Ask the Expert

Air Up There

Ensuring indoor air is fresh, clean and safe is one of many tasks that boards and managers must oversee on behalf of

their residents. SARS-CoV-2, the virus that causes COVID-19, has made this even more daunting. The World Health Organization tells us the virus normally spreads through tiny droplets when an infected person coughs, sneezes or even speaks. This knowledge has caused prevailing uncertainty over potential exposure to the virus through building ventilation systems. How concerned should condo communities be and what measures can they undertake to reduce transmission? Robert Borovina, director of mechanical engineering at McGregor Allsop offers some guidance.

The American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) has recently published their position document on infectious aerosols, in which they state that transmission of SARS-CoV-2 COVID-19 through the air is sufficiently likely, so airborne exposure to the virus should be controlled.

The document also states that ventilation and filtration provided by heating, ventilating and air-conditioning (HVAC) systems can reduce the airborne concentration of SARS-CoV-2 and therefore the risk of transmission through the air. Disabling HVAC systems is not a recommended measure to reduce the transmission of the virus.

In general, pathogen transmission through the air occurs via droplets or aerosols. While larger droplets fall by gravity to the floor or surrounded surfaces within two metres of their source, the operation of the HVAC systems do not affect their transmission. Contrary, the smaller infectious aerosols, such as droplet nuclei (particles smaller than 10 microns) that can form from desiccation (drying) of the larger droplets, can stay suspended in the air for longer periods, with HVAC system operations affecting their pattern.

Precautionary Measures

There are a number of measures to reduce the transmissions of pathogens via HVAC systems, however, few can be readily implemented. They include:

Dilution of room air by increasing the amount of outdoor air in the overall recirculation;

Increasing the efficiency of the filtration system or use of single space high-efficiency filtration units (portable or fixed);

Maintaining proper temperature and relative humidity to reduce desiccation of larger droplets into aerosols.

HVAC for condominium buildings is quite different from commercial office buildings. Some precautionary measures that may require implementation in commercial buildings are not necessary for condominiums.

Reducing Transmission in Floor Corridors, Suites and Common Spaces

There are three distinctive HVAC systems in typical mid to high-rise condos. The first one is HVAC for the floor corridors. These areas are served by the dedicated make-up air unit (MAU) that supplies 100 per cent of outdoor air, without any recirculation within the building. In some cases, the MAU only provides heating and ventilation and in other cases air conditioning as well. Since the MAU only provides outdoor air there are no special filtration sections required, other than standard filtration for this type of operation. The MAU generally does not provide humidification during winter months.

The second HVAC system relates to the individual suites. This typically includes fan coils or heat pumps. In newer buildings, individual suites are also equipped with

dedicated energy recovery ventilators (ERV), that provide continuous ventilation for the suites, utilizing energy recovery from the suite bathroom exhaust.

In older buildings, pressurized corridors provide outdoor air for suites, forcing air through the door cracks of the individual suites that are normally kept under negative pressure through centrally or individually operated bathroom exhausts. In buildings where suites are provided with ERVs, there is practically no possibility of cross-contamination between corridors

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and individual suites. In buildings where suite ventilation is provided via pressurized corridors such a possibility exists, especially in winter months when dry make-up air can desiccate droplets into aerosols capable of being suspended in the air for longer periods. Although dilution of the air in the corridors is significant, due to a large amount of outdoor air being introduced into such areas, it would be a good practice for residents to carry protective wear when walking through the corridors and elevators, primarily to prevent possibility of creating droplet particles by coughing or sneezing.

The third HVAC system relates to common spaces, such as lobbies, recreational rooms or facilities. Due to the building stack effect, lobbies are generally diluted with large amounts of outdoor air any time the main entrance doors are used, so no additional measures for the HVAC units are required. The outdoor air for recreational rooms or facilities are usually directly ducted from the outside to the HVAC units serving such spaces. The amount of outdoor air is usually limited to two air changes per hour at the best, which is not enough for proper dilution of the air in the space. In cases where upgrades to the HVAC system to enable larger amounts of outdoor air are too costly or technically challenging, it is recommended that such spaces become equipped with high efficiency, self-contained filtration units. It is also recommended that temperature and relative humidity is kept at the proper levels, especially in the winter.

