What is IAQ and how do we measure it?


Vince House of Aereco explores what indoor air quality (IAQ) really means as residents are confined to their homes more than ever.

There has been a lot of talk around Indoor Air Quality (IAQ), especially during the pandemic, but what does IAQ really mean? There are various pollutants in the air which will contribute to poor IAQ, one of those being Carbon dioxide (CO2). Recorded levels above 1000 parts per million (ppm) inside properties can be associated with deteriorating air quality, so it seems like a good measure to focus on.

What is interesting is when we monitor CO2 and moisture together, they rise and fall at almost the same rate. This stands to reason as generally where there is a human there is also CO2 and moisture caused by breathing. As a result, in the right circumstances using moisture as a proxy to CO2 can be just as effective as measuring CO2 itself. While also providing the benefit of measuring moisture too, this is often not the case in reverse.

There are of course other things we can measure. Total Volatile Organic Compounds – or TVOC’s – are becoming more well–known now, and can have a damaging effect on our internal environment. VOC’s are gasses which emanate from all sorts of things in our homes, furniture, toys, deodorants, paints, aerosols, cleaning products, etc. The list is exhaustive. There’s also Radon gases in parts of the country, NO2 and PM10, 2.5, 1’s and below (of which there is still extensive research being carried out to understand the effects).

When talking about ventilation, some are quick to talk about air conditioning to continue the conversation. It is important to note however that although the name “air conditioning” would imply that the air is being purified, it is not always. These units heat or cool the air, but unless they take the air out and replace it with fresh air, they are not providing ventilation. The true definition of ventilation is “the controlled or designed replacement of stale indoor air with fresh outdoor air.” Sounds easy, but it is much harder than you would think.

By and large, it is us and what we do in our homes that causes stale air; cooking, cleaning, washing, even breathing – all these things contribute to reducing the IAQ. A typical family of four will produce 16 litres of moisture a week.

One issue lies in the fact that we are all unique and we all have different habits and lifestyles. This can be very difficult if you are looking to set just the right level of ventilation in a home for good IAQ, as there is a constant moving target. Each room will have a rising and falling demand for ventilation at different times of the day. If you over ventilate, there will be comfort issues as the property will be too cold. If the ventilation is not enough, this will lead to issues with excess moisture in the home, causing condensation and ultimately creating an environment for mould to develop and grow.

Ventilation often gets overlooked by landlords and housing professionals when other home improvement measures are being installed. Improving insulation or upgrading windows to reduce infiltration can put a strain on the existing ventilation system (unless it had been designed to deal with more airtight properties). The results can be very damaging to IAQ and the buildings.

So, how can we effectively measure IAQ in our homes? There has been a real step forward in low cost monitoring equipment, and it has become much more popular in recent years with Smart Home controls, for instance.

There has been a shift towards large monitoring schemes by housing providers, Peabody, Renfrewshire, Flagship and Riverside Housing to name just a few. Big data seems to be the way forward to monitor the IAQ and health of buildings.

A recent survey into ventilation carried out by Aecom for the Government concluded that 79 out of 80 properties did not meet minimum building regulations. Monitoring would certainly highlight these issues quickly.

One thing is certain, that the more information we gather, the more we learn about the internal environment, the more equipped we are to overcome any issues found.

Vince House is head of Sales and operations UK at Aereco