"Efficiency Plus" - resource efficiency, climate protection and production site viability at Viessmann head office in Allendorf (Eder)

Strategic "Efficiency Plus" sustainability project

With its strategic sustainability project "Efficiency Plus", Viessmann has shown that the energy and climate policy targets set for 2050 can already be achieved today. Through the use of commercially available technology, energy efficiency in particular has been significantly increased, as well as operational and material efficiency. Consumption of fossil fuels fell by two thirds, while CO2 emissions were reduced by 80 percent.

All relevant fuel types are utilised in the new energy centre – oil and gas as well as biomass, solar energy and heat sourced from the air and ground. Efficient technologies, such as condensing and CHP, make a vital contribution.

Woodchips produced from the company's own short rotation coppices are used to generate heat and power in an environmentally responsible way. Poplar and willow trees are grown on an area of 180 hectares, covering around half of the annual demand (7000 tonnes) of solid biomass.

> Efficiency Plus – energy efficiency in practice (PDF)

Viessmann is way ahead of political goals

The German Federal Government has set a broad timeframe for reaching its climate goals: A reduction of CO2 emissions by 80 percent is aimed for no sooner than 2050, whilst the proportion of renewables should by then have increased to 60 percent.

Viessmann is ahead of these goals by decades: The company has already achieved the required values and will continue to improve on them in the years to come.

Klimaziele erreicht

Viessmann grows poplar and willow trees in short rotation coppices to obtain biomass.

Energieoptimierte Anlagen und Prozesse in der Produktion

Significance of Efficiency Plus in manufacturing

With the Efficiency Plus project, Viessmann already meets the German Government's energy and climate goals for 2050 at its Allendorf site.

By increasing energy efficiency by 22 percent and substituting 18 percent of fossil fuels with renewables, the consumption of oil and gas has been reduced by 60 percent, whilst CO2 emissions have dropped by 80 percent. On the consumption side, this was achieved by energy-optimised production plants and processes, consistent heat recovery and improved thermal insulation of the buildings.

Substituting fossil fuels

In the Viessmann energy centre, all future oriented technologies are being used, such as highly efficient condensing technology and combined heat and power plants. In addition, fossil fuels are being substituted for renewables in ever increasing amounts. The focus is on the use of solid biomass and biogas, utilisation of solar energy from solar thermal and photovoltaic plants, and air source or geothermal heat pump technology.

The material flux diagram of the Allendorf site gives a clear overview of where the most energy is used and where the highest costs or emissions occur.

Fertigung von Wärmetauschern

Energy management – lower consumption through extensive system control

At Viessmann, the energy management system is of critical importance. It continually checks where potential savings can be made in current production. For this, the most relevant factors are energy consumption and the supply of energy generated on site into the grid.

Always up to date on consumption

The energy management system is visualised as an energy cockpit using flow diagrams. Meters integrated into the network provide information on current consumption, as well as the amount of energy generated on site or yielded through heat recovery and returned to the energy cycle.

Individually adjustable consumption controllers raise automatic alarms if energy consumption is unusually high compared to previous values.

ISO 50001 specifies the requirements of an energy management system. These include developing an efficient energy policy within the company, taking the necessary steps to improve performance, and reducing energy costs and CO2 emissions.

Übersichtliche Darstellung und permanente Kontrolle der Energieverbräuche

Networking energy streams affects consumers and generators

Apart from rigorously reducing the energy demand on the consumption side, the substitution of oil or gas with renewables and the efficiency increase on the generation side are important levers to sustainably reduce fuel consumption. In particular, the increased use of biomass enables substantial potential to be exploited.

Compound energy system bundles residual and waste heat

The networking of energy streams supplies an additional efficiency bonus through heat recovery. Waste heat is channelled via a common return into a compound energy system and reused to supply heat.

The waste heat originates from compressed air generation, the IT centre and from test beds in production and R&D.

Lastganganalysen zeigen deutlich die Bedarfsspitzen eines Produktionstages auf

Load profile analyses illustrate the actual energy demand

One important prerequisite for optimising the energy demand is the systematic compilation and illustration of the energy and material flux in a company. To this end, a detailed mass flow analysis is carried out, which forms the basis for understanding individual processes and sequences within the system as a whole.

Load profile analyses provide greater insight into the data obtained, using statistical measurements and processes. These analyses aim to provide a structured definition of the steps and procedures that can help to reduce energy demand, and consequently costs and emissions.

Utilising energy potential without incurring expenditure

The potential analysis represents a further step in this endeavour. It investigated the potential available at a production facility within the Viessmann Group for an energy concept with an assured future.

