Maintenance and Repairs

July 15, 2026 Published by Golden Horseshoe Chapter - By Jaime Rodriguez

Modernizing Makeup Air Units: Improving Comfort, Efficiency, and Building Performance in Aging Condos

From the Volume 28, Summer 2026 issue of the CCI GHC Condo News Magazine

Between the late 1990s and early 2010s, the Greater Toronto Area (GTA) experienced a substantial wave of mid- and high-rise condominium construction. Driven by the 2005 Greenbelt Act and broader urban intensification policies, this development transformed the region into one of North America’s most vertically urbanized metropolitan areas and shifted the housing market from mid-century rental apartments toward investor-driven condominium presales. Similar trends have continued across Southern Ontario, including throughout the Golden Horseshoe.

Because a large wave of mid-and-high-rise condominiums were built, a vast cluster of vital rooftop and mechanical equipment are aging out simultaneously, especially MUA units or MUAs. Many condo MUAs are reaching their end-of-life because these continuous-duty mechanical systems generally last only 20 to 30 years.

Replacing or upgrading aging makeup air units can improve system reliability, reduce operating costs, and enhance overall building performance. Understanding the role these systems play, the factors that contribute to their deterioration, and the indicators that signal the need for modernization can help condominium boards and managers make informed decisions and plan proactively.

What are MUAs

MUAs serve a fundamental purpose in condominium building ventilation by introducing fresh outdoor air to replace indoor air that has been exhausted from the building. When exhaust systems remove air from corridors and other common spaces, that air must be replaced to prevent negative pressure conditions that can compromise safety, comfort, and other equipment performance. Without adequate MUA, buildings can experience back drafting of combustion appliances, difficulty opening doors, reduced exhaust hood effectiveness, and infiltration of unconditioned air through unintended pathways. These units differ from standard HVAC systems in that they handle 100% outdoor air rather than recirculating indoor air. The energy implications of conditioning 100% outdoor air are significant, which is why modern MUAs increasingly incorporate sophisticated heat recovery technologies, variable speed controls, and intelligent management systems. As energy costs rise and environmental regulations tighten, the efficiency of MUA systems has become a critical factor in overall building performance and operating costs.

Factors Contributing to the Deterioration and Obsolescence of Makeup Air Units

There are several mechanical, environmental, and technological reasons that result in deterioration of MUAs over time:

• Mechanical Wear and Tear: MUAs run continuously year-round, conditioning massive volumes of freezing outdoor air in the winter and humid air in the summer. Over time, bearings wear out, belts degrade, and fan blades suffer from fatigue.
• Harsh Climate Exposure: In Ontario and similar climates, extreme temperature fluctuations and freeze-thaw cycles cause significant stress and rust to the metal cabinets, dampeners, and interior housing.
• Outdated Controls and Parts Obsolescence: As units age, electrical boards fail, and replacement parts are frequently discontinued by the original manufacturer, making ongoing repairs uneconomical.
• Decreased Energy Efficiency: Older units use constant-speed motors and lack modern heat recovery capabilities, causing them to consume substantially more energy and fuel than today’s high-efficiency models.
• Safety and Regulatory Risks: Gas-fired heating coils and heat exchangers eventually rupture or perforate due to constant heating and cooling. This can draw dangerous combustion gases into the building’s air supply, necessitating immediate replacement for fire and life safety compliance.
• Resident and building maintenance staff complaints: Typically, when MUAs begin to degrade, you will begin to receive comments and objections from building occupants regarding uneven suite temperatures, air quality discomfort, constant repairs and maintenance challenges.

State of the Art in MUAs

Energy efficiency is driving innovation in MUA unit design and operation. Heat recovery systems typically recover heat in the exhaust air and have significantly improved the energy efficiency of buildings, representing a dramatic advancement over traditional systems that simply exhausted conditioned air without recovering its thermal energy.

Modern MUA units employ multiple strategies to minimize energy consumption. Variable speed fans adjust airflow based on actual demand rather than running continuously at full capacity, reducing electrical consumption during periods of lower ventilation requirements. Advanced motor technologies, including electronically commutated motors (ECMs) and permanent magnet motors, deliver the same airflow with significantly less energy input compared to traditional motor designs.

These systems can be customized with a variety of cooling and heating options, filtration options, direct digital control (DDC) systems, and sizes and configurations to meet your application needs, allowing building owners to optimize their MUA systems for specific operational requirements and climate conditions. This customization extends to the selection of heat recovery technologies, with options including plate heat exchangers, rotary heat exchangers, heat pipe systems, and run-around coil configurations, each offering distinct advantages for different applications.

These advanced units can be controlled remotely, often via smartphones or home automation systems, allowing for better control of air quality and energy use. Integration with smart home systems is becoming more common, as consumers seek seamless, efficient solutions that can adapt to their specific needs. This trend toward intelligent, connected systems represents one of the most significant shifts in MUA unit technology.

