 But here's something you don't see every day. This is an elevator shaft inside of a house. Here's the elevator. Here's the door on the second floor. So this has a knee wall surrounding it. You can see there's this sheathing around it with an R-value of one. And the edges are not sealed, so there's plenty of air sneaking through here. If you look at the corner of this bat right here, you can see where it's got a lot of dirt in it. It is dirt that it has filtered out of the air going through there. So if we get this job, this is going to be one of the many things we're going to have to tackle in this house. We've also found a ton of open wall cavities where I could see pipes from bathrooms below, lots of other air sealing opportunities. Just because it's a big house doesn't mean that anybody took a lot of care on the air sealing side of things.