CS85 Energy Code Feasibility Study in Worcester, Massachusetts

Energy code feasibility study for a 74-unit high-rise in Massachusetts. Compares multiple design paths. Recommended: HERS (All-Electric). View full study.

Study Type: Energy Code Feasibility Study
State: Massachusetts
Units: 74
Building Type: high-rise
Fuel Type: All-Electric
Recommended Path: HERS (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

Worcester, MA 01609
1 Building | 74 Units | 48,565 SF Conditioned
New Construction | 5-story high-rise multifamily (x1)
All-Electric | 2021 IECC with MA Amendments (Specialized Opt-In Code) | HERS ≤ 45 OR PHIUS Core 2024 | ENERGY STAR MFNC v1.2 | Indoor airPLUS v2 (optional) | DOE Efficient New Homes (optional)

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

Both paths are modeled to comply, the HERS path on a lean margin and the PHIUS path as a passing Passive House design. The dollars below are energy-related costs, not the whole building budget. The study recommends the less expensive HERS path even where Worcester's Specialized Opt-In requires the Passive House path for this five-story building.

HERS (All-Electric): Recommended

This is the least expensive path in energy-related cost, at approximately $65.65/sf net, and it is the more builder-friendly of the two, with the air barrier on the sheathing. It stays fully electric, which aligns with the direction Massachusetts energy code is heading, and it gives up about $2,000 per unit in energy-related incentives by taking the ENERGY STAR high-rise incentive instead of the Passive House tier. For this project, this is the right choice.

PHIUS (All-Electric): Not Recommended

At approximately $67.99/sf net in energy-related cost, this path costs about $2/sf more than the HERS path after incentives and about $264,000 more in energy-related cost before incentives, so it remains the more expensive design. The premium is mostly windows, walls with continuous insulation, and whole-building air sealing, which also makes it the more labor-intensive build. The only reason to choose it is that Worcester's Specialized Opt-In requires the Passive House path for this five-story building.

What Changes Between Paths

Item	PHIUS	HERS (Recommended)
Exterior Walls	≥ R-21 cavity insulation (2x6 @ 16" o.c.) with ≥ R-12.6 continuous exterior insulation.	≥ R-23 cavity insulation (2x6 @ 16" o.c.), no continuous insulation.
Slab	≥ R-10 perimeter insulation, 2 ft deep, at the interior face of the slab edge, plus ≥ R-10 under-slab insulation; provides a full thermal break.	≥ R-15 perimeter insulation, 2 ft deep, at the interior face of the slab edge, plus ≥ R-15 under-slab insulation, 2 ft wide; provides a full thermal break.
Rim Joists	≥ R-34 rim/band insulation at floor transitions.	≥ R-23 rim/band insulation at floor transitions.
Windows & Glass Doors	High performance, U ≤ 0.18 / SHGC ≤ 0.18.	High performance, U ≤ 0.25 / SHGC ≤ 0.25.
Air Sealing	Whole-building blower door test at or below 0.06 CFM50 per sq ft of gross enclosure, and unit compartmentalization at ≤ 0.30 CFM50 per sq ft of shell area; tested.	≤ 0.30 CFM50 per sq ft of shell area; tested.
Cost $/sf	$72.59	$67.15
Incentive $/sf	$5.71	$2.67
Net $/sf	$67.99	$65.65

Code Path

HERS: Worcester is a Specialized Opt-In Code town. The buildings are 5-story Group R under 225 CMR 23, and the dwelling units comply by per-unit HERS under section C407.4. The all-electric Specialized Opt-In ceiling is HERS ≤ 45 (Table C407.4, new construction column). Section C407.4.1 requires the building to meet ENERGY STAR Multifamily New Construction.
PHIUS Core 2024: Worcester Specialized Opt-In Code. The building is five stories and 48,565 sf of R-2 multifamily, so 225 CMR 23 governs and Appendix CC Table CC101.2 requires the Passive House path of section C407.3 (the C401.2.1 prescriptive and performance paths are N/A for R-2 over 12,000 sf). The all-electric building complies through section C401.2.2 item 1, Passive House Compliance, which requires sections C401.3, C402.3, C405, C407.3 and C408, by certifying to Phius CORE 2024 (section C407.3.1). Phius design certification and final certification replace the HERS route of section C407.4, so there is no HERS ceiling.

