If you decline probation on a DUI, first offense below .15, the minimum you will receive is seven days in jail. The maximum allowed is 60 days. You will most likely be allowed to apply for and serve the jail time under House Arrest.
Most Lancaster County judges, on sentences for DUI involving 30 days of jail or less, will allow you to serve the jail time under House Arrest. House Arrest involves wearing an ankle bracelet to monitor your movements. Under House Arrest you will only be allowed to leave your house for work and school only.
For jail sentences in excess of 30 days, work and school release may be granted, allowing you to leave the Work Release Center only for those two purposes.