LISTEN...

Windows and doors are typically the weakest spot in the building envelope. When you're looking at replacing existing units with new ones, consider using something with higher energy efficiency.

Windows and doors are measured for thermal conductivity in U-Value, or how much heat loss the assembly is expected to have - Remember: a lower U-Value is better.

A high performance door unit will have the following parts:

1. Slab - The main part of the door. Exterior doors will normally have an insulated slab with a durable facing on the outside, and a finish layer on the inside.
2. Glazing - Some doors will have windows set into the slab. Door glazing should perform the same as a high-end window unit.
3. Hardware - Hinges, lock sets / deadbolts and opening mechanisms.
4. Jambs and Threshold - On some door units, the slab is already hung in the surrounding jambs - these are the vertical parts on either side and top of the slab where hinges attach and where parts of the locking mechanism are installed. The threshold is the horizonal piece along the bottom of the opening, usually made of metal or wood.