Your Name: Erika DeRoche
Email Address: ed@zeroenergy.com
Phone: 6178614795
May we contact you about your entry in the future? Yes
If yes, which contact method do you prefer? email
Your building company: Alpha Smart Builders
Your builder's name: Deliandro Dias
Your architecture firm: ZeroEnergy Design
Your architect's name: Erika DeRoche
Passive building consultant: ZeroEnergy Design
Street address of the retrofit: 171 Columbia Street
Town or city: Cambridge
State or province: MA
Original construction year: 1902
Year when passive building work was or will be completed: 2023
Lot type: urban
Type of structure: wood-frame
Building use type: residential
Brief description of the retrofit project: Emergency reconstruction/ gut renovation of three-unit affordable triple decker with energy efficiency focus following a fire. Most of the existing siding remained with insulation and air sealing occurring from the interior, in addition to window replacement with triple glazed tilt/turn uPVC windows, electrification, all new building systems and complete interior renovation. The project is not attempting passive house certification but achieved DOE's Zero Energy Ready Homes certification and anticipates Enterprise Green Communities certification.
Why did you choose to do a whole, partial, or phased retrofit?
Total area of the structure (in square feet): 4700
Total renovated area of the retrofit project (in square feet) : 4700
Date when the project began or is expected to begin (enter "01" for the day if you only know the month and year): 01/04/2022
How many months did the renovation take? If ongoing, how many months is the renovation expected to take? : 12
What were the main goals of the retrofit? Were these goals driven by you, a client or both? :
Were people living in the building during renovation? no
Was this a registered historic building? no
Did you use historic tax credits? no
Passive house certified? no
If certified by another group, please list the organization:
Air tightness (ACH) before renovation:
Air tightness (ACH) after renovation: 1.46
Total annual electricity costs before renovation (in dollars):
Total annual electricity costs after renovation (in dollars): 4431
Total annual electricity usage before renovation (in kWh):
Total annual electricity usage after renovation (in kWh): 22155
Total annual heat costs before renovation (in dollars):
Total annual heat costs after renovation (in dollars): 1740
Total annual heat usage before renovation (in kBtu) :
Total annual heat usage after renovation (in kBtu) :
Heat source(s) before renovation: other
Heat source(s) after renovation: heat-pump
Annual hot water cost before renovation (in dollars):
Annual hot water cost after renovation (in dollars): 532
Hot water system before renovation: a:1:{i:0;s:5:"other";}
Hot water system after renovation: a:1:{i:0;s:20:"air-source-heat-pump";}
Annual hot water energy usage before renovation (in kWh):
Annual hot water energy usage after renovation (in kWh): 2658
Energy Use Intensity (EUI) of the structure before renovation:
Energy Use Intensity (EUI) of the structure after renovation: 16.06
Is the retrofit now using renewable energy sources? no
If using renewable energy, please describe the type, kWh generation and any other system specs:
Were/are any passive house certified materials used? a:0:{}
Please describe your reasoning in using certified or non-certified materials:
Door type before renovation: hollow masonite
Door type after renovation: insulated fiberglass
U-value of doors before renovation:
U-value of doors after renovation: 0.14
Please describe any methods you're using for controlling thermal bridging, water, vapor and air movement related to doors:
Window type before renovation: Dual-glazed, Double Hung Vinyl replacement window
Window type after renovation: Triple-glazed, argon-filled uPVC casement window
U-value of windows before renovation:
Please describe any methods you're using for controlling thermal bridging, water, vapor and air movement related to windows:
Please give this assembly a name (label), if you are entering multiple assemblies: Wood-Framed Wall
List all materials in the wall assembly before renovation (please list from outside to inside): Fiber cement siding, #15 building felt, board sheathing, 2x3.75 wood stud,lath & plaster
List all materials in the wall assembly after renovation (please list from outside to inside): Fiber cement siding, #15 building felt, board sheathing, 2x3.75 wood stud dense-packed with cellulose, vapor variable air barrier, 2x strapping with mineral wool board, ⅝” type x gypsum wallboard
R-value of wall assemblies before renovation:
R-value of wall assemblies after renovation: 18
Please describe methods for controlling thermal bridging, water, vapor and air movement related to the wall assembly, e.g. materials used and construction: Careful detailing, Careful air sealing, limited use of low-GWP closed cell spray foam insulation at floor plates and challenging geometry, taping air barrier where ripped, diagnostic blower door testing, other methods mentioned for openings, sleeved penetrations
Do you have another assembly to add? yes
Please give this assembly a name (label), if you are entering multiple assemblies: Foundation Wall
List all materials in the wall assembly before renovation (please list from outside to inside): 12” brick and field stone foundation wall
List all materials in the wall assembly after renovation (please list from outside to inside) Copy: 12” brick and field stone foundation wall with limited repointing, 3” low-GWP closed cell spray foam insulation, stud wall finished with type X gypsum wallboard
