Author: Gabriele Cerri
Key Points on On-Demand VMC
- A point-of-use mechanical ventilation system provides air exchange in individual rooms without a ductwork network.
- In building envelope retrofits, air quality and energy efficiency must be considered together.
- Single-flow, alternating-flow, and dual-flow systems offer different operating modes.
- The most advanced units incorporate sensors and remote control to regulate localized ventilation.
- Space, noise levels, and maintenance are key factors in choosing between a point-source and a ducted mechanical ventilation system.
When we talk about energy-efficiency retrofits, it’s natural to think of measures such as exterior wall insulation, windows and doors, and the installation of heat pumps and solar panels. However, less attention is often paid toindoor air quality , even though it is one of the factors that most significantly affects comfort and health.
Today, however, the situation has changed, thanks to the new Construction Sector CAMs that took effect on February 2, 2026, which have strengthened the requirements for ventilation by mandatingthe installation of ventilation systems in the following cases:
- New buildings and major first-level renovations;
- Second-levelrenovations;
- Energy retrofits involving the replacement of the generator and power transmission/distribution systems .
The topic of Air exchange is especially critical in building retrofitsbuilding envelope.The installation of exterior insulation and the replacement of windows and doors bring significant benefits in terms of energy savings, but they reduce the naturalair exchangethat occurs through air infiltration, making proper ventilation management essential.
However, when renovating existing buildings , it is not always feasibleto install centralized ventilation systems with ducted distribution—for example, because there may not be enough space in the drop ceilings to house the ducts.
In these situations,localized controlled mechanical ventilation ( VMC) systems come into play.
Table of Contents
- What Is Point-Source Mechanical Ventilation?
- The Different Types of Point-Source Mechanical Ventilation
- On-Demand VMC and Remote Control
- Why Zone-Based Mechanical Ventilation Is a Viable Option for Renovation Projects
- The Limitations of Zone-Specific VMC and a Comparison with the Ducted System
- Frequently Asked Questions About Point-Source VMC
- Point-Source VMC in Renovation Projects: Balancing Air Quality and Efficiency
What Is Spot VMC?
Point-based controlled mechanical ventilation, or point-based CMV, is a decentralized solution consisting of standalone units installed directly on the exterior walls of individual rooms without the need for ductwork. This makes it possible to achieve the benefits of mechanical ventilation even in situations where integration with existing systems is difficult.
In fact,on-demand mechanical ventilation improves air quality by regulatinghumidity and reducing pollutants such as pollen, dust, mold, and volatile organic compounds emitted by building surfaces.
How Heat Recovery Works in a Point-Source Mechanical Ventilation System
On-demand mechanical ventilation also helps reduce utility bills by lowering the thermal load associated with ventilation, thanks to the heat recovery unit it is equipped with. In fact, the heat recovery unit transfers someof the energy from the outgoing air to the incoming air.
This way, in the winter,the outside air enters the building already preheated, while in the summer there are benefits—especially if the system includes room cooling—as the incoming air cools down through heat exchange withthe exhaust air. As a result, air exchange occurs with a lower impact on energy consumption.
The Different Types of Spot-Type Mechanical Ventilation Systems
The main types of spot ventilation systems are:
- Single flow punctual VMC , used for the extraction of air in bathrooms and kitchens and which therefore does not allow heat recovery ;
- Punctual VMC with alternating flow (push-pull): The unit extracts air for about 1 minute, heating a ceramic heat exchanger, then reverses the flow and draws in outside air, which is heated as it passes through the heat exchanger.
- Dual-flow cross-flowVMC: The unit supplies and exhausts air simultaneously by passing the airflows through a heat exchanger, thereby ensuring constant pressure balance.
Enthalpy Recovery Units and Air Filtration
To maximize comfort and air quality, these units can be equipped with enthalpy recovery systems, which facilitate the exchange of both sensible and latent heat, thereby maintaining relative humidity at optimal levels for occupant comfort.
In addition, they are equipped with filters that meet F7 standards, which are essential for supplying healthy air.
On-time VMC and remote control
Another interesting aspect of point-based mechanical ventilation is its integration with remote control in the most sophisticated devices, which can thus be configured as true IoT (Internet of Things) devices.