Although preliminary research results have been released on the transmission of COVID-19, there is a general consensus that HVAC systems in non-medical buildings may contribute very little to the transmission of the disease. This is particularly true for condos, therefore, basic principles of social distancing, surface cleaning and disinfection, should be more important at this moment than contemplating major retrofits of the HVAC system. 1

Robert Borovina is the director of mechanical engineering at McGregor Allsop, Toronto. He brings 37 years experience in all aspects of HVAC engineering.

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The Design-Build Advantage

The benefi ts of a condo refurbishment partner

Condo refurbishment reaps benefi ts for owners and residents alike. Making it through the process successfully, however, is no small task. From planning to design, and project scheduling and team coordination, refurbishments can overwhelm even the most seasoned property management team. Here’s where partnering with a Design-Build General Contractor can have its advantages.

“There’s a lot to consider during a refurbishment, and there are challenges throughout every stage that require the perspective of an experienced contractor,” says David Petrozza, a Director at PAC Building Group. “Having a Design-Build partner at the table from the very beginning provides property managers and owners with additional skills, knowledge, and insights they need to see their vision through.”

A PARTNER FOR ALL PHASES There are numerous reasons why property stakeholders trust end-toend contracting fi rms to quarterback a project. At a high level, they include:

Single point of contact: Between architects, designers, engineers, and on-site crews, there is no shortage of teams to keep track of during a refurbishment. That said, having a general contracting partner to serve as your voice and manage thirdparties reduces stress, strengthens collaboration, and helps to avoid miscommunications.

“It simply comes down to having one contract, and a single point of responsibility,” says David. “The key advantage of a specialized contractor is leveraging their management process. They integrate all the moving parts necessary to complete a project, and that has tremendous value.”

A consistent vision: It’s diffi cult to see a vision from its inception to completion. Having a specialized Design-Build General Contracting fi rm on the team from the start ensures all parties (trades, residents, property teams) begin on the same page and remain in alignment. Here again, establishing a single point of contact between property owners/ managers and their refurbishment teams keeps everyone on track and moving towards the same goals.

Greater accountability: With a single point of contact comes greater visibility into the progress of a refurbishment. General contractors can be the “eyes on the ground” to monitor activity, address challenges, and hold other trades and vendors to task.

“All workers are an extension of the contractor and need to represent the client accordingly,” says David.

Safety fi rst: Timelines and budgets are key, but nothing is more important than keeping everyone safe. This includes the crews on the ground, building residents, and the property management team. Herein, an experienced general contractor can enforce leading safety practices at all times and ensure worker health and wellbeing is a top priority throughout all the stages – even, for example, through a worldwide pandemic.

For example, says David: “As a reopened business, we adapted with new policies and procedures to operate under Ontario’s health and safety guidelines. We are positioned to approach all projects with a focus on constant sanitization and optimal physical distancing.”

Avoiding surprises: A general contractor will know what to watch out for. As such, they can help tackle (or outright avoid) the common pitfalls and “surprises” that creep up during a refurbishment project. After all, says David, “It’s construction – there can always be new challenges.

That’s why being dynamic and responsive is imperative to a contractor’s success in upholding their client’s best interest.”

PUTTING RESIDENTS FIRST

The success of a refurbishment project is measured largely by its impact on residents. To that end, one of the largest advantages of working with a Design-Build general contractor can help keep resident comfort, safety, and preferences in the spotlight through each stage.

“It’s important to be proactive and communicative with building occupants that will be directly affected by any construction work,” offers Rep, adding, “Transparency in condo communities ensure there are no surprises and enable a project to transition smoothly through the primary phases of construction.”

Yet while keeping residents in the spotlight is key during construction, making sure their voices are heard during initial planning is also critical for delivering results that make all the disruptions and investments worth it in the end.

“At the end of the day, it’s about creating spaces where people can thrive,” notes Rep. “It is not simply about changing carpet, wall-paper, and paint; We believe every condo renovation project is an opportunity for a fundamental re-invention and elevation of the human experience.”

David is with PAC Building Group. For more information visit

www.pacbuildinggroup.com