## 8.6 HVAC Issues

### 8.6.1 No Cooling Installed

When a building does not have a proposed cooling system, there is no compliance credit. The air-conditioning system is modeled to be equivalent to Package A. A hypothetical cooling duct system is modeled as equivalent to Package A (for example, Attic, R-6) or as matching the heating system ducts. Modeling no ducts is not an appropriate assumption.

### 8.6.2 Equipment Without SEER or HSPF

For equipment without a tested seasonal energy efficiency ratio (SEER), the energy efficiency ratio (EER) is used in place of the SEER. Another option is to use the EER of the equipment and use it for both the SEER and EER entry. If this approach is used, the EER must be verified by a HERS Rater.

Equipment without an heating seasonal performance factor (HSPF) rating is assumed to have 3.41 HSPF (electric resistance), 3.55 (electric radiant), or an HSPF calculated from a COP as

HSPF = (3.2 x COP) – 2.4

### 8.6.3 Multiple HVAC Systems

Buildings with multiple HVAC systems can be treated several ways as follows:

1. For buildings that have more than one system type, equipment type, or fuel type, where the types do not serve the same floor area, model either the building zone or enter the floor area served by each zone type.

2. When multiple system types serve different thermal zones in one building, model each system and the associated thermal zone separately from other systems and zones.

Note: If both zones are associated with attic space, then a portion of the attic must be modeled with each zone.

3. Floor areas that are served by more than one heating or cooling system, equipment type, or fuel type must be modeled for compliance using the system with the most TDV energy consumption. For any areas served with electric resistance heat and another heating system (except for wood heating), the electric resistance shall be deemed to be the most TDV energy consuming system. The only exceptions to this are supplemental heating units may be installed in a space served directly or indirectly by a more efficient primary heating system. This is allowed if the thermal capacity of the supplement unit does not exceed 2 kilowatts (kW), or 7,000 British thermal units per hour (Btu/h), and if the supplemental unit is controlled by a time-limiting device not exceeding 30 minutes. See §150.1(c)8C.

When there is more than one system meeting the heating or cooling load for the same space, all systems must still meet all the mandatory requirements of the Energy Standards.

For example, in a building with an appliance rated gas fireplace in combination with a central gas furnace, the central furnace would be used as the primary system and the fireplace would be treated as the supplemental system. The controls for the fireplace would not need to meet the setback thermostat requirements of §110.2(c)) due to the exception.

For rooms such as the bedroom or bathroom, spot heating with a supplemental system may be desirable. Exception to §150.1(c)6 is provided for installing either a 2 kW electric resistance or 7,000 Btu/h gas heaters, with a 30-minute timer control for such instances. Therefore, this type of supplemental space heating need not meet the setback thermostat requirement.

### 8.6.4 Existing + Addition + Alteration Approach

The performance approach may be used to show compliance for alterations in existing buildings, new additions, and Existing + Addition + Alteration discussed in Section 9.7 of this manual. The following table can be used to model existing conditions based on the year of the building construction.

#### Table 8-1 - Default Assumptions for Year Built (Vintage)

Conservation Measure | Before 1978 | 1978 to 1983 | 1984 to 1991 | 1992 to 1998 | 1999 to 2000 | 2001 to 2003 | 2004 to 2005 | 2006 to 2013 | 2014 to 2016
INSULATION U-FACTOR
Cool Roof | 0.10 | 0.10 | 0.10 | 0.10 | 0.10 | 0.10 | 0.10 | Pkg. A | Pkg. A
Radiant Barrier | None | None | None | None | None | None | Pkg. A | Pkg. A | Pkg. A
Roof/Ceiling | 0.079 | 0.046 | 0.046 | 0.046 | 0.046 | 0.046 | 0.046 | 0.046 | 0.031
Wall | 0.356 | 0.110 | 0.110 | 0.102 | 0.102 | 0.102 | 0.102 | 0.102 | 0.102
Raised Floor –Crawl Space | 0.099 | 0.099 | 0.099 | 0.049 | 0.049 | 0.049 | 0.049 | 0.049 | 0.037
Raised Floor-No Crawl Space | 0.238 | 0.238 | 0.238 | 0.064 | 0.064 | 0.064 | 0.064 | 0.064 | 0.049
Slab Edge F-factor | 0.73 | 0.73 | 0.73 | 0.73 | 0.73 | 0.73 | 0.73 | 0.73 | 0.73
Ducts | R-2.1 | R-2.1 | R-2.1 | R-4.2 | R-4.2 | R-4.2 | R-4.2 | Pkg. A | Pkg. A
LEAKAGE
Building (ACH50) | 7.7 | 7.7 | 7.7 | 7.7 | 7.7 | 7.7 | 7.7 | 6.8 | 5.0
Duct Leakage (%) | 15% | 15% | 15% | 15% | 15% | 15% | 15% | 15% | 6%
FENESTRATION
U-factor | Use Energy Standards Table 110.6-A , §110.6 for all Vintages
SHGC | Use Energy Standards Table 110.6-B , §110.6 for all Vintages
Shading Devices | Interior: Assumed to have draperies (not user editable). Exterior: Assumed to have 50% bugscreens, model actual overhangs.
SPACE HEATING EFFICIENCY
Gas Furnace (Central) AFUE | 0.75 | 0.78 | 0.78 | 0.78 | 0.78 | 0.78 | 0.78 | 0.78 | 0.78
Gas Heater (Room) AFUE | 0.65 | 0.65 | 0.65 | 0.65 | 0.65 | 0.65 | 0.65 | 0.65 | 0.65
Hydronic/Comb Hydronic | 0.78 | 0.78 | 0.78 | 0.78 | 0.78 | 0.78 | 0.78 | 0.78 | 0.78
Heat Pump | HSPF | 5.6 | 5.6 | 6.6 | 6.6 | 6.8 | 6.8 | 6.8 | 7.4 | 7.7
Electric Resistance HSPF | 3.413 | 3.413 | 3.413 | 3.413 | 3.413 | 3.413 | 3.413 | 3.413 | 3.413
Electric Resistance Radiant HSPF | 3.55 | 3.55 | 3.55 | 3.55 | 3.55 | 3.55 | 3.55 | 3.55 | 3.413
SPACE COOLING EFFICIENCY
All Types, | SEER | 8.0 | 8.0 | 8.9 | 9.7 | 9.7 | 9.7 | 9.7 | 13.0 | 13.0
WATER HEATING
Energy Factor | 0.525 | 0.525 | 0.525 | 0.525 | 0.575 | 0.575 | 0.575 | 0.575 | 0.575
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