Pipistrel d.o.o. Ajdovščina was established in 1989 and has by now gained the reputation of the world leader in development and production environment-friendly aircraft. Our entire production goes on in an energy self-sufficient complex that does not pollute the environment, we hold some important innovations and world-firsts… and more.

We proudly introduce our environmental politics, named ECOLUTION.

ECOlution ® – fly green, think green and act green every step of the way!
Follow the green line and discover… ECOlution ®!

Pipistrel follows the ECOlution philosophy on every step. We make sure that

…our aircraft
…our working environment
…our deeds and actions towards outside world

are green.


Green products

Becoming the world leader in development and production environment-friendly aircraft was made possible only by our progressive thinking and innovative production philosophy: the policy of our aircraft design has been based on aerodynamically clean lines and a perfect surface right from the start. This provides the aircraft with more lift while at the same time minimises drag, yielding much lower fuel consumption than comparable aircraft. CO2 emissions are thereby significantly lower, as is the noise produced by Pipistrel aircraft. Result are aircraft that are simply superior.

Flying green

Already in the early days of Pipistrel’s aircraft design, every aeroplane followed the same guidelines: perfect surfaces to maximise lift and minimise air resistance. Sinus was the first example of this policy, with her 1:27 gliding ratio and the ability to turn off the engine completely and thus save the fuel. Her sister, Virus, was even faster and more economic. This aircraft won the NASA Centennial Challenge two years in a row – for being the most useful, economic and at the same time fast small personal aircraft on the market.

The next logical step was the Taurus – the first microlight two-seat glider with an auxiliary, fully retractable engine. After the huge success of this airplane we decided to take this same idea a step further.
We wanted to:
-offer the pilots a REAL glider or it’s self-lauching version with an auxiliary, yet fully retractable engine and glide ratio of at least 1:40;
-make gliding cheap;
-provide a fully equipped aircraft, including a total rescue ballistic parachute system which saves the aircraft and both pilots, all instruments, radio etc. at a reasonable price;
-provide the owner with complete freedom and independence – even the helper holding the wing tip during take-off is now not needed any more by providing two main wheels in parallel configuration;
-have the most comfortable cockpit on the market with a separate ventilation system for each pilot and side-by-side seating arrangement;
-be pilot-friendly oriented without simple & straight-forward systems handling.

… and all this, we wanted to offer with an ELECTRIC ENGINE!

The substitution of the internal combustion engine with its electric counterpart wasn’t an easy task, especially since we decided to pursue a set of sky-high goals:

1.) Aggressive Pricing: Sell it for the same price as piston engine Taurus
2.) Equal performance: Keep take-off distance and climb profile of piston engine Taurus
3.) Keep the weight down Empty weight the same as piston engine Taurus with fuel
4.) Make it REALLY useful Climbs in excess of 6000 ft on a single battery charge; user friendly and care-free handling

Several teams and research laboratories around the world have been researching the possibility of producing and electric-powered aircraft. Using the latest findings in the fields of batteries and charge storage as well as the recent developments of synchronous electric motors with small mass and high specific torque, the flight of electric-powered aircraft became reality.

However, to achieve electric powered flight, and doing this for a two person crew for the first time ever, there are quite a few hurdles to overcome. To name just a few:
-the specific weight of the batteries is still high and the number of charge cycles (life span) relatively low (measured in thousands of cycles);
-specific capacity of the batteries could be higher;
-low efficiency of the existing solar cells and their current price;
-aviation legislation, which is very slow to follow the advancements in this field;
-customers being skeptic to the new type of propulsion.

Because of all of the above the direct substitution of the classic aircraft engine with internal combustion on powered aircraft is not yet possible. The most plausible application of electric-motor propulsion however points to the powered-gliders.

Pipistrel’s Taurus is a two-seat glider with higher approved take-off mass than the single seat gliders where the electric-motor propulsion has been tested so far. Therefore the Taurus requires a more powerful electric motor.

