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Choosing an efficient and environmentally friendly heating system for your home is important to reduce your ecological footprint. In this article, we will conduct a comparison of the most common heating systems and examine what a sustainable energy concept could look like.

Gas Heating Systems

Gas heaters are widely used in many households due to their convenient heating method and previous cost efficiency. They burn natural gas to generate heat and require a well-developed infrastructure for gas supply. Gas heating is considered relatively clean compared to oil heating because it produces fewer carbon emissions. However, it still contributes to global warming, as burning natural gas releases greenhouse gases like carbon dioxide (CO₂). Natural gas is a fossil fuel that is only available in limited quantities. In terms of sustainability, gas heating is not the most environmentally friendly option.

Biogas heating systems are an alternative to conventional gas heaters. Biogas is produced through the fermentation of organic materials such as biomass, agricultural waste, and food scraps. While biogas is considered a renewable energy source, its availability is limited and depends on the quantity and type of available organic materials. Additionally, the production of biogas requires careful monitoring and control to ensure that ecologically valuable areas or food production are not compromised.

Oil Heating Systems

In the past, oil heaters were widely used, but nowadays they are even prohibited in some countries for new constructions due to their significant environmental impact. Oil heaters burn heating oil, a fossil fuel, for heat generation, leading to substantial greenhouse gas emissions. From an ecological standpoint, oil heaters are not a sustainable option.

Bio-oil heating systems use plant or animal oils as fuel, obtained from renewable resources. It is argued that bio-oil heaters generate lower greenhouse gas emissions compared to conventional oil heaters. However, there are also concerns about their sustainability. The production of bio-oil requires agricultural land and resources such as water and fertilizers.

Wood and Pellet Stoves

The combustion of wood in wood and pellet stoves generates CO2 emissions. Especially in older stoves, significant amounts of particles and pollutants can be released, leading to substantial air pollution. However, modern low-emission devices are equipped with filtering mechanisms that can capture a large portion of these particles.

To utilize wood and pellets as environmentally friendly fuels, a prerequisite is that the source material comes from sustainable forestry practices.

Heat Pumps

Heat pumps are an efficient and environmentally friendly heating option that utilizes heat energy from the ambient air, ground, or groundwater. They operate on the principle of heat transfer and require only a fraction of energy for operation while obtaining the rest from the surroundings. Heat pumps do not produce direct on-site emissions, thus contributing to the reduction of greenhouse gas emissions. However, the sustainability of heat pumps also depends on the type of electricity generation. If the electricity comes from renewable sources, the heat pump is highly eco-friendly.

• Air-to-Water Heat Pumps

Air-to-water heat pumps utilize heat energy from the ambient air and transfer it to the heating system of a house. They are easy to install and are well-suited for existing buildings. One drawback is that the performance of the heat pump is dependent on the outside temperature. In regions with very cold winters, the efficiency of air-to-water heat pumps may be compromised.

• Ground-Source Heat Pumps (Geothermal)

Ground-source heat pumps utilize the heat energy stored in the ground. This is achieved through the installation of ground loops or an earth collector for heat exchange. They are highly efficient and provide a consistent output regardless of the outside temperature. They are particularly suitable for new constructions or larger properties. However, the installation of a geothermal heat pump involves higher upfront costs due to the necessary excavation work.

• Water-Source Heat Pumps

Water-source heat pumps utilize heat energy from groundwater or a nearby body of water. This type of heat pump achieves high efficiency as groundwater maintains a relatively constant temperature. However, the installation requires access to a suitable water reservoir, which may not always be feasible.

The advantages of heat pumps in general include high energy efficiency and minimal CO2 emissions. When choosing the appropriate type of heat pump, it's important to consider the specific characteristics of the building, local climate conditions, and a cost-benefit analysis.

Solar Thermal

Solar thermal is another sustainable heating option that utilizes solar energy to heat water or air. By installing solar collectors on the roof, solar energy can be captured and used for space heating or water heating. Solar thermal systems produce no emissions and are thus a reliable source of renewable energy. However, their efficiency depends on sunlight exposure and the orientation of the house. In regions with low sunlight exposure, additional heating sources may be necessary.

Electric Heating Systems

In electric heating systems such as electric radiators, infrared heaters, or electric underfloor heating, the efficiency is lower compared to other heating systems, as there can be energy losses in conventional power plants during electricity generation. The sustainability of an electric heating system largely depends on the type of electricity generation. If the electricity comes from renewable sources, the electric heating system is more environmentally friendly. The use of fossil fuels in electricity generation has negative impacts on the environmental footprint. In addition, purely electric heating systems also result in higher operating costs, especially when the electricity price is high.

