is probably due to the fact that floors and roofs must be constructed out of material that is strong in bending, while walls must be strong in compression, and there are many more materials that have strong compressive strength than there are materials that have strong bending strength.¹

Note: construction diagrams are examples only, not intended for actual construction.

Foundation Systems

There are only three common foundation systems: slab on grade, crawl space, and full basement. There are two other possibilities, but of which are not very common: a house on posts, and an adobe floor. The common foundations are all on concrete, while post houses use little to no concrete. The common varieties can also be done without concrete in some places, but convincing an inspector to let you can be difficult.

Wall Systems

Since walls are where most of the variation in envelope design is, this document will continue the grand tradition of spending an inordinate amount of space on walls. To a large degree the emphasis here is because walls have traditionally had less insulation in them than roofs, but also because there are just more ways to handle a compressive load, which is what walls do.

Traditional 2x4 framing uses more wood than structurally necessary, resulting in both increased framing costs and a lower insulating value. Advanced framing, which has been around at least since 1980 addresses these issues, but still does not make a truly superinsulated house. In the meantime, many alternative building systems have emerged, most geared at much higher levels of insulation, each with its own set of advantages and disadvantages.

The following discussions compare some of the common (and some not so common) wall systems, both in environmental terms, level of insulation, condensation potential and construction ease. Most of these methods are only suitable for new construction. If you're remodeling, start with the remodeling guide, and ignore all wall methods except Rigid skin, Larsen truss, and SIP.

Roof Systems

As with foundations, there are only three kinds of roofing systems, and of these, the majority of roofs built in the last 30 years are all truss roofs. There is also a fourth kind of roof system, which is the arch and with arches you can build a roof out of heavy material with little to no bending strength because the shape of the arch transmits any bending load into a compressive load. You also need to decide the roof pitch (ie how steep it is), and what roofing material you will use (see roof design for design info).

Climate Control

Here we modify the structure to keep out the rain, keep ground water out, keep air from moving thru, control vapor movement, and keep the temperature moderate. What is presented here are general techniques--what you actually do will depend very heavily on your climate, how the building is constructed, the microclimate and occupant behavior.

Barrier Cheat Sheet

Confused about what the various barriers are? So is most everyone who isn't an expert. Read the various barriers section and hope that helps².

First you need to keep the water out with Water Barriers.

Second, you need to keep air from moving thru the envelope with air barriers. For background on moisture and health issues, see moisture control in the health section. For background on the energy issues, see air infiltration in the energy section. The simple summary is: (1) that although all air leaks generally increase energy use, not all of them cause mold (2) controlled air intake (ie mechanical ventilation) is both better for health and energy use.

Third, somewhat less critical than air movement, but still important is dealing with vapor diffusion which involves understanding vapor retarders and along with that, the condensing potential of any assembly.

Fourth, is that you need insulation, which is covered in the energy section. In addition to the standard concerns of getting the right R-value, cost, availability, and environmental impact, ultimately it important to know how your insulation interacts with moisture movement, so at this stage keep in mind the permeability of the insulation.

Fifth, likely you will need a ventilation system. See infiltration for why nature does not provide a good ventilation system. For background on air quality and moisture issues see ventilation in the health section. During this process consider which HVAC system to choose and how it integrates with the ventilation system.

Finally, see moisture strategies to integrate the various components in a way that will note likely have mold problems in your climate.

Utility layers

To be added. The pros and cons of keeping utilites inside the insulated space.

Finish materials

Summary to be added. This is mostly covered in the materials section.

Remodeling

There are unique challenges in remodeling even for those with no green considerations, but of course re-using an old building is often greener than building new, even if re-using means taking the existing building apart and just reusing the materials. More details are in the remodel section (currently only a stub).

Building Materials

There is nothing inherently better about building with one material than another, and although different materials have different environmental impacts, buildings are complex enough that a straight comparison is difficult.

All the descriptions of construction methods assume a familiarity with standard construction materials and methods, so for those who aren't familiar, the building materials section contains background info on these materials and standard building methods using them.

Understanding Structural Engineering

While you don't really need to know structural engineering, at least a vague understanding of it helps you see why things are built the way they are, and it also explains terms used in the following sections. So here it is: structural engineering without math.

Resources

Building with Vision: optimizing and finding alternative to wood, Watershed Media (2001).

Buildings of Earth and Straw, Bruce King covers all the structural issues of these alternative buildings.

EEBA builders guide series (one for each climate), Joseph Lstiburek, 2004-2010 (depends on climate).

SIP manufactures association at www.sips.org

Insulating Concrete forms association at www.forms.org

The Last Straw -journal of strawbale info - thelaststraw.org

Notes

1: The one caveat to this is using arches to build stone roofs, but there are so many difficulties in doing this, that the method has been largely abandoned. The same arch concept can be used with cob, papercrete or any other material with reasonable compressive strength that can be formed into blocks.

2: Alas, although I've studied this for a long time, and done tons of research, I'm not an expert by any means.