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	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	61.99%	Operational Carbon Savings	-2.14 tCO2eq/yt

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

Modified Larsen Truss added to exterior walls (R-45.5 Nominal)
Basement ceiling joists filled with dense pack cellulose (R-26 Nominal)
Existing roof framing filled with 28″ of blown in cellulose, additional 2×4 framing overtop as ventilation cavity with added underlay. (R-102 Nominal)
Passive House Certified ENERsign Aluminum Clad Wood Windows (U-Factors between 0.22-0.55)
Passive House Certified ENERsign Doors (U-Factors between 0.11-0.15)
Continuous Air barrier and improved air tightness (0.57 ACH @ 50 Pa)
Removal of Oil Furnace, full electrification of mechanical systems.
Zehnder ComfoAir Q350 ERV and Coway Air Mega 150 HEPA Filtration for air purification.
Fujitsu 15000 BTU Mini Split Air Source Heat Pump with Convect Air Electric Backup (2 kW)
40 Gallon Electric Domestic Hot Water Tank with Drain Water Heat Recovery (DWHR) (46.1% eff)

Project Description

Planning the Retrofit

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 Updated exterior cladding overtop of original building. Aged appearance. Some evidence of moisture damage around window openings.	After Renewed exterior. Removal of exposed floor. Improved building envelope construction. Modernized building to 2050 standard.
Comfort	Before Drafty building envelope with leaky windows.	After Vastly improved air quality, comfortable even temperature and reduced exterior noise.

Envelope
	Before	After
Ceiling/Attic Insulation	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.
Ceiling/Attic Insulation	Before 22.5 R	After 49.6 R
Foundation Insulation	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 Insulation	Before 1.4 R	After 1.8 R
Wall Insulation	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 Insulation	Before 16.4 R	After 37.8 R
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 Changes per Hour	Before 12.17 ACH50	After 0.57 ACH50
Air Sealing	Before None, leaky windows, leaky exposed floor for bay window.	After Continuous air barrier installed on interior walls, exterior walls and roof. Air barrier applied to decking of first floor to isolate uninsulated basement air volume.

Mechanical & Electrical
	Before	After
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.
Cooling	Before None	After Fujitsu 15,000 BTU Mini Split Air Source Heat Pump (10 SEER)
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 No Data	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
Light and Appliance Energy Consumption	Before 11.97 GJ	After 11.7 GJ
Other electrical consumption	Before 13.68 GJ	After 14.3 GJ
Space Cooling	Before 0 GJ	After 3.9 GJ
Space Heating	Before 129.96 GJ	After 22.1 GJ
Ventilation Energy Use	Before 0 GJ	After 0 GJ
Water Heating	Before 15.39 GJ	After 13 GJ
Total Net Consumption (with Renewables)	Before 171 GJ	After 65 GJ
Total Annual Consumption	Before 171 GJ	After 65 GJ
Annual Cooling Demand Intensity	Before 0 kWh/m2/a	After 6.28 kWh/m2/a
Annual Electricity Consumption	Before 11944 kWh	After 18056 kWh
Annual Heating Demand Intensity	Before 195.56 kWh/m2/a	After 35.57 kWh/m2/a
Other energy performance	Before 127	After 0
Energy Use Intensity	Before 257.31 kWh/m2/a	After 104.61 kWh/m2/a

Carbon Emissions
	Before	After
Annual Operational Carbon Emissions – Electricity	Before 4180.56 KgCO2e	After 6319.45 KgCO2e

Prima, Non Ultima

Project Team

Project Priorities

Project Goals

Upgrades

Project Description

Planning the Retrofit

Getting to Net Zero

Before & After

General

Building Condition

Before

After

Comfort

Before

After

Envelope

Ceiling/Attic Insulation

Before

After

Ceiling/Attic Insulation

Before

After

Foundation Insulation

Before

After

Foundation Insulation

Before

After

Wall Insulation

Before

After

Wall Insulation

Before

After

Windows and Doors

Before

After

Air Changes per Hour

Before

After

Air Sealing

Before

After

Mechanical & Electrical

Heating

Before

After

Cooling

Before

After

Hot Water

Before

After

Ventilation

Before

After

Electrical Service

Before

After

Mechanical Other

Before

After

Annual Energy Usage

Light and Appliance Energy Consumption

Before

After

Other electrical consumption

Before

After

Space Cooling

Before

After

Space Heating

Before

After

Ventilation Energy Use

Before

After

Water Heating