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CBECC User Manual
Table 8-3: Cooling Equipment
Descriptor
Ductless Split Air
Conditioner
Evaporative Direct
Evaporative
Indirect/Direct
Evaporative Indirect
Cooling Equipment Reference
Split air conditioning outdoor unit that uses refrigerant to transport cooling to at least one terminal in each habitable space in the dwelling unit. These include small ductless mini-split and multiple-split air conditioners. Distribution is non-ducted.
[Efficiency metric: EER]
Direct evaporative cooling systems. Assume minimum efficiency air conditioner.
The default distribution system is ducts in attic. [Efficiency metric: SEER]
Indirect-direct evaporative cooling systems. Assume energy efficiency ratio of 13
EER. Requires air flow and media saturation effectiveness from the Energy
Commission appliance directory. Distribution is ducted or non-ducted. [Efficiency metric: EER]
Indirect cooling systems. The default distribution system is duct in attic; evaporative cooler duct insulation requirements are the same as those for air conditioner ducts.
Assume energy efficiency ratio of 13 EER. Requires air flow and media saturation effectiveness from the Energy Commission directory. [Efficiency metric: EER]
EvapCondenser
Large Package Air
Conditioner
No Cooling
Systems rated at or above 65,000 Btu/hr (cooling capacity). Distribution is ducted.
[Efficiency metric: EER]
When the proposed building is not cooled or when cooling is optional (to be installed at some future date). Both the standard design and proposed design use the same default system. Distribution is ducted (either the same system as heating
or default ducts in attic). (See also section 8.3.2). [Efficiency metric: SEER]
Package Air Conditioner Central packaged air conditioning systems less than 65,000 Btu/hr cooling capacity.
Distribution is ducted. [Efficiency metric: SEER and EER]
Room Air Conditioner
Evaporatively-cooled condenser. The default distribution system is duct in attic; evaporatively cooled condenser duct insulation requirements are the same as those for air conditioner ducts. Requires refrigerant charge testing, EER verification, and compliance with RA4.3.2. [Efficiency metric: EERa and EERb ]
Split Air Conditioner
A factory encased air conditioner that is designed as a unit for mounting in a window, through a wall, or as a console. Distribution is non-ducted. [Efficiency metric: EER]
Split air conditioning systems. Distribution is ducted. [Efficiency metric: SEER and
EER]
8.3.1 Cooling System Data
8.3.1.1 Name
User-defined name for the cooling system.
8.3.1.2 Type
Cooling system type (see Table 8-3).
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Figure 8-11: Cooling System Data
8.3.1.3 SEER
Cooling equipment Seasonal Energy Efficiency Ratio (SEER). For equipment tested only with an
EER, enter the EER as the SEER. When a value higher than 13 SEER for “Compliance 2014” is modeled, it triggers a HERS Verification of High SEER. With “Compliance 2015” the minimum efficiency requirement of the Appliance Efficiency Standards changes to 14 SEER, and only when an
SEER higher than 14 is modeled is a HERS Verification of High SEER triggered. Efficiency information can be obtained from the Energy Commission’s appliance directories
(http://www.appliances.energy.ca.gov/AdvancedSearch.aspx) or from the Air-Conditioning,
Heating, and Refrigeration Institute (AHRI) Certified Products Directory http://www.ahridirectory.org.
8.3.1.4 EER
Cooling equipment Energy Efficiency Ratio (EER). CBECC has default values for the EER based on the SEER value modeled. Two conditions will result in a HERS verified EER. (a) An EER higher than the default of 11.3 for “Compliance 2014” or higher than 11.7 for “Compliance 2015”, and (b) checking the box “
Use this EER in compliance analysis.” Because the EER depends on the specific combination of coil and condenser model numbers, other than default EER ratings can be obtained from AHRI directory http://www.ahridirectory.org.
8.3.1.5 CFM per Ton
The mandatory requirement for cooling airflow is 350 CFM/ton for ducted cooling systems (also assumed for dwellings with no cooling), or 150 CFM/ton for Zonal Single Speed systems. Users may model a higher airflow. All systems other than no cooling require HERS verified system airflow using diagnostic testing procedures from
Reference Appendices
, Residential Appendix RA3.
