Comment # 4 on bug 1197403 from Andreas Stieger

I believe the basic functionality from the feature request already exists.

* Most of the background load topic is covered via systemd.resource-control
* For "only when not on battery" see ConditionACPower
* For "not when in use" conditions I think the correct implementation is
already available ConditionMemoryPressure=, ConditionCPUPressure=,
ConditionIOPressure=

Individual service/timer owners should set appropriate defaults here, or the
user can amend the package provided units to fit his needs.