District Heating

The sustainability of district heating depends on the heat generation method. Renewable energy sources make district heating environmentally friendly, reduce greenhouse gases, and utilize excess heat. However, district heating can also rely on fossil fuels, which is less sustainable. The efficiency of the heat distribution network is equally important. Transport losses can diminish overall efficiency. A well-maintained and insulated network improves efficiency and minimizes energy losses.

If you have the option to use district heating as a heating method, it is recommended to thoroughly research the energy source used and the heat distribution network for district heating supply.

What can a sustainable energy concept look like?

Proper insulation of the house

The most important measure for a sustainable energy concept is effective building insulation. By ensuring good insulation of the walls, roof, and windows, heat loss can be reduced. This, in turn, lowers the energy demand for heating and cooling the house, leading to a reduction in CO2 emissions and lower energy costs.

• Roof insulation: Retrofitting with insulation between or on the inside of rafters can be effective. Alternatively, external rafter insulation may require a roof replacement. If the attic is not utilized, insulation of the top floor ceiling may be sufficient.

• Facade insulation: Though more complex, it is particularly important as it accounts for the most significant heat loss. Consideration should be given to core insulation if necessary.

• Window replacement: Older windows can contribute to substantial energy losses. Replacing them with energy-efficient models is advisable.

• Basement ceiling insulation: If the basement is unheated or unused, applying insulation panels to the basement ceiling may be adequate.

When insulating, it is sensible to work from top to bottom since heat loss is highest in poorly insulated roofs.

The recommended order of insulation would be as follows:

1. Insulate the roof

2. Insulate the top floor ceiling

3. Insulate the facade

4. Replace windows

5. Insulate the basement ceiling

Utilizing a Photovoltaic System

An effective way to implement a sustainable energy concept is by installing a photovoltaic system on the roof. Such a system harnesses solar energy to generate electricity. By generating their own electricity from renewable sources, households become less reliant on conventionally produced electricity, which often comes from fossil fuels.

The photovoltaic system directly converts sunlight into electrical power, increasing the self-consumption of sustainably generated electricity. This means that the household can meet a portion or even the majority of its electricity needs, without depending on conventional power sources. As a result, the demand for electricity from fossil fuels is reduced, leading to a significant decrease in the ecological footprint.

Alternatively, instead of installing a dedicated photovoltaic system, there is the option to choose a renewable energy supplier. In many regions, there are now a variety of providers offering customers the option to switch to sustainably generated electricity.

Installation of an Air-to-Water Heat Pump

For a sustainable energy concept, retrofitting an air heat pump can be beneficial. It utilizes the ambient air as an energy source for power generation, and if a photovoltaic system is available, the electricity consumption of the air heat pump can be reduced.

Solar Thermal for Water Heating

An effective and sustainable way to enhance a house's energy concept is the utilization of solar thermal systems for water heating. This is achieved through the deployment of solar collectors on the roof, which absorb solar energy and utilize it for water heating purposes.

The Use of Tile Stoves or Pellet Stoves during the Transition Period

Another way to complement the sustainable energy concept of a house is by using tile stoves or pellet stoves. When temperatures are still cool in the mornings and evenings but become comfortably warm during the day, tile stoves and pellet stoves offer a flexible solution. They can be strategically used in rooms where additional warmth is needed without activating the entire heating system of the house. A fundamental requirement for a sustainable energy concept is, of course, the use of low-emission devices and wood sourced from sustainable forestry.

The Heat Pump in Detail

Let's take a closer look at how a air-to-water heat pump works.

The air-to-water heat pump is the most sustainable and straightforward retrofitting method for heating a house, as it derives a significant portion of the required energy from the environment. Typically, it draws about three-quarters of the needed thermal energy from the ambient air, ground, or groundwater and uses it to heat the house. This renders the operation of a heat pump efficient and environmentally friendly.

Existing heating systems can be converted to a heat pump quite easily. Only a small amount of electrical energy is required to drive the compressor and pump of the heat pump.

Inefficient functioning of the heat pump is often caused by insufficient building insulation. Poor insulation has adverse effects not only on heat pumps but also on all heating systems in general.

For the operation of a heat pump, radiant heating systems like underfloor heating or wall heating are suitable, as they require lower supply temperatures. This enables the heat pump to operate with higher efficiency. However, installing radiant heating is not obligatory, as modern heat pumps can also work with conventional radiators.

