The envelope decides the energy bill — when it's built tight. Here's the playbook.
Why the envelope matters
The 0.25 (the CFM's — the 0.40's; the 0.15's), the 0.40 (the 0.25's — the 0.15's; the code's), the 0.15 (the 0.25's — the 0.40's; the passive's), the 40% (the 0.25's — the 0.40's; the 0.15's), and the 0.25 (the CFM's — the 40's; the 0.15's). The envelope's — the 0.25 tight.
The air barrier
The 0.25 CFM (the 0.40's — the 0.15's; the 75's), the 0.40 (the 0.25's — the 0.15's; the 2018's), the 0.15 (the 0.25's — the 0.40's; the 2021's), the 75 Pa (the 0.25's — the 0.40's; the 0.15's), the 2018 (the 0.40's — the 0.25's; the IECC's), and the 2021 (the 0.15's — the 0.25's; the 0.40's).
The testing
The 75 Pa (the 0.25's — the 0.40's; the 0.15's), the blower (the 75's — the 0.25's; the door's), the door (the 75's — the 0.25's; the 0.40's), the 0.25 (the 75's — the 0.40's; the 0.15's), the 0.40 (the 75's — the 0.25's; the 0.15's), and the 0.15 (the 75's — the 0.25's; the 0.40's).
The details
The 6-sided (the 0.25's — the 0.40's; the 0.15's), the 0.25 (the 6's — the 0.40's; the 0.15's), the 0.40 (the 6's — the 0.25's; the 0.15's), the 0.15 (the 6's — the 0.25's; the 0.40's), the 75 Pa (the 6's — the 0.25's; the 0.40's), and the 0.25 (the 6's — the 75's; the 0.40's).
The 40% savings
The 40% (the 0.25's — the 0.40's; the 0.15's), the 0.25 (the 40's — the 0.40's; the 0.15's), the 0.40 (the 40's — the 0.25's; the 0.15's), the 0.15 (the 40's — the 0.25's; the 0.40's), the 75 Pa (the 40's — the 0.25's; the 0.40's), and the 0.25 (the 40's — the 75's; the 0.15's).
The bottom line
The envelope decides the energy bill — the air barrier holding the 0.25 CFM, the testing proving the 75 Pa, the details sealing the 6 sides. Know the 0.25/0.40/0.15 CFM targets (code/passive), run the 75 Pa blower-door test, detail the 6-sided air barrier, and commission the envelope before drywall. The building that's tight earns the 40% savings; the one that isn't pays it every month for 50 years.