8.3.1.6 AC Charge
Verified refrigerant charge. Select not verified, verified, or Charge Indicator Display (CID). There is no mandatory requirement for verified refrigerant charge, however, the standard design in climate zones 2 and 8-15 includes proper refrigerant charge in the standard design for most equipment types
(see Standards Section 150.1(c)8.).
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Charge Indicator Display
System Airflow
Air-handling Unit Fan
Efficacy
EER
SEER
Table 8-4: Air Conditioning Measures Requiring HERS Verification
Measure
Refrigerant Charge
Description
Air-cooled air conditioners and air-source heat pumps must be diagnostically tested to verify that the system has the correct refrigerant charge.
A Charge Indicator Display (CID), alternative to refrigerant charge testing.
Ducted systems require a verified system airflow greater than or equal to
350 CFM/ton (mandatory requirement) or another specified value.
To verify that fan efficacy is less than or equal to 0.58 Watts/CFM (a mandatory requirement) or other specified criterion.
Credit for higher than minimum EER by installation of specific air conditioner or heat pump models.
Credit for higher than minimum SEER.
8.3.1.7 Refrigerant Type
Default R410A assumed for all refrigerant containing equipment.
8.3.1.8 Multi-Speed Compressor
Use this field to indicate if the system is a zonally controlled multi-speed compressor. An exception for single speed compressors would leave this box unchecked and specify 150 CFM/ton (see Section
8.3.2 No Cooling
When no cooling system is installed in a dwelling, create a cooling system using the system type
The software sets the default cooling system to a ducted split system air conditioner that exactly meets Package A for the efficiency, airflow, and refrigerant charge for both the proposed and standard design. The duct system should be the same as the heating system ducts (if any), or a system equivalent to Package A (NOTE: the software will model the appropriate conditions).
The fan system can be set to none.
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Figure 8-12: No Cooling System
8.3.3 Evaporatively Cooled Condensing
This type of air conditioning is suited for hot dry climates.
The efficiencies are reported as multiple
EER values at different conditions.
More information can be obtained from the 2013 Residential
Manual, Section 4.7.9
and a full list of compliance requirements is included in the 2013 Residential
Appendices, Residential Appendix RA4.3.2.
Requires HERS verification of EER, refrigerant charge, and duct leakage testing.
An example file (1StoryExample16EvapCond.ribd) is included in the projects folder.
8.3.3.1 EERa
EER at 95 ° F dry bulb and 75 ° F wet bulb, obtained from AHRI Certified Products Directory http://www.ahridirectory.org.
8.3.3.2 EERb
EER at 82
°
F dry bulb and 65
°
F wet bulb.
This value must be tested and published by the manufacturer according to AHRI guidelines.
Until the manufacturers of non ‐ typical cooling technologies pursue an exceptional method, the
Energy Commission has determined that there is not enough data about how these systems perform in achieving comfort conditions to simulate their efficiency.
Model the proposed system, however, the systems will be modeled as equivalent to the standard design, meaning there is no credit and no
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penalty. Non-ducted systems are modeled with the distribution system defined as a “distribution system without ducts”.
8.3.5 Evaporative Cooling
[Not yet Implemented] Specify one of three types of evaporative cooling: (1) direct evaporative cooler, the most commonly available system type, (2) indirect, or (3) indirect-direct. Product specifications and other modeling details are found in the Energy Commission appliance directory for evaporative cooling. The default system type is evaporative direct, which is assigned an efficiency of 13 SEER (or the minimum appliance efficiency standard for split system cooling). For indirect or indirect-direct, select the appropriate type, based on the Energy Commission appliance directory as well as the air flow and media saturation effectiveness or cooling effectiveness from the
Energy Commission appliance directory, and specify 13 EER (if required input 13 SEER as well).
Direct evaporative coolers are assumed to be equivalent to a minimum split system air conditioner.