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, 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).
PHIUS Core 2024: With the building permit application, per 225 CMR 23 section C407.3.2.1 item 1: the Phius Design Certification Letter, issued once Phius design review of the WUFI Passive model, drawings and specifications is complete (Phius 2024 Certification Guidebook sections 1.1.4 and 1.1.5). Where that letter is not yet issued: the Passive House Verification report showing Phius CORE 2024 compliance, a statement from the CPHC that the report matches the permit plans, and evidence of Phius project registration. The construction documents show the EV-ready spaces (C405.13.2) and the solar-ready zone (Appendix CB) per section C103.2 items 14 and 15.

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).
PHIUS Core 2024: Before the final certificate of occupancy, per 225 CMR 23 section C407.3.2.1 item 2: the Phius Final Certification Letter (Guidebook sections 1.1.6 and 1.1.7); or the Design Certification Letter with the as-built Passive House Verification report and its blower door and ventilation results, the CPHC hygrothermal statement, the Phius Verifier statement and the Phius workbook of test results. Field verification follows Guidebook section 1.5.2: mid-construction inspections, a final whole-building blower door test at or below 0.06 CFM50 per sq ft of gross enclosure (Table 1.3.3.2.0), dwelling-unit compartmentalization at or below 0.30 CFM50 per sq ft of enclosure, and ventilation airflow testing and balancing. C405.13 EV-ready and Appendix CB solar-ready compliance is verified at the same time (C407.3.2.1 item 2f).

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: $129,500 - $240,500

MassSave Multifamily High Rise Program Energy Star Tier ($129,500) (Program Breakdown): You get this rebate for having your building(s) certified for the Energy Star MFNC v1.2 program. 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 - $111,000) (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

Worcester County, MA · heating -2.0°F/70.0°F · cooling 90.0°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
1-Bedroom	2.3	0.8	0.0	1.4	3.8	2.3	10.6 @ -2°F	10.6 @ -2°F
2-Bedroom	2.8	0.0	3.6	3.5	5.5	3.1	18.5 @ -2°F	18.5 @ -2°F

Design heat gain · components

Unit type	Solar through glazing	Envelope conduction	Internal gains	Infiltration & ventilation	Latent	Total heat gain	Sensible heat ratio
1-Bedroom	1.5	0.9	2.1	1.9	2.8	9.3	0.69
2-Bedroom	2.8	1.6	2.3	2.8	4.1	13.6	0.70

Selection

Unit type	Cooling Capacity	Minimum Heating Capacity
1-Bedroom	8.4 to 20.0 kBtuh rated	≥ 10.6 kBtuh @ -2°F
2-Bedroom	12.2 to 20.0 kBtuh rated	≥ 18.5 kBtuh @ -2°F

ENERGY STAR Total UA

Item	Detail
Climate zone	IECC 5A (2021 IECC map)
Program	ENERGY STAR MFNC National v1.2 Rev. 05
Rule	Design Review Item 2.1 / Fn 11-12; Proposed UA ≤ Reference UA
Code reference	Exhibit 1 Table 1 (2021 IECC CZ); Design Review Item 2.1 / Fn 11-12
Version basis	explicit program key (v1.2)
Note	Code minimum for this permit is v1.1; v1.2 used for explicit program key (v1.2). Confirm certification path matches the incentive or AHJ requirement. Reference wall U is 2021 IECC Table C402.1.4 Group R, wood framed and other (U-0.051 in this zone). v1.2 Table 2, ERI commercial option, uses that column for a 4-story-or-taller building. Footnote 12.i (U-0.064 in Climate Zone 5) applies only when the reference is the 2009 IECC commercial chapter, so it is not used on v1.2. Proposed U for walls, roof, windows, doors is the area-weighted Ekotrope assembly U. Any component without an Ekotrope U keeps the spec lookup. Slab F-factor is 0.45, Charles 2026-10-22.

