CS86 Energy Code Feasibility Study in Brockton, Massachusetts

Energy code feasibility study for a 36-unit high-rise in Massachusetts. Compares multiple design paths. Recommended: ELECTRIC (All-Electric). View full study.

Study Type: Energy Code Feasibility Study
State: Massachusetts
Units: 36
Building Type: high-rise
Fuel Type: Mixed Fuel
Recommended Path: ELECTRIC (All-Electric)

Goal

To find the most cost-effective compliance path, this report isolates energy code related costs from total construction. We use real bid data from vendors & clients to create a reliable framework for aligning incentives and design, with all recommendations confirmed by detailed energy modeling.

Project

Brockton, MA 02301
1 Building | 36 Units | 33,414 SF Conditioned
Substantial rehab & addition | 6-story high-rise multifamily (x1)
All-Electric OR Mixed Fuel | 2021 IECC with MA Amendments (Stretch Code) | HERS ≤ 58 (All-Electric) OR HERS ≤ 55 (Mixed Fuel) | ENERGY STAR MFNC v1.1

Overview

Read This: This report compares different ways you can build the project and meet energy code, looking at both cost and incentives, with the ultimate goal as finding the most affordable path.

The overview outlines the key differences between each of the paths we show in this report and why we recommend the one we picked over the others.
The recommended design section is where we share the requirements and incentives for the path we think is best based on affordability.
The path comparison section shows the detailed requirements and incentives for each path we compared, basically showing our work if you want to dig in.

Product Recs: All product recommendations are recommendations only and can be substituted with any equivalent or better match.

Path Summaries

All three paths meet the Massachusetts Stretch Code and are modeled to pass on a lean margin. ELECTRIC is the lowest net cost. GAS-HEAT and CURRENT are great alternatives when the fuel mix should be different.

ELECTRIC (All-Electric): Recommended

This is the least expensive path at approximately $49.82/sf net, and it is the simplest of the three to build. It keeps the project fully electric, which preserves the $36,000 Mass Save Base multifamily high-rise incentive ($1,000 per unit) and aligns with the direction Massachusetts energy code is heading. The wall air barrier sits on the sheathing and the roof air barrier sits on the deck with the cold plane outside the deck, and for this project this is the right choice.

GAS-HEAT (Mixed-Fuel): Alternative

A great alternative at approximately $50.58/sf net, about $0.76/sf more than the ELECTRIC path. Choose it when the building should heat with gas: an 85 AFUE furnace, separate cooling, and Teal's centralized condensing water heater with two 100 gallon tanks. It does not earn the Mass Save Base incentive because the heat is gas.

CURRENT (Mixed-Fuel): Alternative

A great alternative at approximately $52.89/sf net, about $3/sf more than the ELECTRIC path. Heating stays electric, so it keeps the same $36,000 Mass Save Base incentive, and hot water is Teal's centralized condensing system. Choose it when the project wants heat pumps and gas water heating.

What Changes Between Paths

Item	CURRENT	GAS-HEAT	ELECTRIC (Recommended)
HVAC	Ducted air-source heat pump; SEER2 ≥ 16; HSPF2 ≥ 8.5. See HVAC Design Loads.	Natural gas furnace; AFUE ≥ 85; cooling by a separate system, cooling only; SEER2 ≥ 16. See HVAC Design Loads.	Ducted air-source heat pump; SEER2 ≥ 16; HSPF2 ≥ 8.5. See HVAC Design Loads.
DHW	Centralized gas water heating system with two 100 gallon tanks and a temperature-controlled recirculating system; ≥ 0.80 energy factor.	Centralized gas water heating system with two 100 gallon tanks and a temperature-controlled recirculating system; ≥ 0.85 energy factor.	Electric resistance storage water heater; UEF ≥ 0.92; 50 gal.
Cost $/sf	$53.26	$49.97	$50.38
Incentive $/sf	$1.08	$0.00	$1.08
Net $/sf	$52.89	$50.58	$49.82

Permit / Certificate of Occupancy Requirements

High Rise Buildings

Code Path

HERS: Brockton is a Stretch Code town. The buildings are 6-story Group R under 225 CMR 23. Existing-building work follows Chapter 5 (sections C501.2, C502 and C503). The dwelling units comply by per-unit HERS under section C407.4. The all-electric Stretch ceiling is HERS ≤ 58 and the mixed-fuel Stretch ceiling is HERS ≤ 55 (Table C407.4, Major alterations, additions, or change of use column, footnote b), prior to onsite renewable electric generation (footnote a). Section C407.4.1 requires the building to meet ENERGY STAR Multifamily New Construction.

Permit Requirements

HERS: With the building permit application, per 225 CMR 23 section C407.4.2.1: the proposed HERS Index on the title page and plans, the rater's name, the software name and version, all modeled inputs, and a certificate showing each dwelling unit type at or below the Table C407.4 ceiling for its fuel, with the component specifications behind it (insulation R-values and U-factors, assumed duct and envelope leakage, and heating, cooling, ventilation, and water-heating types and efficiencies), on the worst-case orientation where no site-specific report is produced. ENERGY STAR Multifamily New Construction design review by the rater is part of that package (C407.4.1).

Certificate of Occupancy Requirements

HERS: Before certificate of occupancy, per 225 CMR 23 section C407.4.2.2: the final HERS Index on the title page and plans, a confirmed as-built HERS certificate for each rated unit with the duct and envelope air-leakage test results and the installed equipment efficiencies, and documentation that each unit meets ENERGY STAR Multifamily New Construction (item 7). C405.13 EV-ready and Appendix CB solar-ready compliance close out with it (item 9). A certified HERS rater verifies the package (C407.4.3). Air-leakage testing follows ANSI/RESNET/ICC 380, and RESNET sampling is permitted because each building has more than 8 units (C402.5.2.2).