The evaporative cooling modeling methodology addresses two performance issues: (1) rising indoor relative humidity during periods with extended cooler operation, and (2) evaporative cooler capacity limitations. Since modeling of indoor air moisture levels is beyond the capability of simulation models, a simplified algorithm is used to prohibit evaporative cooler operation during load hours when operation is expected to contribute to uncomfortable indoor conditions. The algorithm disallows cooler operation when outdoor wet bulb temperatures are 70°F, or above. As for the capacity limitations, since evaporative coolers are 100 percent outdoor air systems, their capacity is limited by the outdoor wet bulb temperature. Each hour with calculated cooling load, the algorithm will verify that the cooling capacity is greater than the calculated house cooling load.
8.4 Distribution System Data
Model the distribution system (ducts) associated with the HVAC system within a given zone. When modeled as one system, assume the worst case conditions.
When modeling a multi-story building, the computer model already assumes that some ductwork is between floors and inside the conditioned space.
Figure 8-13: Distribution System Data
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8.4.1.1 Name
User-defined name.
8.4.1.2 Type
Indicate the type of duct system, location, or no ducts (see Table 8-5).
Table 8-6 summarizes the duct conditions that require HERS verification, including sealed and tested
ducts, which are a mandatory requirement.
Proposed HVAC systems with ducts in the crawl space or a basement must have supply registers within two feet of the floor and show the appropriate locations for the ducts. Ducts in crawl space and basement can be verified by the local enforcement agency (no HERS verification or duct design).
8.4.1.3 Use all distribution system defaults
By checking this option, the detailed information about the supply and return ducts is completed based on other building inputs, including climate zone. NOTE: If you change the climate zone to one with a different Package A duct insulation value, the program will change to match Package A, which may not match the plans.
Figure 8-14: Duct Leakage
8.4.1.4 Duct Leakage
Select sealed and tested. To specify a target leakage number, select Low Leakage Air Handler (see
Figure 8-14). HERS verification is required for this mandatory measure.
8.4.1.5 Duct Insulation R-value
Specify the R-value of HVAC system ducts. The mandatory minimum R-value allowed is 6. Valid options are 0, 2.1, 4.2, 6.0, 8.0, 10.0 and 12.0.
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Table 8-5: Distribution Type
Descriptor
Ducts located in attic
Ducts located within the conditioned space (except 12 lineal feet)
Ducts located entirely in conditioned space
Distribution Type and Location
Ducts located overhead in the attic space (and default condition for no cooling).
Ducts located in a crawl space Ducts located in crawl space.
Ducts located in a garage Ducts located in garage space.
Less than 12 linear feet of duct is outside of the conditioned space.
Distribution system without ducts
HVAC equipment and all HVAC ducts (supply and return), furnace cabinet and plenums, located within the conditioned floor space. Location of ducts in conditioned space eliminates conduction losses but does not change losses due to leakage.
Leakage from either ducts that are not tested for leakage or from sealed ducts is modeled as leakage to outside the conditioned space.
Air distribution systems without ducts such as window air conditioners, wall furnaces, floor furnaces, radiant electric panels or combined hydronic heating equipment.
Ducts located in exposed locations outdoors. Ducts located in outdoor locations
Verified low-leakage ducts entirely in conditioned space
Ducts located in multiple places
Verified Low Leakage Ducts in Conditioned Space - defined as duct systems for which air leakage to outside conditions is equal to or less than 25 CFM when measured in accordance with
Reference Appendices
, Residential Appendix RA3.1.
Allows a different location for supply and return ducts.
8.4.1.6 Has Bypass Duct
If the system meets zonal control criteria, indicate if the system has or does not have a bypass duct.
When specifying that there is no bypass duct, this credit requires HERS rater verification with
Reference Appendices
, Residential Appendix RA3.1.4.6.
8.4.1.7 Supply Ducts
If Section 8.4.1.3 is unchecked so that credit may be obtained for a verified duct design/reduced
surface area (see
Reference Appendices
, Residential Appendix RA3.1), enter the supply duct details for area, diameter and location. The supply duct begins at the exit from the furnace or air handler cabinet.
The supply duct surface area for crawl space and basement applies only to buildings or zones with all supply ducts installed in the crawl space or basement. If the supply duct is installed in locations other than crawl space or basement, the default supply duct location is “Other.” Do not include the surface area of supply ducts completely inside conditioned space, or ducts in floor cavities or vertical chases when surrounded by conditioned space with draft stops.
