This article is part of a two-part series examining why ventilation is failing in Canada's older multi-unit residential buildings — and what a workable solution looks like.

1. Why Ventilation Is Failing in Older Buildings (this article)
2. Retrofitting Older Buildings: Why Replacing Equipment Isn't Enough

Most older buildings in Canada—whether public or private—fail to meet even the most basic standards for indoor air quality. Residents often breathe in stale hallway air, second-hand smoke, and cooking fumes from their neighbours—without even realizing it.

In 2023, BC Housing released a report on indoor environmental quality (IEQ) in five buildings from their portfolio. While this series draws on publicly available BC Housing data, the issues identified—outdated ventilation systems, poor indoor air quality (“IAQ”), and retrofit challenges—are common in older buildings across Canada, regardless of ownership. What the report found confirmed what many building managers already suspected: these buildings relied on outdated ventilation strategies that compromised both comfort and health.

This article is the first in a two-part series using the BC Housing report as a lens into a broader problem. These five buildings rely on outdated ventilation strategies still common in many older buildings across Canada. In this series, we’ll show why those strategies no longer meet modern expectations—and how decentralized systems like Lunos provide a practical, retrofit-ready solution. The report titled "Indoor Environmental Quality of Social Housing Buildings in British Columbia", examines key indoor environmental parameters—temperature, humidity, and carbon dioxide (CO₂) levels—in existing multi-unit residential buildings (“MURBs”).

Rethinking ventilation retrofits for older buildings begins with reconsidering a long-standing assumption: that ventilation performance depends on centralized duct infrastructure to deliver it. It doesn't. What a building needs is fresh air supplied reliably to the people living in it. How that air gets there is a separate question — and in retrofit contexts, it's often the more important one.

This distinction opens the door to a different kind of retrofit strategy. Rather than replacing aging centralized systems entirely — costly, disruptive, and often structurally impractical — LUNOS can be deployed at the suite level to fill the gaps those systems leave. The centralized system continues doing what it does. LUNOS handles what it can't. The building performs better, residents breathe better, and the retrofit works within the constraints of the building rather than against them.

Critically, installation requires only a 6.25-inch wall penetration, no ductwork, and no mechanical room access. In occupied buildings, that means retrofits can proceed suite by suite without displacing tenants — something that matters enormously in social housing, affordable housing, and any building where residents cannot simply be asked to leave.

The second article in this series examines why that strategy matters — and what the evidence shows happens when buildings are retrofitted without it.

BC Housing defines ventilation as the process of supplying air to and/or removing air from a space for the purpose of controlling air contaminant levels, humidity, or temperature. It is an important contributor to the health and comfort of an indoor environment. Specifically, ventilation serves two primary purposes: to provide fresh air for occupants to breathe and to dilute or remove contaminants. That definition is straightforward. What's less straightforward is whether the systems in these buildings are actually delivering on it.

Poor ventilation traps moisture generated by cooking, showering, breathing, and daily living. Without adequate air exchange, that moisture condenses on cold surfaces — walls, windows, concealed cavities — leading to damp, mould growth, and the gradual deterioration of building assemblies. These aren't cosmetic problems. They affect occupant health, structural integrity, and the long-term performance of the building envelope. This is what it means to say that ventilation affects the health of the occupant and the health of the building — and why addressing it is inseparable from any serious retrofit strategy.

In older buildings, the question isn't whether ventilation matters. It's whether the systems in place are actually delivering it. That begins with understanding the difference between natural and mechanical ventilation — and why that distinction increasingly determines whether a building meets modern expectations for indoor air quality, comfort, and code compliance.

Whether it’s a new build or a retrofit (as is the case of these five buildings), when it comes to ventilation, building managers and homeowners have two main options: non-mechanical and mechanical systems:

Non-Mechanical Ventilation: Also known as natural ventilation, this method uses wind and thermal buoyancy to move air through a building via windows, vents, or other openings. While simple and passive, it can lead to drafts, inconsistent comfort, and increased heating or cooling demands. Because it depends on outdoor conditions and pressure differentials, performance is often unreliable—especially during calm weather or in tightly sealed buildings.

