Buildings account for a massive 40% of global energy usage, making them an obvious target for potential savings. HVAC systems alone – that’s heating, ventilation, and air conditioning – are responsible for 38% of a building’s consumption. In a world that urgently needs to become more sustainable, we cannot ignore the opportunities to increase the energy efficiency of HVAC systems. Let’s look at what the future holds for ventilation.
Energy-efficient ventilation on demand
Ventilation has many scientific and technical definitions, but its main objective is to bring clean outside air in, while removing the pollutants that are generated indoors. When it comes to energy efficiency, not all ventilation systems are created equal. Demand-controlled ventilation matches the airflow rate to the demand, based on accurate CO₂ measurements. This means a lower average airflow rate without over or under ventilation, and less energy needed for fans, heating, and cooling.
In fact, a demand-controlled ventilation system with CO₂ concentration control can use over 50% less energy than a constant air volume system. It also keeps the indoor temperature at a comfortable level for building occupants. This type of system ensures the level of ventilation is always optimal even in spaces where the occupation level varies over time – when the CO₂ level is high, the system will ventilate more; when the level is low it knows that less ventilation is needed.
The importance of clean, healthy air
Energy savings are crucial, but they’re not the only important factor to consider. Indoor air quality is also a health issue – airborne transmission is the dominant mode of transmission of any respiratory infection, making the way buildings are designed, operated, and maintained an essential factor in minimizing the spread of airborne disease. Often people don't realize the impact that ventilation and indoor air quality have on building occupants. For example, scientific research shows that improved ventilation and air quality:
• Improve health and decrease sick leave rates
• Alleviate sick building syndrome
• Improve people’s performance and productivity
• Improve sleep quality
This makes it extremely important to have clean air and a low concentration of CO₂ in occupied spaces – not to mention the significant effect productivity improvements can have on a company’s bottom line.
Consider outdoor air quality
There are increasing concerns about how best to prevent outside air pollution affecting indoor air quality. Outdoor air quality can vary widely depending on the day or time of year. Ventilation should be increased when the outside air is clean, and reduced or even stopped if the outdoor air quality is very low. In these cases, indoor air should be recirculated to prevent polluted air from entering the system.
In the future, ventilation will need to be controlled more frequently based on outdoor air quality. This is supported by the fact that for many indoor pollutants it is the average exposure that informs their risk, not the peak values. That means that it is sometimes best to reduce ventilation and increase indoor air pollution levels for a few hours, then ramp up the volume of outdoor air when the quality is higher to bring down indoor air pollution levels. All of this makes being able to monitor air quality and control ventilation essential.
Looking to the future
The European Performance Directive is being revised in 2023 to state that indoor air quality should be measured and controlled. This directive will be adopted in European member states in the next few years, making it compulsory for all new buildings. Currently around 30% of new buildings use demand-controlled ventilation, but experts predict that figure will rise to 50% and beyond in the next 10 years.
In the future there will be more and more indoor air quality-based control measures, with ventilation being just one of these. Protection against airborne infection will also be considered, with future ventilation guidelines and building codes taking it into account. New global regulations to ensure clean indoor air are likely to be introduced in the coming decades.
Sensors you can rely on
As discussed, CO₂ measurements give an indirect indication of indoor air quality and how well your ventilation system is working. To measure CO₂ you need reliable sensors, which should be placed so that the reading is representative of the air quality in that specific room. One common mistake is to install the sensors where they are exposed to supply air flow, which is clean air. Another is installing a low-quality sensor in the return duct, where it is exposed to all the dust in the room, which can lead to malfunction.
Vaisala Carbocap sensors, such as the GMP231 CO2 probe, use sensing elements that provide long-term measurement stability and are impervious to dirt and dust. This makes it extremely reliable, making it the ideal solution for demand-controlled ventilation systems in combination with the Indigo 80.