When autumn and winter bring back the obligatory bad weather and low temperatures, a cozy home is an even greater joy. At least if the walls and roof are properly insulated and the windows do not let in drafts, the homeowner can save energy. This not only makes staying in your own four walls uncomfortable, but also drives up the costs for energy and heating. If there is a need for action in this regard, energy-efficient building renovation should be seriously considered. Only 6 steps are necessary to ensure significantly better efficiency.
Saving energy – Step 1: Define the problem
Goal: energy transition and heat transition
Drafty windows and excessive heat loss through poorly insulated walls are the concrete symptoms of a much larger problem and prevent you from saving energy. At the beginning there is the need for an energy transition, the move towards a more efficient use of and a sustainable form of energy production. The constantly increasing need and consumption of resources has made it necessary to rethink many areas.
In order to be able to comply with this, the federal government has drawn up an overall strategy for Germany that is intended to address the energy transition in all aspects. The implementation of concrete measures can still only be one piece of the puzzle to a real energy transition, because a heating transition is also required as an important supplement. This is needed, among other things, because the share of energy consumption for heating or cooling accounts for around 40 percent of total energy consumption. Heating and hot water preparation in private households not only incur costs - they also use up around 70 percent of the energy consumed. They are thereAlternatives for more efficient heatingquite diverse.
On the one hand, this is due to the different financial possibilities of the owners, but on the other hand, support programs are often not accepted because they do not seem attractive enough. Support from a fund financed through energy savings could help here, as could better communication of the cost-benefit ratio of renovation measures.
Save energy – Step 2: Take stock
The next step on the path to building renovation and saving energy is to take stock of your own home in order to identify and remediate those causing unnecessary costs. The focus should be on the heating and any weak points in the building itself.
Old heating systems are one of the most common causes of poor energy and heat efficiency. For example, new condensing boilers offer potential savings of up to 30 percent in energy consumption.
Checking the energy efficiency of a heating system hardly requires any effort; it is carried out by a skilled tradesman using a standardized procedure according to DIN 4792. The approximately one-hour procedure (in a single-family home) costs around 100 euros. Among other things, exhaust gas loss, heat loss, condensing value utilization, pipe insulation and others are examined.
Depending on the condition, points are awarded for the individual areas - however, in this case, more points mean a correspondingly greater need for improvement.
Building check
Homeowners should also consider a building inspection. These are made on siteEnergy advisors from consumer advice centersoffered. The scope includes an inventory of electricity-consuming devices, an assessment of electricity and heating energy consumption and a discussion of savings options in these areas. In addition, the building envelope with all of its components - i.e. external walls, windows, doors and roof - is examined and, if not already done separately, the energy efficiency of the heating system is checked. This goes hand in hand with assessing the possibilities for using renewable energies. Approximately two hours should be allowed for the building check.
Save energy – Step 3: Find advice
Once the results of the first efficiency reviews are available, any necessary restructuring measures can be addressed more specifically. It also makes sense to consult experts for this planning step in order to achieve an optimal result within the scope of the available financial possibilities.
If you would like to get a rough overview of the renovation and funding options in advance, you can, for example, visit the BMWi's energy advice pageRenovation configuratorto use.
However, the online tool can only replace advice from an expert to a limited extent. The energy consultants also take on the application for possible subsidies from the federal authorities or KfW in advance of their work on site. These are generally 60 percent of the eligible consulting costs. For one- and two-family houses, the maximum subsidy is 800 euros, and for at least three residential units there is up to 1,100 euros.
Basically, there are two options for advice, depending on the desired path to renovation:
The necessary measures are being worked out for a comprehensive renovation in one step with the aim of meeting the new building standard or, better, in accordance with the requirements of the KfW Efficiency House.
In the case of a step-by-step renovation, a timetable is drawn up that lists the possible individual measures according to their priority for the renovation.
Saving energy – Step 4: Weigh up options
The key role that heating systems play in the heat transition and the still large number of old and inefficient heating systems make modernization in this area one of the most important measures for energy-efficient building renovation. In addition to systems that run on fossil fuels such as oil and gas, there are also alternatives that use renewable energy sources or geothermal energy, which can help you save energy.
Save energy – heating with renewable raw materials
The most important renewable and sustainable energy source is wood. Sustainable primarily because burning the wood does not release more CO2 emissions than its natural decay. In addition, heating with wood offers quitedifferent options for practical implementation. The most common and widespread variant is certainly still the fireplace stove, but various forms of biomass boilers are also suitable as a central heating system.
These include wood gasification boilers in which logs are burned. The high level of technology in these systems ensures an equally high level of efficiency with very low pollutant production. After the boiler has been filled, the wood is burned for several hours, the resulting heat is transferred to a buffer storage and can be used as needed. However, the prerequisite for heating to be as loss-free as possible is good insulation of the heating pipes.
They are also another possibilityecologically compatible pellet heating systems, which in their mode of operation range from stoves for living spaces to fully automatic systems including conveying and storage space. As with wood gasification boilers, improved energy efficiency and reduced pollutant emissions can be achieved by combining them with a buffer storage system. Particular attention should be paid to the reduced fuel efficiency with only short burning phases and the sufficient certification of the pellets, for which the European standard for solid biofuels has applied since 2011.
Save energy – solar thermal energy as an alternative
Heating buildings using solar energy is also possible. So-called solar thermal systems are primarily used to prepare hot water, but with a sufficiently large collector area - between ten and 14 square meters - and a powerful storage system - either a buffer or a combination storage system - heating can also be supported. To ensure that the heat gained is not lost, it is recommended to install the storage tank close to the collectors. The advantage of solar thermal energy is not only its contribution to sustainable heat generation, but also its ability to be combined with other heating systems.
