I’m a second-generation home builder working in northeastern Connecticut, and I’ve been building net-zero energy homes for about 10 years. In my early years doing this, I experimented with structural insulated panels (SIPs) and other methods, but these days, I have settled down to a formula based on a cellulose-insulated double stud wall sheathed with plywood on the outside, and a flat attic with deep blown cellulose.