Assembly	Proposed spec
Walls	≥ R-23 cavity insulation (2x6 @ 16" o.c.), no continuous insulation.
Roof	Sealed attic: ≥ R-30 insulation + ≥ R-30 continuous insulation.
Windows	High performance, U ≤ 0.25 / SHGC ≤ 0.25.
Doors	Opaque door, U ≤ 0.20 (R-5.0).
Slab	≥ R-15 perimeter insulation, 2 ft deep, at the interior face of the slab edge, plus ≥ R-15 under-slab insulation, 2 ft wide; provides a full thermal break.

Envelope Takeoffs

Building	Opaque walls (sf)	Roof (sf)	Windows (sf)	Slab perimeter (lf)
1	26,657	10,430	5,682	1,086

Component UA

Component	Quantity	Proposed U or F	Proposed UA	Reference U or F	Reference UA
Opaque exterior walls	26,657 sf	0.057	1,524	0.051	1,359
Roof / ceiling	10,430 sf	0.017	172	0.024	250
Windows & glass doors	5,682 sf	0.250	1,420	0.270	1,534
Slab edge (F x perimeter)	1,086 lf	0.450	489	0.480	521

Total UA

Building	Proposed UA	Reference UA	% of reference	Result
1	3,606	3,665	98.4%	PASS
Site total	3,606	3,665	98.4%	PASS