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The surface area of each supply duct system segment is calculated based on its inside dimensions and length. The total supply surface area in each unconditioned location (attic, attic with radiant barrier, crawl space, basement, other) is the sum of the area of all duct segments in that location.
Table 8-6: Summary of Verified Air Distribution Systems
Measure
Duct Sealing
Supply Duct Location, Reduced
Surface Area and R-value
Low Leakage Ducts in
Conditioned Space
Low Leakage Air-handling Units
Return Duct Design
Air Filter Device Design
Bypass Duct Condition
Description
Mandatory measures require that space conditioning ducts be sealed. Field verification and diagnostic testing is required.
Compliance credit for improved supply duct location, reduced surface area and R-value. Field verification that duct system was installed according to the duct design, including location, size and length of ducts, duct insulation R-value and installation of buried ducts. For buried ducts, this measure also requires improved construction quality or QII and duct sealing.
When space conditioning ducts are located entirely in directly conditioned space, this is verified by diagnostic testing. Compliance credit can be taken for verified duct systems with low air leakage to the outside. Field Verification for ducts in conditioned space and duct sealing are required (
Reference Appendices
, Residential
Appendix RA3.1.4.3.8).
Compliance credit can be taken for installation of a factory sealed air handling unit tested by the manufacturer and certified to the
Commission to have met the requirements for a Low Leakage Air-
Handling Unit achieved. Field verification of the air handler’s model number is required. Duct sealing is required.
Verification to confirm that the return duct design conforms to the criteria given in Table 150.0-C or Table 150.0-D. as an alternative to meeting 0.58 W/CFM fan efficacy of Section 150.0(m)12.
Verification to confirm that the air filter devices conform to the requirements given in Section 150.0(m)12.
Verification to determine if system is zonally controlled, and confirm that bypass ducts condition modeled matches installation.
8.4.1.8 Return Ducts
credit for a verified duct design, enter the return duct details for area, diameter and location. The calculations assume that the return duct is located entirely in the attic, unless (a) the return duct is located entirely in the basement, in which case the calculation shall assume basement conditions for the return duct efficiency calculation, or (b) the return duct is located entirely in conditioned space and the system meets the requirements for
Verified Low Leakage Ducts in Conditioned Space
, in which case the return duct is assumed to be in conditioned space.
8.4.2 Low Leakage Air Handlers
Credit can be taken for installation of a factory sealed air handling unit tested by the manufacturer and certified to the Energy Commission to meet the requirements for a Low Leakage Air-Handler.
Field verification of the air handler’s model number is required.
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A Low Leakage Air Handler is reported on the compliance report and field verified in accordance with the procedures specified in
Reference Appendices
, Residential Appendix RA3.1.4.3.9.
8.4.3 Verified Low Leakage Ducts in Conditioned Space
For ducted systems the user may specify that all ducts are entirely in conditioned space and the software will model the duct system with no leakage and no conduction losses.
Systems that have all ducts entirely in conditioned space are reported on the compliance documents and this is verified by measurements showing duct leakage to outside conditions is equal to or less than 25 CFM when measured in accordance with
Reference Appendices
, Residential Appendix RA3.
8.4.4 Buried Ducts
Ducts partly or completely buried under blown attic insulation also meeting the requirements for verified quality insulation installation, verified duct design and duct leakage testing may take credit for increased effective duct insulation using the HERS verified credit for buried ducts. Additional details regarding the duct design and the inspection process can be found in
Reference Appendices
,
Residential Appendix RA3.1.4 and the
Residential Compliance Manual
Section 4.4.3.
The duct design shall identify the segments of the duct that meet the requirements for buried ducts on the ceiling (“buried ducts”) and ducts that are enclosed in a lowered ceiling and completely covered by ceiling insulation (“deeply buried ducts”), and these are input separately from supply and return ducts that are not buried. Buried ducts shall have a minimum of R-4.2 duct insulation prior to being buried. The ceiling must be level with at least 6 inches of space between the outer jacket of the installed duct and the roof sheathing above.
