How much energy does mechanical ventilation consume?

We measure the energy consumption of a mechanical ventilation system in kilowatt-hours per annum or kWh/a. So you use this figure to check out your appliance’s consumption in kWh and convert it to annual basis.

It is of course impossible to calculate your exact consumption in advance. A ventilation system almost always has three settings that move different volumes of air, depending on how the unit is set up. These three settings require different fan speeds which affects power usage.

There are also many factors that affect the energy consumption of your mechanical ventilation and sensors play an important role when it comes to saving energy.

And exactly how much power does DUCO mechanical ventilation consume?

You will find a detailed answer further on in this blog, but we are happy to summarise it for you as well.

In short, for a simple mechanical extract ventilation (MEV) system such as the DucoBox Silent Connect it is 120.2 kWh/a. This installation includes manual operation without sensors. A similar mechanical ventilation unit with heat recovery (MVHR), such as the DucoBox Energy Premium, uses 258.1 kWh/a.

You can use demand control and sensors to reduce a ventilation system’s energy consumption. Using them will cut power consumption for the DucoBox Silent Connect with CO₂ sensors to 50.8 kWh/a. A DucoBox Energy Premium cuts power consumption to 112.4 kWh/a.

 

You can read more about this in this blog:

•    Factors determining power consumption
•    Energy consumption of mechanical supply using mechanical ventilation with heat recovery versus natural supply
•    Impact of demand control on energy consumption
•    40% energy savings thanks to zonal ventilation

 

Factors affecting mechanical ventilation power consumption

The energy usage of a ventilation system depends on its operation throughout the year. In addition, factors such as the size of the rooms to be ventilated, the type of installation and user behaviour also play a role.

1.   Living space

An obvious factor but not to be ignored. The size of the home and the rooms to be ventilated in it has a major impact on mechanical ventilation consumption.

Ventilation systems extract air from the home through a duct system which extends throughout the building. Logically, a larger home means a more extensive ductwork system. Longer distances to cover means the ventilation system will have to work harder to achieve the desired air extraction.

2.   The installation

The way the ventilation unit was installed also determines the final power consumption per annum.

The layout of the ductwork system is crucial in this regard. Too much flexible ducting relative to rigid ducting causes resistance, which means that the ventilation unit has to work harder, thus increasing power consumption.

In addition, too constricted a duct diameter can have a similar effect. Especially at the outlet where all the exhaust air leaves the home, too constricted a diameter will reduce ventilation capacity on the whole installation. The mechanical installation will use significantly more as a result.

How to cut the ventilation system power consumption? Follow our guidelines for installing residential Mechanical Extract Ventilation and Mechanical Ventilation with Heat Recovery.

3.   Occupant behaviour

The last factor is often overlooked: user behaviour. Here we are referring not only to direct use, but also to indirect use.

Of course, as the home occupant, you have control over the ventilation system. For installations without sensors, the activation of the device is entirely in the hands of the user. If there are no user commands, the unit will maintain a basic level that uses very little energy. This obviously affects the air quality in the home, as does switching off your ventilation box completely.

But even with sensors, indirect occupant behaviour affects the power consumption of the MVHR or MEV system. A ten-minute shower with lukewarm water generates less moisture than a half-hour hot shower. Hence the water temperature and time under the shower also has an effect on the activation of the unit.

In addition, a family of three generates less CO₂ than a family of five. Even evening rituals have a role to play: does the whole family sit together in the living room or are there family members who spend their leisure time outdoors or in their own rooms?

 

Energy consumption of mechanical supply using mechanical ventilation with heat recovery versus natural supply

An approximation (AEC) is often used when calculating energy usage Below, we compare an MEV system with an MVHR system.

For a simple MEV system, our DucoBox Silent Connect, it works out at 120.2 kWh/a. This is a system without sensors, with manual control only. Expanding the system with CO₂ and/or humidity sensors has a positive impact on energy consumption (see below).

A similar installation but featuring mechanical ventilation with heat recovery, such as our DucoBox Energy Premium, manages 258.1 kWh/a. This is about double that of an MEV system. This makes sense, as this unit also blows air in as well as extracting, so there are two fans in operation (instead of one).

 

Impact of demand control on mechanical ventilation energy consumption

In the previous comparison, we referred most explicitly to units with manual control only. However, upgrading the installation with sensors will have a major impact on energy consumption.

In a simple demand-controlled system with central demand control, we will have a humidity sensor in the bathroom for example. This sensor controls the unit to activate and ventilate as soon as the relative humidity in the bathroom exceeds a certain level.

And what does demand control mean for the consumption of the previously mentioned units?

Energy consumption with mechanical extract ventilation - DucoBox Silent Connect

The DucoBox Silent Connect power consumption will be cut from 120.2 kWh/a to 86.8 kWh/a. With a manual system, you switch the unit on just before showering and switch off again yourself. This means you often start ventilating a little too soon and possibly for too long as well. The sensor ensures that ventilation takes place only when needed.

Further upgrading the system with CO₂ sensors, for instance, will refine this to an even greater extent. A central system with local control can ensure that energy consumption is cut even further to 50.8 kWh/a.

Energy consumption for mechanical ventilation with heat recovery - DucoBox Energy Premium

The DucoBox Energy Premium starts off using 258.1 kWh/a but immediately drops to 188.1 kWh/a by adding a sensor. Here too, the same principle applies as with the Silent Connect.

With a further upgrade to installation (2+ sensors), this is cut even further to 112.4 kWh/a.

With both units therefore we see energy usage halving when increasing the use of sensors.

 

 

40% energy savings thanks to zonal ventilation

The previous upgrade from manual to local controlled is a sound step in terms of energy efficiency, but there is still room for improvement.

Zonal ventilation uses the principle of local control and combines it with control valves that ensure that only the relevant zone is ventilated as well.

Extract unit activation has a major impact on the unit’s consumption. If the home is divided into zones, it will need to run for less time and at a lower rate. This brings about energy savings of up to 40%.

In addition, a zonal ventilation system generates up to 30% less noise. This is because zone control ventilates only those rooms where it is needed, whereas a centralised system covers the entire home.

Remember the paragraph on user behaviour? Zonal ventilation has a major positive impact on this factor. A correctly set and well-considered zonal ventilation system needs hardly any manual operation. Zone control will also ensure that ventilation only operates where it is actually needed.

In short, various factors affect the energy efficiency of the ventilation system. You will get the best results by combining a good layout plan with the right unit.  Automatic control and quiet operation also provide enhanced living comfort.

 

 

 

 

More blogs on ventilation and energy efficiency

• 3 Advantages of energy efficient ventilation
• May I switch off the ventilation system?
• Poor or insufficient ventilation in your home? These are the consequences
• Smart ventilation? Use a DucoBox!
• 6 advantages of CO2-controlled ventilation
• What to do with the ventilation when I am on holiday?
• 5 practical tips to efficiently ventilate damp rooms