Mechanical Ventilation: This method uses powered components—such as fans, heat exchangers, and ductwork—to control the movement of air. It offers control over air quality and temperature, regardless of external weather conditions. Mechanical ventilation offers a more efficient, predictable and secure manner of ventilation in comparison to open windows.

* In B.C., exhaust only ventilation used by all measured suites in the report has been unacceptable in Part 9 construction since 2014. Currently the B.C. Energy Step Code requires outdoor air to be supplied directly to each suite by mechanical ventilation. This reflects an evolving understanding of how airflow, IAQ, and energy use interact in MURBs

With mechanical ventilation systems, air exchange is controlled automatically rather than relying on open windows. This allows windows to remain closed, so that the heat generated by the building’s heating system stays within the space, helping maintain stable indoor temperatures while still providing fresh air

As older buildings undergo energy upgrades and retrofits, improvements to the building envelope often make them significantly more airtight. While this reduces heat loss and improves overall energy performance, it also increases the importance of providing a reliable, controlled source of fresh air. In these conditions, mechanical ventilation is no longer optional—it becomes a fundamental requirement for maintaining indoor air quality and occupant comfort in retrofit scenarios.

Within mechanical ventilation, there are two types of systems: centralized and decentralized.

Centralized systems typically employ fewer, larger air handling units (AHUs) located on the building’s rooftop or in a dedicated technical room, distributing air to the entire building or portions of the building through a network of ducts and grilles from a central location. Centralized ventilation systems distribute air through this duct network, where delivered airflow and system efficiency are influenced by duct layout, sealing, and overall air leakage within the distribution system. When leakage occurs, conditioned supply air may not fully reach occupied spaces, and the effective removal of stale air can be reduced, meaning rooms may not receive the full ventilation rate the system is designed to provide

Both system types have their place—but decentralized systems are uniquely well-suited to retrofits, where space, cost, and disruption are key concerns.

For decades, ventilation performance and the infrastructure used to deliver it have often been treated as inseparable. Building codes, testing standards, and design practices evolved alongside centralized ducted systems, which made duct distribution the default reference point when evaluating ventilation solutions. Decentralized ventilation requires a shift in perspective. Rather than assuming ventilation must be delivered through a shared duct network, systems like LUNOS demonstrate that airflow, heat recovery, and indoor air quality can be achieved directly at the room level. This distinction separates the performance requirements of ventilation from the distribution infrastructure historically used to deliver it, opening new possibilities for both new construction and retrofit applications.

While the BC Housing report highlights the limitations of the current ventilation strategies in these buildings, the reality is that replacing those systems entirely is often costly, disruptive, and structurally challenging. LUNOS can provide a practical alternative — not as a full replacement, but as a flexible complement that strengthens a building’s overall ventilation strategy. By working alongside centralized systems, Lunos helps owners deliver balanced airflow, address IAQ concerns, and reduce strain on aging infrastructure without triggering a full mechanical overhaul.

This approach is the foundation of a ventilation strategy: designing airflow intentionally—by combining centralized and decentralized systems to meet a building’s actual layout, condition, and usage. Lunos doesn’t compete with the existing system—it complements it. It delivers fresh, balanced air where centralized systems struggle to reach, without overhauling ductwork or disrupting tenants. The result is a tailored solution that meets code, improves comfort, and works with the building, not against it.

This is precisely the shift that makes LUNOS not just viable — but the logical choice. Once airflow, heat recovery, and indoor air quality are considered independently from centralized duct networks, decentralized solutions can be evaluated as practical tools within a broader ventilation strategy. By installing units directly within the building envelope, fresh air can be introduced and stale air removed at the suite level without requiring extensive ductwork or centralized mechanical rooms. This allows ventilation improvements to be implemented in a way that aligns with the realities of older buildings, where space, cost, and disruption are often the most significant constraints.

