Are earth-covered buildings more costly or less so than conventional buildings?
Earth-covered buildings require a reallocation of most building budgets. More capital is needed for excavation and fill, landscape development and the structure. On the other hand, less capital is needed for exterior finish materials as well as for equipment for heating, cooling and lighting. (Windows cause glare; therefore, those parts of the building without windows need less artificial light.) The economic trade-off between below-grade moistureproofing versus above-grade roofing costs can go either way. How these budget changes work out depends critically on the design of the building and the selection of its site. Consequently one cannot flatly say whether earth-covered buildings cost more or less to build than alternatives. (However, the long-term costs are almost certainly less for all earth-covered buildings. How much less depends on design.) The excavation cost for the University of Minnesota's bookstore was about equal to the cost of the face brick that would have been used if the building had been built above grade. The building itself cost no more to build than one above grade. The new Central Library in Fort Worth is being constructed below grade because that solution was more economical of construction costs than any of the six above grade alternatives. Professional estimates of costs for student designs for earth-covered dwellings indicate that the use of precast components makes earth-covered dwellings competitive with ordinary suburban tract housing (about $22.00 per square foot in Fort Worth, Texas in December 1976 for houses of 1600 to 1800 square feet). Several cast-in-place dwellings have run about $35.00 per square foot. It is of interest that people with allergies who live in earthcovered buildings may save money by losing less time from illness. There is some evidence that the buildings contain much less dust and pollen than other buildings.