Recommended Design

This section outlines the design requirements, product recommendations, and incentives for the design that we believe will be the most affordable path to meeting energy code.

Recommended Design - Incentives

Incentives Available: $36,000 - $90,000

MassSave Multifamily High Rise Program Base Tier ($36,000) (Program Breakdown): You get this rebate for having your building(s) meet energy code. This requires pre-approval via an application to be submitted before construction starts. This rebate comes in the form of a check within 4 months of certification documentation being provided to MassSave, typically this is 4 months after construction is complete.
DOER Alternative Energy Credits ($0 - $54,000) (Program Breakdown): This rebate is received for installing APS eligible air source heat pumps (click here for the list). There is an extensive process to get this incentive. It comes in the form of a check approximately 6-12 months after the heat pumps are installed and fully operational.
- IMPORTANT: Although an estimate is provided, this incentive can vary widely typically between $300-1,500 per heat pump. It's based on expected kWh usage of the system as well as the market value of the alternative energy credits when sold.
- Risks: Massachusetts is rewriting this program right now. The House bill would stop the state from accepting new applications on January 1, 2028, the Senate version leaves heat pumps out of that cutoff, and the two are in conference. The application needs the equipment installed and operating, so a project that will not reach that point before the deadline should treat this as upside rather than a budgeted line.

HVAC Design Loads

Plymouth County, MA · heating 9.0°F/70.0°F · cooling 88.0°F/75.0°F · all values kBtuh

Design heat loss · components

Unit type	Walls & rim joists	Roof / ceiling	Slab, floors & below grade	Windows & doors	Infiltration	Ventilation	Design heat loss	Design heat loss at selection
2-Bedroom	4.4	1.6	0.0	3.9	6.1	2.4	18.4 @ 9°F	19.6 @ 5°F
3-Bedroom	3.9	1.4	0.0	6.9	6.3	2.4	21.0 @ 9°F	22.3 @ 5°F

Design heat gain · components

Unit type	Solar through glazing	Envelope conduction	Internal gains	Infiltration & ventilation	Latent	Total heat gain	Sensible heat ratio
2-Bedroom	1.7	2.2	2.3	2.6	4.3	13.1	0.67
3-Bedroom	5.7	2.7	2.5	2.6	4.6	18.2	0.75

Selection

Unit type	Cooling Capacity	Minimum Heating Capacity
2-Bedroom	11.8 to 20.0 kBtuh rated	≥ 19.6 kBtuh @ 5°F
3-Bedroom	16.4 to 23.7 kBtuh rated	≥ 22.3 kBtuh @ 5°F

ENERGY STAR Total UA

Item	Detail
Climate zone	IECC 5A (2012 IECC map)
Program	ENERGY STAR MFNC National v1.1 Rev. 05
Rule	Design Review Item 2.1 / Fn 11-12; Proposed UA ≤ Reference UA
Code reference	Exhibit 1 Table 1 (2012 IECC CZ); Design Review Item 2.1 / Fn 11-12
Version basis	v1.1
Note	Reference wall U for the exterior wall is U-0.089. Proposed wall U stays the Ekotrope assembly U. Proposed U for walls, roof, windows, doors is the area-weighted Ekotrope assembly U. Any component without an Ekotrope U keeps the spec lookup. Proposed wall U 0.060 is the area-weighted Ekotrope assembly U (0.060). The v1.1 wood-framed-wall exception is the Reference U in this table (0.089), not a replacement for a better Ekotrope U.

Assembly	Proposed spec
Walls	Existing brick walls (stories 1-4): closed-cell spray foam filling the 2x6 cavity, against the existing wood sheathing. The foam is the air barrier and the vapor retarder. New walls (stories 5-6): ≥ R-21 cavity insulation (2x6 @ 16" o.c.), no continuous insulation. Class II vapor retarder on the drywall. Air barrier on the sheathing.
Roof	Sealed attic: ≥ R-30 continuous insulation.
Windows	Double pane, U ≤ 0.30 / SHGC 0.30-0.40.
Doors	Opaque door, U ≤ 0.20 (R-5.0).
Slab	N/A

Envelope Takeoffs

Building	Opaque walls (sf)	Roof (sf)	Windows (sf)
43	23,229	5,928	4,134

Component UA

Component	Quantity	Proposed U or F	Proposed UA	Reference U or F	Reference UA
Opaque exterior walls	23,229 sf	0.060	1,388	0.089	2,067
Roof / ceiling	5,928 sf	0.030	178	0.021	124
Windows & glass doors	4,134 sf	0.300	1,240	0.270	1,116

Total UA

Building	Proposed UA	Reference UA	% of reference	Result
43	2,806	3,308	84.8%	PASS
Site total	2,806	3,308	84.8%	PASS

