Heating system with a central standard boiler went into service by gas in a kind of collective system since 1982. Through the exchange of the boiler with a new gas calorific value boiler and re-adaption of the performance the ESM was optimized within the project AFTER.

It costs including installation between 19 100 EUR  which can save ca.10-20% of energy per year comparing to the existing 20-year-old standard boiler. The results in  Heinhemmerstraße shows highest results with an average of 40% of savings after the implementation of the new boiler.


Hydraulic balancing of the heating system was implemented by resizing the radiators according to the old supply temperature instead of replacing them to ensure each radiator connected to the heating system to get the same temperature for a better comfort and more efficient energy saving wherever radiators are installed in the building. If it’s possible, a saving of between 3% and 7% in consumption is a goal.

The most expected objective of this intervention goes to a high economic benefit from the optimization, nevertheless, the social and energetic factors are obviously the very important assessment criterion. The new calorific boiler works at a lower flow temperature than the previous standard boiler. The performance of hydraulic balancing and the suitability of the thermostatic valves are to be examined during the implementation.


The subcontractor Energie & Haus creates with the help of the analytical method Heating ECG (DIN 15378) the basis for the optimal operation of heating systems. By Heating ECG it can be determined how efficiently a heating system is actually working. From the results of a 24h measurement period for the heating system the errors can be detected and the relevant solution and suggestion can be doped out.

Based on a 24h measurement it was found out that the range of heat power of the existing boiler is 15 – 54kW which is actually slightly oversized and the currently existing heating system probably based on the previously installed also non-modulating boilers so that it can’t meet the need of modern boilers any more. At the same time it showed that the hydraulic adjustment leaded to a large temperature fluctuation and thus much time is spent for regulating work or clocking which causes unnecessary wear-out in burner and boiler, except that the temperature variations with corresponding excessive temperature have led to a larger heating loss. Mostly the boilers were not shut off by the desired temperature but rather a highest temperature and the whole equipment is running at a high flow temperature too.


The optimization of the system based on the results of the Heating ECG leads usually to save at least 5% (4% as an average on the Heinhemmer Pilot Site with a peak of 5,94% of savings for some months). Due to the small investment (5500 EUR) required heating optimization based on the heating ECG is highly economical. This particular ESM has been under the expected amount of energy savings targeted as the monitoring period has been very short (5 months) and by a human error (cf report) that has troubled the first month of measurement. Total amount of energy saved per 5 months of monitoring is about 524 kWh.




Mathildenstr. 36-40 which is a 4/5 storey apartment building and was destroyed in World War II as well was rebuilt in the 1954 with a simple design. The heating energy carrier is natural gas and the last building refurbishment was carried out in 2008.

The intervention of optimized ESM#2 consists in regulation of ventilation system and heating system:

–      New controlled ventilation system with supply air through the window frame and a central system in the cellar;

–      New heating system with a low temperature central boiler and decentralized heat exchanger in the dwelling.

In addition, the thermal insulation of the building’s coat was checked up and renovated, such as the façades are provided with thermal insulated tint windows and the balconies house in house number 40 were repaired. Not only the apartments but also the basement ceiling and roof are controlled by technical staff completely and detected errors as well provided renovation. The replacement of the outer shell was also fresh and wasted pipes were completely redone. There was a total renovation was implemented for the heating system that a modern central heating system with the so-called “Satellite

Stations Homes” which function as water-based heat exchanger.

After the implementation of the ESM the Energy Consumptions dropped considerably  by 69 to 80 percent. This sharp decrease is due to the global refurbishment because it involved the external shell, the windows, the renovation of the heating system and the new ventilation system.

Except the technical remedy the optimization of ESM#2 is to adapt the ventilation system to tenants’ behaviour by switch off in summer and regulate the heating system’s control by shut down at night.

Through a 24h measurement it was found out that the existing boiler is slightly oversized with a max. heat power of 80kW and the modulation capability of the burner is not completely used, approx.20% of the boiler power output is wasted through the exhaust gas during the measurement period. It is expected to set a suitable indoor temperature according to the outdoor climate condition through the new regulation of heating system, that is to say, it is possible to reduce the energy consumption from 4% to 7% by a re-adaption of the heating curve.

This intervention gives the opportunity to evaluate certain aspects considerable significance in the context of building’s monitoring which aims to inspect any deficiency in the technical equipment or the whole ventilation and heating system regularly and timely, for example, to find out any deficiency of insulation in coat, walls and windows which leads to heat loss; to search for water infiltration, integrity of pipes insulation; to identify the moisture and damage in walls; to find out deficiencies of the central boiler or heat exchanger like bad regulation, deficiencies of pumps or valves like bad regulation of frequency etc.


Economical and energetic effects are two vital evaluation standards for the intervention. BAUVEREIN spent 110.371,00 € for the implementation of the ESM. The additional initial costs were 16.556,00 €. The technical costs for the optimisation of the ESM were 2.500,00. The staff costs for the optimisation of the ESM were 3.000,00.



Regarding to low energy house the ESM in the passive house building WohnArt 3 (double flow ventilation system, triple heat protection glass and an insulation of the facade with 30 cm EPS, district heating system) was optimized within the project AFTER.

The actual consumption for heating and domestic hot water in Wohnart3 in 2011 accounted for 41.4 kWh/(m²a). This value is about 69 % lower than the German actual average of 133.0 kWh/(m²a) in 2011. Figures refer to treated floor area as used in the PHPP calculation (Wohnart3) resp. the living area (German average); both areas are supposed to be fairly comparable.

The hot water will take place over a hot water tank. The provision of hot water is done via a circulation pump that allows both day and night time hot water to be available in the apartments. That means on the other hand we have a lot energy losses during the period in which there is no need of  hot water by tenants. In view of a high hot water consumption which is in relation to the entire heating consumption is around 50%, the whole hot water supply system and the running time of the circulation pumps were inspected and optimized taking account of the tenants’ behaviour at least.

Experience has demonstrated that there are some hours during a day in which there is no need of hot water but it circulates still in the pipes and leads to some heat losses. For the optimization solution it was checked out to what extent the circulation pump can be turned off, for example in the night time, so that a reduction of energy consumption up to 7% is to be expected.

Social performance is one of most important assessment criterion so as to take full account of the tenants’ behaviour and their awareness. While implementing the optimization, the fact is a reduction of energy consumption and energy cost by tenants and yet accompanied by a reduced living comfort because of the technical intervention of reducing the working hours of the circulation pump. However, as there is little investment (2100 EUR) and no additional technical and staff costs after optimization then a financial benefit could be provided to tenants. Besides, a thorough discussion and interchange between tenants and SHO in tenants’ meeting has gone far towards tenants’ awareness. They have accepted the suggestion for saving energy consumption and shown great interest on more information.