What kind of materials are you going to use?
In the research for materials and techniques to build a house as efficiently and ecologically as possible, I ran into a conundrum. While I would like it to be otherwise, materials from renewable sources are not always the best ecologic choice by default. Although I'm not at all a fan of petroleum products, sometimes they offer the greenest alternative when considering the whole equation of production, transportation and recycling.
This realisation came to me when researching PopUp House, a French concept aiming to make the construction of passive houses easy and fast. Their system is simple, yet very smart. The main building component is insulation, making the buildings extremely well insulated. Large blocks of graphite-injected, EPS (expanded polystyrene) with a thickness of 300mm, account for the majority of the construction. Layers of structural plywood support the foam structure, and everything is fixed together with screws.
Not only is its construction fast, it's also very affordable. As for transportation of building materials, EPS foam consists of about 98% air, thereby making it easy to transport and manipulate. As a bonus, it is also 100% recyclable into new building blocks. And because the structure is not glued together in any way, PopUp houses can be taken apart again, and most of their materials used to build new constructions.
Polystyrene got a bad name because it is (ab)used by the packaging industry. In fact, that can be said for plastics in general. If you think of it, plastics should not be used to create disposable products. Knowing it will sustain for hundreds of years makes it almost criminal for one-time use. But that makes it all the more suitable for more long-term, permanent structures like buildings. Material for thought, no pun intended.