Recommended Design - Units

Item	Detailed Specifications
Exterior Walls	Existing brick walls (stories 1-4): R-21 closed-cell spray foam against the existing wood sheathing. The foam is the air barrier and the vapor retarder. New walls (stories 5-6): ≥ R-21 cavity insulation (2x6 @ 16" o.c.), no continuous insulation. Class II vapor retarder on the drywall. Air barrier on the sheathing.
Below Grade Walls	N/A
Corridor Walls	N/A
Slab	N/A
Floor Over Unconditioned Space	N/A
Floor Over Garage	N/A
Floor Over Podium	N/A
Rim Joists	Stories 1-4: R-21 closed-cell spray foam at the rim band, tight to the sheathing. The foam is the air barrier. Stories 5-6: ≥ R-21 rim/band insulation at floor transitions. Air barrier on the sheathing.
Roof	Sealed attic: ≥ R-30 continuous insulation.
Windows & Glass Doors	Double pane, U ≤ 0.30 / SHGC 0.30-0.40. (Product Rec).
Doors	Opaque door, U ≤ 0.20 (R-5.0).
Air Sealing	≤ 0.30 CFM50 per sqft of enclosure (compartmentalization); tested. (Air Sealing Protocol)
HVAC	Ducted air-source heat pump; SEER2 ≥ 16; HSPF2 ≥ 8.5. See HVAC Design Loads. (Product Rec).
Ductwork	Supply and return ducts in conditioned space insulated to code minimum.
Duct Sealing	≤ greater of 80 CFM25 or 8 CFM25 per 100 sqft of conditioned floor area; tested at final. (Duct Sealing Protocol)
HVAC Grading	Fan Flow Test: Grade II Watt Draw Test: Grade II Refrigerant Charge: Grade I (weigh-in method) HVAC installer must provide photo of the digital refrigerant scale showing the amount charged, with the tank on the scale and hoses connected to the outdoor unit, along with a photo of the outdoor unit's data plate. If the non-invasive procedure in ANSI / RESNET / ACCA 310 is not permitted to be used during the final inspection of a unit (i.e., due to the equipment type or to outdoor air temperatures that do not meet the requirements of the non-invasive method), then the unit is permitted to be certified with a default refrigerant charge designation of Grade III. Note that in these circumstances, the weigh-in method procedure in ANSI / RESNET / ACCA 310 may still be used to pursue a Grade I designation.
Mechanical Ventilation	In-unit ERV (Product Rec). 2-bedroom: 90 CFM, ≥ 71% ASRE 3-bedroom: 90 CFM, ≥ 71% ASRE
Local Mechanical Exhaust	Bathroom(s): at least 50 CFM intermittent and up to 3.0 sones, or at least 20 CFM continuous and up to 2.0 sones. Kitchen(s): at least 100 CFM intermittent and up to 3.0 sones, or continuous at 5 ACH. Both: exhaust directly outdoors with ENERGY STAR certified fans. A balanced ERV or HRV serving the space may satisfy this requirement.
Thermostats	Programmable thermostat.
DHW	Electric resistance storage water heater; UEF ≥ 0.92; 50 gal. (Product Rec).
DHW Piping	Supply piping insulated to ≥ R-3.
Water Fixtures	WaterSense certified (Lavatory ≤ 1.2 GPM; Shower ≤ 2.0 GPM; Kitchen ≤ 2.2 GPM).
Refrigerator	≤ 650 kWh/yr; electric. (Product Rec).
Dishwasher	≤ 269 kWh/yr; electric. (Product Rec).
Clothes Washer	IMEF ≥ 2.06; IWF ≤ 4.2; ≤ 152 kWh/yr; electric. (Product Rec).
Clothes Dryer	Standard electric dryer; vented; CEF ≥ 3.93. (Product Rec).
Stove / Oven	Electric range. (Product Rec).
Lighting	≥ 100% high-efficacy (LED).
Solar Ready	A solar system will be installed, so solar-ready requirements are exempt.
EV Ready	20% of parking spaces EV-ready. 40-amp dedicated branch circuit, or a larger branch circuit with automatic load management. Wiring suitable for 6.6 kW or higher Level II EVSE, run to within 6 feet of the space. One Level II space may be replaced by three Level I spaces wired for 20-amp, 120-volt EVSE. 225 CMR 23 C405.13 and Table C405.13
HPWH Ready	N/A
Paperwork & Modeling	ENERGY STAR energy model to the target (per-unit HERS or whole-building ASHRAE path), the ENERGY STAR design-review checklist and multifamily workbook, and an HVAC design report.
Testing & Verification	ENERGY STAR field verification: pre-drywall and final inspections, unit air-tightness (blower door), duct-leakage, ventilation and exhaust airflow, and HVAC functional testing.