Recommended Design - Units

Item	Detailed Specifications
Exterior Walls	≥ R-23 cavity insulation (2x6 @ 16" o.c.), no continuous insulation.
Below Grade Walls	N/A
Corridor Walls	N/A
Slab	≥ R-15 perimeter insulation, 2 ft deep, at the interior face of the slab edge, plus ≥ R-15 under-slab insulation, 2 ft wide; provides a full thermal break.
Floor Over Unconditioned Space	N/A
Floor Over Garage	N/A
Floor Over Podium	N/A
Rim Joists	≥ R-23 rim/band insulation at floor transitions.
Roof	Sealed attic: ≥ R-30 insulation + ≥ R-30 continuous insulation.
Windows & Glass Doors	High performance, U ≤ 0.25 / SHGC ≤ 0.25. (Product Rec).
Doors	Opaque door, U ≤ 0.20 (R-5.0).
Air Sealing	≤ 0.30 CFM50 per sq ft of shell area; tested. (Air Sealing Protocol)
HVAC	Ducted air-source heat pump (as modeled); SEER2 ≥ 17; HSPF2 ≥ 10. 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). 1-bedroom: 75 CFM, ≥ 86% ASRE 2-bedroom: 100 CFM, ≥ 83% ASRE
Local Mechanical Exhaust	The in-unit ERV fulfills local mechanical exhaust with 25 CFM in each bathroom and 50 CFM in the kitchen.
Thermostats	Programmable thermostat (as modeled).
DHW	1-Bedroom: Heat pump water heater (HPWH) (as modeled); UEF ≥ 3.88; 40 gal (Product Rec). 2-Bedroom: Heat pump water heater (HPWH) (as modeled); UEF ≥ 3.88; 50 gal
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	≤ 600 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	Heat pump dryer; ventless; CEF ≥ 6. (Product Rec).
Stove / Oven	Electric induction cooktop; convection oven. (Product Rec).
Lighting	≥ 100% high-efficacy (LED).
Solar Ready	Reserve at least 40 percent of the roof as a solar-ready zone, kept clear of vents and equipment and shown on the drawings. Design the roof for an extra 5 psf and leave a pathway to the electrical service. A heavily shaded roof, a roof that already has renewables, or a roof that cannot fit the zone is exempt.
EV Ready	At least 20% of parking spaces wired EV-ready (40-amp Level II; shared circuits with load management allowed).
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	≥ R-23 cavity insulation (2x6 @ 16" o.c.), no continuous insulation.
Below Grade Walls	N/A
Corridor Walls	N/A
Slab	≥ R-15 perimeter insulation, 2 ft deep, at the interior face of the slab edge, plus ≥ R-15 under-slab insulation, 2 ft wide; provides a full thermal break.
Floor Over Unconditioned Space	N/A
Floor Over Garage	N/A
Floor Over Podium	N/A
Rim Joists	≥ R-23 rim/band insulation at floor transitions.
Roof	Sealed attic: ≥ R-30 insulation + ≥ R-30 continuous insulation.
Windows & Glass Doors	Fixed, U ≤ 0.30, SHGC ≤ 0.38. Operable, U ≤ 0.32, SHGC ≤ 0.33. 225 CMR 23 Table C402.4. SHGC is the projection-factor-below-0.2 value.
Doors	Glazed entrance door, U ≤ 0.60, SHGC ≤ 0.40. Swinging opaque door, U ≤ 0.37. Nonswinging opaque door, U ≤ 0.31. ENERGY STAR MFNC v1.2 Reference Design, climate zone 5 (glazed entrance). 225 CMR 23 Table C402.1.4 (opaque doors).
Air Sealing	Continuous air barrier for these spaces. Corridors, stairwells, and enclosed spaces not greater than 1,500 sq ft are verified by inspection of the continuous air barrier. 225 CMR 23 C402.5.1 and C402.5.2.2 Exception.
HVAC	No fossil-fuel heating equipment. Ducted split heat pump: SEER2 15.2, HSPF2 7.8. Ductless heat pump: SEER2 16, HSPF2 8.2. Equipment selected per ACCA Manual S. ENERGY STAR MFNC v1.2 Reference Design.
Ductwork	Distribute conditioned air to all occupied common spaces. Ducts and air-handler units located entirely within conditioned space. Design and test to standard duct-design and duct-leakage practice.
Duct Sealing	Per system, final test (at 25 Pa): 6 CFM per 100 sqft or 60 CFM (no return ducts) 8 CFM per 100 sqft or 80 CFM (1 to 2 return ducts) 12 CFM per 100 sqft or 120 CFM (3+ returns). Rough-in: 3/30, 4/40, or 6/60. All ducts and AHU in conditioned space. Tested.
HVAC Grading	N/A
Mechanical Ventilation	Conditioned corridor: 0.06 cfm/sqft. Management office: 5 cfm/person + 0.06 cfm/sqft. Community room: 5 cfm/person + 0.06 cfm/sqft. Gym: 20 cfm/person + 0.06 cfm/sqft. Demand control ventilation for a space over 500 sq ft with an occupant load of 15 or more people per 1,000 sq ft, where the system has an economizer, a modulating outdoor-air damper, or more than 3,000 cfm of outdoor air. Energy recovery when the supply fan exceeds the climate zone 5A airflow in Table C403.7.4.2, at an enthalpy recovery ratio of at least 50 percent. 225 CMR 23 C403.7.1 and C403.7.4.2. ENERGY STAR MFNC, ASHRAE 62.1 Section 6.
Local Mechanical Exhaust	Mechanical equipment rooms: exhaust ducted directly outdoors, ENERGY STAR certified fans. 225 CMR 23 C403.7.
Thermostats	Individual thermostatic control in each zone, with a deadband of at least 5°F. Setback by automatic time clock or programmable control, to 55°F heating or 85°F cooling. 225 CMR 23 C403.4.1, C403.4.1.2, and C403.4.2.
DHW	Electric tank or instant hot water heater for common sinks. Efficiency per Table C404.2. 225 CMR 23 C404.2.
DHW Piping	Hot-water piping insulation thickness per Table C403.12.3. 1 inch for pipe smaller than 1.5 inches, and 1.5 inches for pipe from 1.5 inches to less than 4 inches, for 105–140°F water. 225 CMR 23 C404.4.
Water Fixtures	WaterSense Lav 1.5 GPM Toilet 1.28 GPF Urinal 0.5 GPF
Refrigerator	N/A
Dishwasher	N/A
Clothes Washer	N/A
Clothes Dryer	N/A
Stove / Oven	N/A
Lighting	100% LED. Conditioned corridor: 0.41 W/sqft. Stairwell: 0.49 W/sqft. Management office: 0.74 W/sqft. Community room: 0.97 W/sqft. Gym: 0.90 W/sqft. Trash room: 0.38 W/sqft. Mail and package: 0.38 W/sqft. Bike room: 0.38 W/sqft. 225 CMR 23 Table C405.3.2(2).
Lighting Controls	Occupant sensors in the corridor, management office, community room, and storage rooms. Corridor lighting reduces to 50 percent within 20 minutes. Time-switch controls where occupant sensors are not used. Daylight-responsive controls where general lighting exceeds 150 W in a primary sidelit zone, 300 W in a sidelit zone, or 150 W in a toplit zone. 225 CMR 23 C405.2.1, C405.2.1.4, C405.2.2, and C405.2.4.
Solar Ready	Reserve at least 40 percent of the roof as a solar-ready zone, kept clear of vents and equipment and shown on the drawings. Design the roof for an extra 5 psf and leave a pathway to the electrical service. A heavily shaded roof, a roof that already has renewables, or a roof that cannot fit the zone is exempt.
EV Ready	At least 20% of parking spaces wired EV-ready (40-amp Level II; shared circuits with load management allowed).
HPWH Ready	N/A
Electric Readiness	N/A
Vestibules	Enclosed vestibule at public entrances, with self-closing doors. 225 CMR 23 C402.5.8.
Efficiency Credits	N/A
Paperwork & Modeling	HERS Index of 45 or less for each all-electric dwelling unit, documented at permit and at certificate of occupancy. ENERGY STAR MFNC v1.2 workbook, design-review checklist, and common-space HVAC supplement. EV-ready parking and the solar-ready zone shown on the plans. 225 CMR 23 C407.4, Table C407.4, C405.13, and C402.3.
Testing & Verification	Ventilation balancing per design. Duct leakage testing at rough-in and final. HVAC functional testing by FT agent (mandatory). Lighting controls testing. Air barrier inspections.

