Service Water Heating (SWH)

Overview

The service water heating category covers parameters related to the service water heating equipment and demand. Table 11 summarizes the checks included in this group.

Table 11: Service Water Heating Quality Control Checks Overview

Focus of the Check Type of Check Proposed Design Baseline/Budget Design
SWH System Components CF inputs reflect design documents SWH01-P SWH03-P NA
CF inputs reflect requirements of ECB/PRM NA SWH01-B
CF inputs reflect requirements of ECB/PRM NA SWH03-B
Meet mandatory requirements SWH02-P NA
Simulation inputs consistent with CF SWH05-P SWH05-B
Simulation outputs consistent with CF NA NA
Hot Water Demand CF inputs reflect design documents SWH04-P NA
CF inputs reflect requirements of ECB/PRM NA SWH04-B
Meet mandatory requirements NA NA
Simulation inputs consistent with CF NA NA
Simulation outputs consistent with CF SWH06 SWH07 SWH06 SWH07
Legend: PASS/FAIL/NA outcome is determined automatically in the Quality Control Checks tab of the Compliance Form.

The following strategies may be used to prioritize the review:

  1. If there are multiple water heater types, the review should focus on water heaters with the largest capacity or a representative smaller unit.
  2. Hot water demand checks should only be performed for Appendix G projects where different hot water demand is reported in the Compliance Form for the baseline versus proposed design.

For 90.1 2022 PRM alterations subject to G3.3 (i.e., Minor Alterations), the summary tables on the Quality Control Checks tab in the Compliance Form may not reflect correct values for the baseline since projects, for the most part, only enter proposed design information and provide notes as to what was modeled in the baseline in the notes fields associated with the proposed design related tables. Refer to the 90.1 2022 Section G3.3 Performance Calculations for Other Alterations section for more information regarding 90.1 2022 G3.3.

SWH01-P Proposed SWH system type, efficiency and capacity reported in the Compliance Form reflects design documents

90.1 2016 and 2019/2022 ECB
Table 11.5.1 Column A #11/Table 12.5.1 Column A #11

The service water-heating system type and all related performance parameters, such as equipment capacities and efficiencies, in the proposed design are determined as follows:

  • Where a complete service water-heating system exists, the model must reflect the actual system type using actual component capacities and efficiencies.
  • Where a service water-heating system has been designed and submitted with design documents, the service water-heating model must be consistent with design documents.
  • Where no service water-heating system exists or has been submitted with the design documents, no service water heating must be modeled.
  • Piping losses must not be modeled
90.1 2016, 2019, and 2022 PRM
Table G3.1 #11, Proposed Building Performance

The service water-heating system type and all related performance parameters, such as equipment capacities and efficiencies, in the proposed design must be determined as follows:

  1. Where a complete service water-heating system exists, the proposed design must reflect the actual system type using actual component capacities and efficiencies.
  2. Where a service water-heating system has been designed and submitted with design documents, the service water heating model must be consistent with design documents.
  3. Where no service water-heating system exists or has been designed and submitted with design documents, but the building will have service water-heating loads, a service water-heating system must be modeled that matches the system type in the baseline building design, serves the same water-heating loads, and comply with but not exceed the requirements of Section 7. Exception: For alterations subject to 90.1 Section G3.3, because the same system types are modeled in the baseline and proposed, if no service water heating system exists in the proposed then none will be modeled in the proposed or baseline.
  4. For buildings that will have no service water-heating loads, no service water-heating system is modeled.
  5. Piping losses must not be modeled.
Review Tips
  1. Proposed SWHs are listed in Table 1 of the Service Water Heating tab. If projects include multiple water heaters, identify SWH types with the highest total nameplate input rate calculated as the product of the number of heaters and nameplate input rate per heater, and focus the review on these units only.
  2. Cross-check information provided for the SHWs in the design documents with the inputs in Table 1. The reference to drawings/specs where information for each heater is available should be included in Table 1 for each heater. Request cutsheets if any of the parameters are missing.

SWH02-P Proposed SWH system efficiency reported in the Compliance Form meets the mandatory requirements of 90.1 Section 8

Review Tips
  1. Confirm that the rated efficiency exceeds the minimum required efficiency and that the rated standby loss is below the maximum listed in Table 1. These reference values are based on 90.1 Table 7.8 and are mandatory. Failure to meet these requirements should be flagged. For most SWHs, the reference values will be determined automatically. If the auto-populated default is over-written, the value is shown in bold brown font and should be confirmed.

SWH02-B Baseline/budget SWH system type, efficiency and capacity reported in the Compliance Form is established correctly

90.1 2016 and 2019/2022 ECB
Table 11.5.1 Column B #11/Table 12.5.1 Column B #11

The SWH system type and fuel must be the same as in the proposed design, except a dedicated SWH system must be modeled if the proposed design has a combination space/service water heating system. Storage tank volume in the budget design must be the same as in the proposed design. Piping losses must not be modeled.