Recommended Design - Common Areas

Item	Common Areas (Residential Building)
Exterior Walls	Existing brick walls (stories 1-4): R-21 closed-cell spray foam against the existing wood sheathing. The foam is the air barrier and the vapor retarder. New walls (stories 5-6): ≥ R-21 cavity insulation (2x6 @ 16" o.c.), no continuous insulation. Class II vapor retarder on the drywall. Air barrier on the sheathing.
Below Grade Walls	N/A
Corridor Walls	N/A
Slab	N/A
Floor Over Unconditioned Space	N/A
Floor Over Garage	N/A
Floor Over Podium	N/A
Rim Joists	Stories 1-4: R-21 closed-cell spray foam at the rim band, tight to the sheathing. The foam is the air barrier. Stories 5-6: ≥ R-21 rim/band insulation at floor transitions. Air barrier on the sheathing.
Roof	Sealed attic: ≥ R-30 continuous insulation.
Windows & Glass Doors	Fixed U ≤ 0.34. Operable U ≤ 0.43. SHGC ≤ 0.40. ENERGY STAR MFNC Multifamily Reference Design, common-space windows, climate zone 5.
Doors	Glazed entrance U ≤ 0.60. ENERGY STAR MFNC Multifamily Reference Design, common-space glazed entrance doors, climate zone 5.
Air Sealing	Continuous air barrier for these spaces. Hallways, and enclosed common spaces not greater than 1,500 sqft, verified by inspection. 225 CMR 23 C402.5.2.2
HVAC	Ducted split heat pump: HSPF2 7.8 / SEER2 15.2. Ductless heat pump: HSPF2 8.2 / SEER2 16. Packaged heat pump: HSPF2 7.7 / SEER2 15.2. Room air conditioners: ENERGY STAR certified. Electric resistance heat, where used, is not more than 12 kBtuh per enclosed space and has automatic thermostatic controls. ENERGY STAR MFNC National Program Requirements, Exhibit 1, Tables 1 and 2.
Ductwork	Ducts and air handlers serving these spaces are in conditioned space. A duct outside conditioned space is insulated to at least R-6. ENERGY STAR MFNC Exhibit 1; HVAC Design Supplement for Common Spaces, Item 5.3.
Duct Sealing	Supply, return, and exhaust ducts and plenums serving these spaces are sealed at transverse joints, longitudinal seams, and duct wall penetrations. ENERGY STAR MFNC HVAC Design Supplement for Common Spaces, Item 5.4.
HVAC Grading	N/A
Mechanical Ventilation	Outdoor air to the community space and the hallways, at the ASHRAE 62.1 Section 6 rate for that space. The design rate is not more than 50 percent above the ASHRAE 62.1-2013 minimum. The system runs automatically. ENERGY STAR MFNC HVAC Design Supplement for Common Spaces, Items 2.1 and 2.12.
Local Mechanical Exhaust	N/A
Thermostats	Programmable thermostat. ENERGY STAR MFNC Multifamily Reference Design, Exhibit 1.
DHW	electric tank or instant hot water heater, UEF ≥ 0.93 ENERGY STAR MFNC Multifamily Reference Design, common-space electric water heating.
DHW Piping	N/A
Water Fixtures	WaterSense bathroom faucets, aerators, and showerheads. ENERGY STAR MFNC Multifamily Reference Design.
Refrigerator	N/A
Dishwasher	N/A
Clothes Washer	N/A
Clothes Dryer	N/A
Stove / Oven	N/A
Lighting	100% LED. Community space 0.59 W/sqft. Hallways 0.41 W/sqft. Basement storage 0.38 W/sqft. Maintenance and electrical rooms 0.43 W/sqft. IECC 2021 Table C405.3.2(2)
Lighting Controls	Occupant sensors in the community space, hallways, and basement storage. Hallway sensors reduce lighting to not more than 50 percent of full power within 20 minutes after the corridor is empty. Interior exit stairways are exempt from lighting controls. Daylight-responsive controls where general lighting exceeds 100 W in a primary sidelit zone, 300 W in a sidelit zone, or 100 W in a toplit zone. IECC 2021 C405.2.1.4 225 CMR 23 C405.2.4
Solar Ready	A solar system will be installed, so solar-ready requirements are exempt.
EV Ready	20% of parking spaces EV-ready. 40-amp dedicated branch circuit, or a larger branch circuit with automatic load management. Wiring suitable for 6.6 kW or higher Level II EVSE, run to within 6 feet of the space. One Level II space may be replaced by three Level I spaces wired for 20-amp, 120-volt EVSE. 225 CMR 23 C405.13 and Table C405.13
HPWH Ready	N/A
Electric Readiness	N/A
Vestibules	N/A
Efficiency Credits	N/A
Paperwork & Modeling	HERS index certificate at permit and at certificate of occupancy. ENERGY STAR Multifamily New Construction workbook, design-review checklist, field checklist, and common-space HVAC supplement. EV-ready space locations, wiring diagram, and load calculations. 225 CMR 23 C407.4.2 and C405.13.2
Testing & Verification	Hallways and enclosed common spaces not greater than 1,500 sqft verified by inspection of the continuous air barrier. Common-space outdoor airflow measured. HVAC functional testing of common-space and central systems. Lighting controls tested. 225 CMR 23 C402.5.2.2 and C408 ENERGY STAR MFNC HVAC Functional Testing Checklist

Assembly Moisture Check

This section shows which air and vapor barriers are needed, and why.

Inputs

Item	Value
Climate zone	5A
Indoor air	70 F, 35% RH
Dewpoint of that indoor air	41 F
Outdoor air	9 F
Code	2021 IBC Section 1404.3, Table 1404.3(2)

New walls (stories 5-6)

#	Layer (inside to outside)	R	Running R	Temp	Dewpoint target	Vs dewpoint
1	Drywall	1.13	1.13	67.0 F	41 F	OK
2	Class II vapor retarder	0.00	1.13	67.0 F	41 F	OK
3	R-21 cavity insulation with 2x6 wood studs	21.00	22.13	11.1 F	41 F	First below dewpoint
4	Wood sheathing	0.62	22.75	9.5 F	41 F	Below dewpoint
5	Air barrier	0.00	22.75	9.5 F	41 F	Below dewpoint
6	Siding / cladding	0.17	22.92	9.0 F	41 F	Below dewpoint

Conclusion: This is the new wall on stories 5 and 6. Layer 3 is the first row below dewpoint. It is the cold plane we protect. Indoor moisture can turn to water if it gets there, and can eventually cause mold. It can get there two ways. It gets there through the drywall, which is why the vapor retarder is on the inside of the wall. It also gets there through holes (outlets, gaps, plates), which is why the air barrier is on the sheathing. Same at the rim.

Existing brick walls (stories 1-4)

#	Layer (inside to outside)	R	Running R	Temp	Dewpoint target	Vs dewpoint
1	Drywall	1.13	1.13	67.0 F	41 F	OK
2	R-21 closed-cell spray foam	21.00	22.13	11.8 F	41 F	First below dewpoint
3	Wood sheathing	0.62	22.75	10.2 F	41 F	Below dewpoint
4	Existing brick	0.44	23.19	9.0 F	41 F	Below dewpoint

Conclusion: Layer 2 is the first row below dewpoint. It is the cold plane we protect. Indoor moisture can turn to water if it gets there, and can eventually cause mold. An air barrier cannot be installed between the brick and the wood sheathing. R-21 closed-cell spray foam, tight to the sheathing, is the air barrier and the vapor retarder. It does not fill the rest of the 2x6 cavity. Indoor air does not reach the cold sheathing. Same at the rim on stories 1-4.

Roof (sealed attic)

#	Layer (inside to outside)	R	Running R	Temp	Dewpoint target	Vs dewpoint
1	Interior / attic	0.68	0.68	68.7 F	41 F	OK
2	Roof deck	0.62	1.30	67.5 F	41 F	OK
3	Air barrier	0.00	1.30	67.5 F	41 F	OK
4	R-30 continuous insulation	30.00	31.30	9.3 F	41 F	First below dewpoint
5	Roofing	0.17	31.47	9.0 F	41 F	Below dewpoint

Conclusion: Layer 4 is the first row below dewpoint. That plane is outside the deck, in the continuous insulation. The deck stays warm. Indoor moisture can turn to water if it gets to a cold face, and can eventually cause mold. The air barrier is on the deck so room air cannot leak into the insulation.