Delivering ventilation directly at the suite level — rather than through centralized duct infrastructure — creates practical advantages that matter most in precisely the buildings where traditional upgrades are hardest to implement.

Simplified Installation with minimal structural impact (Centralized systems are structurally invasive by design)

Ducted systems require ceiling drops, soffits, and bulkheads — transforming your building to fit the equipment. LUNOS fits the building. Each unit installs through a single 6.25-inch wall opening with no ductwork, no mechanical rooms, and no need to reconfigure walls, ceilings, or shared infrastructure. Units operate on low-voltage wiring and can be installed suite by suite with minimal disruption to occupants — making them particularly well suited to older buildings where low ceilings, tight wall cavities, or occupied conditions make centralized ductwork impractical.

Lower Costs (Centralized systems require more infrastructure by design)

Centralized systems come with high design, installation, and maintenance costs — because they're built to serve an entire building from a few centralized locations. LUNOS avoids this complexity entirely by working at the suite level. No ductwork, no mechanical rooms, no need for hallway pressurization or balancing dampers. Units operate at 1.4 to 3.3 watts per pair — a fraction of the electrical demand of centralized air handling equipment — and require only periodic filter changes rather than costly ongoing maintenance contracts. Heat recovered from exhaust air reduces the heating load on the building, lowering energy costs over time.

Enhanced Flexibility (Centralized systems remove control)

In a centralized system, airflow is balanced at the building level — and every suite lives with whatever that system delivers. In a decentralized system, each suite becomes its own ventilation zone. LUNOS gives building professionals the ability to tailor installations suite by suite, responding to each space's layout, climate, and usage patterns without overcomplicating the system. That same flexibility extends to the building as a whole. LUNOS can operate independently where no centralized system exists, or work alongside existing infrastructure — reducing the load on aging air handling equipment, filling the gaps centralized systems struggle to reach, and allowing a ventilation strategy to be built around the building's actual conditions rather than forcing the building to adapt to a new mechanical infrastructure. This design-level flexibility helps building professionals respond to real constraints—without compromising performance or compliance.

Air quality (Centralized systems distribute air unevenly)

When ventilation is designed around a single mechanical core, air often travels the path of least resistance. Some suites receive stale air, while others experience drafts or pressure imbalances. LUNOS decentralized HRVs address this directly by introducing fresh filtered outdoor air into each suite independently — removing dust, pollen, and airborne pollutants before they enter the living space, and making each unit particularly well suited to buildings in urban or wildfire-prone areas where outdoor air quality can vary significantly.

Because each LUNOS unit operates independently at the suite level, it also maintains true compartmentalization — preventing cross-contamination from adjacent suites and common corridors, which is one of the most persistent air quality problems in older buildings relying on corridor pressurization or passive ventilation. Stale air, cooking odours, and tobacco smoke stay where they belong rather than migrating through shared pathways.

Every LUNOS unit also includes a fine-mesh bug screen on the exterior wall penetration. In older buildings where windows and wall openings may not be fully sealed, uncontrolled pest entry is a genuine concern — particularly in summer when windows are open and occupants are actively ventilating. The bug screen ensures that the wall penetration LUNOS requires doesn't become an entry point, addressing a practical concern that matters to occupants and building operators alike

Want to see how decentralized ventilation fits into your building’s strategy?

Good ventilation is no longer a nice-to-have. It's essential for health, energy performance, and code compliance. In the next article in this series, we examine why the BC Housing study's own findings point toward suite-level ventilation as the necessary path forward — and why replacing equipment without changing the ventilation strategy isn't enough.

Explore Real-World Retrofit Applications

To explore technical considerations, system configurations, and real-world retrofit applications, see the examples below demonstrating how LUNOS can transform ventilation in aging buildings across Canada.