90.1 2016 and 2019 PRM
Table G3.1 Baseline Building Performance column #11

The SWH system type and fuel must be as prescribed in 90.1 Table G3.1.1-2 based on the building type, irrespective of system type and fuel source in the proposed design. For example, all multifamily occupancies have a central gas storage water heater; all office occupancies have a central electric resistance storage water heater. In mixed use buildings, e.g. in a building with multifamily occupancy on the top 10 floors and office occupancy on the lower 3 floors, a separate baseline SWH system type must be modeled for each occupancy. Storage tank volume in the budget design must be the same as in the proposed design.

90.1 2022 PRM
G3.2 New Construction/Major Alterations

Requirements are the same as Table G3.1 Baseline Building Performance column #11 for the 90.1 2016 and 2019 PRM described above.

G3.3 Minor Alterations
Service water heating systems included in the scope of the alteration are required to be modeled with the minimum requirements in 90.1 Section 7.1.4 with the same system type modeled as specified in proposed design. All unmodified service water heating systems and equipment shall be modeled the same as in the proposed design.

Review Tips
  1. Baseline/budget SWHs are listed in Table 2 of the Service Water Heating tab. All values are set automatically by applying the appropriate 90.1 rules to the project. Default values over-written by the modeler are shown in brown bold font in the table and should be verified by reviewer. Refer to 90.1 2022 Section G3.3 Performance Calculations for Other Alterations for review tips for alterations subject to 90.1 2022 Section G3.3 (i.e., Minor alterations).
  2. Common mistakes (these are not applicable to alterations subject to 90.1 2022 PRM Section G3.3):
    • Assuming distributed water heaters in the PRM baseline when there are distributed water heaters in the proposed design. Baseline always has a central water heater for each building occupancy type. Multiple service water heaters may only be included in mixed-use buildings
    • Where proposed design has distributed water heaters, assuming that the capacity of the central baseline water heater is equal to the sum of capacities of the specified water heaters. Instead, baseline systems must be sized according to the provisions of 90.1 Section 7.4.1 to avoid excessive oversizing and low operating efficiency.
    • Where proposed design has combination space/service water heating boiler, assuming that the capacity of the central baseline water heater is equal to the capacity of the specified space/service water heating boiler. Instead, baseline systems must be sized according to the provisions of 90.1 Section 7.4.1 to avoid excessive oversizing and low operating efficiency.

SHW03-P The ancillary components of the proposed SWH system reported in the Compliance Form reflect design documents

90.1 2016 and 2019/2022 ECB, 90.1 2016/2019/2022 PRM

Based on Tables 11.5.1 #11/12.5.1 #11 and G3.1 #11, ancillary components include recirculation pumps, service hot water preheat and condenser heat recovery

Review Tips
  1. Table 1 includes fields for specifying recirculation pumps and hot water reheat strategies, if applicable. The review check should be completed for projects with entries in either of these fields or if service water heating is identified as one of the impactful end uses.
  2. Cross-check information provided in the table with the design documents to verify alignment.

SHW03-B Ancillary components of the baseline/budget SWH system reported in the Compliance Form are established correctly

90.1 2016 and 2019/2022 ECB
Table 11.5.1 Column B #11 Exception 3/Table 12.5.1 Column B #11 Exception 3

For 24-hour facilities that meet the prescriptive criteria for use of condenser heat recovery systems described in Section 6.5.6.2, a system meeting the requirements of that section must be included in the baseline building design, regardless of the exceptions to Section 6.5.6.2. If a condenser heat recovery system meeting the requirements described in Section 6.5.6.2 cannot be modeled, the requirement for 90.1 Energy Cost Budget and Performance Rating Method Submittal Review Manual 127 including such a system in the actual building must be met as a prescriptive requirement in accordance with Section 6.5.6.2 and no heat recovery system must be included in the proposed design or budget building design.

90.1 2016 and 2019 PRM
Table G3.1 #11, Baseline Building Performance column, (e) & (f)
  • For large, 24-hour-per-day facilities that meet the prescriptive criteria for use of condenser heat recovery systems described in Section 6.5.6.2, a system meeting the requirements of that section shall be included in the baseline building design regardless of the exceptions to Section 6.5.6.2. If a condenser heat recovery system meeting the requirements described in Section 6.5.6.2 cannot be modeled, the requirement for including such a system in the actual building must be met as a prescriptive requirement in accordance with Section 6.5.6.2, and no heat recovery system would be included in the proposed design or baseline building design.
  • Where recirculation pumps are used to ensure prompt availability of service water-heating at the end use, the energy consumption of such pumps must be calculated explicitly.
90.1 2022 PRM
G3.2 New Construction/Major Alterations

Requirements are the same as Table G3.1 #11, Baseline Building Performance column, (e) & (f) for the 90.1 2016 and 2019 PRM described above.

