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External Storage Tank Insulation |
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|---|---|
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Applicability |
All water heating systems that have an external storage tank |
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Definition |
Some water heating systems have a storage tank that is separate from the water heater(s) that provides additional storage capacity. This building descriptor addresses the heat loss related to the external tank, which is an additional load that must be satisfied by the water heater(s). |
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Units |
R-value (h-ft2-°F/Btu) |
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Input Restrictions |
As specified in manufacturer data and documented on the construction documents |
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Baseline Building |
Heat loss associated with the storage tank in the baseline building shall meet the requirements for an unfired storage tank in the baseline standards (Standard 90.1-2019, Table 7.8), which is an insulation R‑value of 12.5. The surface area and location of the storage tank shall be the same as the proposed design. |
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External Storage Tank Area |
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|---|---|
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Applicability |
All water heating systems that have an external storage tank |
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Definition |
Some water heating systems have a storage tank that is separate from the water heater(s) that provides additional storage capacity. This documents the entire exterior surface area of the tank. |
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Units |
ft2 |
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Input Restrictions |
As specified in manufacturer specifications |
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Baseline Building |
Same as proposed |
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External Storage Tank Location |
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|---|---|
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Applicability |
All water heating systems that have an external storage tank |
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Definition |
Location of the storage tank, used to determine the heat loss rate and energy exchange with the surroundings |
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Units |
List: Schedule, Zone, Outdoors |
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Input Restrictions |
As designed |
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Baseline Building |
Same as proposed |
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Heat Recovery |
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|---|---|
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Applicability |
Water heating systems that are coupled to heat recovery equipment |
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Definition |
Building equipment such as air conditioners, chillers, gas-fired generators, and others produce thermal energy that may be recovered and used to heat water. The heat-producing characteristics are generally defined for the equipment that is producing the heat, not the equipment that is receiving the heat (water heaters in this case). The building descriptors will vary depending on the equipment. The models for heat-producing equipment need to produce output hourly so that the schedule of heat production and heating needs can be aligned and evaluated in the water heating model. |
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Units |
Data structure: depends on the equipment producing the heat |
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Input Restrictions |
There are no restrictions, other than agreement with the construction documents |
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Baseline Building |
The baseline building requirements for condenser heat recovery are documented in Section 3.8.7 of this manual |
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Solar Thermal |
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|---|---|
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Applicability |
Water heating systems with a solar thermal system |
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Definition |
A solar thermal water heating system consists of one or more collectors. Water is passed through these collectors and is heated under the right conditions. There are two general types of solar water heaters: integrated collector storage (ICS) systems and active systems. Active systems include pumps to circulate the water, storage tanks, piping, and controls. ICS systems generally have no pumps and piping is minimal. Solar systems may be tested and rated as a complete system or the collectors may be separately tested and rated. SRCC OG-300 is the test procedure for whole systems and SRCC OG-100 is the test procedure for collectors. The building descriptors used to define the solar thermal system may vary with each software application and with the details of system design. The solar fraction shall be estimated by the f-chart procedure for solar water heating systems. |
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Units |
Data structure: will vary with the software and system details |
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Input Restrictions |
As designed. The proposed design may have a combined space and water heating system. |
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Baseline Building |
Not applicable |
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Combined Space Heating and Water Heating |
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|---|---|
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Applicability |
Projects that use a boiler to provide both space heat and water heating |
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Definition |
A system that provides both space heating and water heating from the same equipment, generally the space heating boiler. Such systems are restricted by the baseline standards, but may be modeled in the candidate building. The restrictions are due to the misalignment of the space heating load and the water heating load. The first is highly intermittent and weather dependent, while the latter is more constant and not generally related to the weather. |
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Units |
Data structure |
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Input Restrictions |
As designed. The proposed design may have a combined space and water heating system. |
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Baseline Building |
The baseline building shall be modeled with separate space heating and water heating systems, according to the baseline system type and corresponding requirements in Section 3.1.1 and baseline water heating system type and requirements identified in Section 3.9.1 . |
