"Owing to variations in humidity and likely clothing, recommendations for summer and winter may vary; a suggested typical range for summer is 23 °C (73 °F) to 25.5 °C (78 °F), with that for winter being 20 °C (68 °F) to 23.5 °C (74 °F)."
https://books.google.ca/books?id=KBbHmp2yisEC&lpg=PA149&ots=yTqUP4xIOx&dq=%2BASHRAE+%2B%22recommended+temperatures%22&pg=PA149&redir_esc=y&hl=en#v=onepage&q=%20ASHRAE%20%20%22recommended%20temperatures%22&f=false
my personal preference would be in the higher end of that range - and actually even higher than that, if the external temperature allows for it.
j
