Raymond,
My family of 5 lived in a 380sqft apartment (with a 750sqft productive garden) for nearly 13 years (+6 years before children) and it seemed that the key for us was love, respect and utter discipline over stuff. So if you are moving into a smaller space the key is in ensuring that you only take what you need, and that you plan how want to access your stuff in that space. Use permaculture principles in the way you understand the multipurposeness of everything. My wife and I have been sleeping on a folding futon sofa/bed for more than 20 years (not the same futon - we
compost them every 8-10 years!). Your storage space needs to suit the accessibility of your stuff, seasonal clothing could be deep-stored etc. For modern houses there is often too little crop storage, so build a north-facing larder. But most importantly make a plan, like you would for a garden, divide the plan into projects that take a morning or so, and keep to plan (until the plan needs changing!). Hope that helps.
Nathan,
Metal buildings need to be insulated first, with an air-gap so that condensation doesn't rust the building. It is best to use the metal skin as a rain-screen, and make an internal framework with a breathable external skin. It would be good to leave an 18-24" gap between metal skin and internal building so that you can get between to maintain it. Fit removal insect screens around the gap to stop critters from living in between, while allowing air to move moisture up to an extraction chimney. Of course you will need to penetrate the metal skin for daylight and the deep internal window ledges will provide a place to sit. Do not underestimate the power of condensation to destroy a metal-skinned building! 1600sqft should be enough for 3-5 small families, providing you build communal spaces for laundry, cooking (especially if you want to include a wood-fired oven). Furniture could be built in, fold-away beds, storage etc. Don't let you workers sleep under a metal roof, it's deafening when it rains!
Jane,
A cabin in the woods benfits from the reduction in exposure from extreme weather, providing that you haven't chopped down all the trees to form a clearing. Most cabins were built from local materials (timber), but the design was key. You could build with a dirt floor but in areas of high-rainfall (such as BC) you would be wise to build with a raised floor, building off corner poles that sit on small concrete pads (oil drums that are sunk into holes that leave the top 4-6" showing work well). Put a square of lead sheet under the pole and then design the cabin with beams with good insulation and a rain-proof but breathable external skin. Unless you are building in a massive style (e.g log cabin) you will need to put in a couple of diagonal struts to reinforce the structure. Of course you could always build a tree house - there are some seriously cool designs out there.
Sherakee,
There are a number of different underground styles structurally. You could 'mine' a structure (like the limestone houses in Turkey or around the opal mines in Australia), you could build a cellar under an existing structure (which depending on the original building's foundation will require the use of I-beams) or build an earth-bermed structure either into a hill-side or like an Earhship. Earth is heavy and usually is porous and so will hold water. Earth can be resistant against thermal extremes, it has significant thermal mass, but it should not be confused with an insulator. Strawbale houses will always be better insulated than earth-mass houses. In every case where you want to build underground you must understand that earth is very dense and you will need to design to keep water out and so design a means to remove condensation (warm moisture in the structure condensing on a wall in contact with the soil it is holding back). To design any underground structure you will need employ an engineer and work to your local building codes. Not all I-beams are created equal, so it is important to utilise beams that are sufficiently deep in section to support the load over the distance you need. Underground building is a complex subject, and there a number of good books out there, but at the end of the day, in order to keep safe you will need to make sure you use an engineer. Guitar player is my eldest son - his bedroom is just above my small office - I love that!