New walls (stories 5-6) (ELECTRIC)

Existing brick walls (stories 1-4) (ELECTRIC)

Roof (sealed attic) (ELECTRIC)

Rim Joists, stories 5-6 (ELECTRIC)

Path Comparison

This section shows the detailed requirements and incentives for each path we compared, basically showing our work of how we determined the recommended path is the most affordable way of meeting energy code compliance.

Path Comparison - Incentives

CURRENT / ELECTRIC: $36,000 - $90,000

MassSave Multifamily High Rise Program Base Tier ($36,000) (Program Breakdown): You get this rebate for having your building(s) meet energy code. This requires pre-approval via an application to be submitted before construction starts. This rebate comes in the form of a check within 4 months of certification documentation being provided to MassSave, typically this is 4 months after construction is complete.
DOER Alternative Energy Credits ($0 - $54,000) (Program Breakdown): This rebate is received for installing APS eligible air source heat pumps (click here for the list). There is an extensive process to get this incentive. It comes in the form of a check approximately 6-12 months after the heat pumps are installed and fully operational.
- IMPORTANT: Although an estimate is provided, this incentive can vary widely typically between $300-1,500 per heat pump. It's based on expected kWh usage of the system as well as the market value of the alternative energy credits when sold.
- Risks: Massachusetts is rewriting this program right now. The House bill would stop the state from accepting new applications on January 1, 2028, the Senate version leaves heat pumps out of that cutoff, and the two are in conference. The application needs the equipment installed and operating, so a project that will not reach that point before the deadline should treat this as upside rather than a budgeted line.

GAS-HEAT: $0

Path Comparison - Net Cost Summary

Path	Total Cost $/sf	Total Incentives $/sf	Net $/sf	OpEx Factor
ELECTRIC	$50.38	$1.08	$49.82	1.01
GAS-HEAT	$49.97	$0.00	$50.58	1.01
CURRENT	$53.26	$1.08	$52.89	1.01

Path Comparison - Envelope

Item	Path	Detailed Specifications	Cost $/sf	Incentive $/sf	Net $/sf	OpEx
Exterior Walls	CURRENT	Existing brick walls (stories 1-4): R-21 closed-cell spray foam against the existing wood sheathing. The foam is the air barrier and the vapor retarder. New walls (stories 5-6): ≥ R-21 cavity insulation (2x6 @ 16" o.c.), no continuous insulation. Class II vapor retarder on the drywall. Air barrier on the sheathing.	$5.14	$0.00	$5.14	0.95
	ELECTRIC	Existing brick walls (stories 1-4): R-21 closed-cell spray foam against the existing wood sheathing. The foam is the air barrier and the vapor retarder. New walls (stories 5-6): ≥ R-21 cavity insulation (2x6 @ 16" o.c.), no continuous insulation. Class II vapor retarder on the drywall. Air barrier on the sheathing.	$5.14	$0.00	$5.14	0.95
	GAS-HEAT	Existing brick walls (stories 1-4): R-21 closed-cell spray foam against the existing wood sheathing. The foam is the air barrier and the vapor retarder. New walls (stories 5-6): ≥ R-21 cavity insulation (2x6 @ 16" o.c.), no continuous insulation. Class II vapor retarder on the drywall. Air barrier on the sheathing.	$5.14	$0.00	$5.14	0.95
Below Grade Walls	CURRENT	N/A	$0.00	$0.00	$0.00	1.00
	ELECTRIC	N/A	$0.00	$0.00	$0.00	1.00
	GAS-HEAT	N/A	$0.00	$0.00	$0.00	1.00
Corridor Walls	CURRENT	N/A	$0.00	$0.00	$0.00	1.00
	ELECTRIC	N/A	$0.00	$0.00	$0.00	1.00
	GAS-HEAT	N/A	$0.00	$0.00	$0.00	1.00
Slab	CURRENT	N/A	$0.00	$0.00	$0.00	1.00
	ELECTRIC	N/A	$0.00	$0.00	$0.00	1.00
	GAS-HEAT	N/A	$0.00	$0.00	$0.00	1.00
Floor Over Unconditioned Space	CURRENT	N/A	$0.00	$0.00	$0.00	1.00
	ELECTRIC	N/A	$0.00	$0.00	$0.00	1.00
	GAS-HEAT	N/A	$0.00	$0.00	$0.00	1.00
Floor Over Garage	CURRENT	N/A	$0.00	$0.00	$0.00	1.00
	ELECTRIC	N/A	$0.00	$0.00	$0.00	1.00
	GAS-HEAT	N/A	$0.00	$0.00	$0.00	1.00
Floor Over Podium	CURRENT	N/A	$0.00	$0.00	$0.00	1.00
	ELECTRIC	N/A	$0.00	$0.00	$0.00	1.00
	GAS-HEAT	N/A	$0.00	$0.00	$0.00	1.00
Rim Joists	CURRENT	Stories 1-4: R-21 closed-cell spray foam at the rim band, tight to the sheathing. The foam is the air barrier. Stories 5-6: ≥ R-21 rim/band insulation at floor transitions. Air barrier on the sheathing.	$0.20	$0.00	$0.20	0.95
	ELECTRIC	Stories 1-4: R-21 closed-cell spray foam at the rim band, tight to the sheathing. The foam is the air barrier. Stories 5-6: ≥ R-21 rim/band insulation at floor transitions. Air barrier on the sheathing.	$0.20	$0.00	$0.20	0.95
	GAS-HEAT	Stories 1-4: R-21 closed-cell spray foam at the rim band, tight to the sheathing. The foam is the air barrier. Stories 5-6: ≥ R-21 rim/band insulation at floor transitions. Air barrier on the sheathing.	$0.20	$0.00	$0.20	0.95
Roof	CURRENT	Sealed attic: ≥ R-30 continuous insulation.	$1.21	$0.00	$1.21	1.10
	ELECTRIC	Sealed attic: ≥ R-30 continuous insulation.	$1.21	$0.00	$1.21	1.10
	GAS-HEAT	Sealed attic: ≥ R-30 continuous insulation.	$1.21	$0.00	$1.21	1.10
Windows & Glass Doors	CURRENT	Double pane, U ≤ 0.30 / SHGC 0.30-0.40.	$5.89	$0.00	$5.89	1.00
	ELECTRIC	Double pane, U ≤ 0.30 / SHGC 0.30-0.40.	$5.89	$0.00	$5.89	1.00
	GAS-HEAT	Double pane, U ≤ 0.30 / SHGC 0.30-0.40.	$5.89	$0.00	$5.89	1.00
Doors	CURRENT	Opaque door, U ≤ 0.20 (R-5.0).	$0.35	$0.00	$0.35	0.95
	ELECTRIC	Opaque door, U ≤ 0.20 (R-5.0).	$0.35	$0.00	$0.35	0.95
	GAS-HEAT	Opaque door, U ≤ 0.20 (R-5.0).	$0.35	$0.00	$0.35	0.95
Air Sealing	CURRENT	≤ 0.30 CFM50 per sqft of enclosure (compartmentalization); tested.	$1.20	$0.00	$1.20	0.95
	ELECTRIC	≤ 0.30 CFM50 per sqft of enclosure (compartmentalization); tested.	$1.20	$0.00	$1.20	0.95
	GAS-HEAT	≤ 0.30 CFM50 per sqft of enclosure (compartmentalization); tested.	$1.20	$0.00	$1.20	0.95

