Device displaying thermal loss of a residential house
Energy efficiency

Energy efficiency

How to leverage the heating energy transition

How can Germany drastically reduce its heating consumption? Petra Bühner, an expert from KfW, has analysed a number of studies and drawn up her own calculations. The outcome: five measures with the potential for enormous savings.

The author
Petra Bühner

Petra Bühner has a degree in Engineering and works as a Technical Expert at KfW.

1. Refurbish buildings

Older buildings are normally poorly insulated. Heat escapes through windows and walls. As a result, lots of energy ends up getting pumped out for nothing. A total of 13 million residential properties – that's two thirds of homes in Germany – were built before November 1977, which was when the first ordinance on thermal insulation came into force.

Around 30% of these buildings have since undergone complete or partial energy-efficient refurbishment. Good thermal insulation is an effective way to save on heating energy. Insulating the facades, roof and basement alone results in 40% savings. For owners of a typical 1970s two-family house, this means that heating requirements are reduced up to 100 kilowatt hours per square metre.

And if you then replace the windows and install state-of-the-art heating and hot water systems, you can add another 30 to 40 per cent on top. Similar effects are being achieved through the energy-efficient refurbishment of the 2.7 million factories, offices and publicly owned property in Germany.

SAVINGS POTENTIAL: Refurbishment measures can reduce heating energy requirements for older buildings by 80%.

Primary and final energy

Primary energy is the term used to refer to sources of energy that occur in nature. This includes fossil fuels such as oil or coal, as well as regenerative sources like solar and wind power. Final energy on the other hand is the amount of energy that arrives at the consumer – in other words, the proportion of primary energy that can still be used following losses for conversion or transport.

2. Build energy-efficient houses

Builders are still far from making the most of energy-saving options. Many of them stick solely to the German Federal Government's Energy Saving Ordinance. This law defines the maximum primary energy consumption levels for new buildings. However, there are already ways to make sure buildings significantly undercut this threshold. In 2016, over 50% of the around 100,000 new residential buildings completed met the KfW Efficiency House Standard 70. This means, that these buildings consume 30% less energy than allowed.

The German Federal Government is therefore cutting the maximum limit under the Energy Saving Ordinance even further. Since January 2017, new houses arel only allowed to consume just 75% of the previous primary energy threshold. Over the long-term, the KfW Efficiency House 55 is likely to become the benchmark: This would mean that new buildings would consume 55% of the current amount of energy permitted. As its next step, KfW is setting its sights on the Efficiency House 40. Something that is already technically possible could go on to become standard: 60% less energy consumed per house compared to current construction standards.

Furthermore, the importance of a concept known as Efficiency House Plus is set to increase. This is the name given to buildings that require hardly any heating energy and can produce their own power using renewable energy.

SAVINGS POTENTIAL: New buildings could soon need just 40% of the permitted quantity of primary energy.

A scale that displays the colour flow of a thermograph from low to high thermal losses

Images captured with a thermal camera show where heat escapes from building envelopes.

3. Streamline processes

Making better use of process heat means saving energy. After all, a fifth of Germany's annual energy requirements goes towards process heat; by far the largest proportion of this heat is used in industry. Lots of products can only be manufactured under very high temperatures, like iron for example. Plenty of other industrial processes also require heat, like bottle cleaning.

There are many ways to handle process heat in an efficient manner. One option is to use exhaust heat. Large data centres are already using this solution, for example. The heat generated from cooling down the servers is used to regulate temperatures in offices.

Or another option: exhaust heat flows back into production. If a company needs to dry components, it can do so using the exhaust heat from other production processes. And finally, you can also use technical innovation to reduce energy consumption by decreasing the temperatures required for production processes, for example.

SAVINGS POTENTIAL: With efficient processes and more intensive use of exhaust heat, industrial operations can reduce their energy consumption by 25%.

4. Use renewable energy

When it comes to heat production, regenerative energy can and must take on a more important role. Today, just over ten per cent of heat are produced by means of renewable energy. This figure is capable of being five times higher. However, this can only be achieved if three requirements are met: old houses need to be insulated, new buildings have to be built to be energy-efficient and the amount of heat required by industry needs to be reduced.However, if the amount of heat energy required remains at its current level, regenerative energy will only be able to contribute a little over 25%. Normally we burn oil to generate heat. When compared to this approach, the use of renewable energy sources like the sun or biomass has two benefits.

First of all: oil is an important source of fossil fuel. It is finite and must not be wasted. Second of all: burning oil generates CO₂, a killer for our climate.When we generate heat from regenerative energy, we therefore save non-renewable energy sources for other important purposes and promote protection of the environment.

SAVINGS POTENTIAL: Over 50% of heating requirements could be covered by renewable energy.

5. Generate power and heat together

A combined heat and power plant (CHP) generates power and heat at the same time. Compared to generating the two forms of energy separately, highly efficient CHP plants that use fossil fuels save at least ten per cent of primary energy. If renewable resources like biogas are used instead, savings are even significantly higher.

Cover CHANCEN on the subject of heat

This article appeared in the spring/summer 2015 issue of CHANCEN magazine on the subject of heat.

To German edition

At the moment, 14% of heat produced in Germany comes from combined heat and power plants. In future, small CHP plants could even produce something known as balancing energy . This is energy that balances out any unforeseen power fluctuations for mains network providers.

Balancing energy is becoming increasingly important because lots of power producers feed energy into the grid on an irregular basis. This is the case for wind power plants, for example. Unless it is needed straight away, the heat produced in CHP plants would have to be stored.

SAVINGS POTENTIAL: 25% of total heat requirements could be supplied using combined heat and power.

Published on KfW Stories: Tuesday, 21 March 2017