An alternative to installing radiant heating is to enlarge the existing radiators. Installing larger radiators increases the surface area for heat dissipation, leading to lower supply temperatures. This reduces the energy demand of the heat pump and enhances efficiency.

Hydraulic balancing of radiators is another measure to optimize heat distribution within the house. Hydraulic balancing optimally adjusts volume flows and pressure ratios in the heating system. This achieves even heat distribution throughout the house, increasing the efficiency of the heat pump and resulting in savings on electricity costs.

The Exact Functioning of a Heat Pump

A heat pump is a versatile heating system that can be distinguished based on the energy source from the environment, such as air, earth, or water.

A typical heat pump heating system consists of three main components: the heat source system, which extracts the required energy from the environment, the actual heat pump, which makes the harvested environmental heat usable, and the heat distribution and storage system, which distributes or stores the thermal energy in the house.

The functioning of a heat pump can be described as follows:

In the heat source system, a fluid circulates, which also contains an antifreeze agent. This fluid absorbs the environmental heat, for example, from the ground, and transports it to the heat pump. In the case of air heat pumps, outside air is drawn in by a fan to supply the heat pump with ambient heat.

The refrigeration cycle within the heat pump consists of four steps: evaporation, compression of a gas, condensation, and expansion.

To transfer heat, a refrigerant is used, which vaporizes at low temperatures. To vaporize the refrigerant, heat energy from the surroundings is required. Even temperatures as low as -20 degrees Celsius are sufficient. The vaporized refrigerant is then highly compressed, resulting in temperatures of up to 100 degrees Celsius. The compressed refrigerant vapor condenses and releases heat to the heating system. As a result, the pressure of the liquid refrigerant drops significantly, and the temperature of the liquid returns to its initial level. The process can then start again.

The generated heat is either directly transferred to radiators or underfloor heating systems in the building to achieve a comfortable room temperature or it can be stored in a hot water buffer tank for later use in domestic hot water supply. The heat pump thus enables efficient and sustainable heating of the house.

Myths and Possible Concerns Regarding Heat Pumps

Despite the numerous benefits and sustainable functionality of heat pumps, there are still some myths and concerns that are often raised against this heating system. Let's take a closer look at possible concerns.

• Electricity Demand and Grid Overload
  A common argument is the assumption that widespread use of heat pumps would lead to an enormous electricity demand and potentially overload the power grid. It is true that heat pumps require electricity to operate. However, modern heat pumps are highly energy-efficient and utilize a significant amount of heat energy from the environment.
  
  

• Insufficient Heating Performance at Low Outside Temperatures
  Another myth states that heat pumps lose their efficiency and cannot effectively heat during extremely cold outside temperatures. However, modern heat pumps are capable of operating efficiently even at low temperatures. There are special systems, such as hybrid heat pumps, which can be combined with an additional heat source when necessary to ensure heating performance.
  
  

• Noise and Disruptions
  Some individuals are concerned that heat pumps might be disruptive due to operational noise. However, modern heat pumps have become significantly quieter and typically produce only minimal noise, comparable to the operation of a refrigerator. Additionally, suitable measures such as sound barriers or choosing an appropriate location can help minimize potential noise disturbances.

As you can see, most of the mentioned concerns are based on outdated information or misunderstandings. Through technological advancements and continuous development of heat pump technology, most of these myths have been debunked. It is advisable to seek advice from qualified professionals to obtain accurate information and make an informed decision regarding the use of a heat pump.

Closing Words

It is clear that conventional heating systems such as gas and oil furnaces are not the most sustainable options. They contribute to high greenhouse gas emissions and rely on limited or non-renewable resources. Even wood and pellet stoves are only a sustainable option if they use low-emission devices and rely on sustainable forestry practices.

The heat pump represents an extremely efficient and environmentally friendly heating option that utilizes heat energy from the surroundings. Depending on the type of heat pump, the heat source can be air, ground, or groundwater. Heat pumps do not produce direct emissions on-site and thus contribute to the reduction of greenhouse gas emissions. However, the sustainability of heat pumps also depends on the type of electricity generation. To optimize their environmental impact, it is important to utilize renewable energy sources for electricity supply.

Solar thermal energy is a meaningful addition for most households as a hot water storage option. It is a reliable source of renewable energy but relies on sunlight and the orientation of the house.

And one thing is clear: Without proper insulation of the house, even the best sustainable heating system makes no sense. This is always the first step that needs to be taken.