In fact, they often feature control systems compatible with BMS , humidity, temperature and CO2 sensors that allow the flow rates to be adjusted according to the actual needs of the environment.
In addition, they allow for scheduled operation, automatic filter replacement alerts , and the application of advanced control logic —such as the use of free cooling on dual-flow heat recovery units when conditions permit.
Why On-Demand Mechanical Ventilation Is a Viable Option for Renovation Projects
Point-based CMV becomes particularly interesting when a ducted solution is not feasible or not cost-effective . This often happens in existing buildings , especially when:
- There isno space available for suspended ceilings and shafts for the ducts;
- There is a need to keep costs and installation time down ;
- We want to avoid an overly invasive project, which would otherwise require demolition and the installation of extensive suspended ceilings;
- The building is occupied and must remain in use during the construction work;
- Work is being carried out on properties with architectural or layout-related restrictions.
In all these cases, the VMC Puntuale allows you to implement control of the Air exchange systems that require minimal and quick construction work thanks to their ease of installation.
This solution is well-suited for buildings of modest size, such as schools, small offices, and individual rooms, where the goal is not to serve large, uniform spaces but to effectively ensureair quality where needed, in accordance with the building’s characteristics.
The Limitations of Point-Source VMC and a Comparison with the Ducted Solution
However, it is important to remember that localized mechanical ventilation is not the solution to every ventilation need.
In very large buildings—for example, in complexes with many similar rooms or in new buildings with well-designed mechanical systems—a ducted system may be neater and more efficient. In fact, point-based mechanical ventilation has certain limitations in large spaces.
If there are many rooms to be served, there is a risk of increasing the number of units—and thus also the costs associated with maintenance, filter replacement, and the management and coordination of the devices. In addition, careful consideration must always be given to perceived noise levels,the architectural integration of the units into the building’s facade and the surrounding environment, and ease of access to components for maintenance.
Therefore, on-demand mechanical ventilation should be selected for the specific contexts for which it is designed, in order to derive the greatest benefits from it.
Frequently Asked Questions About Spot VMC
When is a point-source mechanical ventilation system preferable to a ducted system?
It’s preferable in existing buildings where there isn’t enough space for ducts, when time and costs need to be kept in check, when the building remains occupied during construction, or when there are architectural constraints. In buildings with many rooms to serve, a ducted system can be more streamlined, as a ducted system requires multiple units, filters, and maintenance.
How much maintenance does it require?
The units require periodic filter replacement and cleaning of the heat exchanger, at intervals specified by the manufacturer and based on outdoor air quality. Many models automatically alert you when the filters need replacing.
How many types of point-source mechanical ventilation systems are there?
Essentially three: single-flow (used in bathrooms and kitchens, which therefore do not allow for heat recovery), alternating-flow (push-pull), and dual-cross-flow.
Does a demand-controlled ventilation system also work in the summer?
In units equipped with a heat recovery system, heat recovery can be useful even in the summer, especially when rooms are air-conditioned: the incoming outdoor air can transfer some of its heat to the exhaust air. In pre-configured dual-flow models, free cooling can also be activated when conditions permit.
Can a point-of-use VMC be integrated with remote control?
The most sophisticated devices can incorporate remote control, BMS-compatible systems, and sensors for humidity, temperature, and CO₂. These features allow you to adjust airflow rates based on the room’s needs, schedule operating times, and alert you when filters need to be replaced.
VMC: Leading the Way in Renovations That Balance Air Quality and Efficiency
In today’s context, building retrofits must not only take energy savings into account but must also prioritize air quality, as required by the CAM Edilizia guidelines.
Improving a building’s insulation, replacing windows and doors, and reducing heat loss are essential, but without adequate ventilation, there is a risk of creating spaces that are more energy-efficient but less healthy and less comfortable for those who live in them every day.
It is precisely in this scenario that on-demand mechanical ventilation is most efficient: a flexible and effective solution for providing controlled ventilation even where a ducted system would not be feasible or sustainable.
The strength of localized centralized mechanical ventilation lies in its ability to adapt to existing buildings, minimize the invasiveness of the work, and provide an effective balance between comfort, health, ease of installation, and energy efficiency.
For more information on on-demand VMC please contact our Enertech Solution team; for more details on energy retrofits, read our news.