The motives to develop an electric-powered Taurus self-launching glider were the following:

-to offer the customers with a new, high-tech and innovative aircraft propulsion;
-to reduce the pollution to the atmosphere;
-to reduce noise when flying under engine power;
-to reduce the cost of flying because of ever higher oil prices;
-to become the first truly useful two-seat electric powered self-launching glider (aircraft).

All design goals have been fulfilled and the Taurus Electro performed its first flight on 21 December, 2007. In 2008 it withstood rigorous testing and it is now in serial production. You can read everything about the Taurus Electro HERE.

But the Taurus Electro isn’t the only green aircraft we can boast with.

–>The new Virus SW was declared the best small aircraft by NASA for two years in a row, because of its low consumption, low noise and simple handling. Read all about the NASA challenge 2007 PAV challenge HERE or HERE, or CLICK HERE for the NASA 2008 GAT challenge.

–>Project Hydrogenius: Working with University of Stuttgart’s Institute of Aircraft Design (IFB), Pipistrel is developing a hydrogen-powered aircraft Hydrogenius.


Green work environment

Becoming the world leader in development and production environment-friendly aircraft was made possible only by our progressive thinking and innovative production philosophy: the policy of our aircraft design has been based on aerodynamically clean lines and a perfect surface right from the start. This provides the aircraft with more lift while at the same time minimises drag, yielding much lower fuel consumption than comparable aircraft. CO2 emissions are thereby significantly lower, as is the noise produced by Pipistrel aircraft. Result are aircraft that are simply superior.

But just making environment-friendly aircraft is not enough. If we want to save the nature, we have to start at the very beginning – so we decided that our green aircraft must be produced in an environment-friendly building, as a part of a wholesome green philosophy of our company.

The Research & Development building – our facility, 100% eco-friendly!

Staying on top is much harder than just reaching the top once, and Pipistrel is well aware of this. Therefore, all available funds are transferred directly into Research and Development. For this very purpose a research centre for applicative technologies, featuring an aerodynamics laboratory, laboratory for development of composite materials, laboratory for development of application of organic photo-voltaic solar cells to uneven surfaces and the laboratory for aircraft testing was built in 2007.

We can expect a rapid increase of energy prices and stricter limitations on energy consumption. Pipistrel is already aware of this challenge, that is why we built the research institute with the goal of energy efficiency and environment conservation in mind.

The project…
…and the reality!

The R&D building’s footprint measures 2400 m2 and had been designed as environmentally friendly and emission-free. All energy consumed by the building and the activities inside do not put any stress on the environment. Energy is used very rationally and efficiently, allowing the building to be completely energy self-sufficient, only using renewable energy sources.  The construction of the building was a huge challenge, especially since it represented a huge short-term expense while the results of nature protection are only visible long-term.

The systems

The buildings location, orientation, as well as the shape of the roof had to be adjusted so that the solar radiation could be taken advantage of as much as possible. A major difficulty is the local phenomenon called “Burja”, a very strong and gusty wind, at times exceeding speeds of 200 km/h. Pipistrel’s virtual wind tunnel produced an aerodynamic study about Burja’s effect on the building and its shape. As a result of this analysis, the building is oriented at an azimuth of 170° and not exactly southwards. The roof is inclined at a 30% bank, providing optimal efficiency to the solar power plant.

Solar radiation
All main glass surfaces face north (away from the sun), so that only diffuse light can enter the building. All doors and windows have above-average insulation (K=1.0). To minimize thermal losses, polyurethane roof and side walls (so called “sandwich” panels) with thermal coefficient of K=0.18 are used. All the windows that face south are designed with an precisely calculated extended roof or balcony above them, so that in the summer the direct sunlight and heat cannot enter. In the winter however, when the building could use additional energy, the lower angle of the sun allows the sunlight to enter the building.

Greenest technology
The building incorporates geothermal heat exchangers in symbiosis with a large geothermal accumulation field. The heart of the building is a large solar power plants which (combined with a co-generation module) covers for all energy needs of the building, electricity and thermal energy conditioning included. Air conditioning is established in an efficient manner, using ground radiation heating and cooling. This allows for the minimum possible temperature difference between highest and lowest fluid temperature in the building, yields maximum efficiencies, and spares costs. The central intelligent supervisory system controls the whole building, including the lighting with regard to the current insolation, energy recuperation and ventilation systems – all that with respect to current input economic parameters.

