Canada’s 14.5 milling dwellings account for more than one-sixth of national energy use and close to 14% of Canada’s energy-related greenhouse gas emissions [1]. Heat loss through the envelope (roof, walls, and foundation) represents about two-thirds of the energy use in a typical Canadian home. Despite this, only a small share of energy retrofits includes whole-building envelope performance upgrades. Barriers to deep retrofits are commonly (1) a high amount of disruption, (2) cost uncertainty, and (3) complexity, amongst others. CanmetENERGY-Ottawa developed a Prefabricated Exterior Energy Retrofit (PEER) approach to address these barriers. PEER involves scanning a building, prefabricating custom panels with all control layers, and rapidly installing these on an existing building to dramatically improve energy efficiency, extend the service life, and enhance occupant comfort, while reducing cost, complexity, and disruption. This industrialized approach to net-zero energy (NZE) retrofits originated in Europe, and CanmetENERGY is evaluating this approach for Canadian homes. CanmetENERGY-Ottawa and Ottawa Community Housing (OCH) piloted this approach in a demonstration project in Ottawa, Canada in 2020. The paper reports on the hygrothermal performance of the above-grade wall system monitored pre- and post-retrofit. CanmetENERGY measured the temperature, relative humidity and moisture content of moisture-sensitive layers and air spaces at five heights on the north, south and east facades. Data collection started in 2020. The moisture-sensitive layers in the assembly showed limited risk despite high initial moisture content from precipitation in the existing brick veneer that was overclad at the time of retrofit.