What is demand control ventilation?
Once installed there are many ways heating and ventilation system performance can be optimized ranging from utilizing dampers to programmable thermostats and beyond. One effective energy-saving approach is demand control ventilation. We’ll examine it more closely in this blog.
No facilities manager should want to ventilate a room when doing so isn’t necessary. It would be neither cost effective nor energy efficient. Fortunately, that’s a situation that can be avoided although, less fortunately, it often isn’t.
The general goal of an effective heating and ventilation system is this: to deliver the right in-room conditions at the right time. If, for instance, a zone, room, or area within a building is in a period of only partial occupancy, it would make little sense not to adjust the rate at which ventilated (outdoor air) is delivered into it accordingly.
Delivering ventilation when and where it’s needed. Not where it isn’t
That’s where demand-controlled ventilation come in, the underlying concept of which is simple enough - giving occupants the right amount of fresh air at the right time and in the right location. If this can be achieved – think of demand control ventilation as intelligent airflow management – then by reducing the requirement for ventilation, both energy usage and costs are reduced. Conversely, at times when there’s a need for increased ventilation, that can be addressed too.
The point here is that demand-controlled ventilation is a continuous process or function that constantly makes adjustments to ensure that heating and air quality are optimized on an automated basis, all of the time. Let’s look at some of the reasons this is an attractive proposition. To start with, here are eight.
1. Optimal heating consumption
As much as half the thermal losses in a facility can generally be attributed to ventilation issues. By a combination of automatically controlling airflow and better preserving heat in less occupied zones, this problem is reduced.
2. Moisture reduction
All activity by building users in an occupied space increases humidity and, in turn, condensation. The latter can be destructive - for instance by creating conditions that encourage the growth of molds. With controlled ventilation, humidity-sensitive exhaust functions can open automatically to remove excess moisture from the air.
3. Greater comfort
As noted earlier, the goal of effective ventilation is to deliver air to the areas where it’s needed. Occupied rooms have higher humidity and require better, increased airflow. The same is true of wet rooms, where stale air is common and needs to be removed. Control ventilation enables airflow to be managed in a way that allows requirements such as these to be met as necessary within each different building zone.
4. Reduced power consumption
When (see examples above) the required airflow rate is optimized across a facility, the result is it will be reduced when less is demanded of the exhaust fan which, without control ventilation would simply work at the maximum airflow rate, at a much higher power requirement. That requirement is reduced when components only need to work “as necessary”.
5. Improved equipment lifespan
Taking reduced power consumption into account, an exhaust fan (and other equipment) that is not required to work at maximum output all the time will benefit from lower operational demands and equipment life will be extended. The lifespan of an exhaust fan in particular is highly dependent on how it used. The lower the airflow it’s required to deliver, the longer it will last.
6. Better system performance
Reduced (or optimal) airflow means a reduction in the number of air particles present that can damage or negatively impact overall HVAC system performance, meaning filters and ductwork can be reduced in number, components are less likely to become clogged or even to break down, and system maintenance requirements will be reduced accordingly. Better system performance and lower costs result.
7. Optimal pressure and airflow
Demand control ventilation removes unnecessary airflows in a facility and avoids overloading ducts while at the same time enabling those ducts to be used where increased airflows are necessary. In other words, ventilation is directed where it’s needed. Not where it isn’t. Thus, air losses in ductwork are reduced and system performance optimized correspondingly.
8. Improved space usage within the facility
The ability to modulate airflow that derives from demand-controlled ventilation means that ductwork, which often comes with heavy space requirements, can sometimes be reduced. That’s because it can be sized for airflow without presuming that maximum airflows will be required all of the time. So, for instance, smaller air ducts may come into play, reducing the total space required in a building for ductwork to be sited.
Demand control ventilation: reap the benefits
To summarize, demand-controlled ventilation can confer multiple benefits ranging from enabling the delivery of an optimal and healthy climate in a facility without putting an unnecessary workload on the HVAC system, to improved air quality and a reduction in environmentally damaging issues (such as mold, moisture, and others) within the facility. Furthermore, the approach is fully automated, generally easy to install, simple to operate, and highly cost-effective. So, why not use it?
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