Modern MUA units increasingly feature sophisticated control systems that go far beyond simple on/off operation. The integration of smart technologies like IoT enables real-time monitoring and optimization of ventilation systems, enhancing their appeal. These systems can monitor multiple parameters including outdoor temperature, humidity, indoor air quality, exhaust fan operation, and building pressure, making continuous adjustments to optimize performance and efficiency.

Integration with building automation systems (BAS) allows MUA units to coordinate with other HVAC equipment, lighting systems, and occupancy sensors to optimize overall building performance. For example, a MUA unit can automatically adjust its operation based on signals from kitchen exhaust hoods, reducing airflow during periods of low cooking activity and ramping up when exhaust demands increase. This coordination ensures proper building pressurization while minimizing energy waste.

Reserve Fund Planning and Lifecycle Cost Considerations

Long-term financial planning is essential to ensure the continued maintenance and replacement of building mechanical systems. A well-funded reserve fund provides the financial framework necessary to support the future repair or replacement of aging MUAs as they approach the end of their service life.

A careful evaluation of the building’s mechanical systems by experienced mechanical specialists will present a complete view of the MUAs state and estimated useful life remaining with a 30-year projection review, to provide a true picture of the condition and have a financial plan for repair or replacement.

By looking at both the immediate and long-term, it is possible to establish a reserve-funding plan, that accurately predicts the HVAC needs of the building. This projection gives the Corporation the necessary information to develop yearly contributions, based on an average over several years, and assists its investment strategy for the funds as it identifies when repairs will be needed.

A well-maintained building and well-funded reserve can help to increase the value of the property by demonstrating to potential buyers and lenders that the corporation is committed to maintaining the property in good condition.

Managing Occupied-Building Retrofit Projects

Managing replacement of mechanical systems while the building is occupied requires coordinating construction efficiency with occupant comfort. Some strategies to achieve a well-planned project include effective, open resident communication, phased construction staging to minimize disruption, and establishing a single point of contact. It is crucial to coordinate work hours around peak usage times.

Executing major MUAs upgrades without disturbing occupants requires meticulous, organized management. Core strategies include:

Construction

• Sequential Staging: Breaking the projects into smaller, manageable, chronological segments. This method isolates specific tasks to maintain continuous site operations, protect workers and the public, and systematically advance the build without overwhelming infrastructure.
• Zone-by-Zone Approach: Sequence the work by floors, wings, or specific risers. This isolates the active construction zones, confining noise, dust, and utility shutoffs to limited areas rather than the entire building.
• Targeted Scheduling: Confine heavy, intrusive construction to designated daytime weekday hours minimizes disruption to the occupants’ routines.

Resident & Occupant Coordination

• Single Point of Contact: Designate a dedicated liaison (like a retrofit manager) to field inquiries, coordinate schedules, and handle access arrangements.
• Clear Notice Protocols: Issue structured timelines specifying when different units or spaces will be affected by utility shutoffs, suite entries, or hallway blockages.
• Swing Spaces: Provide designated quiet spaces or temporary relocation areas within or outside the building to give vulnerable or sensitive occupants a refuge.

Dust, Noise, and Air Quality Controls

• Containment Strategies: Utilize temporary barriers, negative air pressure machines, and specialized dust-containment tents to prevent construction debris from spreading into occupied common areas and units.
• Material Management: Store heavy materials, equipment, and hazardous items securely away from active common areas and walkways to protect building occupants.

Resources and guidelines are available for specific regions. In Canada, for instance, you can consult the A Field Guide to Retrofits in Occupied Buildings or explore resources offered by the Canada Mortgage and Housing Corporation (CMHC) for proven multi-unit best practices.

As condominium buildings constructed during the late 1990s and early 2000s continue to age, many MUA units are approaching the end of their operational life. Replacing these systems presents both technical and financial challenges; however, modern MUA technologies offer significant improvements in energy efficiency, indoor air quality, system reliability, and building performance. Through proactive reserve fund planning, comprehensive condition assessments, and carefully managed retrofit strategies, condominium corporations can reduce lifecycle costs while improving occupant comfort and environmental performance.

Replacing an MUA is a major capital project that requires careful planning, as it often involves renting industrial cranes to lift equipment to the roof and extensive rewiring.

If you are looking to understand the timeline or costs for your specific complex, I can help:

• Review your building’s most recent engineering or Reserve Fund Study.
• Compare the replacement costs and energy savings of modern MUA technology.

Let me know if you would like to narrow down the details for your location.

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Jaime Rodriguez, B.Tech (Arch.Sc.), C.E.T., RRO, Branch Manager, leads operations in Southern Ontario and the GTA at Keller Engineering. With a focus on building science, mechanical, and building envelope engineering for condominiums, Jaime and his team provide design support and repair/replacement planning, quality control, building envelope forensics, diagnostic testing, and contract management services. He is primarily engaged in project management, delivering technical expertise, as well as building condition assessments, and Phase I Environmental Site Assessments.