Ask any modular builder in America about sustainability and they will say "we're green, we build in the factory where there is less waste and higher quality." Then you find that they are using exactly the same materials as any site builder.
The always wonderful Sanctuary magazine, in a feature on prefab, shows a project by Australian modular builder Ecoliv. They tell a bigger sustainability story. This house was built as a show home for Sustainable Living Festival in 2014. Sanctuary describes the 69.29 m2 (746 SF) home:
This functional 8 star prefab modular design by Ecoliv has a suite of sustainable features. There’s a vertical garden at the entry, a surrounding dry-tolerant garden fed with an energy-efficient greywater recycling system, a 2kW grid-connected solar system, solar hot water system, electric car charging point and high-efficiency appliances internally. The modules are designed to work within standard building measurements to avoid any off-cuts.
The builders make a good sustainability case, offering as well a 10,000 liter water cistern, sustainably harvested timber framing and lots of insulation. Finishes and materials are all low VOC, which is more expensive than conventional materials.
Ecoliv Buildings minimise the use of plywood, MDF and particleboard due to their formaldehyde content. To reduce VOCs all manufactured timber products have a formaldehyde content of less than 1mg/litre. Ecoliv Buildings incorporates passive and active internal air circulation systems through strategically placed louvre windows to allow for cross ventilation therefore improving air quality.
That's interesting; most North American modular builders use particle board sheathing. Ecoliv uses a rigid insulation panel called Foilboard which acts as an insulated sheathing.
They also take embodied energy into account, which is still really rare.
It was previously thought that the embodied energy content of a building was insignificant compared to the energy used in operating the building over its life, but CSIRO [ Commonwealth Scientific and Industrial Research Organisation] research indicates otherwise. The average household contains about 1,000 GJ of energy embodied in the materials used in its construction – equivalent to about 15 years of normal operational energy use.
I found this interesting and dug up some of the research. More on this subject to follow.
The builder describes the house:
The Eco Balanced is a finely tuned yet modest design, which significantly exceeds expectations for its typology. Its contemporary form and streamlined layout combine a holistic approach to solar design and systems integration which contributes to aspirations of sustainability by achieving an 8 star thermal rating.
The star rating system is complicated, but "use computer simulations to determine the potential thermal comfort of Australian homes on a scale of zero to 10 stars. The more stars, the less likely the occupants will need cooling or heating to stay comfortable."
More photos of this and other projects at Ecoliv. I think this is the plan: