Renovating old buildings: from CO2 guzzlers to energy-plus homes
Investment in an apartment building from the seventies pays for itself in less than eight years
- Apartment building from the 1970s with 3 residential units in 86862 Lamerdingen
- Heating heat pump
- eXergiemaschine 5 kW
- Solar thermal 16 m²
- Peak load pellet boiler (12 kW)
- Total heating storage tank 2400 liters
- Fresh water station
- VarCon380 system controller
- Special feature: PV system for self-supply
Andreas Ruf's renovation project proves it: With the right technology, a 50-year-old building that was previously heated with oil can be transformed into an energy-plus house. Instead of an oil burner, a 16 m² solar thermal system, a 5 kW heat pump and a 5 kW eXergiemaschine now ensure a comfortably warm home.
The eXergiemaschine supplements the heating heat pump and the solar thermal system and raises the temperature up to 65 °C so that the conventional radiators can be operated and hot water can be prepared hygienically. A 12 kW peak load burner fired with wood pellets is only used on extremely cold days. A varmeco controller VarCon380 manages the heating system.
The project was subsidized due to the well thought-out concept. As a result, thanks to the efficiency of the new heating system and the fact that it is self-sufficient in electricity, the Ruf family will save so much money that the renovation costs will have paid for themselves in around 7.5 years.
| Before refurbishment | After refurbishment | |
|---|---|---|
| Usable space / residential units | 330 m² / 5 residential units | |
| Energy source heating | Heating oil | Electricity / solar thermal / pellet heating |
| Heating requirement | 40,000 kWh/a | |
| Heating costs | 4,200 Euro/a | Pellet heating 625 Euro/a Solar thermal 0 Euro/a Heat pump and eXergiemaschine 0 Euro/a (due to own power generation) |
| Plant park | Heating value boiler heating oil |
Pellet heating 12 kW Solar thermal 16 m² Heat pump 5 kW eXergiemaschine 5 kW PV system 16.5 kWp Wind turbine 3 kW |
| Investment | Approx. 68,000 euros | |
| Less subsidy | Approx. 37,000 euros | |
| Effective investment | Approx. 31,000 euros | |
| Amortization period | 7.5 years | |
| CO² emissions | 12,000 kg/a | 0 kg/a |
Read the whole article „Investment in an apartment building from the seventies...“
Frequently asked, simply explained
From a physical point of view, energy is always conserved. However, it consists of usable parts, the exergy, and not directly usable parts, the so-called anergy.
Energy = exergy + anergy
In technical thermodynamics, exergy refers to the part of the energy that can perform work. In heating technology, exergy is the part that leads to heat flows due to the higher temperature level and thus makes space heating and domestic hot water heating possible in the first place.
Exergy, the proportion of energy that determines whether heat is usable, must be given greater focus. After all, exergy optimization is the key to system efficiency.
If the different temperature ranges of a well-stratified water storage tank are completely mixed, the water ends up with a uniform average temperature.
The energy content of the storage tank remains unchanged. During this process, the hot water transfers its heat to the colder water. This means that the exergy that existed at the higher temperature level compared to the average temperature and was required, for example, for
which would be necessary to heat drinking water, has disappeared, irretrievably, irreversibly. Exergy has become anergy. Anergy is energy that can no longer be used (without a new supply of energy). Only by using auxiliary means (e.g. electricity) can it be used again.
exergy arise.
In contrast to energy, exergy can therefore be reduced or even completely destroyed.
The varmeco fresh water technology uses instantaneous water heaters to heat domestic hot water only when required, eliminating the need to store it in a domestic hot water tank and inhibiting the growth of germs (e.g. legionella). The integrated VarCon211 controller only activates the charging pump when drinking water is required, which saves energy and ensures hygiene at the same time.
Thanks to the separation of heating and domestic hot water and adaptive control, the system adapts optimally to daily requirements. The circulation pump control keeps the domestic hot water at the right temperature and prevents the proliferation of legionella bacteria, ensuring a high level of hot water comfort and safety.
The eXergiemaschine recycles waste heat that escapes unused in many businesses and turns it into usable heat. It raises the temperature of the waste heat to a usable level and simultaneously cools the lower part of the heat storage tank, which improves the efficiency of the heat sources. This efficient use saves energy and is easy on both the wallet and the environment.
The eXergiemaschine is a special heat pump that enables high source temperatures and a wide temperature spread. This makes it an ideal partner for renewable energy systems, such as solar thermal and hybrid modules, which work more efficiently and supply more energy.
Questions? With pleasure!
Get in touch with us. Whether you are the owner of a
Heating system, commercial/industrial customer or local authority
Here you will find your contact to varmeco.
Would you like to become a specialist partner?
Take advantage of information benefits as a partner!
Don't have any login details yet?
Registration is quick and non-binding.