It's only happened a few times in the 15-year history of the Charter Schools Act in Colorado. Districts tend to frown on sharing their facilities with charter schools; although many charter school applicants have asked to share space over the years.
Denver Public Schools is allowing several newly-approved charter schools to open in district facilities with underused space. Beginning next fall, the second campus of W Denver Prep, the new KIPP high school, Envision and Edison will all be located in district facilities.
DPS was viewed as being reticent to charter schools in the 1990's. Now DPS is known as a model charter authorizer utilizing several unique approaches to chartering such as releasing a Request for Proposals to make it known they need specific types of new schools in specific geographical parts of the district. This type of "portfolio management" by a district looks at the total public school offerings with equal consideration for current and prospective charter school models. DPS has embraced the notion of charter schools in meeting the broad educational needs of students in the district.
Charter school law prohibits a district from charging rent for excess facility space, but since DPS would be paying for upkeep and utilities on these underused spaces anyway, it appears to be a win-win for both parties.