Using the date and time information already entered at the creation of a new event, it would handy to have the available spaces on the SPACES screen "highlighted" in a bold green - as in good to go.

This would reduce the number of steps in creating the event before there is an actual conflict. Secondly, if you have a multiple spaces that are served by the same HVAC unit, it would allow you select a space that already has the HVAC on rather than a space that would turn on another HVAC unit. (I have the HVAC unit # in my space names for the event creators to see.)