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	-2 F
Code	2018 IBC Section 1404.3

Exterior Walls

#	Layer (inside to outside)	R	Running R	Temp	Dewpoint target	Vs dewpoint
1	Drywall	1.13	1.13	66.7 F	41 F	OK
2	Class II vapor retarder	0.00	1.13	66.7 F	41 F	OK
3	R-23 cavity insulation with 2x6 wood studs	23.00	24.13	0.3 F	41 F	First below dewpoint
4	Wood sheathing	0.62	24.75	-1.5 F	41 F	Below dewpoint
5	Air barrier	0.00	24.75	-1.5 F	41 F	Below dewpoint
6	Siding / cladding	0.17	24.92	-2.0 F	41 F	Below dewpoint

Conclusion: 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.

Slab

#	Layer (inside to outside)	R	Running R	Temp	Dewpoint target	Vs dewpoint
1	Concrete slab	0.50	0.50	69.4 F	41 F	OK
2	Vapor retarder	0.00	0.50	69.4 F	41 F	OK
3	R-15 under slab and at the interior edge	15.00	15.50	50.0 F	41 F	OK
4	Gravel / ground	0.00	15.50	50.0 F	41 F	OK

Conclusion: No row drops below dewpoint. This is not the wall problem. Indoor air is not leaking to a cold sheathing. The vapor retarder is under the slab to stop moisture coming up from the ground. The slab itself is the air barrier.

Roof (sealed attic)

#	Layer (inside to outside)	R	Running R	Temp	Dewpoint target	Vs dewpoint
1	Gypsum ceiling	1.13	1.13	68.7 F	41 F	OK
2	Air barrier	0.00	1.13	68.7 F	41 F	OK
3	R-30 at the underside of the deck	30.00	31.13	33.8 F	41 F	First below dewpoint
4	Roof deck	0.62	31.75	33.1 F	41 F	Below dewpoint
5	R-30 continuous insulation	30.00	61.75	-1.8 F	41 F	Below dewpoint
6	Roofing	0.17	61.92	-2.0 F	41 F	Below dewpoint

Conclusion: 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 through the insulation strapped under the deck, which is why the air barrier is the sealed gypsum on the room side of that insulation. The layer on the deck does not satisfy this.

Exterior Walls (Recommended Design)

Slab (Recommended Design)

Rim Joists (Recommended Design)

Roof (sealed attic) (Recommended Design)

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

HERS: $129,500 - $240,500

MassSave Multifamily High Rise Program Energy Star Tier ($129,500) (Program Breakdown): You get this rebate for having your building(s) certified for the Energy Star MFNC v1.2 program. 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 - $111,000) (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.

