# §150.1(c): The prescriptive package
What it is
The prescriptive package is the simpler of the two compliance paths in Title 24 Part 6. It's a fixed set of per-climate-zone values for every major building component:
- §150.1(c)1, Ceiling insulation R-value
- §150.1(c), Wall insulation R-value (cavity + continuous insulation)
- §150.1(c)3, Floor insulation
- §150.1(c), HVAC efficiency (HSPF2 / SEER2 / EER2)
- §150.1(c), Water heating equipment type
- §150.1(c), Fenestration U-factor and SHGC
- §150.1(c)14, Solar PV size (newly constructed only)
If your project meets every prescriptive value for its climate zone, you pass, no performance model required.
When it applies
Newly constructed residential. Additions and alterations use a modified performance path under §150.2(a) / §150.2(b) but borrow the §150.1(c) values as the building blocks of the standard design.
The alternative
Performance compliance, model the proposed design in the Title 24 2025 compliance engine and demonstrate it uses no more annual energy than a "standard design" built to the prescriptive package. The two paths are interchangeable for compliance purposes; you pick whichever has the lower cost / smaller envelope hit for your project.
How we use it
Our three design options correspond to three different points along the prescriptive ↔ performance spectrum:
- Prescriptive, exact §150.1(c) values for your climate zone.
- 2x4 Performance, same envelope as the §150.1(c) baseline, with HVAC + DHW upgrades that buy back the §150.1(c) CI requirement (drops the continuous-insulation sheathing).
- 2x6 Enhanced, better wall, lighter HVAC tier, the high-envelope-low-equipment trade.
All three reference the §150.1(c) baseline directly. See the per-climate-zone landing pages (e.g. Climate Zone 12) for the exact prescriptive numbers in each zone.