Earth Sheltered Structures: Soil Temperature Variation and Site Aesthetics

Abstract

Soil temperature variations were evaluated at an earth-sheltered church and several ancillary sites in Lubbock, Texas. The objectives were to compare the fluctuations in soil temperature over an existing earth sheltered structure versus those in a native soil, and to evaluate the influence of vegetation and water management on soil temperature fluctuations. In experiment I, thermocouples were installed at various depths under a bermudagrass (Cynodon dactylon) turf above the roof of an earth sheltered church and in a similarly vegetated area adjacent to the church. Temperatures were measured daily in both sites at four depths from July, 1983 through March, 1986. Mean soil temperatures above the roof were approximately 5° F warmer from March to September and 5° F cooler from October to February than the adjoining soil area. In a second experiment, the vegetative cover was evaluated using (1) bermudagrass, (2) buffalograss (Buchloe dactyloides), (3) and bare soil. Results indicated grass covers did not significantly (< 2° F) influence temperatures below 18 in. Separate water management studies indicated less temperature fluctuation in moist soils than in dry soils (11 vs. 14 °F) and temperature fluctuation was greater (14 vs. 9° F) in summer than winter. Soil cover no deeper than 18 in. and plants able to thrive without irrigation should be advocated for this area's earth sheltered structures.