By Ian Rogers, Sales Director Gilberts Blackpool

Indoor air quality (IAQ) is now an established concept in modern building. What is not established is how we can actually achieve it, especially in non-domestic buildings. However good the design on paper, too often it differs from what is actually built and fails to address how the occupants will utilise the space.

We spend 90% of our time indoors(1), of which for most of us a large proportion is spent at work or at play. Without wishing to scaremonger, dirty air in non-domestic buildings may contribute to almost as many deaths as outdoor air pollution(2), which is already a staggering 48,000+ each year(3)! That starkly shows why indoor air quality (IAQ) matters.

New research by the University of Leeds(4) is calling for improved legislative air quality performance standards to be set, to address levels of key pollutants such as carbon dioxide and carbon monoxide, to ensure recommended numbers of air changes, and to address indoor-generated pollutants so they are removed faster than they are generated. 

It may seem odd, but currently there is NO legal requirement nor standard. Building Regulations are only advisory/good/best practice. BREEAM allocates credits for indoor air quality (Hea 02), but that is just one element of a bigger scheme. Maybe it is time for a dedicated IAQ grading system to be introduced- an equivalent to the hygiene standard for catering establishments- that puts good IAQ as a legal requirement…?

It matters. Good indoor air quality is key to our health, wellbeing and performance. With the drive to reduce emissions and be energy efficient, we are building tight to conserve heat within and avoid uncontrolled, gratuitous ventilation with its associated heat loss but in the process often failing to get the ventilation balance right. Hence why Sick Building Syndrome- a key indicator of poor indoor air quality- is still a major influencer in our workplaces(5).

We know what the ventilation should do and design in elements to provide the Regulatory airflow (minimum 10m3/hr/m2 @ 50Pa). We forget or ignore that the occupants will undermine the design intention through intellectual misconceptions and lack of understanding. They will shut windows to prevent heat loss or external noise penetration (sound too is an air pollutant!). They will forget to open trickle vents. They will turn off continuously running fans again because of the noise or assumed cost.

Perhaps therefore we- the architects, building services consultants and everyone involved in delivering a great indoor environment -need to take control?

In non-domestic buildings, this is easier than we think! Building management systems will monitor and control the main plant within the designated presets. Appropriate choice of air delivery- the grilles and diffusers- also affects the IAQ. Advances in technology now mean too that we can finitely control the ventilation within each zone/sector to maintain the desired air quality and comfort. And they have the benefit of, where relevant, the airflow direction being set at the time of installation. There is no potential nor need for occupant intervention nor involvement going forward.

The grilles and diffusers need to be chosen to effectively deal with the specific issues in each zone, to maintain the determined indoor ambient temperature, velocities and acceptable C02 and noise levels. There also needs to be consideration as to the use of the space- computers generate heat, food preparation zones generate smells and steam, people generate heat and cough, sneeze, splutter. Doors opening and closing transfer air in and out- whether from different zones internally or a rush of cold air from outside. All these activities affect the air quality- the humidity, temperature and airborne pollutants. 

One has to consider the space and positioning of the grilles and diffusers to maintain comfort conditions, not just across the space but in relation to each other, bearing in mind the air velocity will decay over the length of the air throw. 

The latest evolution is thermal sensitivity, whereby the air delivery unit automatically senses a change in ambient temperature and adjusts the airflow vertically or horizontally to maintain the preset without any stratification or cold ‘dumping’. All this happens within seconds, to the extent the occupants most likely do not even notice, and without any requirement for auxiliary power!

With the latest computer modelling software we can test and validate all aspects of the ventilation whilst our designs are still on the drawing board. We can see how the air will move within the space and at what speed. We can adjust the air change rate to influence the IAQ and make adjustments to the design to improve the performance- for example, adding a Coanda plate to a swirl diffuser in exposed ductwork will enhance the throw and intermixing of the fresh incoming air. 

The objective of achieving good IAQ does not mean aesthetics are impaired. For example, it is the shape of the Coanda plate rather than its composition that affects the air movement. The Coanda can be manufactured from numerous materials, powder-coated, foiled or even backlit! Similarly, the face plates of many grilles and diffusers can be bespoke designed to reflect a particular motif or branding.

We as manufacturers are giving you as architects the tools to deliver good IAQ without compromising your design. Let’s make good use of them, to create the best occupied internal environments we can!