These sites were suggested by participants of the Society of Building Science Educators list.
Computer program for calculating window thermal performance
http://windows.lbl.gov/software/window/window.html
Window Performance for Human Thermal Comfort [Feb. 2006 report]
http://windows.lbl.gov/software/window/window.html
Energy Plus Simulation Software -- models energy flows including lighting
http://www.eere.energy.gov/buildings/energyplus/