Geothermal heat exchangers placed around the building are the primary source of thermal energy. A total of 1,200 metres of vertical geothermal heat exchangers provide approximately 36 kW of thermal energy.

The Geothermal accumulation field is a ground collector which functions as a storage for exchange and deriving of thermal energy at rate of 25 W/m2. The capacity of the accumulation field measures 5000 m3 and is placed underneath the whole of the building in form of 4 collectors each 250 m2 in footprint.

Geothermal heat-exchangers are connected to the Geothermal accumulation field so that it is also possible to run the system without using the heat pump on days when pumping the heat transfer medium around the building suffices.
As requirements for the higher or lower temperature of the medium arise, the heat pump is activated by the system automatically.
Spare heat is accumulated inside the Geothermal accumulation field.

Co-generation unit.
Covering own need for electrical power while at the same time supplying the technical heat necessary for the building, a co-generation unit of 43 kW heating power is installed. The co-generation plant is powered by a natural gas motor to be later exchanged for a biomass-driven motor. It produces both electricity and heat. Mechanical energy is used to run the generator, which produces electric power. By cooling-down the motor and exhaust gases, which are ran through a catalyser and a built-in heat exchanger, also the spare energy is transferred and used for heating up water further used for technological processes. This water reaches a temperature of 80° C. The heat produced by the co-generator can be sent to the heating distributor (35° C point) in the new power station, as well as to the boiler station inside the existing production facility. The total energy efficiency of the co-generation system reaches 85%, which yields considerable savings.

Heat pump
The heat pump is used to either chill or heat the heat transfer medium (glycol-based fluid). The heat pump is a compact type with three built-in parallel hermetic compressors. Hence there is only the need for a single cooling circuit with a flat freonic steam generator (condenser), cooling controllers and electric harness. Derived heat from the geothermal heat exchangers heats the 30% glycol transfer medium on the primary side of the pump the lower temperature (35/25° C) transfer medium on the secondary side. The medium is then pumped throughout the circuit.

Heating and cooling is established in an efficient manner using ground radiation. This allows for the minimum possible temperature difference between highest and lowest water temperature in the building and yields maximum efficiencies and savings. The ground radiation system consists of a mesh of pipes made of high-density polyethylene PE-Xc. The temperature system of heated water is 35/25° C, in the summer 13° C. The distance between pipes in the mesh was chosen carefully so that the ground is never heated to more than 29° C. Ground radiation covers for the complete thermal losses of the building.

Ventilation inside the building is carried out using recuperators that are able to intercept 90% of thermal energy returning to the rooms. Gasses from the welding shop are also recycled with ionisators and return to the rooms at the same temperature (via recuperators).

Solar Power Plant
The heart of the building is a solar power plant which, combined with a co-generation module covers for all energetic needs of the building, electricity and thermal energy conditioning included. The entire roof of the building is covered with photo-voltaic panels, capable of producing 107 kW of energy and thus earning a place among the largest solar power plants in private ownership in Slovenia.

Panels used are SolarWorld mono-crystal silicon panels with 25 year of guarantee until 80% off-peak efficiency value. The photo-voltaic panels are coupled with 13 network inverters SMA Sunny Mini Central with 98% efficiency. Network inverters converts DC power from the panels to AC network distribution power and send it via a counter directly into the distribution network. Sunny WebBox monitoring hardware and software provides data around the solar power-plant for public view on the internet. The solar power plant has potential to grow to 200 kW power by adding photo-voltaic panels to the existing Pipistrel building as well.

System control and optimization
The central intelligent supervisory system controls the whole building (the geothermal heat exchangers, the air conditioning, heating and cooling of the building ), including the lighting with regard to the current insolation, energy recuperation and ventilation systems.
Alongside these tasks the central processor prioritizes the main system units (boiler, co-generator, heat pump, direct heat exchange, by-pass of the heat pump, etc.) according to the chosen economy-based input values. This is how the most efficient and cost effective operation of the complete building is ensured.

