1973年6月28日，科罗拉多州Sprtngs市宣布暂停新的天然气连接，因为该地区的管道无法提供额外的天然气。宣布暂停后，菲尼克斯公司（一家非营利组织）和该市公共事业部成立了一家合资企业，开展太阳能应用的研发工作。凤凰城项目迅速成形。一个太阳能单户住宅被及时设计和建造，以参加1974年在科罗拉多州斯普林斯举行的住宅巡游。 当时还启动了一个为期两年的研发项目，该项目现在参与了tn NSF RANN和ERDA太阳能项目。引文:华盛顿州西雅图ASHRAE学报第82卷第2部分研讨会

On June 28th, 1973 the City of Colorado Sprtngs declared a moratorium on new natural gas connections due to the unavailability of additional natural gas from the pipeline that serves the area. After the moratorium was declared, a joint venture was formed between the Phoenix Corporation (a non-profit organization) and the city's Department of Public Utilities to conduct research and development work on solar energy' applications. The Phoenix Project rapidly took shape. A solar-powered single-family residence was designed and built in time to participate in the 1974 Parade of Homes in Colorado Springs. A 2-yr. research and development program was also started at that time, and this program now participates tn NSF RANN and ERDA solar energy programs.