Sap for Lazarus is a program that implements the SAP 2005 Standard Assessment Procedure of the United Kingdom. It calculates, based on sizes, type of walls, insulation, glazing and heating type the Energy qualification for a dwelling as well as the Co₂ emissions.

Although the program follows the procedure calculation sheets and the results are in line with SAP 2005, this program does not produce an official certificate.

The program and it's documentation gives an excellent insight in the how's of the Assessment procedure. It also is an excellent example of a not too complicated but nevertheless complex program. It uses a number of more sophisticated ways of handling components. Also the complex calculation is a good starting point for your own more complex expertise systems.

Use this program also to asses the "relevance" of improvements like double or triple glazing, better insulation or other boilers. The calculations will help you by making decisions about the investments you are going to make to improve your home.