G3.3 Minor Alterations
Alterations subject to 90.1 2022 Section G3.3 (i.e., Minor Alterations) are only required to model condenser heat recovery systems if the requirements are applicable based on the scope of the alteration and based on the language in 90.1 Section 6.1.4. This means, based on the language in 90.1 Section 6.1.4, that only alterations in which new cooling systems are installed to serve previously uncooled spaces would need to minimally comply with 90.1 Section 6.5.6.2 in the baseline.

Review Tips
  1. The ancillary components of service hot water systems are reported in Table 2 of the Service Water Heating tab. The values are auto populated but may be over-written. The overwritten defaults should be verified to confirm that they are justified (for alterations following 90.1 2022 Section G3.3 see Table 1 for baseline and proposed design model inputs and examine the Notes section under Table 1 for clarifying notes regarding modeled values).

SHW04-P Proposed service hot water demand reported in the Compliance Form is reasonable.

90.1 2016 and 2019/2022 ECB and PRM

Table 11.5.1 Column B #11/ Table 12.5.1 Column B #11, Table G3.1 #11 Baseline Building Performance column: Service water-heating energy consumption shall be calculated explicitly based on the volume of service water heating required, the entering makeup water, and the leaving service water heating temperatures. Entering water temperatures shall be estimated based on the location. Leaving temperatures shall be based on the end-use requirements.

Review Tips
  1. The check should only be performed for PRM projects if hot water demand reported in the Compliance Form is different between the baseline/budget and proposed.
  2. SHW demand assumptions are provided in Tables 4 - 6 of the Service Water Heating tab.
    1. Table 4 calculates SHW demand for multifamily projects based on the entered flow rates for the specified fixtures in showers and sinks, average supply SHW temperature, entering cold water temperature and temperature at the fixture point of use. The calculations are based on requirements of the EPA ENERGY STAR Multifamily New Construction Program Simulation Guidelines. Verify that entered flow rates match design documents.
    2. Table 5 shows default service hot water use for non-residential building types. The default values are based on typical hot water use in buildings of similar type provided in ASHRAE 90.1 2013 User’s Manual. If default is overwritten, the input is shown in brown font and should be verified.

SWH04-B Difference between the baseline/budget and proposed hot water demand reported in the Compliance Form is as allowed

90.1 2016 ECB

Change in service water heating load is not listed as a trade-off opportunity in the section, thus must be modeled the same in the budget and proposed design. This is further clarified in the updates to this section incorporated into 2019 edition of 90.1 shown below.

90.1 2019/2022 ECB

Table 11.5.1 Column B #11/Table 12.5.1 Column B #11: Service water loads and use shall be the same for both the proposed design and baseline building design and typical of the proposed building type.

90.1 2016 and 2019/2022 PRM

Table G3.1 #11 Baseline Building Performance column: Exception to (g) states that service water heating use can be reduced due to the following:

  • Water conservation measures that reduce the physical volume of service water required. Examples include low-flow shower heads.
  • Reducing the required temperature of service mixed water, by increasing the temperature, or by increasing the temperature of the entering makeup water. Examples include alternative sanitizing technologies for dishwashing and heat recovery to entering makeup water.
  • Reducing the hot fraction of mixed water to achieve required operational temperature. Examples include shower or laundry heat recovery to incoming cold-water supply, reducing the hot-water fraction required to meet required mixed-water temperature.

Such reductions must be demonstrated by calculations.

2019 and 2022 editions include the following clarification in Table G3.1 #1, Baseline Building column:
Where the baseline building systems and equipment are permitted to be different from the proposed design but are not prescribed in this appendix, the baseline must be determined based on the following, in the order of priority:

  • Requirements in Sections 5 through 10
  • Requirements of other efficiency or equipment codes or standards applicable to the design of the building systems and equipment
Review Tips
  1. Hot water demand is reported in Table 4 of the Service Water Heating tab for the residential occupancies and in Table 5 for all others.
  2. ECB: the amount of service hot water consumed in the building is not a trade-off opportunity and must be modeled the same in the budget building and the proposed design.
  3. PRM:
    1. Projects may document a reduction in demand provided the methodology is approved by the building official. For example, on projects with low-flow fixtures, hot water demand in the Proposed Design may be reduced to reflect the lower flow rates of the installed fixtures compared to the maximum flow allowed by the applicable code or standard.
    2. Table 4 of the Service Water Heating tab automatically calculates savings from common water-savings technologies found on residential projects such as low flow plumbing fixtures and ENERGY STAR appliances. Baseline values are set by defaults and should be verified if overwritten.
  4. Common Mistakes
    1. Modeling hot water demand reduction on projects following ECB
    2. Using baseline flow rate based on requirements of the outdated standard such as Energy Policy Act 1992 (EPACT 1992). The baseline must be based on the maximum allowed flow rates of the applicable codes such as state International Plumbing Code.

