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01 Celle Cluster 1.jpg

GREEN LOCAL HEATING WITH GEOTHERMAL HEATING

Reference project: "Lower Saxony" real estate portfolio

Table of contents:

  1. Introduction

  2. Consumption in kWh per year

  3. Reference building "An den Weiden 14-16, 27356 Rotenburg (Wümme)

  • Final and primary energy requirements before modernization

  • Final and primary energy demand after modernization

  • transmission heat loss

  • primary energy demand

  • Annual heating demand

  • Fixed Expense Figure

  • CO2 emissions according to DIN 4701 (Gemis)

  • Energy Balance (Monthly Losses and Usable Gains)

  • Summary

1 Introduction

In January 2014, Christoph F. Trautsch acquired a real estate portfolio with 360 residential units that includes two clusters with a total of 72 buildings in the cities of Celle and Rotenburg (Wümme). From March 2014 to December 2015, the largest geothermal renovation of old stock to date in Europe in terms of drilling meters and number of systems took place. In addition, another 90 apartments were built in the free attic areas. After completion, the total living space amounted to approx. 30,000 m².

The entire heating and hot water supply was converted to a geothermal supply. A total of more than 22 kilometers of drilling was carried out. The 110 heat pumps installed ensure the supply of around 1,200 residents. The portfolio has been owned by LEG Immobilien SE since 2021.

With a total investment in the local heating supply of approx. 2.8 million euros, the annual income amounts to around 450,000 euros. The average investment in the local geothermal supply was therefore around 95 euros per square meter, the average investment in the thermal envelope area was around 124 euros per square meter.

01 Celle Cluster 1.jpg

2. Consumption in kWh per yearMr

3. Reference building: Auf der Weiden 16-18, 27356 Rotenburg (Wümme)

The object under consideration is a two-storey semi-detached house built in solid construction from 1965 with a gabled roof. The rented area in the house at An den Weiden 16/18 is a total of 568m².

It is important to note that the limitations and requirements of water law permits may vary by location and local conditions. It is therefore advisable to commission a DGC potential study before starting a geothermal project. This study provides comprehensive information about the applicable approval procedures and requirements.

Current state before modernization

Condition after modernization

Energy balance: An den Weiden 16/18, calculated with EnEV-Wärme & Dampf V15.56

Summary

The calculation program assumes a heat pump with an annual performance factor ß of 4.5. However, a system combination with an annual performance factor ß of 4.8 to 5.2 for heating units was actually installed. For the hot water heat pumps, the annual performance factor ß was 3.2.

To verify the results of the calculation program, the current electricity consumption is compared with the results of the monthly building energy requirements.

The power purchase of both aggregates from 01.12.2015. until 01/31/16 was 7,206.4 kWh.

The energy balance presented above shows that the building's energy requirement for the period under review December and January was calculated at a total of 30,000 kWh.

This results in an annual performance factor ß of 4.16 for the property.

After the insulation of the pipes in the area of the basement routes and the building moisture has dried out, an annual performance factor ß of 4.5 is assumed.

The actual kwh consumption up to and including the year 2021 for the operation of all local heating networks in the different clusters corresponded within a range of +-2% and adjusted for the so-called cold days, the forecast from 2014.

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