PHIUS: $302,500 - $413,500

MassSave Passive House Pre-Certification ($55,500) : You get this rebate for having your project PHIUS pre-certified. Pre-Certification typically occurs toward the end of the pre-construction phase. This rebate comes in the form of a check within 4 months of the pre-certification paperwork being provided to MassSave.
MassSave Passive House Certification ($222,000) : You get this rebate for having your project PHIUS certified. Certification typically occurs at the end of construction around when certificate of occupancy is received. This rebate comes in the form of a check within 4 months of the certification paperwork being provided to MassSave.
MassSave Passive House Feasibility Study ($5,000) : You get this rebate for having a PHIUS feasibility study completed for your project & having a 1 hour charette with the design team and MassSave representative to review that study. This process must be completed before construction is complete. This rebate comes in the form of a check within 4 months of the charette taking place.
- IMPORTANT: The incentive is capped at 100% of the applicable service charge.
MassSave Passive House Energy Model ($20,000) : You get this rebate for having a PHIUS energy model completed for your project & having a 1 hour charette with the design team and MassSave representative to review that study. This process must be completed before construction is complete. This rebate comes in the form of a check within 4 months of the 1 hour meeting taking place.
- IMPORTANT: The incentive is capped at 75% of the applicable service charge.
DOER Alternative Energy Credits ($0 - $111,000) (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.

Path Comparison - Net Cost Summary

Path	Total Cost $/sf	Total Incentives $/sf	Net $/sf	OpEx Factor
HERS	$67.15	$2.67	$65.65	1.02
PHIUS	$72.59	$5.71	$67.99	1.02

Path Comparison - Envelope

Item	Path	Detailed Specifications	Cost $/sf	Incentive $/sf	Net $/sf	OpEx
Exterior Walls	HERS	≥ R-23 cavity insulation (2x6 @ 16" o.c.), no continuous insulation.	$4.20	$0.00	$4.20	0.95
	PHIUS	≥ R-21 cavity insulation (2x6 @ 16" o.c.) with ≥ R-12.6 continuous exterior insulation.	$5.76	$0.00	$5.76	0.90
Below Grade Walls	HERS	N/A	$0.00	$0.00	$0.00	1.00
	PHIUS	N/A	$0.00	$0.00	$0.00	1.00
Corridor Walls	HERS	N/A	$0.00	$0.00	$0.00	1.00
	PHIUS	N/A	$0.00	$0.00	$0.00	1.00
Slab	HERS	≥ R-15 perimeter insulation, 2 ft deep, at the interior face of the slab edge, plus ≥ R-15 under-slab insulation, 2 ft wide; provides a full thermal break.	$0.08	$0.00	$0.08	0.90
	PHIUS	≥ R-10 perimeter insulation, 2 ft deep, at the interior face of the slab edge, plus ≥ R-10 under-slab insulation; provides a full thermal break.	$0.35	$0.00	$0.35	0.90
Floor Over Unconditioned Space	HERS	N/A	$0.00	$0.00	$0.00	1.00
	PHIUS	N/A	$0.00	$0.00	$0.00	1.00
Floor Over Garage	HERS	N/A	$0.00	$0.00	$0.00	1.00
	PHIUS	N/A	$0.00	$0.00	$0.00	1.00
Floor Over Podium	HERS	N/A	$0.00	$0.00	$0.00	1.00
	PHIUS	N/A	$0.00	$0.00	$0.00	1.00
Rim Joists	HERS	≥ R-23 rim/band insulation at floor transitions.	$0.20	$0.00	$0.20	0.95
	PHIUS	≥ R-34 rim/band insulation at floor transitions.	$0.27	$0.00	$0.27	0.95
Roof	HERS	Sealed attic: ≥ R-30 insulation + ≥ R-30 continuous insulation.	$1.59	$0.00	$1.59	1.10
	PHIUS	Sealed attic: ≥ R-30 insulation + ≥ R-30 continuous insulation.	$1.59	$0.00	$1.59	1.10
Windows & Glass Doors	HERS	High performance, U ≤ 0.25 / SHGC ≤ 0.25.	$6.46	$0.00	$6.46	1.00
	PHIUS	High performance, U ≤ 0.18 / SHGC ≤ 0.18.	$8.80	$0.00	$8.80	1.00
Doors	HERS	Opaque door, U ≤ 0.20 (R-5.0).	$0.35	$0.00	$0.35	0.95
	PHIUS	Opaque door, U ≤ 0.20 (R-5.0).	$0.35	$0.00	$0.35	0.95
Air Sealing	HERS	≤ 0.30 CFM50 per sq ft of shell area; tested.	$1.20	$0.00	$1.20	0.95
	PHIUS	Whole-building blower door test at or below 0.06 CFM50 per sq ft of gross enclosure, and unit compartmentalization at ≤ 0.30 CFM50 per sq ft of shell area; tested.	$2.40	$0.00	$2.40	0.95