Quite apart from the numerous savings of the new building (enabled by the super-efficient insulation, low-temperature system of heating and air conditioning, ventilation air energy recuperation, intelligent light system, geothermal heat exchangers, geothermal accumulation field for energy storage, heat pump and co-generator, the and solar power plant alone is expected to reduce the carbon footprint for 65,000 kg of CO2 every year.
On top of that, the savings from replacing the oil based heaters amount to 37,295 kg of CO2.
Replacing the earth-gas heaters means additional saving of 49,990 kg of CO2, and savings from using energy co-generation: 33,350 kg of CO2 per year.
A rough estimate for yearly savings of energy is 95.000 kWh.
The total CO2 savings from all the systems combined are 180,635 kg of CO2 per year!

Economic savings (pay-off period and other economic indicators) were intentionally not considered in the project, as the environmental benefits outweigh them by far. Being energetically independent in case of energy use limitations in the future was more important.

The value of the new complex and financing
The new Pipistrel’s research & development center utilizes all the best and most economic energy systems known at this moment. It is unique in this part of Europe and one of the most advanced structures in the world!
The value of the investment is 2,5 million Euro, out of this 370.000 EUR of non-refundable funding by the government and the European Union.
The company financed this investment with its own resources and with credits granted by the “EKO” fund and NKBM bank with subsidized interest rates by the Municipality of Ajdovščina.

Pipistrel continues its philosophy already demonstrated in form or World-class award-winning aircraft by investing into environmentally-friendly premises, researching new energy sources and innovative propulsion systems. The future will bring highly important strategic decisions, demanding the preservation of the environment – and the company is already well aware of this. Every single strategic document describing company’s vision and future already mentions energy preservation as the first priority.

Regardless of the higher costs of construction and planning of such buildings, Pipistrel believes that it will soon become evident that such energetically self-sufficient constructions are indeed more cost effective over longer periods of time. Furthermore, we are convinced that other businesses will need to follow this vision shortly due to the sheer need for energy preservation as well as for the upcoming environment fees which governments will impose sooner or later.


Green actions

Not only our aircraft and our production facility are green, but also our actions towards the wider environment. Our actions:

-Project “Zemljo so nam posodili otroci

-Sparrow of Hope

In 2009 we decided not to send any paper Christmas cards anymore, but only electronic ones. Why?

Each year we typically sent approximately 1000 greetings cards. Every greeting is composed of a card and an envelope. So that is at least 2 sheets of paper (times 1000). Altogether this makes 2000 sheets of paper. Taking into account the environmental effect of producing this much paper (production impact and raw materials corresponding to 1/4 of a tree. A full-grown tree would otherwise absorb around 16kg of CO2 yearly, so that amounts to 4kg of CO2) and the world-wide delivery (est. 25-50g CO2 per letter), this sums at 54 kg of CO2 per Christmas!
Would you really wish to give anyone 54 kg of CO2 for Christmas?

This is exactly why we decided to start distributing holiday greetings only through our website and e-mail.

But there is more! Not only have we saved CO2 emissions by not sending out paper greeting cards, we gave the best possible holiday gift to the Nature. We decided to plant 4 new trees next to our premises in Ajdovščina.

Did you know that:
-Pipistrel powers 100% of its energy needs from our own sustainable means, among others a large solar power plant, state-of-the-art geo-thermal system and co-generation.
-using these technologies, Pipistrel saves 180,600 kg of CO2 every year
-fact is that a healthy adult tree absorbs around 16 kg of CO2 per year
-Pipistrel hence saves the equivalent of CO2 otherwise absorbed by more than 11,288 trees!!!

Of course, at Pipistrel we keep our promises – but not quite to the word.
We didn’t plant four trees. Instead we planted TEN of them! 🙂 Read the story here:

Planting trees

The deed was accepted very well and we received a lot of positive feedback, so this encouraged us to take it a step further. This was the time when we were thinking about our new construction facility in Italy (foundation laid in 2014). To prevent it from being just one huge grey box, we decided to plant trees all along the sides.