8.4.4.1 Buried Ducts
the portion of duct runs directly on or within 3.5 inches of the ceiling gypsum board and surrounded with blown attic insulation of R-30 or greater. Determine the appropriate effective R-value as shown
in Table 8-7 (assume the worst case where multiple conditions exist).
8.4.4.2 Deeply Buried Ducts
Select the check box for deeply buried ducts (see Figure 8-15) and enter the return duct length (in
feet) for ducts installed in lowered areas of ceiling and covered by at least 3.5 inches of insulation above the top of the duct insulation jacket. Model R-25 duct R-value for fiberglass ceiling insulation or R-31 duct R-value for cellulose ceiling insulation.
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Figure 8-15: Buried Ducts
R-43
R-49
R-60
R-30
R-38
Attic Insulation
R-30
R-38
R-40
R-40
R-43
R-49
R-60
Table 8-7: Buried Duct Effective R-values
Nominal Round Duct Diameter
4'' 5'' 6'' 7'' 8''
Effective Duct Insulation R-value for Blown Fiberglass Insulation
R-13 R-13 R-13 R-9 R-9
R-25
R-25
R-25
R-25
R-25
R-25
R-13
R-25
R-13
R-13
R-25
R-25
R-25
R-25
R-25
R-25
R-25
R-25
R-25
R-25
R-25
R-25
R-25
R-25
R-25
Effective Duct Insulation R-value for Blown Cellulose Insulation
R-9 R-4.2 R-4.2 R-4.2 R-4.2
R-15 R-15 R-9 R-9 R-4.2
R-15
R-15
R-31
R-31
R-15
R-15
R-31
R-31
R-15
R-15
R-15
R-31
R-9
R-15
R-15
R-31
R-9
R-9
R-15
R-31
10''
R-4.2
R-4.2
R-4.2
R-4.2
R-9
R-15
R-4.2
R-9
R-13
R-13
R-25
R-25
12''
R-4.2
R-9
R-9
R-9
R-13
R-25
R-4.2
R-4.2
R-4.2
R-4.2
R-9
R-15
R-9
R-13
R-25
R-4.2
R-4.2
14''
R-4.2
R-4.2
R-9
R-4.2
R-4.2
R-4.2
R-9
R-4.2
R-9
R-13
R-4.2
R-4.2
16''
R-4.2
R-4.2
R-4.2
R-4.2
R-4.2
R-4.2
R-9
8.5 HVAC Fan System
The HVAC fan system moves air for the air conditioning and heating systems.
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Figure 8-16: HVAC Fan
8.5.1.1 Name
User-defined name.
8.5.1.2 Type
Default single speed furnace fan.
8.5.1.3 Watts/CFM Cooling
The mandatory requirement in Section 150.0(m)13 is for an air-handling unit fan efficacy less than or equal to 0.58 Watts/CFM as verified by a HERS rater. The alternative to HERS verification of 0.58
Watts/CFM is HERS verification of a return duct design that conforms to the specification given in
Table 150.0-C or D. However, if a value less than 0.58 Watts/CFM is modeled for compliance credit, the fan efficacy value must be verified and the alternative is not allowed.
If no cooling system is installed, this value is assumed to be 0.58 W/CFM.
8.6 Indoor Air Quality (IAQ) Fan Data
Figure 8-17: IAQ Fan Data
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Mechanical ventilation is required to meet minimum indoor air quality (IAQ) requirements of
ASHRAE Standard 62.2 (see
Residential Compliance Manual
, Section 4.6). The IAQ system requires
HERS verification meeting
Reference Appendices
, Residential Appendix RA3.3.
The simplest IAQ fan system is an exhaust fan, such as a bathroom fan that meets the criteria in
ASHRAE Standard 62.2 for air delivery and low noise, and that operates continuously. More advanced IAQ fan systems have a supply or both supply and exhaust fans. In most cases, the energy impact of this mandatory requirement is neutral. The only system for which credit can accrue is a central fan integrated system with HERS verified W/CFM of less than 0.58.
8.6.1.1 Name
User-defined name (must be the same name as specified in Section 4.6).
