Calculating office building performance? Yep, there’s an app for that

123 Zero build is a free tool for calculating the performance of a market-ready carbon-neutral office building design. The app estimates the discounted payback for constructing a zero emissions office building in any U.S. location, including the investment needed for photovoltaics to offset annual carbon emissions, payback calculations, estimated first costs for a highly energy efficient building, photovoltaic costs, discount rates, and user-specified fuel escalation rates.