Path Comparison - Mechanical

Item	Path	Detailed Specifications	Cost $/sf	Incentive $/sf	Net $/sf	OpEx
HVAC	HERS	Ducted air-source heat pump (as modeled); SEER2 ≥ 17; HSPF2 ≥ 10. See HVAC Design Loads.	$20.57	$0.00	$20.57	1.15
	PHIUS	Ducted air-source heat pump (as modeled); SEER2 ≥ 17; HSPF2 ≥ 10. See HVAC Design Loads.	$20.57	$0.00	$20.57	1.15
Ductwork	HERS	Supply and return ducts in conditioned space insulated to code minimum.	$6.86	$0.00	$6.86	1.00
	PHIUS	Supply and return ducts in conditioned space insulated to code minimum.	$6.86	$0.00	$6.86	1.00
Duct Sealing	HERS	≤ greater of 80 CFM25 or 8 CFM25 per 100 sqft of conditioned floor area; tested at final.	$1.18	$0.00	$1.18	1.00
	PHIUS	≤ greater of 80 CFM25 or 8 CFM25 per 100 sqft of conditioned floor area; tested at final.	$1.18	$0.00	$1.18	1.00
HVAC Grading	HERS	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
	PHIUS	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	HERS	In-unit ERV 1-bedroom: 75 CFM, ≥ 86% ASRE 2-bedroom: 100 CFM, ≥ 83% ASRE	$3.63	$0.00	$3.63	1.20
	PHIUS	In-unit ERV 1-bedroom: 75 CFM, ≥ 86% ASRE 2-bedroom: 100 CFM, ≥ 83% ASRE	$3.63	$0.00	$3.63	1.20
Local Mechanical Exhaust	HERS	The in-unit ERV fulfills local mechanical exhaust with 25 CFM in each bathroom and 50 CFM in the kitchen.	$1.67	$0.00	$1.67	1.05
	PHIUS	The in-unit ERV fulfills local mechanical exhaust with 25 CFM in each bathroom and 50 CFM in the kitchen.	$1.67	$0.00	$1.67	1.05
Thermostats	HERS	Programmable thermostat (as modeled).	$0.20	$0.00	$0.20	1.05
	PHIUS	Programmable thermostat (as modeled).	$0.20	$0.00	$0.20	1.05

