The issue of Interior Air Quality (IAQ) has gained importance during recent discussions surrounding the post-COVID building environment, forcing owners and developers of commercial and public buildings to take a fresh look at air filtration.
In fact, groups of scientists around the world are pressing the World Health Organization (WHO) to issue international air quality and humidity standards. Some suggest that air distribution and filtration systems in commercial and public buildings should more closely match those installed in hospitals.
It’s important that the residential building industry is not left out of these discussions.
The issue has become more critical as building codes across the country begin requiring increased insulation and tighter building envelopes. Coupled with the recent fear of airborne viruses, it should result in more attention being placed on the ‘V’ in Heating, Ventilation and Air Conditioning (HVAC) systems for residential projects of all sizes.
“Occupants generally have little control over natural ventilation, aside from opening and closing windows,” says Health Canada. “Ventilation solely by window opening can lead to excessive energy costs, particularly due to heat loss in the winter or loss of conditioned air in the summer. Window opening can also create challenges in managing relative humidity in the winter and summer.”
Heat Recovery Ventilators (HRVs) and Energy Recovery Ventilators (ERVs) are widely regarded as superior mechanical solutions to address IAQ in individual homes. Yet, there is little direct guidance regarding these advanced devices in Canada’s current National Building Code (NBC).
Part 9 of the National Code 9.32.3, covering buildings less than three storeys and 600 square-metres in area, does not specifically require an HRV/ERV or any other defined ventilation systems. Instead, the code outlines overall ventilation requirements and performance specifications that can be achieved through various mechanical solutions. The necessary performance criterion could be met, it says, using a series of exhaust and supply fans and air balancing systems, including HRVs and ERVs, and even elements of the heating and cooling system itself.
Similar guidance is mirrored in almost all provincial buildings codes across the country. The notable exception is Ontario. In January 2017, the Ontario Building Code SB-12 was revised to require HRVs in all new homes.
Of course, building codes across Canada prescribe only minimum requirements. There is no reason why builders of homes, apartments and condominiums can’t do better. In fact, consumer demand in the post-COVID-19 world may insist on levels that exceed code-minimums.
Air quality in apartment and condominium buildings is particularly ripe for improvement. As part of overall energy efficiency and air filtration upgrades, developers are beginning to consider the replacement of whole-building systems with individual HVAC systems in each unit. Operating windows can also be retrofitted. However, the associated costs for older buildings, let alone for new ones, can run into the millions.
There are, however, non-mechanical ventilation improvements that are not particularly costly to incorporate into new buildings, such as reconfigured common areas, wider stairwells and private outdoor spaces like balconies for all units.
At the high end of the market, increased private green spaces, larger kitchens, elevators that service fewer units, separate delivery entrances and touchless technology are other features that can increase occupants’ air quality and safety. The dilemma facing developers of larger residential buildings is how much renters and purchasers are willing to pay.
Are there environmental consequences of improved IAQ systems? Some argue that mechanical systems like HVACs increase energy use and consequently create more greenhouse gas emissions. However, this is countered by NBC data published in B.C.’s Heat Recovery Guide for Houses that show how HRVs and ERVs can, in fact, reduce overall heating and cooling energy costs depending on local climates. Annual savings range from $50 in Vancouver to $160 in Fort McMurray, Alta.
Rethinking air filtration, ventilation and building design will likely start with higher end homes, apartments and condominiums. How much will trickle down to mid and low-priced housing is the question.
John Bleasby is a Coldwater, Ont.-based freelance writer. Send comments and Inside Innovation column ideas to firstname.lastname@example.org.