R744 is the refrigerant name of CO2, (Carbon Dioxide), and is a natural gas which is all around us.

In fact, we even cannot live without it!

But as with anything, adding too much to our environment while the demand of the natural use from nature, is rapidly decreasing by cutting down forests, ( also for the use of fire wood and fuel pellets! )  is becoming a problem rapidly.

The proof is all around us ( see picture above) even on our doorstep every day in many forms, and still humanity is not entirely convinced. 

Time is running out is often heard, lets take action etc. etc. etc.

Some of my thoughts in these are,


Why did we ever stopped with sailing our goods over the oceans, using free and sustainable wind, and stopped a development which was already that far ahead, that it still can be, and is used today.

If we watch the Volvo Ocean race, we can see the possibility's, but why still use this for fun only in most cases?? 


Why did we stop using wind for a lot of small propulsion needs like we did successfully in the 

middle ages?


Off course the answer will be;  industrial progress.. 

But was it really?……………


How to use the same product causing so much problems, to build one of the solutions to stop global warming by humanity?



The working of a heat pump system. 


Heating or cooling a building is done for years by adding heat, burning some kind of fuel, and cooling, by a refrigeration system taking out the heat of a building and throw it in the direct environment of the building (roof mostly).

Creating and using energy, to throw away energy, is seen to be the “smart solution of the “intelligent” species called humanity.

Most animals does far better than we do I can ensure you. 

They use insulation in most cases, and also the natural sources wind, and sun.


A heat-pump is axially a refrigeration system, working the other way around.

That simple, nothing more and nothing less.

How it works its all in the name;   




It is designed to transfer heat from one place to the other, not to create heat.


To take away the heat out of a product, and move it to the other. (Air or water are the most common products to “take out”, or “pump to” the heat). 

In order to transport the heat, we have to place it in a something which is able to take up heat, and deliver it too.



Heat-pump scheme of the Sanden Aquaeco2 R744 heat-pump, air to water (the evaporator is a air cooler in this case) . 




This something is the refrigerant, and is pumped around by the compressor of a heat-pump in a closed system.

The amount of heat which is able to be transported by heat pump, depends on the amount of heat which can be put in to the refrigerant.

And here is one the biggest benefits for using CO2 as refrigerant!                                                   

It is able to contain, and transport a lot of heat in every gram.

Test in practice showed it is the most efficient refrigerant (next to water, which can’t be used in practice because it will freeze below 0ºC) 

Also it is a natural gas, which is non flammable or aggressive, and even used bubbles in drinks, and off course as a fire extinguisher . 

Look at the bubbles in your beer, or lager.. CO2 refrigerant is often a by product of the proces of making this liquid, which also mean that even producing this refrigerant has low energy use en environmental impact.. 

CO2 therefore is the best refrigerant to use of all known, and was already, in the past refrigeration/heat-pump history sinds 1896!  But off course “smart” humanity thought it could do better than nature again! 

The CFC and HCFC’s were developed around 1930, with devastating results for our ozon layer! 





At the moment of publication of this website, (April 2016) there is already a lot of refrigerant installations build, with CO2 as refrigerant, and build to reuse the heat as much as possible.

However most heat pump and airco systems suppliers do not, and are still holding on to technique which is in order to be phased out, even knowing that all the technique for using natural refrigerants, is available at the moment of publishing this article.

Thermopunt Katwijk however is,  although certificated to work with all refrigerants, using CO2 as main refrigerant, and was the first to install a Heat-pump system in the Netherlands in a   private estates home .

This was in April 2015, and now a year further it proved to be a system which is able to maintain comfort in a well insulated home also in winter, without any use of extra heat sources (Combined or so called hybrid systems)  and is able to provide al heat and domestic hot water with a temperature of 65ºC  even when it is freezing outside.

Also a benefit of CO2 comparing with other refrigerants, there is a bigger temperature difference possible between low and high temperature, than most of the other refrigerants.

And less refrigerant needed, does mean a smaller system.

Well, look at the next picture’s of the system replacing a gas-heater in the Netherlands, all placed in a small corner of the attic. 



Sanden Aquaeco2 heatpump system making this home a fossil fuel free one, in combination with solar panels and wind energy.


Also see :






All possible against a very reasonable price, and high quality. 

Of course it is also possible for systems with almost any demand, cooling, heating and or HVAC.

For sport facility's, elderly home's, hospitals, low temperature heat recovery, also for industry, hotels, swimming pools, schools, and everywhere a possible solution for the need of lots of DMHW (Domestic hot water , and heating, using fossil free electricity from wind, water and solar power.

Using those systems on bigger scale, can be helpful to release grids from overcapacity, and will ease the use smaller local emergency power plants and still have comfortable heating and saving fuel.


Please contact for more information,



Tinus de Vreugd

Thermopunt Katwijk              

Duinstraat 12                    

2225 RC Katwijk aan/zee                     

Tel: 0652717578

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