A precise ventilation concept is essential for the efficient operation of a building - otherwise energy costs can rise rapidly. In order to correctly dimension the relevant ventilation systems and adapt them to existing requirements, an exact calculation of the ventilation heat losses is necessary. Modern software solutions can provide crucial support here.
Especially in times of rising energy costs and a rapidly changing climate, every kilowatt hour saved counts. In this article, we provide an in-depth breakdown of the key methods for calculating ventilation heat losses and how the results can be integrated as seamlessly as possible into complex construction projects.
The most important facts in brief
Ventilation heat losses represent the energy losses caused by ventilation in buildings and rooms
The losses result in additional heat demand - which has to be covered by more energy input
They are a decisive factor for calculating the standard heating load in accordance with DIN EN 12831
What is meant by ventilation heat loss?
The term is central to the conceptual planning of ventilation systems. But what does this term actually mean and how does it affect the energy balance of a building?
Ventilation heat losses are caused by the necessary exchange of stale, polluted indoor air with fresh outdoor air. This process is essential to ensure a healthy and comfortable indoor climate. However, the ventilation process is also accompanied by the release of heat into the environment, which is referred to as ventilation heat loss.
The energy efficiency of a building therefore depends largely on its ability to minimize heat loss and reduce the energy required for heating and cooling.
Losses can be a significant challenge here, as they can account for a considerable proportion of a building's total energy requirements.
More efficiency with a system
In order to minimize ventilation heat losses, modern buildings rely on sophisticated ventilation concepts. This involves the use of complex systems that enable controlled air supply and extraction. A heat recovery unit can use the exhaust air heat to preheat the incoming fresh air and thus reduce heat loss.
Why are ventilation heat losses important for calculating the heating load?
Ventilation heat plays a decisive role when calculating the heating load of a building. These heat losses, which are caused by the necessary air exchange, must not be neglected under any circumstances - because they have a considerable influence on the energy requirement for heating.
The heating load of a building is the amount of thermal energy required to keep the indoor temperature at a comfortable level, even at the coldest outside temperatures. Not only the standard outside temperature and the specific heat capacity of the air through the building envelope, but also that through the ventilation must be taken into account.
This is because ventilation heat losses can account for a significant proportion of the total heating load. If they are not adequately taken into account, this can result in an underestimation of the actual energy requirement.
The possible consequence: the heating system is potentially undersized and may not provide sufficient heat in winter (or only with high energy consumption) to maintain a comfortable room temperature.
Complex overall presentation
In order to carry out a realistic calculation of the heating load, all factors that lead to heat losses must therefore be included. In addition to ventilation heat losses, these include transmission through the building envelope, solar input and internal heat sources such as people, lighting and electronic devices.
Today, modern calculation methods and BIM software make it possible to accurately record ventilation heat losses and precisely determine the heating load. This is particularly important for dimensioning an efficient and energy-optimized heating system.
Image: Thanks to modern calculation techniques and BIM software such as Trimble Nova, it is now possible to record ventilation heat losses with great accuracy and determine the heating load precisely.
What are other factors in the heating load calculation?
The parameters of a correct heating load calculation are defined in DIN EN 12831. It thus sets the regulatory framework for a proper and comparable calculation of the respective heating load of a building. In addition to the air heat losses already mentioned, the following factors are essential for determining the heating load:
Transmission heat loss: This includes the heat loss through the building envelope. A detailed analysis of the building construction, the building materials used and the insulation is necessary to determine the thermal conductivity of the building. The better the building envelope is insulated, the lower the transmission heat losses.
Additional heating capacity: In the heating load calculation, this is a key figure that describes the additional energy required by a heating system to bring the room back to the desired temperature after a heating break. This factor is determined separately for each room and then added to the calculated heating load.
The right key figures as a calculation key
As a basis for these parameters, one thing is needed above all - data. And as precise as possible. This includes, for example:
Building information: Data on floor plan area, building height, roof pitch and external wall surfaces are essential for calculating the heat transfer through the building envelope.
Building materials and insulation: The thermal properties of the materials used influence the transmission heat losses of the building.
Window areas: The size, orientation and glazing of the window areas also have a significant influence on solar heat gains and transmission heat losses.
Air tightness: The air tightness of the building influences the ventilation heat and must be taken into account in the calculation.
Air change rate: The number of air changes per hour is important for determining the ventilation heat losses. It depends on the use of the building and the ventilation technology used.
Standard indoor temperature: The desired room temperatures and the temperature difference between inside and outside are decisive for the heating load calculation.
Internal heat gains: The heat emitted by people, lighting, electronic devices and other sources in the building influences the heating requirement.
Outdoor temperature: The standard outdoor temperature or the climate data for the region in which the building is located are important for determining the heating requirement.
5 strategies to minimize ventilation heat losses
The term implies it - losses always reduce efficiency. And therefore cost money, especially in long-term building operation. This is because a fundamentally incorrectly dimensioned and designed ventilation system has an impact on the energy efficiency of a building for years to come.
Accordingly, the reduction of ventilation heat losses plays a central role in the planning of energy-efficient buildings. Five targeted strategies can be used to reduce energy consumption and thus make a valuable contribution to greater efficiency and climate protection:
Modern ventilation systems with heat recovery: one of the most effective measures. These systems use the heat from the exhaust air to preheat the fresh air supplied. This recovers a large proportion of the ventilation heat losses and significantly reduces energy consumption.
Demand-based ventilation: Allows the air exchange rate to be adjusted to the actual demand. Modern ventilation systems can react automatically to the number of people in the room or the room temperature. This avoids unnecessary losses of ventilation heat.
Airtight building envelope: A building envelope that is as well insulated and airtight as possible minimizes heat loss through leaks and ensures that the heat stays where it is actually needed.
Thermostatic valves and room controllers: The insert allows the room temperature to be set individually. This means that the heating output in individual rooms can be adjusted as required and excess heat can be avoided.
Cross ventilation: Especially in mild climates, natural cross ventilation can serve as an alternative to mechanical ventilation systems. Open windows on opposite sides of the building enable efficient air circulation and the exchange of stale air.
Conclusion - Ventilation heat losses must be displayed correctly in order to achieve higher energy efficiency
The correct representation of potential ventilation heat losses is crucial in order to identify opportunities for greater energy efficiency - and is therefore always a decisive component of a ventilation concept in accordance with DIN 1946-6.
It is therefore always part of a complex system that directly and sustainably influences the energy efficiency of a building through the interplay of various parameters. Accordingly, it is important to calculate the individual key figures precisely and to embed them in an overall model that is comprehensible to the various project participants.
Software support can ensure a smooth BIM workflow and thus contribute to enormous increases in productivity. In this context, Trimble Nova proves to be particularly powerful CAD and calculation software that can model even highly complex ventilation concepts realistically and in real time.
Integrated networking with Trimble Connect opens up additional efficiency benefits that are of key importance for effective collaboration in a shared data environment. This ensures that all trades and project participants have access to the necessary data and parameters without losing time - and can thus identify and eliminate potential sources of ventilation heat losses at an early stage.