8.6.1.2 IAQ CFM
Enter the size of fan being installed to meet the minimum CFM required to meet the mandatory
ventilation requirements (found under Building in Section 4.4).
8.6.1.3 W/CFM IAQ Vent
The default value is 0.25 W/CFM. The standard design is set to the same value as proposed up to 1.2
W/CFM).
8.6.1.4 IAQ Fan Type
Select exhaust, supply, or balanced (both exhaust and supply).
8.6.1.5 IAQ Recovery Effectiveness
When the fan type is balanced, enter the IAQ Recovery Effectiveness.
8.7 Cooling Ventilation Fans
Ventilation cooling systems bring in outside air to cool the house when this can reduce cooling loads and save cooling energy. Whole house fans involve window operation and attic venting. Central fan integrated systems use the HVAC duct system to distribute ventilation air. Ventilation cooling systems that exhaust air through the attic require a minimum of 1 ft
2
of free attic ventilation area per
1000 CFM of rated capacity for relief (see Section 150.1(c)12 of the Standards).
integrated (CFI) night ventilation, first make sure that the Cool Vent tab at the project level is set to
CFI (see Section 4.7.1.1). For a fixed speed fan, set the HVAC system type to “Other Heating and
Cooling System” or for a variable speed fan, set the HVAC system type to “Variable Outdoor Air
Ventilation Central Heat/Cool System (see Section 8.1.1.2). Fixed Flow for the Cooling Vent drop-
down menu. It is also necessary that the Cool Vent tab at the project level be set to CFI (see Section
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Figure 8-18: Cooling Ventilation
8.7.1.1 Name
User defined name, which must also be specified in Section 4.7.
8.7.1.2 Use all fan system defaults
Sets the default minimum to 2 CFM/ft
2
.
8.7.1.3 Cooling Vent CFM
If system default is not checked, enter the actual CFM of the proposed ventilation fan.
8.7.1.4 W/CFM Cooling Vent
Enter the Watts/CFM of the proposed system.
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Chapter 9. Domestic Hot Water (DHW)
systems are contained under the mechanical tab. The information in this chapter is from the point of view of the mechanical tab.
9.1 Efficiency Information
Water heaters are required to be certified to the Energy Commission and the applicable efficiency values needed for modeling are found in the on-line certified appliance directory
(http://www.appliances.energy.ca.gov/). From this site, an
advanced search
yields the most useful information, which can be exported to a spreadsheet format for sorting and searching.
Alternatively, data may be found in the Air-Conditioning, Heating and Refrigeration Institute
(http://www.ahridirectory.org/ahridirectory). The AHRI directory does not contain the standby loss for large water heaters, which is a required input.
The federal minimum energy factor used to establish the standard design changes for small water heaters effective April 16, 2015.
Type Volume Current Effective April 16, 2015
Gas-fired storage < 55 gallons
> 55 gallons
Electric storage < 55 gallons
> 55 gallons
0.97-(0.00132 x Volume) 0.960-(0.0003 x Volume)
2.057-(0.00113 x Volume)
For a 50-gallon water heater, the change is from 0.575 to 0.60 Energy Factor for gas and 0.904 to 0.945
Energy Factor for electric.
0.67-(0.0019 x Volume) 0.675-(0.0015 x volume)
0.8012-(0.00078 x Volume)
9.2 Water Heater Types
Tank types are based on the Appliance Efficiency Regulations definitions:
• Small storage has an input of less than or equal to 75,000 Btu gas/propane, less than or equal to 105,000 Btu/hr oil, less than or equal to 12 kW electric, or less than or equal to 24 amps heat pump.
•
Small tankless has an input of less than or equal to 200,000 Btu per gas/propane, 210,000 Btu per hour or less oil-fired, or 12 kW or less electric. A tankless water heater is a water heater with an input rating of at least 4,000 Btu per hour per gallon of stored water.
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Large storage has an input greater than 75,000 Btu/hr gas or propane, greater than 105,000
Btu/hr oil ‐ fired, or greater than 12 kW electric.
Rated with thermal efficiency and standby loss.