Save energy – geothermal energy
Another variant is the use of thermal energy that is stored in the ground and groundwater. Various methods can be used for this, but heat pump systems are mainly used in the private sector. Above all, the suitability of the heat pump for the selected energy source and the requirements of the property to be equipped must be taken into account.
The different approaches to using geothermal energy include, for example, underground collectors that are installed horizontally at a relatively shallow depth of 1.5 meters, meaning that the energy yield depends on the season. Geothermal probes that reach between 50 and 150 meters vertically into the ground are significantly more powerful, but also more complex in every respect. A further technical development is the CO2 geothermal pipes filled with liquid and gaseous carbon dioxide.
Such geothermal systems can cover up to 75 percent of a building's thermal energy requirements.
Saving energy – combined heat and power and combined heat and power plants
With the help of a combined heat and power plant (CHP), electricity and heat can be generated at the same time. Even if the term “power plant” may seem irritating at first glance, the corresponding systems are now available in miniature versions that are also suitable for private households.
In conjunction with a heat storage unit, combined efficiencies of up to 90 percent can be achieved, while at the same time reducing costs and pollutant emissions. The sustainability of such systems can be increased even further if renewable fuels such as biogas or wood are used to operate the generator instead of natural gas and oil.
Save energy Step 5: Use subsidies
An energy-efficient building renovation is rarely a cost-effective affair, even if it is initially limited to individual measures in the area of heat generation and use. After all, those wanting to renovate are provided with various funding not only for advice, but also for the actual implementation.
BAFA maintains several funding programs designed to support the energy and heat transition. In addition to basic funding, there is also further innovation and additional funding for the construction or expansion of biomass plants, such as pellet, wood chip or firewood plants.
The funding of heat pumps depends mainly on the type of operation; the heat source itself is only noticeable in electrical systems. Here too, significantly increased amounts can be achieved as part of innovation and additional funding.
Solar thermal systems for pure hot water preparation must have an area of at least three square meters to be eligible for funding; the basic funding is then 50 euros per square meter or part thereof, but at least 500 euros.
Combined heat and power systems are supported with two independent programs: Firstly, with a one-off investment grant, the amount of which depends on the electrical output of the system. The second procedure provides for electricity remuneration over a certain period of time by the network operator. CHP systems that were put into operation after July 19, 2012 will receive a surcharge of 5.41 cents per kilowatt hour for a period of between five and ten years.
Save energy Step 6: Consider further measures
Renovation measures in the heating sector are undoubtedly of great importance due to their contribution to the heat transition, but from the point of view of the most complete renovation possible, they can only be viewed as individual measures. Follow-up steps are essential to further increase the efficiency of a property.
Building insulation
For example, the most modern heating system offers few advantages in terms of sustainability and cost reduction if the building insulation is inadequate. Efficient insulation and efficient heating are interdependent in such a way that they should not essentially be seen as separate measures.
Critical points where buildings may release too much heat energy to the outside are walls, windows, roofs and basements. Even the cost-effective insulation of the roof, which has been mandatory since the Energy Saving Ordinance (EnEV) of 2014, with the mandatory exceptions, can reduce heating requirements by 20 percent. In the same way, the insulation of basement rooms is specified by the EnEV, as the edge areas of the floor slab in particular can experience large heat losses. The outer walls can be prepared against such losses using a variety of different methods and insulation materials.
The advantage of the right insulation is not just the expected cost savings, it also plays a significant role in living comfort by minimizing thermal bridges. Incidentally, no one should be afraid of the financial outlay - the costs for certain measures such as insulating the roof are comparatively low and can also be financed with the help of the BAFA and KfW funding programs described above.
Electricity generation with renewable energies
This also applies to generating electricity from renewable energies, which represents, so to speak, the final step on the way to an energy-efficient and sustainable home. Wind and solar energy in particular are suitable for environmentally friendly electricity generation. In view of the development of electricity prices, small wind turbines are becoming an increasingly interesting alternative to photovoltaic systems, but the dependence on a constant wind yield and the right choice of location makes electricity production significantly more complex. In most cases, installation is only worthwhile if the electricity generated is used directly.
The situation is different with photovoltaic systems, which, due to their performance, can certainly produce surpluses for feeding into the public power grid. However, the remuneration rates as well as the funding for the construction of such systems decrease from year to year - photovoltaics are therefore hardly suitable as an investment anymore. On the other hand, the possible returns increase as technical developments occur, so that the investment is definitely worthwhile considering the savings.
In addition, photovoltaic systems can now also provide heat in a single system: However, photothermal systems are currently hardly widespread. This may be due to the criticism of inefficiency due to the actually contradictory requirements of the individual processes - photovoltaics need low temperatures, while solar thermal energy needs the highest possible temperatures. Remedy in this regard are combination modules that ensure cooling of the photovoltaic modules or integrated systems that make the waste heat usable through heat pumps.
The possibilities for improving energy and heat generation in private households are therefore far from exhausted. The ongoing need to rethink how to use resources more efficiently and more sustainably will therefore continue to lead to technical innovations in the future that will drive energy restructuring - not just in the private sector.
Save energy – mount solar panels on the roof
Modern house with solar panels on the roof
Use the roof practically
Bungalow Design
Integrated solar panels
Useful roofing
