In upstate New York, hundreds of passive solar homes have been designed and constructed, which have exhibited extremely low energy requirements for heating. Key features of the homes are a superinsulated envelope, glazing oriented to south, a sand mass storage system, and simple construction.A detailed evaluation program monitored key temperature and electrical data for a one-year period, utilizing a computerized data acquisition system. Hourly data were gathered, and computer algorithms were developed to reduce and evaluate data. Methods of measurement and analysis and the corresponding results are presented. Economic performance of key residence com- ponents is also included.