school year round is a terrible idea from a financial standpoint. Districts already don't have any money....now you'd be asking them to keep schools open during the summer months, where electric bills will skyrocket due to the summer heat.
It wouldn't surprise me to find they keep many schools air-conditioned in over the summer.
They have to, otherwise you end up with other major maintenance nightmares. That said, they do so at a much lesser level than what is needed when you have 500+ heat producing people in your building. Not only do people create heat, but they prefer the ambient temp to be at a lower level than what the facility needs to maintain it's integrity. In other words, you can let a facility cool it's self to 80degrees during July rather than 74 degrees, and yes 6 degrees is a huge financial difference in a facility the size of a school.
Also, you can cut your maintenence staff hours during the off season. Not as many trash cans to empty, bathrooms to clean as often, etc. There is a lot of cost savings in facilities in the summer, or any time off for that matter.
That said, the year round plan I have seen was one that would have allowed for the same amt of time off, just at more frequent intervals for shorter durations.
If you are dealing with a annual budget, it would come close to equaling out in the end.