Uncomfortable Occupants Cost More Than Efficient HVAC Systems


Azmi Abou Hoda

For building owners, improved indoor air quality will increase the value of their building. For business owners, it will increase the productivity of their employees. That’s according to Azmi Aboul-Hoda, Managing Director at EMergy, who has pinpointed a negative trend among building owners where they sacrifice air quality in a bid to drive down energy costs.

He argues that this trend doesn’t make sense from a commercial point of view and breaks down the numbers to prove it. He calculates that the cost of people in the Middle East, their salaries, and the cost of building operations (excluding energy), comes in at around $6800 per square metre per year. Comparatively, the average cost of energy is only $55 per square metre per year.

“The people cost in your building (salaries, etc.) is 100, and the energy cost is only 1, so if we do something in a building to sacrifice air quality, and it in turn reduces productivity, even just one percent of productivity, that is equal to the cost of all the energy the building consumes.”

The good news is that there are ways to increase efficiency of HVAC systems and operation in order to reduce the energy cost, without sacrificing the indoor air quality.

First and foremost, understand how the building operates, how it behaves, how people use it, what they need, and what they don't need. Understanding all of this and more will help propose the correct solutions to improve indoor air quality.

Second then, based on the output requirements and especially in the Middle East, is to consider which standards to follow. The ASHRAE 62.1 Standard, for example, is based on people who are adapted to the space - when someone enters into a new area they need 10 to 15 minutes to adapt to the air quality in that space. Meanwhile, several European standards are based on non-adapted people, and require much higher rates of fresh air.

Azmi uses a comparison between retail stores and office spaces to show different criteria to consider: if you are doing ventilation design for a retail store, and are concerned about visitor optimum satisfaction in terms of air quality, then use a standard based on non-adapted people, since visitors of a store don’t enter the space at the same time; unlike meeting rooms, for example, where people normally enter all together.

Speaking on which of the latest HVAC trends is most prominent to him, Azmi point to personalised ventilation. He asks us to consider the amount of fresh air supplied to a building and then the huge cost of cooling this fresh air, saying that only one percent of that fresh air is actually being used - the other 99 percent is getting recirculated and is becoming return air.

“Why not deliver this fresh air directly to the people using it? So, instead of delivering 1,000 litres per second of fresh air to a huge space, and mixing it with return air, lets deliver 100 litres per second, but make it more personalised by using outlets on or above work stations, right next to people. This is a clear example of how one can improve the indoor air quality, while reducing the energy costs.”