What Can and Cannot Be Traded Off in the Performance Method?
The performance method lets a strong feature offset a weak one, provided the whole stays within budget. It never lets you trade away a mandatory measure, since those sit inside the baseline. Lighting and appliance energy is not eligible either. Solar alone cannot stand in for efficiency measures.
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What does move
Space conditioning, water heating and ventilation are modeled together, so better insulation, tighter ducts or a more efficient heat pump can offset more glass. Quality insulation installation is a good example: it is not a mandatory measure, so the performance route may trade it off against other efficiency features, although the software assumes it in the standard design and penalizes a proposed design that skips it.
What stays fixed
- Mandatory measures. The standard design includes them and meets, but does not exceed, the prescriptive requirements. Additions still have to meet Sections 110.0 to 110.9 and the listed parts of Section 150.0 whichever route they take.
- Lighting and appliances. Their energy is not eligible for trading.
- Your inputs. The manual warns that software may not check mandatory measures for you, so the values entered must be at least as efficient as those measures.
Solar and batteries
Solar has no effect on the Efficiency LSC metric, so it cannot replace efficiency measures. The only opening is a battery of at least 5 kWh coupled with solar, which lends part of its credit to efficiency in a new home.
Where the model draws the boundary
An addition modeled alone cannot borrow credit from upgrades to the old house. The manual gives a 400 square foot addition: it may use a 30 percent glass limit when modeled with the existing house, but only 20 percent as an addition alone. In an alteration-only job, if one part misses its prescriptive level, other alterations must exceed theirs to make up for it.
If you are checking your own case, read prescriptive versus performance, the CF1R report types, the existing plus addition method and what to change. Our residential reports run the model.
Common Title 24 Questions
- What is Title 24?
- Do I need a Title 24 report?
- How much does a Title 24 report cost?
- How long does a Title 24 report take?
- What is included in a Title 24 report?
- What plans do I need to upload?
Frequently Asked Questions
Yes, within the performance method, as long as the mandatory measures and the budget are both met.
Not through the efficiency check. Solar helps only the Total LSC figure, so a house short on Efficiency LSC still needs an efficiency fix.
Explore Failed Compliance
- What Does a Compliance Margin Shortfall Mean on a CF1R?
- What Happens If You Have No Title 24 Report?
- My Design Does Not Comply: Which Changes Bring It Back?
- Why Does a Title 24 Design Not Comply?
- Title 24 Compliance in California
View all Failed Compliance guides → · Permits and Compliance · Title 24 guide