Thermal Performance of a Monolithic Thin-Shell Concrete Dome

A 3,000 sq.ft., two-story monolithic thin-shell concrete dome custom home was constructed in 2005 in Mesa, AZ, by the author. This architectural construction style represents a small, but growing, commercial and residential market, one of whose selling points is energy efficiency. During the preliminary architectural design phase, the only anecdotal and case studies available to the author were mainly related to cold-weather climates. No technically adequate thermal performance studies were found for the opposite, high temperature extreme of climate conditions. To address this need, two models are developed and explored. First, a preliminary lumped-parameter model (initially created to lend technical credence to the exuberant claims of dome aficionados and provide rationalization for the custom home construction project), is compared with actual data collected at the dome during construction. Because the correlation is not very good, a second model based on thermal two-port transmission line theory, is developed. This model provides additional insight, and in particular, comparison with the actual data suggests that model verification will require a somewhat different approach to data collection itself (and to the manner in which the model is utilized). This is confirmed using a small set of subsequent trial data. Thermal models aside, actual utility consumption data for the dome is compared with two conventional block-construction homes in the same geographic locale, showing that the dome thermal performance, at least during the hot months of the year, provides a measurable advantage. Finally, it is shown how the transmission line model makes it very easy to explore the thermal effects of reversing the order of the primary material layers (insulation and concrete).