R-value of wall assemblies before renovation:
R-value of wall assemblies after renovation: 20
Please describe methods for controlling thermal bridging, water, vapor and air movement related to the wall assembly, e.g. materials used and construction: Space between stud wall and foundation wall for continuous spray insulation, dimpled membrane/mat
Do you have another assembly to add? no
Please give this assembly a name (label), if you are entering multiple assemblies:
List all materials in the wall assembly before renovation (please list from outside to inside):
List all materials in the wall assembly after renovation (please list from outside to inside):
R-value of wall assemblies before renovation:
R-value of wall assemblies after renovation:
Please describe methods for controlling thermal bridging, water, vapor and air movement related to the wall assembly, e.g. materials used and construction:
Materials in the roof assemblies before renovation: Rigid insulation of sheathing, EPDM roofing membrane, existing board sheathing, 7” existing rafters
Materials in the roof assembly after renovation: Adhered TPO roofing system, ½” protection board, R-33 polyiso rigid insulation, vapor retarder, existing or new sheathing, 7” existing rafters dense packed with cellulose, vapor variable air barrier
R-value of roof assemblies before renovation:
R-value of roof assemblies after renovation: 59
Please describe methods for controlling thermal bridging, water, vapor and air movement related to the roof assembly, e.g., materials and construction:
Construction makeup of the foundation and ground water/vapor management systems before renovation:
Construction makeup of the foundation and ground water/vapor management systems after renovation:
R-value of foundation and ground water/vapor management systems before renovation:
R-value of foundation and ground water/vapor management systems after renovation:
Please describe any methods for controlling heat, water, vapor, and air movement related to the foundation and ground water/vapor management systems:
Ventilation strategy (type and number of ERV or HRV) before renovation: Natural ventilation
Ventilation strategy (type and number of ERV or HRV) after renovation: Individual Broan ERV for each apartment, Kitchen hood direct vent to exterior.
If any make-up air systems were used, please describe: Make-up air ventilator for basement laundry room.
Please describe any thermal bridging issues before renovation: Uninsulated walls and foundation wall, extensive existing wood structure and blocking.
Please describe strategies to mitigate thermal bridging after the renovation: Utility/electrical chase at interior allowed for interior insulation between furring, flash & batt used at overhanging second floor and basement ceiling beneath front entry.
Please describe any moisture issues before renovation:
Please describe the moisture control strategy after renovation: Drainage mat installed at interior of foundation wall, dehumidifier installed in basement, epoxy coating applied to existing slab, reconstructed roof corner, positive roof drainage to interior drain/overflow drain, new roof edge, limited repointing of brick foundation wall, careful detail and execution of opening and penetration flashing.
What rough percentage (0 - 100) of the wall assemblies have thermal bridges after renovation? 5
On a scale of 1 to 10, what was the perceived comfort of the structure before renovation?
On a scale of 1 to 10, what is the perceived comfort of the structure after renovation? 10
What was the total cost, or estimated cost, of design for the retrofit project (in dollars)? 1414306
Total construction cost per square foot, or estimated cost, for the project (in dollars): 300
Total door cost (in dollars):
Total windows cost (in dollars): 84326
Total wall assembly cost (in dollars):
Total roofing cost (in dollars):
Total foundation cost (in dollars):
Total ventilation cost (in dollars): 83750
Roughly what percentage (0 - 100) of the project was financed?
If you calculated it, what was the energy return on investment, i.e. the EROI (in dollars)?
On a scale of 1 to 10, how much did you take the EROI into consideration before starting the project (if it was calculated)? 2
What is the expected life of this retrofit (in years)? 100
If you do another retrofit, what would you do differently? Ideally we would air seal and insulate from the exterior and pair that work with siding replacement, maintaining interior dimensions to the greatest extent possible. In this instance the siding was requested to remain.
What do you wish you knew before starting the project? I wish we had required compartmentalization mock-ups and coordinated the data and cable riser before construction.
Any other relevant info or data that we didn’t ask about? After the renovation, the Annual Heat Usage is anticipated to be 6,179.4 kWh (units different than indicated in question above).
The project was funded with an insurance claim and a number of different grants, including energy-related grants from MassCEC. Window replacement was partially funded with a historic preservation grant (after Historic Commission approval).
Financing: 10
Local regulations and rules: 4
Technical challenges: 6
Procuring materials: 7
Working with your builder and/or architect: 5
What would you say was the most successful part of the process? Electrification greatly improves the operational carbon for this property. We also achieved excellent whole building air tightness for a retrofit.