SWH05-B, SWH05-P Modeled baseline/budget and proposed SWH system type, efficiency, capacity and ancillary features reflect parameters reported in the Compliance Form

Review Tips
  1. Review the simulation reports to confirm that the modeled SWH system parameters are as reported in the Compliance Form.
eQUEST
PV-A, PS-H
Trane TRACE 700
Plant Information entered values report
Trane TRACE 3D Plus
System Component Summary report
IESVE
Plant Loops & Equipment Report, Florida Energy Code Compliance Report, Room Loads Report, Zone Loads Report, System Loads Report, Energy Model Output Report, PRM Compliance Report, ECB Compliance Report, BPRM Report
EnergyPlus
eplustbl.html ‘Equipment Summary’ report, ‘Service Water Heating’ section
OpenStudio
eplustbl.html ‘Equipment Summary’ report, ‘Service Water Heating’ section
Carrier HAP v5
“Plant Input Data” report, “Boiler Input Data” report.
Design Builder
Service Water Heating sheet in LEED Minimum Energy Performance Calculator (.xlsm)

SWH06 Difference in the baseline/budget and proposed hot water use is reasonable based on the system parameters reported in the Compliance Form

Review Tips
  1. ECB: Since the budget SWH system must be of the same type and use the same fuel as the proposed system and the reduction in the hot water demand is not a trade-off opportunity, the difference in SWH energy use between the budget and proposed design depends only on the difference in efficiencies of the budget and proposed systems.


    SWH_Useprop * SWH_Effprop = SWH_Usebudget * SWH_Effbudget

    SWH_Use [MMBtu] = the annual SWH use from simulation output reports

    SWH_Eff = SWH efficiency reported in the submittal

    Projects that do not show this pattern should be flagged and explanation and supporting documentation should be requested. Higher savings may be demonstrated by projects that have solar hot water preheat as allowed by 90.1 Section 11.4.3.1/12.4.3.1, or other means of service hot water preheat, such as use of condenser heat recovery, that differs between the budget and proposed design.

  2. 90.1 PRM: The baseline SWH system may be of a different type and use a different fuel than the proposed SWH system and there may be a difference in hot water demand between the baseline and proposed design, thus this check cannot be effectively performed. For alterations following 90.1 2022 Section G3.3 (i.e., Minor Alterations) that are not modeling a reduction in hot water demand the check described in review tip #1 can be performed using the baseline and proposed efficiency values reported in Table 1 on the Service Water Heating tab in the Compliance Form.
eQUEST
BEPU
Trane TRACE 700
Equipment Energy Consumption report
Trane TRACE 3D Plus
LEED Summary Section 1.6
IESVE
Detailed Simulation Report, Plant Loops & Equipment Report, Room Loads Report, Zone Loads Report, System Loads Report, Energy Model Output Report, PRM Compliance Report, ECB Compliance Report, BPRM Report
EnergyPlus
NA
OpenStudio
NA
Carrier HAP v5
“Monthly Simulation Results” report for an SHW plant
Design Builder
Service Water Heating sheet in LEED Minimum Energy Performance Calculator (.xlsm)

SWH07-P Modeled proposed SWH effective full load hours are reasonable

Review Tips
  1. SWH effective full load hours are equal to the ratio of the annual service water heating energy use from the simulation outputs to the reported service water heater capacity. Effective full load hours which are higher than typical included in Appendix A may indicate that modeled service water heating demand exceeds the values anticipated by the design team and that the modeled service water heater energy use is exaggerated. EFLH exceeding typical by more than 25%, or exceeding 8760 hours per year, should be flagged.
eQUEST
BEPU
Trane TRACE 700
Equipment Energy Consumption report
Trane TRACE 3D Plus
LEED Summary Section 1.6
IESVE
Room Loads Report, Zone Loads Report, System Loads Report, Energy Model Output Report, PRM Compliance Report, ECB Compliance Report, BPRM Report, Plant Loops & Equipment Report, Florida Energy Code Compliance Report
EnergyPlus
eplustbl.html ‘LEED Summary’ report, ‘EAp2-4/5. Performance Rating Method Compliance’ section
OpenStudio
eplustbl.html ‘LEED Summary’ report, ‘EAp2-4/5. Performance Rating Method Compliance’ section
Carrier HAP v5
“Monthly Simulation Results” report for an SHW plant.
Design Builder
Service Water Heating sheet in LEED Minimum Energy Performance Calculator (.xlsm)