Prima, Non Ultima

"Prima, Non Ultima" is a deep energy retrofit of a 1937 Charlottetown home, transforming it into a high-performance, Passive House-inspired dwelling with exceptional indoor air quality and drastically reduced energy use. By systematically improving the insulation, air sealing, mechanical systems, and smart electrical infrastructure, the project cut annual energy consumption by over 60% and space heating demand by more than 80%.

Building Type	Single-Family 2+ Stories	Location	Charlottetown, PE
Year Built	1937	Foundation Type	Concrete (Full Basement)
Structure Type	Wood-Framed	Post-Retrofit Total Floor Area	172.6m²
Climate Zone	6	Heating Degree Days	4460
Retrofit Status	Complete	Year Completed	2024
Retrofit Phasing	No	Geometry Changed	Yes
Annual Energy Savings	62.15%	Operational Carbon Savings	7.71 tCO2eq/y
Retrofit Type	Envelope and Mechanical	Performance Level	Net-Zero Ready

Project Team

Gomex Engineering ( Passive House Designer )
Homesol Building Solutions ( Energy Advisor )

Project Priorities

Improve Indoor Air Quality

Project Goals

The overarching goal for the project was to create a model home that showcases that high performance buildings can in fact reduce both operational and embodied carbon while improving indoor air quality with careful selection of healthy building materials.

Following the main priority of improving Air quality of the home, the other priorities were:

Minimizing embodied carbon of materials used for the retrofit.
Following Passive House principles
Avoiding red list chemicals where possible in materials and products utilized

Upgrades

Envelope Improvements

Wall Insulation – Exterior – Larsen Truss
Attic / Roof Internal Insulation
Foundation Walls Interior Insulation
Air Sealing / Airtightness
Air Barrier

Windows and Door Improvements

Window Replacement – Triple Pane
Door Replacement – High Performance

Mechanical: Heating and Cooling Improvements

Air Source Heat Pump – Mini-Split
Gas / Fossil Fuel Disconnection
Electric Backup Heating

Mechanical: Ventilation Improvements

Energy Recovery Ventilator (ERV)

Mechanical: Hot Water Improvements

Electric Hot Water Tank
Drain Water Heat Recovery (DWHR)

Electrical Improvements

Full Electrification

Health, Safety & Sustainability Improvements

MERV 13 or Above Air Filtration

Project Description

The Retrofit Story

The retrofit plan for "Prima, Non Ultima" aimed to transform a 1937 wood-framed home into a high-performance, low-carbon, and healthy residence guided by Passive House principles. The approach prioritized exceptional indoor air quality, minimized embodied carbon through sustainable materials, and dramatically reduced energy use. Key strategies included upgrading the thermal envelope with high R-value insulation, enhancing airtightness, installing high-performance windows and doors, and integrating advanced mechanical systems for ventilation, heating, air purification, and humidity control.

Getting to Net Zero

Bringing the property as close to net-zero as possible centered on dramatically reducing energy demand through a high-performance building envelope, ultra-efficient mechanical systems, and smart material choices. Using Passive House-level insulation, a continuous air-barrier, and balanced ventilation, the home minimized heating and cooling loads. Efficient systems like a mini-split heat pump, energy recovery ventilation, and drain water heat recovery were combined with low-carbon materials to reduce both operational and embodied carbon emissions. Finally, a 200-amp electrical upgrade with real-time monitoring and EV readiness ensured the home was prepared for future solar integration if the homeowners choose to do so, making it net-zero ready.

Before & After

General
	Before	After
Building Condition	Before Original – Minor Performance Upgrades	After High-Performance / Passive House-Level

Envelope
	Before	After
Attic/Roof Assembly	Before 2×4 frame cathedral ceiling filled with blown in fiberglass. Flat portion in attic had two layers of 3.5” fiberglass batts	After 2×4 frame cathedral ceiling filled with dense pack cellulose. Flat portion in attic had 29” of blown in cellulose. Existing Roof boards remained and were wrapped with mento 3000 connect then furred with 2×4 (ventilation cavity), 5/8” sheathing, Roofing underlayment and then metal roof with ridge vent.
Attic/Roof Assembly Effective Thermal Resistance	Before R-22.5	After R-49.6
Wall Assembly	Before Vinyl exterior, 2×4 rough cut wood frame, 16 inch centers, R12 Fiberglass batts, gyp rock interior finish.	After 5″ Modified Larsen truss assembly filled with dense pack cellulose, existing 2×4 frame augmented with 2×4 horizontal stud 24″ O/C, entire cavity filled with dense pack cellulose (7.25″), Pro Clima Intello vapour barrier installed on internal wall and then double strapped to create a service cavity for electrical, followed by 5/8” Type X drywall.
Wall Assembly Effective Thermal Resistance	Before R-16.4	After R-37.8
Foundation Wall Assembly	Before Bare concrete foundation walls, uninsulated slab	After Basement walls untouched. Air barrier added to 1st floor decking. Basement header filled with dense pack cellulose.
Foundation Wall Assembly Effective Thermal Resistance	Before R-1.4	After R-1.8
Windows and Doors	Before Mix of original windows on foundation wall and updated mid 1990’s Vinyl windows on main floors. (Window U-Values 0.4-0.93, Door U-Values 0.18-0.48)	After All new ENERsign Passive House Certified windows and doors (Window U-Values 0.22-0.55, Door U-Values 0.11-0.15)
Air Tightness	Before 12.17 ACH50	After 0.57 ACH50