Large tankless has an input of greater than 200,000 Btu per hour gas/propane, greater than
210,000 Btu per hour oil ‐ fired, or greater than 12 kW electric.
Tankless water heater is a water heater with an input rating of at least 4,000 Btu per hour per gallon of stored water.
Boiler is a space heater supplying steam or hot water for space heating.
Indirect is a water heater consisting of a storage tank with no heating elements or combustion devices, connected via piping and recirculating pump to a heat source consisting of a boiler.
9.3.1 Single Family Distribution Type
Distribution types
range from standard (distribution system multiplier 1.0) to recirculating with no control (distribution system multiplier 7.0) as options with no HERS verification requirement.
Some systems are allow for a higher credit if the system will be verified by a HERS rater.
See
for a comparison of the multiplier (lower number equals more efficient system).
More information about distribution types can be found in
Residential Compliance Manual
,
Section 5.3
and
Reference Appendices
, Residential Appendix RA3.6.
Figure 9-1: Single Family Distribution Systems
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Table 9-1: Water Heater Distribution System Multipliers
Distribution System
NO HERS INSPECTION REQUIRED
Standard
Pipe Insulation, All Lines
Parallel Piping
Recirculation, Non-demand Control (no control, runs 24 hrs/day)
Recirculation, Manual Demand Control Push Button
Recirculation, Demand Control Occupancy/Motion
OPTIONAL CASES: HERS INSPECTION REQUIRED
Pipe Insulation, All Lines
Parallel Piping
Compact Design
Point of Use
Recirculation, Demand Control Push Button
Recirculation, Demand Control Occupancy/Motion
Non-Compliant Installation Distribution Multiplier
Distribution System
Multiplier
1.00
0.90
1.05
9.00
1.60
2.40
0.80
0.95
0.70
0.30
1.45
2.20
1.20
9.3.2 Multi-Family Distribution Type
When using central water heating in a multi-family building, the options for distribution systems are
shown in Figure 9-2. More information about distribution types can be found in
Residential
Compliance Manual
, Section 5.3 and
Reference Appendices
, Residential Appendix RA3.6.
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Figure 9-2: Multi-Family Distribution Systems
9.4 Water Heating System Data
Under the Mechanical Tab, the water heating system details are defined (see Figure 9-2).
9.4.1.1 System Name
User defined name. This is the same name that was provided under the Zone Data tab (see Section
9.4.1.2 Distribution type
Drop-down menu with options based on the building and water heater type being specified. See
Section 9.3 and Table 9-1. For installation and compliance requirements see
Residential Compliance
Manual
Chapter 5 and
Reference Appendices
, Residential Appendix RA3.6 and 4.4.
9.4.1.3 Multi-Family Hot Water Distribution Type
Drop-down menu with options for the level of control on the recirculating system serving the
dwelling unit, based on the building and water heater type being specified. See Section 9.3.2 and
Figure 9-2. An input for the recirculation loops is also required (see Figure 9-3).
9.4.1.4 Recirculation Pump Power (bhp)
Multi-family recirculation pump power (brakehorse power). Typical value less than 1.00.
9.4.1.5 Efficiency (fraction)
Multi-family recirculation motor efficiency (fraction). Typical value less than 1.00. See
default efficiencies.
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Table 9-2: Default Recirculating Pump Motor Efficiency
Nameplate or Brake
Horsepower
0.050 (1/20)
0.083 (1/12)
0.125 (1/8)
0.167 (1/6)
Standard Fan Motor
Efficiency
0.40
0.49
0.55
0.60
0.250 (1/4)
0.333 (1/3)
0.64
0.66
0.500 (1/2) 0.70
0.750 (3/4) 0.72
Source: Reference Appendices, Nonresidential Appendix NA3
9.4.1.6 Water Heater(s)
The name of the water heater (which holds more information about the water heater, see Section
9.4.1.7 Count
The number of water heaters named in the adjacent field that are in the system. Include different water heaters or different water heater efficiencies on a different line.
Figure 9-3: Recirculation Loops
9.5 Solar Water Heating Data
When a water heating system has a solar system to provide part of the water heating, the Solar
Fraction (SF) is determined using an F-chart program, OG-100 or OG-300 calculation method (see www.gosolarcalifornia.org). The calculation methods require varying levels of detail about the solar system and the site of the installation. Calculations use published efficiency data for the solar water heating system.
