Cornell Tech's 250-foot-tall dorm could change the way high-rises are built in the city. The residential high-rise will be built to meet the standards of Germany's Passive House Institute, which basically involve creating a completely airtight design. When finished, it will officially be the tallest and largest Passive House building in the world. Why is that a big deal? Let's look at the numbers. Compared to a normal building, it will save 882 tons of CO2 annually, Business Insider reports. That might not sound like much when you consider the 3.5 million tons of CO2 a coal power plant emits each year, but if all urban buildings adopted those standards, it could be a game changer. Cornell Tech's $115M dorm will cost 5% more to develop, but will use 60% to 70% less energy than another building of the same size. That's a lot of money in energy savings. Along with its airtight design, the developers had to get special permission to install a unique ventilator system that channels in fresh air from the outside. Unfortunately, airtight designs and floor-to-ceiling windows that offer sweeping views don't really go together, so Cornell went for slightly smaller windows. Delivery for the Handel-designed 520-person dorm is slated for 2017. [BI]