What is a heat loss survey? Simply explained!

The heat loss survey is an important tool for designing heating systems. It is essential for the efficient operation of your heating system. Here you can find out how to carry out a heat loss survey, which data is required and what costs arise as a result.

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What is a heat loss survey?

A heat loss survey is a standardized procedure that determines the required heating output of a building. It ensures that your house stays warm even when outside temperatures are low. It is based on heat losses through walls, windows, ceilings and floors. This tool ensures the optimal sizing of your heating system.

When should I do a heat loss survey?

You need a heat loss survey if you want to ensure that your heating system works efficiently and is optimally dimensioned. This is particularly important in the following cases:

• Heating modernization: A heat loss survey is necessary before you replace your old heating system, e.g. when replacing an old oil or gas heating system with a heat pump.
• Energetic renovation: After measures such as façade insulation or window replacement, the building's heat demand changes. The heat loss survey helps to design a suitable heating system.
• Neubau: A heat loss survey is required by law for new buildings. It ensures the correct sizing of the heating system and energy efficiency of the building.
• changes of use: If the use of a building changes, for example when converting offices into living spaces, the heat loss must be adjusted. There are other requirements for an optimal indoor climate here.

In all these cases, the heat loss survey ensures that your heating system is neither oversized nor undersized. This saves energy costs in the long term and increases living comfort.

How is the heat losscalculated?

The process of the heat loss survey is MCS compliant. Various values and factors are included in the calculation, which are explained in detail in the national Annex D to the standard. The heat loss is made up of the sum of the following variables:

• Transmission heat loss: Heat losses through building envelope components (e.g. walls, windows, roof).
• Ventilation heat loss: Heat losses that occur as a result of ventilation behavior.
• Additional heating capacity: Required heating capacity, which is required to quickly return to the desired room temperature after a heating break.

Can I create a heat loss survey myself?

You can also create a heat loss survey yourself, for example using online tools such as the heat loass survey tool provided by the German Heat Pump Association. These tools provide an easy way to estimate the stats of your single-family home.

Another option is using the following formula:

Heat loss (in watts) = living area (in m²) X specific heat demand (in W/m²)

The following values are used for the specific heat requirement:

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For example, this would result in the following values for a single-family house of 150 square meters:

The Difference between a simple and detailed process (MCS compliant) lies primarily in accuracy: While the simple method uses standard values, the detailed process is based on specific, individually collected data.

What data is required for a heat loss survey?

In order for a heating installer or an engineering office to carry out a MCS compliant heat loss survey, the required data must be provided in advance. The most important are:

• U-values of the building envelope: The heat transfer coefficient indicates how much heat is lost through a component. It is determined for exterior walls, windows and roof surfaces. These values are crucial for calculating transmission heat losses.
• Storage mass: The larger and more massive a building is, the longer it takes for the heating system to completely heat up the storage mass. It significantly influences the required heating capacity, as it describes the building's ability to store heat.
• Air exchange: Heat losses due to ventilation or leaky windows are taken into account in the calculation. The air exchange rate describes how much air is replaced per hour and is particularly important for ventilation heat loss.
• heating temperature: The desired room temperature and the outside temperature influence the heating output. For indoor use, there are standard temperatures depending on the room, such as 20 degrees Celsius for living rooms and 24 degrees Celsius for bathrooms. Outside temperatures depend on the location of the building and the time of year.

How much does a heat loss survey cost?

The costs for a heat loss survey in a single-family house are between 400 and 1,000 euros. The price depends on the size of the building and the effort involved. Complex calculations by energy consultants can result in higher costs.

Is there funding?

There are various government funding options available for heat loss survey:

• Funding under the Federal Funding for Efficient Buildings (BEG): Up to 50 percent of the costs of a heat loss survey are covered if this is part of subsidized energy planning or construction support.
• Hydraulic balancing support: The state subsidizes the implementation of a hydraulic adjustment, which usually also includes a heat loss survey, with up to 20 percent of the costs.
• Heater replacement: Anyone who installs a heat pump in an existing building can receive a subsidy of between 30 and 70 percent. The eligible costs often also include the heat loss survey. However, there is an upper limit of 30,000 euros for the total eligible costs.

What do I have to consider when calculating the heat loss for a heat pump?

Avoid common mistakes when calculating heat loss

and pay attention to the following points if you want to use a heat pump:

• Capture exact building data: Make sure that all relevant data on the building envelope, such as U values, window areas and insulation quality, is correctly recorded. Inaccurate data leads to incorrect calculations and an inefficient design of the heat pump.
• Taking room temperatures into account: Set the desired temperature for each room. These values are crucial because they determine the heat loss in the different zones of a building.
• Include regional climate data: Use the specific climate data for your region, as these influence the heating output of the heat pump. These values are particularly important in colder regions.
• Take into account the air exchange rate: Pay attention to the correct design of ventilation heat losses. This includes how often the air in the rooms is replaced by ventilation or leaky windows.
• Additional services for peak loads: Consider additional heating outputs for particularly cold days. These can be covered by an additional electric heater without the need to oversize the heat pump.

Do you need an energy consultant to calculate the heat loss?

An energy consultant is not absolutely necessary, but it is useful in many cases. Especially in the case of more complex buildings or extensive renovation measures, an energy consultant ensures that the heat loss survey is accurate and in accordance with standards. In addition, it can identify optimization potential.

If you claim federal funding for efficient buildings (BEG), then an energy consultant is often a prerequisite. In such cases, the consultant not only calculates the heat loss, but also provides support in energy planning and applying for funding.

What is the difference between heat loss and heating demand?

The heat loss is an instantaneous value that describes the peak load. It is used to design the heating system. The heating demand is an annual value that shows the total energy consumption. This is important for calculating energy consumption and costs. Both values ensure efficient and tailored heating planning.

Plan efficiently with modern heat loss survey!

Optimize your heating planning with a precise heat loss survey! Take advantage of this opportunity and book a free demo. Convince yourself of the benefits without obligation and experience how easy and efficient our calculation tools make your work easier.

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