NC-v5 EAc2: Reduce Peak Thermal Loads 1-5 points

Credit language

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Intent

To minimize demand on grid resources and improve the resilience of buildings.

Requirements

Comply with any combination of Options 1–4 for a maximum of 5 points.

For all options, the building envelope must meet the requirements of ASHRAE 90.1, Section 5.5, Prescriptive Building Envelope Compliance Path or ASHRAE 90.1, Section 5.6, Building Envelope Trade-Off Compliance Path per the version of ASHRAE 90.1 referenced in EAp2: Minimum Energy Efficiency. Building envelope efficiency shall not be traded off with other building systems.

Option 1. Infiltration and Balanced Ventilation (1 point)
Comply with both of the following:

Balanced Ventilation
Design the ventilation and exhaust airflows within 10% of each other and include a testing, adjusting, and balancing (TAB) report demonstrating balanced ventilation in the commissioning scope. This requirement does not apply to Core and Shell projects.

AND

Infiltration
Use an air leakage test to demonstrate a measured air leakage of the building envelope less than or equal to Table 1. Buildings smaller than 25,000 square feet (2,322 square meters) must use a whole-building air leakage test.

• Complete air leakage testing using ASTM E779, ANSI/RESNET/ICC 380, ASTM E3158, ASTM E1827, or equivalent.
• For buildings greater than 5,000 square feet (465 square meter), maximum air leakage is determined per sq. ft. or sq. m. of building envelope area (including exterior walls, roofs, and base floor/slab).
• For projects that include both new construction and major renovation, use the weighted average maximum air leakage.

Table 1. Caps on Air Leakage Rates

 NOTE: cfm = cubic feet per meter; L/s/m² = liters per second per square meter; ACH = air changes per hour.

OR

Residential (2 points)

Balanced Ventilation. Meet the New Construction requirements.

AND

INFILTRATION

• Compartmentalize each residential dwelling unit to minimize leakage between units. Perform a blower door test of residential dwelling units, following the procedures in ANSI/RESNET/ICC 380 or equivalent. For each unit tested, demonstrate a maximum leakage of enclosure area that is no more than 1.5 times the thresholds identified in Table 1 (enclosure area refers to all surfaces enclosing the dwelling unit, including exterior and party walls, floors, and ceilings). Demonstrate a weighted average leakage of the enclosure area for the building, including dwelling units, that complies with the caps in the limits identified in Table 1.

AND/OR

Option 2. Ventilation Energy Recovery (1 point)
Each fan system supplying outdoor air must have an energy or heat recovery system with a minimum 70% enthalpy recovery ratio or a minimum of 75% sensible heat recovery ratio. Provisions must be made to bypass or control the energy recovery system during moderate outside air conditions.  

In aggregate, fan systems supplying less than 15% of the project’s total outdoor air can be excluded.

AND/OR

Option 3. Thermal Bridging (1 point)
Comply with the prescriptive thermal bridging requirements of ASHRAE 90.1-2022, Section 5.5.5(a), including all applicable requirements of Sections 5.5.5.1–5.5.5.5, without applying exceptions for projects in climate zones 0–3.

AND/OR

Option 4. Peak Thermal Load Reductions (1–3 points)
Comply with the following:

• Ventilation loads must be included in the determination of peak coincident loads. 
• Measure building envelope air leakage using air leakage testing and use the measured air leakage to calculate the peak loads for Path 1, Path 2 (envelope), and Path 3. (Meeting the leakage rates in Option 1 is not required to pursue this option.) 
• Demonstrate balanced ventilation meeting the criteria in Option 1.

AND

PATH 1. PEAK LOAD INTENSITY (1–3 POINTS)
Limit the sum of peak heating load and peak cooling load per unit of treated floor area to be less than or equal to the thresholds specified in Table 2. Calculate peak loads using one of the following:

• WUFI Passive Design Tool, following the Passive House Institute U.S. protocol.
• Passive House Planning Package, following the Passive House Institute protocol to determine maximum heating load and maximum cooling load.

Table 2. Points for Meeting Caps on the Sum of Peak Heating and Cooling Loads

OR

PATH 2. ASHRAE 90.1 TRADE-OFF METHODS (1–3 POINTS)
Comply with envelope and/or HVAC improvements for a maximum of 3 points.

Envelope loads (1–2 points)
Demonstrate a percent improvement in the sum of system peak heating loads and system peak cooling loads associated with the proposed envelope performance factor compared to the base envelope performance factor determined in accordance with the ASHRAE 90.1-2022, Building Envelope Trade-off Option (Normative Appendix C). Points are awarded according to Table 3.

Table 3. Points for percentage improvement in peak thermal loads from envelope

AND/OR

Ventilation Loads (1 point)
Demonstrate a minimum 10% improvement in the sum of building peak coincident heating loads and building peak coincident cooling loads for the TSPR proposed building design versus the product of the TSPR reference building design and ASHRAE 90.1-2022, Table L5-4, Mechanical Performance Factors (MPF), for the project’s location and climate zone determined in accordance with the ASHRAE 90.1-2022 Mechanical System Performance Rating Method (Normative Appendix L). 

OR

PATH 3. ENERGY SIMULATION (1–3 POINTS)
Demonstrate a PI calculated per ASHRAE 90.1-2019 or later from Normative Appendix G’s Performance Rating Method, replacing all references to cost with the sum of building peak coincident heating loads and building peak coincident cooling loads.

Points are awarded according to Table 4.

Table 4. Points for PI for Peak Heating and Cooling Loads