Assumptions for Non-Verifiable Existing Conditions
Measure | Assumption | Rationale |
---|---|---|
Floor | If insulation exists assume R -19, if no insulation exists assume R-0 | R-19 has been the standard level of insulation since the advent of Title 24. |
Wall* | If insulation exists assume R 11, if no insulation, assume R- 0 | 1985 was the approximate date when R-11 wall insulation requirements for MF buildings were first effectively enforced. |
Ceiling | Measure insulation depth and refer to CEC’s insulation R value table | n/a |
Windows | default table for Title 24 2008 based on frame and glazing type | n/a |
Water Heater – tank type | 0.52 Energy Factor | The Minimum code threshold was 0.52 from 1986-2005. We assume pre-1986 WHs have been replaced since then. |
Water Heater – boiler | 0.70 AFUE | Some older boilers might be slightly less efficient. This represents boilers from 1970s-80s. |
Water Heater - tankless | 0.75 EF | Applies CEC de-rating to older tankless water heaters. |
Wall furnace | 0.45 AFUE | Average wall heater efficiency in the 1980s was 0.60-0.65, but older ones about 0.45. |
Floor furnace | 0.45 AFUE | Average floor heater efficiency in the 1980s was 0.60-0.65, but older ones about 0.45. |
Ducted central furnace | 0.72 and 30% duct leakage | The minimum code threshold for a ducted central furnace has been code since mid-1980s. Research in early 1990s, showed typical leakage of ~30% |
Air Conditioning | 5.0 SEER | The code standard SEER in the 1970 and early 1980s was 6.8, but with normal degradation of systems, SEER 5 is appropriate. |
Heat pump | 1.32 COP |
*Wall Insulation can be verified by two methods; Using an IR Camera to verify all exterior walls have insulation in all elevations, or by following section A-2 of the 2008 HERS Technical Manual Appendix A, ACM section 3.5.2 Exterior Walls. (Determine type and thickness of existing insulation and resultant U-factor). The verification procedures in the HERS Appendix must also be conducted on all exterior wall elevations.