Path Comparison - Mechanical

Item	Path	Detailed Specifications	Cost $/sf	Incentive $/sf	Net $/sf	OpEx
HVAC	CURRENT	Ducted air-source heat pump; SEER2 ≥ 16; HSPF2 ≥ 8.5. See HVAC Design Loads.	$14.26	$0.00	$14.26	1.15
	ELECTRIC	Ducted air-source heat pump; SEER2 ≥ 16; HSPF2 ≥ 8.5. See HVAC Design Loads.	$14.26	$0.00	$14.26	1.15
	GAS-HEAT	Natural gas furnace; AFUE ≥ 85; cooling by a separate system, cooling only; SEER2 ≥ 16. See HVAC Design Loads.	$10.97	$0.00	$10.97	1.10
Ductwork	CURRENT	Supply and return ducts in conditioned space insulated to code minimum.	$5.21	$0.00	$5.21	1.00
	ELECTRIC	Supply and return ducts in conditioned space insulated to code minimum.	$5.21	$0.00	$5.21	1.00
	GAS-HEAT	Supply and return ducts in conditioned space insulated to code minimum.	$5.21	$0.00	$5.21	1.00
Duct Sealing	CURRENT	≤ greater of 80 CFM25 or 8 CFM25 per 100 sqft of conditioned floor area; tested at final.	$0.89	$0.00	$0.89	1.00
	ELECTRIC	≤ greater of 80 CFM25 or 8 CFM25 per 100 sqft of conditioned floor area; tested at final.	$0.89	$0.00	$0.89	1.00
	GAS-HEAT	≤ greater of 80 CFM25 or 8 CFM25 per 100 sqft of conditioned floor area; tested at final.	$0.89	$0.00	$0.89	1.00
HVAC Grading	CURRENT	Fan Flow Test: Grade II Watt Draw Test: Grade II Refrigerant Charge: Grade I (weigh-in method) HVAC installer must provide photo of the digital refrigerant scale showing the amount charged, with the tank on the scale and hoses connected to the outdoor unit, along with a photo of the outdoor unit's data plate. If the non-invasive procedure in ANSI / RESNET / ACCA 310 is not permitted to be used during the final inspection of a unit (i.e., due to the equipment type or to outdoor air temperatures that do not meet the requirements of the non-invasive method), then the unit is permitted to be certified with a default refrigerant charge designation of Grade III. Note that in these circumstances, the weigh-in method procedure in ANSI / RESNET / ACCA 310 may still be used to pursue a Grade I designation.	$0.00	$0.00	$0.00	1.00
	ELECTRIC	Fan Flow Test: Grade II Watt Draw Test: Grade II Refrigerant Charge: Grade I (weigh-in method) HVAC installer must provide photo of the digital refrigerant scale showing the amount charged, with the tank on the scale and hoses connected to the outdoor unit, along with a photo of the outdoor unit's data plate. If the non-invasive procedure in ANSI / RESNET / ACCA 310 is not permitted to be used during the final inspection of a unit (i.e., due to the equipment type or to outdoor air temperatures that do not meet the requirements of the non-invasive method), then the unit is permitted to be certified with a default refrigerant charge designation of Grade III. Note that in these circumstances, the weigh-in method procedure in ANSI / RESNET / ACCA 310 may still be used to pursue a Grade I designation.	$0.00	$0.00	$0.00	1.00
	GAS-HEAT	Fan Flow Test: Grade II Watt Draw Test: Grade II Refrigerant Charge: Grade I (weigh-in method) HVAC installer must provide photo of the digital refrigerant scale showing the amount charged, with the tank on the scale and hoses connected to the outdoor unit, along with a photo of the outdoor unit's data plate. If the non-invasive procedure in ANSI / RESNET / ACCA 310 is not permitted to be used during the final inspection of a unit (i.e., due to the equipment type or to outdoor air temperatures that do not meet the requirements of the non-invasive method), then the unit is permitted to be certified with a default refrigerant charge designation of Grade III. Note that in these circumstances, the weigh-in method procedure in ANSI / RESNET / ACCA 310 may still be used to pursue a Grade I designation.	$0.00	$0.00	$0.00	1.00
Mechanical Ventilation	CURRENT	In-unit ERV 2-bedroom: 90 CFM, ≥ 71% ASRE 3-bedroom: 90 CFM, ≥ 71% ASRE	$1.62	$0.00	$1.62	1.20
	ELECTRIC	In-unit ERV 2-bedroom: 90 CFM, ≥ 71% ASRE 3-bedroom: 90 CFM, ≥ 71% ASRE	$1.62	$0.00	$1.62	1.20
	GAS-HEAT	In-unit ERV 2-bedroom: 90 CFM, ≥ 71% ASRE 3-bedroom: 90 CFM, ≥ 71% ASRE	$1.62	$0.00	$1.62	1.20
Local Mechanical Exhaust	CURRENT	Bathroom(s): at least 50 CFM intermittent and up to 3.0 sones, or at least 20 CFM continuous and up to 2.0 sones. Kitchen(s): at least 100 CFM intermittent and up to 3.0 sones, or continuous at 5 ACH. Both: exhaust directly outdoors with ENERGY STAR certified fans. A balanced ERV or HRV serving the space may satisfy this requirement.	$1.27	$0.00	$1.27	1.05
	ELECTRIC	Bathroom(s): at least 50 CFM intermittent and up to 3.0 sones, or at least 20 CFM continuous and up to 2.0 sones. Kitchen(s): at least 100 CFM intermittent and up to 3.0 sones, or continuous at 5 ACH. Both: exhaust directly outdoors with ENERGY STAR certified fans. A balanced ERV or HRV serving the space may satisfy this requirement.	$1.27	$0.00	$1.27	1.05
	GAS-HEAT	Bathroom(s): at least 50 CFM intermittent and up to 3.0 sones, or at least 20 CFM continuous and up to 2.0 sones. Kitchen(s): at least 100 CFM intermittent and up to 3.0 sones, or continuous at 5 ACH. Both: exhaust directly outdoors with ENERGY STAR certified fans. A balanced ERV or HRV serving the space may satisfy this requirement.	$1.27	$0.00	$1.27	1.05
Thermostats	CURRENT	Programmable thermostat.	$0.15	$0.00	$0.15	1.05
	ELECTRIC	Programmable thermostat.	$0.15	$0.00	$0.15	1.05
	GAS-HEAT	Programmable thermostat.	$0.15	$0.00	$0.15	1.05

