Sucrerie Deep Retrofit

Project Description

Imagine taking an aging barn-turned-house, its roof leaking in multiple places and its exterior clinging to the end of its lifespan, and transforming it into a net-zero retirement haven. That was exactly the vision our client brought to us, even before a suitable property was in hand. We began by combing the market for a structure with excellent solar orientation, a pleasant location, and an older exterior that begged for a retrofit.

When we finally discovered the 1965 barn conversion, it was as if the building itself was inviting a “big coat of insulation.” Its south-facing roof and 8-inch brick ledges were perfect for a high-performance upgrade, while its failing siding and roofing made the prospect of a “chainsaw retrofit” both inevitable and efficient. We tackled most of the work from the outside, using a Larsen truss system loaded with thick layers of cellulose insulation, maximizing energy performance.

The clients envisioned a cozy, four-season veranda with a fireplace—an addition placed outside the main thermal envelope. Because this home would serve as their retirement residence, we prioritized accessibility on the first floor: every essential living space (bedroom, bathroom, laundry, kitchen, and living room) was designed with low thresholds and 36-inch-wide doorways.

During our exploratory work, we found a significant mouse infestation and outdated insulation behind the walls. We decided to replace the interior walls completely, upgrading to 2×6 Rockwool batts for better thermal performance and healthier indoor air. At the same time, we reinforced the roof to handle the weight of a solar array, ensuring both optimal sun exposure and long-term system durability.

Our thoughtful planning turned this once-deteriorating property into a net-zero-ready home with exceptional sustainability, comfort, and accessibility—all in time for our clients’ golden years.

Achieving Net Zero

Our net-zero strategy rested on two main pillars: dramatically reducing energy usage and optimizing the mechanical systems.

1. Energy Reduction:

• We fortified the building envelope by adding 8.5 inches of cellulose insulation on the exterior and 15 inches in the roof, supplementing the existing R-20 in the walls and rafters.
• High-performance European triple-pane windows minimized heat loss while capturing passive solar gains.
• Roof overhangs were extended and adjusted to block excessive summer sun, cutting cooling demand and increasing indoor comfort.

2. Mechanical Optimization:

• We ensured the roof could support a robust solar array, the cornerstone of our net-zero goal.
• A high-performance cold-climate heat pump, paired with an energy recovery ventilator (ERV), provided efficient heating, cooling, and fresh air circulation.
• For hot water, a split-system CO₂ heat pump water heater (Sanden SANCO2) offered exceptional efficiency and lower environmental impact.
• After the owner installs solar, the result will be not just net-zero, but net-positive performance. The solar panels will generate more than enough energy to meet the household’s needs and power the client’s electric vehicle, ensuring this home is ready for a sustainable future.

Challenges:

One of our biggest hurdles was managing the inevitable “while-we’re-at-it” mentality common in retrofits. Although our initial plan focused on the exterior, hidden issues forced us to open the interior walls, leading to three air-barrier layers. While it may have been more efficient to stick with two, these layers did yield an impressively low airtightness level.

Restructuring the crooked roof was another time-consuming obstacle. In hindsight, an over-truss approach might have been simpler. Still, once we straightened and fortified the roof, the remainder of the exterior retrofit—from insulation to airtightness—proceeded quickly and effectively.

What Went Well:

Despite the challenges, several aspects of this project were notably successful:

• Dual Exterior Air Barriers: By employing two exterior air-barrier layers, we could run blower door tests at each stage, ensuring we met airtightness goals before progressing.
• Close Collaboration with the Cellulose Manufacturer: Working hand-in-hand with the insulation supplier allowed us to verify density and ensure top-tier thermal performance.
• Custom Window Bucks: Designing and building our own window bucks streamlined installation, sped up the process, and reinforced airtightness.

In the end, our commitment to adapt and collaborate—despite the project’s surprises—resulted in a high-performance retrofit that exceeded even our client’s ambitious expectations. We not only met net-zero standards but also created a home of exceptional comfort, functionality, and clean-energy surplus for decades to come.