Passive Ventilation: An Active Approach to Fresh Air

In the wake of the ongoing pandemic, architects and specifiers are engaged in holistic discussions around the design and construction of healthy buildings with low risk of disease transmission. One key area stands out: high-quality fresh air.

Recognised for its long and short-term effects on buildings occupants’ health and wellbeing, indoor air quality (IAQ) can make or break a comfortable, even livable, environment.

Symptoms of poor IAQ range from increased allergies, asthma issues and light-headedness to headache and grogginess, called Sick Building Syndrome. At their worst, symptoms include stress, anxiety, poor mental health and serious pulmonary and respiratory disease.

In the care home setting, the risks of leaving IAQ unchecked are high, both for vulnerable residents and the staff who care for them.

Fortunately, passive ventilation offers specifiers an effective, sustainable way to introduce high quality, fresh air into a building.

Here I would like to take the opportunity to clear up a common misconception about natural ventilation, explore its benefits and how it works, the practicalities of installation and its role on the road to a sustainable future.

PASSIVE, NOT PASSÉ

Essentially, passive ventilation is the process of supplying and removing air from a space, with minimal or no mechanical aid. Unfortunately, it is often regarded as little more than manually opening and closing windows.

Modern systems have evolved somewhat, able to incorporate sensors to monitor for variables inside and out, as well as integrate with most common building management software and systems.

These smart controls automatically ensure rooms are supplied with the appropriate amount of ventilation for a healthy indoor environment, keeping the temperature constant and at a pleasant level. This also removes the need for constant manual adjustment.

FEELING FRESH

A 2020 Harvard study of over 3,000 workers across 40 buildings found 57% of total sick leave could be attributed to poor IAQ. A different study of the impact of IAQ in schools revealed a positive correlation between student absence and increased CO2 concentration levels.

It’s not difficult to extrapolate the implications for care homes, where staff play a vital role and residents don’t have the option to go home somewhere else at the end of the day.

Compared to pure play mechanical systems, natural ventilation is associated with lower incidences of fatigue, headaches, throat irritation and concentration problems.

A STUDY IN GREEN

In line with the government’s, and NHS’s, drive towards Net Zero 2050, we’re likely to see passive ventilation systems become the norm in care homes, and the wider built environment, as opposed to the exception.

It’s a key component towards reducing reliance on carbon-intensive mechanical ventilation systems, one integral piece of a much larger green puzzle. Going further, where care homes are designed with eco- friendly building techniques, such as low-energy lighting and a ‘fabric first’ approach, the impact of passive ventilation systems can be amplified to help facilities managers achieve optimal building performance.

It would be short-sighted to suggest that a solely passive approach is the only way forward. The best solutions are situation specific, taking location, design and purpose into account. This may sometimes mean a hybrid approach is most appropriate, which can, in fact, prove to be even more efficient than a purely natural solution.

THE WAY FORWARD

Facilities managers need to understand the benefits of and feel empowered to engage with new ventilation strategies. While they may be carbon intensive, many of the most popular HVAC systems are those that people know, and are comfortable with.

Many care homes may require re-engineering to integrate passive ventilation systems. Fortunately, retrofitting PV is relatively low impact depending on the windows and vents already present. Even where new windows are needed, the disruption is low compared to installing a whole mechanical system.

Ultimately, there are real benefits which will be quickly registered and make the change worthwhile. Not only will care homes see a marked improvement in resident wellbeing, but also a happier, more focused staff, as well as a more sustainable outlook for the future.