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The development and maintenance of Window Heat Gain is supported by user donations. If you found this tool helpful, please consider making a small donation...this can be done quickly and securely by credit card or PayPal account, using the buttons to the right. Your donations will contribute to improvements to this and other solar design tools. Thank you!
The author maintains a private mailing list of users of the SunAngle suite of solar design tools, and is happy to send you very occasional notices about software upgrades and other items of interest. Such notices do not typically occur more frequently than a few times a year.