Site
Location
Locate the house on a previously developed site to encourage density and reduce ecological disruption. Both panelized and modular construction siting have access requirements that may limit the choice of site, including wide access roads for modules, height requirements for a crane, and bridges strong enough to support heavy vehicles.Environmental Impacts
Stay away from fragile or sensitive areas and preserve as much of the existing ecology as possible. Limit access by construction vehicles to specific parts of the site.Orientation
Position the building to take advantage of southern exposure for passive solar heating in the winter. Also consider solar gain in the summer and incorporate shading into the house design.House Design
Small
Keep the house small to minimize material use and operating costs. Small houses can be transported in fewer modules or panels, lessening the transportation energy needed for construction.Simple
Simplify layouts and roof lines to make construction easier—and to make it easier to seal from air and moisture infiltration. Keeping design simple also lowers labor costs.Standardized
Customization often eliminates the efficiencies of factory-line production and raises costs. If many customizations are needed, consider panelized housing, which arrives on site less finished than does modular housing.Energy Efficient
Look for a manufacturer who can offer a high-performance house with R-30 walls, R-50 ceilings, and triple-glazed low-e windows. These specifications may raise cost, especially with modular housing.Construction
Building Techniques and Materials
Look for a manufacturer using best practices for air-sealing, insulation, and material-saving advanced-framing practices. Ask about environmentally friendly materials such as certified wood, low-emitting finishes and materials, and cabinets with low levels of urea formaldehyde.Factory Practices
Ask about waste management and recycling rates. Manufacturers realize the most savings on materials when they order in bulk; this practice also limits the number of shipments to the factory, lessening the amount of fuel used to transport materials.Transportation
Choose a manufacturer with a factory close to the building site. The transportation of the house should take as few trucks as possible. Note that while panelized construction may be the answer for houses built far from a factory, it often requires contractors to make more trips to the site.Buttoning Up
Use a general contractor accustomed to working with prefabricated housing. Ensure that proper air-sealing occurs between panels or modules and along the foundation. Onsite contractors should use the same specifications for finish work as the factory, including low-VOC paints and sealants.
