Each round of combat takes 6 seconds in Pathfinder, so the temporary Hit Points from Force Ward regenerate at a rate of 1 THP every 10 rounds. To figure out how quickly they regenerate between combats, we need to figure out how long common non-combat actions take. Since Force Ward caps the number of THP at the character's level, outside of a dungeon it's probably safe to assume that they fully regenerate between each fight.
Inside a dungeon, it's a little more complicated. We can break down the most common actions that PCs take inside a dungeon into two categories - moving and using skills.
The rules aren't super clear on how PCs move outside of combat. However, the Modes of Movement rules can provide some guidance:
Modes of Movement
While moving at the different movement scales, creatures generally walk, hustle, or run.
- Walk: A walk represents unhurried but purposeful movement (3 miles per
hour for an unencumbered adult human).
- Hustle: A hustle is a jog
(about 6 miles per hour for an unencumbered human). A character moving
his speed twice in a single round, or moving that speed in the same
round that he or she performs a standard action or another move
action, is hustling when he or she moves. (emphasis added)
- Run (x3) – Moving three
times speed is a running pace for a character in heavy armor (about 7
miles per hour for a human in full plate).
- Run (x4) – Moving four
times speed is a running pace for a character in light, medium, or no
armor (about 12 miles per hour for an unencumbered human, or 9 miles
per hour for a human in chainmail).
The description of "Hustle" matches the way that PCs typically act in combat - a standard action and a move action. Based on this, I treat out of combat movement as "Walking" (a single move action per turn) unless the players specifically tell me that they're hurrying (e.g., because they want to get through multiple fights before their buffs wear off). This gives a good indication of how long it takes for the PCs to walk from one area to another on a drawn map (remember to adjust for difficult terrain, etc.).
Some skills, like Disable Device, give clear rules on how long using the skill takes (usually between 1 and 2d4 rounds, depending on the complexity of the device). Others, like Diplomacy, give guidance but leave the DM a fair bit of leeway ("Suggest Course of Action" takes at least a minute, but maybe considerably more).
Unfortunately, the official rules give little guidance on how long Perception takes, which is probably the most common skill PCs will use in a dungeon. Published scenarios suggest that the length of time varies dramatically based on what the PCs are trying to do.
The best guidance I've found comes from PFS scenario #05-11: Library of the Lion. Searching for research materials with a Perception check takes one PC 30 minutes for small room (up to about 25 squares on a 5 ft. map), 1 hr for a medium room, and 2 hrs for a large room (the only one on the map is 264 squares). If more PCs help, the time is divided between them, so it takes 10 minutes for 3 PCs to search a small room. A DM can use this as guidance to determine how long it would take PCs to search a room, based on how many PCs there are and what the room contains (searching a library probably takes a longer than searching a typical room).