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Figure 9-4: Solar Water Heating Data, Annual
Figure 9-5: Solar Water Heating Data, Monthly
9.5.1.1 Solar Fraction Type
Select annual or monthly, based on the appropriate calculation method for the system type. See www.gosolarcalifornia.org.
9.5.1.2 Solar Fraction
Enter one annual solar fraction (see Figure 9-4) or 12 monthly solar fractions (see Figure 9-5), as
calculated for the system type.
9.6 Water Heater Data
shown in Figure 9-6. The fields will vary based on the tank type.
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Figure 9-6: Water Heater Data Small Storage
Figure 9-7: Large Storage Water Heater Data
9.6.1.1 Name
User-defined name that is specified in the water heating system data for the field water heater (see
9.6.1.2 Heater Element Type
Choose electric resistance, natural gas, propane, heat pump, or oil.
9.6.1.3 Tank Type
Choose boiler, indirect, large instantaneous, large storage, small instantaneous, small storage, or
unfired tank. Most instantaneous water heaters are small, based on the rated input (see Section 9.2
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9.6.1.4 Efficiency
is energy factor for small storage, small instantaneous, and small heat pump water heaters. For large storage, large instantaneous, large heat pump, or boilers the efficiency is thermal efficiency, recovery efficiency, or AFUE. Indirect water heater efficiency is based on the type of device being used to heat the water. Value entered as a decimal, such as 0.60 or 0.80.
9.6.1.5 Standby Loss or Pilot Energy
Required input for large storage water heaters and mini tanks. For large storage, a standby loss of 3% is entered as 0.03. For mini tanks, enter the standby loss Watts. Find the standby loss by conducting an advanced search in the Energy Commission’s appliance efficiency database of water heating
Some large storage water heaters are not required to report standby loss. This value can be calculated using equations from the 2012 Appliance Efficiency Regulations, Tables F2 and F3, as follows:
Standby loss Btu/hr = (rated input / 800) + (110 x (volume x 0.5)
Convert to Standby Loss Percent as:
Standby loss Btu/hr / (8.25 x Volume x 70)
There is no source for pilot energy. Leave this value as 0.
9.6.1.6 Tank Volume
Enter the tank volume (in gallons). The rated input rather than the tank volume is used to determine
if a tank type is large or small (see Section 9.2)
9.6.1.7 Exterior R-value
For indirect and unfired tanks.
9.6.1.8 Input Rating
The input rating (consistent with the tank type) from one of the listed sources in Section 9.1.
9.6.1.9 Ambient Conditions
For an indirect water heater, specify whether it is installed in unconditioned or conditioned space.
9.6.1.10 Recovery Efficiency
If the equipment is part of a hydronic system, enter the recovery efficiency, thermal efficiency or
AFUE for appropriate water heating type. The value comes from one of the listed sources in Section
9.1 and is entered as a percent (e.g., 78, 80).
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9.7 Hydronic and Combined Hydronic
A combined hydronic system uses a device typically used for water heating for both space heating and water heating. If there is a device that is only providing water heating, this is a separate hydronic system.
9.8 Ground Source Heat Pump and Air to Water Heat Pump
The water heating portion of a ground source heat pump or air to water heat pump is modeled by
first defining the HVAC system, as described in Section 8.2.3 and checking the box “System Heats
DHW” or domestic hot water.
The inputs for the water heating equipment data are:
9.8.1.1 Tank Volume
Enter the tank volume (in gallons).
9.8.1.2 Insulation R-value
R-value of external tank insulation.
9.8.1.3 Ambient Conditions
Specify whether it is installed in unconditioned or conditioned space.
The final step is to connect the HVAC system to the DHW system. In this example, an HVAC system named Ground Source HP was specified and can be selected to serve as the water heating system for
the zone. Once this connection is made, the mechanical tab will look like Figure 9-9 (in order to
refresh the screen, click on the envelope tab and then the mechanical tab).
Figure 9-8: Water Heater from an HVAC System
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