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External Storage Tank Insulation |
|
|---|---|
|
Applicability |
All water heating systems that have an external storage tank |
|
Definition |
Some water heating systems have a storage tank that is separate from the water heater(s) that provides additional storage capacity. This building descriptor addresses the heat loss related to the external tank, which is an additional load that must be satisfied by the water heater(s). |
|
Units |
R-value (h-ft2-°F/Btu) |
|
Input Restrictions |
As specified in manufacturer data and documented on the construction documents |
|
Baseline Building |
Heat loss associated with the storage tank in the baseline building shall meet the requirements for an unfired storage tank in the baseline standards (Standard 90.1-2022, Table 7.4-1), which is an insulation R‑value of 12.5. |
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External Storage Tank Area |
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|---|---|
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Applicability |
All water heating systems that have an external storage tank |
|
Definition |
Some water heating systems have a storage tank that is separate from the water heater(s) that provides additional storage capacity. This documents the entire exterior surface area of the tank. |
|
Units |
ft2 |
|
Input Restrictions |
As specified in manufacturer specifications |
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Baseline Building |
G3.2 New Construction/Major Alterations Baseline water heater system(s) are required to be sized according to the provisions of Section 7.4.1 which points to generally accepted engineering standards and handbooks acceptable to the adopting authority (e.g., ASHRAE Handbook—HVAC Application). As a result, the baseline storage tank area should be determined using generally accepted engineering standards and principles applicable to the loads being served and the baseline system type. G3.3 Minor Alterations Same as proposed. |
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External Storage Tank Location |
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|---|---|
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Applicability |
All water heating systems that have an external storage tank |
|
Definition |
Location of the storage tank, used to determine the heat loss rate and energy exchange with the surroundings |
|
Units |
List: Schedule, Zone, Outdoors |
|
Input Restrictions |
As designed |
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Baseline Building |
G3.2 New Construction/Major Alterations Same as proposed. G3.3 Minor Alterations Same as proposed. |
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Heat Recovery |
|
|---|---|
|
Applicability |
Water heating systems that are coupled to heat recovery equipment |
|
Definition |
Building equipment such as air conditioners, chillers, gas-fired generators, and others produce thermal energy that may be recovered and used to heat water. The heat-producing characteristics are generally defined for the equipment that is producing the heat, not the equipment that is receiving the heat (water heaters in this case). The building descriptors will vary depending on the equipment. The models for heat-producing equipment need to produce output hourly so that the schedule of heat production and heating needs can be aligned and evaluated in the water heating model. |
|
Units |
Data structure: depends on the equipment producing the heat |
|
Input Restrictions |
There are no restrictions, other than agreement with the construction documents |
|
Baseline Building |
The baseline building requirements for condenser heat recovery are documented in Section 3.8.7 of this manual |
|
Solar Thermal |
|
|---|---|
|
Applicability |
Water heating systems with a solar thermal system |
|
Definition |
A solar thermal water heating system consists of one or more collectors. Water is passed through these collectors and is heated under the right conditions. There are two general types of solar water heaters: integrated collector storage (ICS) systems and active systems. Active systems include pumps to circulate the water, storage tanks, piping, and controls. ICS systems generally have no pumps and piping is minimal. Solar systems may be tested and rated as a complete system, or the collectors may be separately tested and rated. SRCC OG-300 is the test procedure for whole systems and SRCC OG-100 is the test procedure for collectors. The building descriptors used to define the solar thermal system may vary with each software application and with the details of system design. The solar fraction shall be estimated by the f-chart procedure for solar water heating systems. |
|
Units |
Data structure: will vary with the software and system details |
|
Input Restrictions |
As designed. The proposed design may have a combined space and water heating system. |
|
Baseline Building |
G3.2 New Construction/Major Alterations Not applicable G3.3 Minor Alterations Energy generated by existing system capacity shall be subtracted from the baseline design energy consumption prior to calculating the building performance. Additional capacity and/or a new system included in the scope of the alteration is not required to be subtracted from baseline design energy consumption.
|
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Combined Space Heating and Water Heating |
|
|---|---|
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Applicability |
Projects that use a boiler to provide both space heat and water heating |
|
Definition |
A system that provides both space heating and water heating from the same equipment, generally the space heating boiler. G3.2 New Construction/Major Alterations Such systems are not modeled in the baseline but may be modeled for the proposed building. Combined systems are not modeled in the baseline due to the misalignment of the space heating load and the water heating load. The first is highly intermittent and weather dependent, while the latter is more constant and not generally related to the weather. G3.3 Minor Alterations Such systems are modeled in the baseline if specified in the design. |
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Units |
Data structure |
|
Input Restrictions |
As designed. The proposed design may have a combined space and water heating system. |
|
Baseline Building |
G3.2 New Construction/Major Alterations The baseline building shall be modeled with separate space heating and water heating systems, according to the baseline system type and corresponding requirements in Section 3.1.1 and baseline water heating system type and requirements identified in Section 3.9.1 . G3.3 Minor Alterations The baseline and proposed are modeled with the same system type. There are no restrictions with regard to combined space heating and water heating equipment. |