Mechanical & Electrical
	Before	After
Cooling	Before None	After Fujitsu 15,000 BTU Mini Split Air Source Heat Pump (10 SEER)
Heating	Before Oil furnace 55,000 BTU (83% AFUE)	After Fujitsu 15,000 BTU Mini Split Air Source Heat Pump (5.9 HSPF), 2 kW Convectair Resistive electric backup.
Hot Water	Before Electric, 40 gallon hot water tank (0.89 EF)	After Existing 40 gallon hot water tank updated with new anodes and heating element, Drain water heat recovery installed(46.1% Eff)
Ventilation	Before None	After Zehnder ComfoAir Q350 ERV (79% Eff)
Electrical Service	Before 100 Amps	After 200 Amps
Mechanical Other	Before N/A	After Coway Air Mega 150 (HEPA Filtration), Sante Fe Ultra70 Whole Home Dehumidifier, Air Things View Plus (Radon, PM2.5, PM1, CO Humidity, Temp, Pressure), Leviton Combo Meter Main Exterior panel for exterior plugs/lighting. Whole home energy monitor installed for tracking energy use and Flo by Moen installed for monitoring/tracking water consumption and leaks.

Annual Energy Usage
	Before	After
Total Annual Consumption	Before 170.44 GJ	After 64.51 GJ
Total Net Consumption	Before 170.44 GJ	After 64.51 GJ
Energy Use Intensity	Before 256.47 kWh/m2/a	After 103.82 kWh/m2/a
Annual Heating Demand Intensity	Before 194.92 kWh/m2/a	After 35.30 kWh/m2/a
Annual Cooling Demand Intensity	Before 0 kWh/m2/a	After 6.23 kWh/m2/a
Annual Electricity Consumption	Before 12,053.00 kWh	After 17,919.00 kWh
Light and Appliance Energy Consumption	Before 11.93 GJ	After 11.61 GJ
Space Cooling	Before 0 GJ	After 3.87 GJ
Space Heating	Before 129.54 GJ	After 21.93 GJ
Water Heating	Before 15.34 GJ	After 12.90 GJ
Annual Oil Consumption	Before 3300 L	After N/A
Attic/Ceiling Heat Loss	Before 6.48 GJ	After 1.32 GJ
Main Walls Heat Loss	Before 18.13 GJ	After 2.85 GJ
Exposed Floors Heat Loss	Before 2.59 GJ	After 0.22 GJ
Windows Heat Loss	Before 25.91 GJ	After 3.51 GJ
Exterior Doors Heat Loss	Before 1.30 GJ	After 0.66 GJ
Basement Foundation Heat Loss	Before 31.09 GJ	After 12.50 GJ
Air Leakage/Ventilation Heat Loss	Before 44.04 GJ	After 0.88 GJ

Carbon Emissions
	Before	After
Annual Operational Carbon Emissions – Electricity	Before 2,820.40 KgCO2e	After 4,193.05 KgCO2e
Annual Operational Carbon Emissions – Oil	Before 9,084.90 KgCO2e	After N/A
Total Carbon Emissions	Before 11,905.30 KgCO2e	After 4,193.05 KgCO2e

Technical Documents

Videos

Retrofit Canada and The ReCover Initiative hosted Gomex Engineering for a webinar focused on Prima, Non Ultima on Sept 11, 2025..

Retrofit Wall Assemblies: A Deep Dive feat. Zu House and HSS Design Build

Prima, Non Ultima

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Project Team

Project Priorities

Project Goals

Upgrades

Envelope Improvements

Windows and Door Improvements

Mechanical: Heating and Cooling Improvements

Mechanical: Ventilation Improvements

Mechanical: Hot Water Improvements

Electrical Improvements

Health, Safety & Sustainability Improvements

Project Description

The Retrofit Story

Getting to Net Zero

Before & After

General

Building Condition

Before

After

Envelope

Attic/Roof Assembly

Before

After

Attic/Roof Assembly Effective Thermal Resistance

Before

After

Wall Assembly

Before

After

Wall Assembly Effective Thermal Resistance

Before

After

Foundation Wall Assembly

Before

After

Foundation Wall Assembly Effective Thermal Resistance

Before

After

Windows and Doors

Before

After

Air Tightness

Before

After

Mechanical & Electrical

Cooling

Before

After

Heating

Before

After

Hot Water

Before

After

Ventilation

Before

After

Electrical Service

Before

After

Mechanical Other

Before

After

Annual Energy Usage

Total Annual Consumption

Before

After

Total Net Consumption

Before

After

Energy Use Intensity

Before

After

Annual Heating Demand Intensity

Before

After

Annual Cooling Demand Intensity

Before