Path Comparison - Plumbing & Appliances

Item	Path	Detailed Specifications	Cost $/sf	Incentive $/sf	Net $/sf	OpEx
DHW	CURRENT	Centralized gas water heating system with two 100 gallon tanks and a temperature-controlled recirculating system; ≥ 0.80 energy factor.	$3.96	$0.00	$3.96	1.00
	ELECTRIC	Electric resistance storage water heater; UEF ≥ 0.92; 50 gal.	$1.08	$0.00	$1.08	0.90
	GAS-HEAT	Centralized gas water heating system with two 100 gallon tanks and a temperature-controlled recirculating system; ≥ 0.85 energy factor.	$3.96	$0.00	$3.96	1.00
DHW Piping	CURRENT	Supply piping insulated to ≥ R-3.	$0.89	$0.00	$0.89	0.95
	ELECTRIC	Supply piping insulated to ≥ R-3.	$0.89	$0.00	$0.89	0.95
	GAS-HEAT	Supply piping insulated to ≥ R-3.	$0.89	$0.00	$0.89	0.95
Water Fixtures	CURRENT	WaterSense certified (Lavatory ≤ 1.2 GPM; Shower ≤ 2.0 GPM; Kitchen ≤ 2.2 GPM).	$2.23	$0.00	$2.23	1.00
	ELECTRIC	WaterSense certified (Lavatory ≤ 1.2 GPM; Shower ≤ 2.0 GPM; Kitchen ≤ 2.2 GPM).	$2.23	$0.00	$2.23	1.00
	GAS-HEAT	WaterSense certified (Lavatory ≤ 1.2 GPM; Shower ≤ 2.0 GPM; Kitchen ≤ 2.2 GPM).	$2.23	$0.00	$2.23	1.00
Refrigerator	CURRENT	≤ 650 kWh/yr; electric.	$0.92	$0.00	$0.92	1.10
	ELECTRIC	≤ 650 kWh/yr; electric.	$0.92	$0.00	$0.92	1.10
	GAS-HEAT	≤ 650 kWh/yr; electric.	$0.92	$0.00	$0.92	1.10
Dishwasher	CURRENT	≤ 269 kWh/yr; electric.	$0.52	$0.00	$0.52	1.10
	ELECTRIC	≤ 269 kWh/yr; electric.	$0.52	$0.00	$0.52	1.10
	GAS-HEAT	≤ 269 kWh/yr; electric.	$0.52	$0.00	$0.52	1.10
Clothes Washer	CURRENT	IMEF ≥ 2.06; IWF ≤ 4.2; ≤ 152 kWh/yr; electric.	$0.60	$0.00	$0.60	1.10
	ELECTRIC	IMEF ≥ 2.06; IWF ≤ 4.2; ≤ 152 kWh/yr; electric.	$0.60	$0.00	$0.60	1.10
	GAS-HEAT	IMEF ≥ 2.06; IWF ≤ 4.2; ≤ 152 kWh/yr; electric.	$0.60	$0.00	$0.60	1.10
Clothes Dryer	CURRENT	Standard electric dryer; vented; CEF ≥ 3.93.	$0.67	$0.00	$0.67	1.00
	ELECTRIC	Standard electric dryer; vented; CEF ≥ 3.93.	$0.67	$0.00	$0.67	1.00
	GAS-HEAT	Standard electric dryer; vented; CEF ≥ 3.93.	$0.67	$0.00	$0.67	1.00
Stove / Oven	CURRENT	Electric range.	$0.71	$0.00	$0.71	1.00
	ELECTRIC	Electric range.	$0.71	$0.00	$0.71	1.00
	GAS-HEAT	Electric range.	$0.71	$0.00	$0.71	1.00