Path Comparison - Plumbing & Appliances

Item	Path	Detailed Specifications	Cost $/sf	Incentive $/sf	Net $/sf	OpEx
DHW	HERS	1-Bedroom: Heat pump water heater (HPWH) (as modeled); UEF ≥ 3.88; 40 gal 2-Bedroom: Heat pump water heater (HPWH) (as modeled); UEF ≥ 3.88; 50 gal	$3.72	$0.00	$3.72	1.20
	PHIUS	1-Bedroom: Heat pump water heater (HPWH) (as modeled); UEF ≥ 3.88; 40 gal 2-Bedroom: Heat pump water heater (HPWH) (as modeled); UEF ≥ 3.88; 50 gal	$3.72	$0.00	$3.72	1.20
DHW Piping	HERS	Supply piping insulated to ≥ R-3.	$1.18	$0.00	$1.18	0.95
	PHIUS	Supply piping insulated to ≥ R-3.	$1.18	$0.00	$1.18	0.95
Water Fixtures	HERS	WaterSense certified (Lavatory ≤ 1.2 GPM; Shower ≤ 2.0 GPM; Kitchen ≤ 2.2 GPM).	$2.94	$0.00	$2.94	1.00
	PHIUS	WaterSense certified (Lavatory ≤ 1.2 GPM; Shower ≤ 2.0 GPM; Kitchen ≤ 2.2 GPM).	$2.94	$0.00	$2.94	1.00
Refrigerator	HERS	≤ 600 kWh/yr; electric.	$1.24	$0.00	$1.24	1.10
	PHIUS	≤ 600 kWh/yr; electric.	$1.24	$0.00	$1.24	1.10
Dishwasher	HERS	≤ 269 kWh/yr; electric.	$0.69	$0.00	$0.69	1.10
	PHIUS	≤ 269 kWh/yr; electric.	$0.69	$0.00	$0.69	1.10
Clothes Washer	HERS	IMEF ≥ 2.06; IWF ≤ 4.2; ≤ 152 kWh/yr; electric.	$0.78	$0.00	$0.78	1.10
	PHIUS	IMEF ≥ 2.06; IWF ≤ 4.2; ≤ 152 kWh/yr; electric.	$0.78	$0.00	$0.78	1.10
Clothes Dryer	HERS	Heat pump dryer; ventless; CEF ≥ 6.	$1.61	$0.00	$1.61	1.00
	PHIUS	Heat pump dryer; ventless; CEF ≥ 6.	$1.61	$0.00	$1.61	1.00
Stove / Oven	HERS	Electric induction cooktop; convection oven.	$1.27	$0.00	$1.27	1.05
	PHIUS	Electric induction cooktop; convection oven.	$1.27	$0.00	$1.27	1.05

Path Comparison - Electrical

Item	Path	Detailed Specifications	Cost $/sf	Incentive $/sf	Net $/sf	OpEx
Lighting	HERS	≥ 100% high-efficacy (LED).	$4.00	$0.00	$4.00	0.85
	PHIUS	≥ 100% high-efficacy (LED).	$4.00	$0.00	$4.00	0.85
Solar Ready	HERS	Reserve at least 40 percent of the roof as a solar-ready zone, kept clear of vents and equipment and shown on the drawings. Design the roof for an extra 5 psf and leave a pathway to the electrical service. A heavily shaded roof, a roof that already has renewables, or a roof that cannot fit the zone is exempt.	$0.30	$0.00	$0.30	1.00
	PHIUS	Reserve at least 40 percent of the roof as a solar-ready zone, kept clear of vents and equipment and shown on the drawings. Design the roof for an extra 5 psf and leave a pathway to the electrical service. A heavily shaded roof, a roof that already has renewables, or a roof that cannot fit the zone is exempt.	$0.30	$0.00	$0.30	1.00
EV Ready	HERS	At least 20% of parking spaces wired EV-ready (40-amp Level II; shared circuits with load management allowed).	$0.60	$0.00	$0.60	1.00
	PHIUS	At least 20% of parking spaces wired EV-ready (40-amp Level II; shared circuits with load management allowed).	$0.60	$0.00	$0.60	1.00
HPWH Ready	HERS	N/A	$0.00	$0.00	$0.00	1.00
	PHIUS	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	HERS	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.	$0.19	$2.67	-$2.48	1.00
	PHIUS	Register the project with Phius and carry a WUFI Passive v3.5 model through design review to a Phius Design Certification letter before construction. The design submission includes the drawings, the Phius 2024 criteria calculator, fenestration and equipment datasheets, and a letter of intent from the Phius Rater or Verifier. Update the WUFI Passive model to as-built conditions for final certification. 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.	$0.19	$5.71	-$5.52	1.00
Testing & Verification	HERS	ENERGY STAR field verification: pre-drywall and final inspections, unit air-tightness (blower door), duct-leakage, ventilation and exhaust airflow, and HVAC functional testing.	$0.44	$0.00	$0.44	1.00
	PHIUS	Phius field verification includes mid-construction inspections, a whole-building blower door test at or below 0.06 CFM50 per sq ft of gross enclosure, dwelling-unit compartmentalization at or below 0.30 CFM50 per sq ft of enclosure, and ventilation airflow testing and balancing. Update the WUFI Passive model to the tested blower door result. ENERGY STAR field verification: pre-drywall and final inspections, unit air-tightness (blower door), duct-leakage, ventilation and exhaust airflow, and HVAC functional testing.	$0.44	$0.00	$0.44	1.00