Most air handling systems consist of fans, air filters, and equipment that measures temperature and humidity. The sizing and specifying of the air handling plant works to achieve a desired air change rate, as dictated by the building type, size, and expected occupancy levels. Methods for controlling the air in buildings must be adapted further to have intelligent air quality management systems which guarantee a best-case air quality scenario, within the scope of a larger, holistic building operating envelope.
The air quality management system should be an intelligent, computerized add-on that complements existing building systems and technologies such as BMS/BAS. It should be capable of taking data from multiple sources, including indoor air quality sensors, outdoor air quality sensors, weather services, maintenance works, and building occupant feedback. It should have the modelling capacity to determine the best regimes, routines, and actions that will generate the best improvements in air quality conditions under changing operational circumstances.
Let us consider a working example of the building operating envelope. For example, a building situated in a large urban center next to a busy intersection during rush hour. Its ventilation system was enabled one hour earlier, when people began to filter in for a day’s work. The primary sources of air pollution are a) external: the ventilation system is drawing in air from the outdoors, b) internal: materials, processes, and objects can all emit various pollutants, c) personal: people emit carbon dioxide as part of normal metabolic process.
At 8 A.M., with only 10 percent of the building occupied, that’s 90 percent wastage of the energy being used by the air handling plant. At 9 A.M. with maximum traffic levels on local roads, the introduction of noxious traffic emissions is higher than at 10 A.M., just one hour later. Moderating the ventilation rate over this period will achieve a much improved balance between air quality, air quantity, and energy usage. Now consider the various greenspace within the building, and its influence on occupants in close proximity, the type of activities being undertaken, the age of the air handling plant, the state of its filters, outdoor pollen levels and low level ozone prevalence, etc. The model becomes very complex, yet nothing beyond the capability of modern computational systems.
Rethinking the Ecosystem - Build with Air Quality in Mind
The operating envelope of a building is a new way of thinking. It’s a complex model that incorporates cost, comfort, energy usage, and environmental factors. Finding the optimal parameter set that delivers the maximum return against a set of criteria requires deep and relevant insights. This means understanding the complex yet finite set of controllable characteristics that determine the operational state of any building. This new way of thinking is suitable for cloud connected buildings, where fuzzy logic engines can be run against complex parameter sets and data lakes, giving black and white answers to colorful questions.
As a matter of priority for building owners, tenants, and users, we must create optimal indoor environments if our sedentary lifestyles are to continue in health. Accounting for the effects of airborne contaminants, reducing concentrations, and minimizing exposures is essential. Being able to adapt to individual sensitivities within whole building populations and ensure good healthy working environments is key to a prosperous future for all.