Renewable Energy (RE)
Renewable Energy Checks Overview
This group of quality control checks focus on verifying renewable thermal and electricity generation systems. The checks only apply to projects that include such systems.
For projects subject to 90.1 G3.3 (i.e., 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.
RE01 The renewable electricity generation systems reported in the Compliance Form reflect design documents
Review Tips
Renewable electricity generation systems are reported in on the Renewable Energy tab Tables 1 and 2. Confirm that all required information is provided and consistent with the design documents.
PV system details included in the submittal must at minimum include system type, orientation and generation capacity (kW). If PV system was not modeled explicitly in the whole building simulation tool used for the project, the external calculations used to estimate electricity generation must be included in the submittal as described in Exceptional Calculations group of QC checks.
RE02 The renewable thermal energy systems reported in the Compliance Form reflect design documents
Review Tips
Renewable thermal energy systems are reported in Table 3 of the Renewable Energy tab.
RE03 Savings from renewable energy savings reported in the Compliance Form are substantiated
Review Tips
- Refer to Table 4 in the Renewable Energy Tab
- To verify that the reported PV system electricity generation is reasonable, calculate the system EFLH that is equal to the ratio of the reported annual electricity generation (kWh) to the total rated PV system capacity (kW).
- If renewable energy was modeled in the whole building simulation tool, verify that savings reported in the Compliance Form reflect simulation results based on the simulation reports referenced below.
- Projects often model renewable energy using external calculations.
RE04 Contribution of renewable energy toward compliance does not exceed the allowed limit
90.1 2016 and 2019/2022 ECB
11.4.3.1/12.4.3.1: The reduction in design energy cost associated with on-site renewable energy shall be no more than 5% of the calculated energy cost budget. Either the actual rates for purchased energy or state average energy prices published by U.S. Energy Information Administration (EIA) for commercial building customers may be used, but rates from different sources may not be mixed in the same project.
90.1 2016 PRM
There is no limit on the contribution of renewable energy toward compliance. However, such contribution should be verified to ensure that it is not overly optimistic.
90.1 2019 and 2022 PRM
4.2.1.1:The formula used to establish compliance provided in this section limits contribution of renewable energy toward compliance to no greater than 5% of the baseline energy cost.
G3.3 Minor Alterations
For projects subject to 90.1 G3.3 (i.e., 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.
Review Tips
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The applicable cap is automatically accounted for in the Compliance Calculations tab of the
Compliance Form.
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90.1 Section 3 defines on-site renewable energy as “… energy generated from renewable sources
produced at the building site.” Based on this definition, savings associated with systems such
as PV panels, solar service water preheaters, etc. are subject to the cap. As with any systems,
the renewable energy systems can only contribute toward compliance if they are included in the
permit application.
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Example
Q: A project following the ECB path has modeled an energy cost budget of $100,000. The modeled proposed energy cost is $98,000 including $8,000 savings from on-site PV panels which were explicitly modeled in the simulation tool and are included in the permit application. Does the project comply with ECB?The proposed energy cost without accounting for on-site renewables is $98,000 + $8,000 = $106,000. The allowed maximum contribution of renewable energy toward savings is 5% * 100,000 = $5,000. The proposed energy cost with the allowed renewable energy savings is $106,000 - $5,000 = $101,000, which exceeds the energy cost budget. The project does not comply with the ECB.
RE05 Prescriptive on-site renewable energy requirements reported in the Compliance Form are established correctly
90.1 2016 and 2019 ECB and PRM
Not applicable.
90.1 2022 ECB
Table 12.5.1 #15 Budget Building Design columnOn-site renewable energy shall be included in the budget building design when required by Section 10.5.1, and shall be determined as follows:
- Where a system providing on-site renewable energy has been modeled in the proposed design, the same system shall be modeled identically in the budget building design, except the rated capacity shall meet the requirements of Section 10.5.1.1. Where more than one type of on-site renewable energy system is modeled, the total capacities shall be allocated in the same proportion as in the proposed design.
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Where no system exists or is specified to provide on-site renewable energy in the proposed design,
on-site renewable energy shall be modeled as an unshaded photovoltaic system with the following
physical characteristics:
- Size: Rated capacity per Section 10.5.1.1
- Module Type: Crystalline silicon panel with a glass cover, 19.1% nominal efficiency and temperature coefficient of –0.19%/°F; performance shall be based on a reference temperature of 77°F and irradiance of 317 Btu/ft2·h.
- Array Type: Rack-mounted array with an installed nominal operating cell temperature (INOCT) of 103°F
- Total system losses (DC output to AC output): 11.3%
- Tilt: 0-degrees (mounted horizontally)
- Azimuth:180 degrees
90.1 2022 PRM
The Performance Cost Index Target (PCIt) and compliance calculations in Section 4.2.1.1 includes the requirement to account for proposed building performance, excluding any renewable energy system in the proposed design and including an on-site renewable energy system that meets but does not exceed the requirements of Section 10.5.1.1 modeled following the requirements for a budget building design in Table 12.5.1, row 15 (requirements are shown directly above in the 90.1 2022 ECB section).
Review Tips
- Refer to the prescriptive on-site renewable energy system inputs in Tables 5, 6, and 7 on the Renewable Energy tab in the Compliance Form.
- Review Table 5 to verify that prescriptive on-site renewable energy system minimum rated capacity requirements in Section 10.5.1.1 were established correctly.
- To verify that the reported on-site renewable energy system generation is reasonable, calculate the system EFLH which is equal to the ratio of the reported prescriptive annual energy generation to the total rated system capacity using the inputs in Table 6.
- Review Table 6 and the proposed renewable energy tables (Tables 1-3) to verify that the same system(s) that are specified in the proposed design are modeled to determine the prescriptive annual energy generation, except with the rated capacity meeting the requirements of Section 10.5.1.1. Where more than one type of on-site renewable energy system is specified, the total capacities shall be allocated in the same proportion as in the proposed design. If no on-site renewable energy systems are specified in the proposed design, then confirm that prescriptive annual energy generation was modeled following Table 12.5.1 #15 Budget Building Design column b.
- If renewable energy was modeled in the whole building simulation tool, verify that savings reported in the Compliance Form reflect simulation results based on the simulation reports referenced in check RE03. Projects often model renewable energy using external calculations.