It showed, not only the necessary investments, but also the potential that could be realised without incurring expenditure. For example, control optimisation, definition and control of shutdown processes or pressure reductions can save up to 10 percent in energy costs every year without substantial outlay.


Pulverbeschichtung von Gehäuseteilen in der Produktion

Energy potential in processes and plants increases efficiency

The metalworking industry accounts for a large proportion of German manufacturing companies. In many of these, pieces of sheet metal need to be washed and painted following their forming processes. These processes require particular attention when it comes to energy consumption.

Here, processes and plants harbour enormous saving potential. For the Efficiency Plus project at Viessmann, for example, measurements provided pertinent parameters which allowed comparisons between production numbers and energy consumption to be made. The result: in the same process, energy consumption could vary by up to 20 percent.

Utilising process potential

Fluids employed in production are frequently treated and reused several times in sealed circuits before the waste heat is fed into the compound energy system.

Savings with the right lighting

The new lighting concept focused on factors such as economy, effectiveness in the working environment and automation. New LED technology achieves the same level of brightness with substantially less energy and still offers a long service life.

Die Energiezentrale der Viessmann Werke in Allendorf (Eder): rechts im Bild zwei Biomassekessel, daneben zwei Blockheizkraftwerke

Energy centre with around 60 percent proportion of renewables

The energy concept for the Allendorf site concentrates on improving efficiency and substituting fossil fuels with renewables. Viessmann focuses on biomass, which today, already covers 60 percent of the heat demand at the company's head office.

Central heat recovery

The networking of energy streams supplies an additional efficiency bonus – for instance through heat recovery, for which approximately 9600 MWh of waste heat from compressed air generation, the IT centre and test beds is utilised. The plant as a whole is interconnected via the temperature networks to form the compound energy system.

Energy centre with efficient and environmentally responsible technologies

In the energy centre, which was modernised in 2012, all energy sources relevant to the heating market are deployed – oil and gas, biomass, solar energy, as well as heat from the ambient air and the ground. Innovative technologies such as condensing technology and combined heat & power generation ensure highly efficient utilisation of these sources. The energy centre operates in three stages:

●  Two CHP units operated with bio natural gas cover the base heat load and simultaneously generate electricity.

●  When heat demand is higher, for example in winter, the biomass boilers operated with woodchips are also fired up. An ORC turbine uses this heat to generate electricity, too.

●  Oil and gas boilers with downstream flue gas heat exchangers cover peak loads and act as redundancy boilers.

Biofuel already covers 77 percent of the heat demand at the Allendorf site. The long-term aim is a 100 percent supply using this environmentally responsible fuel. Sustainability is the buzz word here, meaning we use only as much biomass as regrows within the same period.

In addition, a biogas plant employing dry fermentation supplies around 2.7 MWh of power and heat every year. The substrate comprises local agricultural and landscape waste, as well as regenerative raw materials. A second biogas plant was completed in 2013. This is a wet fermentation plant, which uses 15,000 tonnes of substrate annually to generate around 1.6 million cubic meters of biogas. This is upgraded to natural gas quality and injected into the natural gas grid.

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Biofuel from Hesse
Die beiden Biogasanlagen der Viessmann Werke: In der linken Anlage wird trockene und rechts nasse Biomasse fermentiert

Biogas plants for on-site consumption and trading in biomethane

The location of a manufacturing company has a significant influence on the degree to which it can generate its own energy – be it for consumption on site or for energy trading. The rural location of the Viessmann site is ideal for the operation of biomass plants.

Dry and wet fermentation

The two biogas plants owned by the company operate according to the principles of dry and wet fermentation. The former operates primarily with residues from agriculture and countryside management.

4500 tonnes of substrate annually supply more than 1.2 million kWh of electricity for which Viessmann receives remuneration according to the German Renewable Energy Sources Act (EEG).

The heat generated from this energy amounts to almost 1.5 million kWh which is used to cover the base load of the heating network at the company's site. A CHP unit with an output of 190 kWel and 238 kWth converts the primary energy.

The second plant is operated with agricultural waste such as slurry and manure.

Biogas to bio natural gas

The biogas created by this process is upgraded to biomethane which has the same qualities as natural gas. Viessmann is remunerated for all the gas it injects into the public mains at a level fixed by the government, in line with the Renewable Energy Sources Act.


The second biogas plant at the Allendorf (Eder) site works employs wet fermentation. The biogas is upgraded to natural gas quality and injected into the natural gas grid.