Path Comparison - Electrical

Item	Path	Detailed Specifications	Cost $/sf	Incentive $/sf	Net $/sf	OpEx
Lighting	CURRENT	≥ 100% high-efficacy (LED).	$4.00	$0.00	$4.00	0.85
	ELECTRIC	≥ 100% high-efficacy (LED).	$4.00	$0.00	$4.00	0.85
	GAS-HEAT	≥ 100% high-efficacy (LED).	$4.00	$0.00	$4.00	0.85
Solar Ready	CURRENT	A solar system will be installed, so solar-ready requirements are exempt.	$0.00	$0.00	$0.00	1.00
	ELECTRIC	A solar system will be installed, so solar-ready requirements are exempt.	$0.00	$0.00	$0.00	1.00
	GAS-HEAT	A solar system will be installed, so solar-ready requirements are exempt.	$0.00	$0.00	$0.00	1.00
EV Ready	CURRENT	20% of parking spaces EV-ready. 40-amp dedicated branch circuit, or a larger branch circuit with automatic load management. Wiring suitable for 6.6 kW or higher Level II EVSE, run to within 6 feet of the space. One Level II space may be replaced by three Level I spaces wired for 20-amp, 120-volt EVSE. 225 CMR 23 C405.13 and Table C405.13	$0.46	$0.00	$0.46	1.00
	ELECTRIC	20% of parking spaces EV-ready. 40-amp dedicated branch circuit, or a larger branch circuit with automatic load management. Wiring suitable for 6.6 kW or higher Level II EVSE, run to within 6 feet of the space. One Level II space may be replaced by three Level I spaces wired for 20-amp, 120-volt EVSE. 225 CMR 23 C405.13 and Table C405.13	$0.46	$0.00	$0.46	1.00
	GAS-HEAT	20% of parking spaces EV-ready. 40-amp dedicated branch circuit, or a larger branch circuit with automatic load management. Wiring suitable for 6.6 kW or higher Level II EVSE, run to within 6 feet of the space. One Level II space may be replaced by three Level I spaces wired for 20-amp, 120-volt EVSE. 225 CMR 23 C405.13 and Table C405.13	$0.46	$0.00	$0.46	1.00
HPWH Ready	CURRENT	N/A	$0.00	$0.00	$0.00	1.00
	ELECTRIC	N/A	$0.00	$0.00	$0.00	1.00
	GAS-HEAT	N/A	$0.00	$0.00	$0.00	1.00

Path Comparison - Soft Costs & Whole-Building Incentives

Item	Path	Detailed Specifications	Cost $/sf	Incentive $/sf	Net $/sf	OpEx
Paperwork & Modeling	CURRENT	ENERGY STAR energy model to the target (per-unit HERS or whole-building ASHRAE path), the ENERGY STAR design-review checklist and multifamily workbook, and an HVAC design report.	$0.27	$1.08	-$0.81	1.00
	ELECTRIC	ENERGY STAR energy model to the target (per-unit HERS or whole-building ASHRAE path), the ENERGY STAR design-review checklist and multifamily workbook, and an HVAC design report.	$0.27	$1.08	-$0.81	1.00
	GAS-HEAT	ENERGY STAR energy model to the target (per-unit HERS or whole-building ASHRAE path), the ENERGY STAR design-review checklist and multifamily workbook, and an HVAC design report.	$0.27	$0.00	$0.27	1.00
Testing & Verification	CURRENT	ENERGY STAR field verification: pre-drywall and final inspections, unit air-tightness (blower door), duct-leakage, ventilation and exhaust airflow, and HVAC functional testing.	$0.64	$0.00	$0.64	1.00
	ELECTRIC	ENERGY STAR field verification: pre-drywall and final inspections, unit air-tightness (blower door), duct-leakage, ventilation and exhaust airflow, and HVAC functional testing.	$0.64	$0.00	$0.64	1.00
	GAS-HEAT	ENERGY STAR field verification: pre-drywall and final inspections, unit air-tightness (blower door), duct-leakage, ventilation and exhaust airflow, and HVAC functional testing.	$0.64	$0.00	$0.64	1.00

Additional Design Considerations Not Represented In This Study

Smaller Heat Pumps on the CURRENT and ELECTRIC Units: A smaller heat pump sized to the cooling load was not used on the CURRENT and ELECTRIC two- and three-bedroom units, because heating set the size. Both paths keep single-stage ducted heat pumps at 24 kBtuh on the two-bedroom, 183.2 percent of the 13.1 kBtuh ELECTRIC cooling load and 184.6 percent of the 13.0 kBtuh CURRENT load, and 30 kBtuh on the three-bedroom, 164.8 percent of the 18.2 kBtuh load. ENERGY STAR MFNC holds a single-stage unit to 130 percent of the cooling load, or to 20 kBtuh when the cooling load is 15 kBtuh or less, and both sizes sit above that limit. The same units cover the design heating load, 21.1 kBtuh against 19.6 kBtuh on ELECTRIC and 19.3 kBtuh on CURRENT for the two-bedroom, and 26.4 kBtuh against 22.3 kBtuh for the three-bedroom. A two-stage or variable-speed unit at the same 24 kBtuh may go to 25 kBtuh when the cooling load is 18 kBtuh or less, which would clear the two-bedroom limit, and that equipment is not in this study. The three-bedroom cooling load is 18.2 kBtuh, so that allowance does not apply, and 30 kBtuh is also above the 160 percent variable-speed ceiling. GAS-HEAT passes both the cooling and heating sizing gates with a separate 12 kBtuh and 18 kBtuh cooling system.