Tuule Mall Kull: Always Keep in Mind the Meaning Behind Numbers


Tamkivi Foundation Fellow Tuule Mall Kull is pursuing her Masters in simulation sciences at RWTH Aachen, creating self-learning algorithms to manage heating systems in order to increase the use of renewable energy over time.

You received a degree in physics from the University of Tartu and graduated cum laude. How important is that for you?

I suppose it is a bit important. It was important to see that all my effort had been enough. However, the further I develop, the less important it becomes.

What helps when you have to stay up all night to study?

In my case, it’s black tea and cold, fresh air.

You are studying simulation studies. What exactly is that?

Basically it deals with computer simulations in the fields of natural sciences and engineering. Besides theory and experiments, it has risen to be the third pillar in research. Simulations are less expensive than experiments – let’s say you want to study how air moves around an airplane’s wings, it is much easier to study it on a computer than build a wind tunnel for a real plane. There are also processes that you actually can’t directly research through experimentation – some extremely rapid chemical processes or quantum effects, for example.

How accurate are the results that a simulation provides?

No model can be entirely accurate, however, results can be very much true to life. And experiments are not entirely accurate either, because in measuring whatever experiments, there are bound to be inaccuracies in measurements.

More specifically, I am specialized in building simulations. This is something that brings together everything I was already interested in when I was in high school: physics, environmental protection and architecture. To create a simulation, you have to turn observable processes into mathematical models. In physics, the models often use the system of differential equations, which is taught to the computer through discretization – while the rest of the world is made up of real numbers, computers only contain ones and zeros, so every model is a simplification.

In addition, you always have to keep in mind what the meaning is behind the numbers (for example, units).

Describing a building in its entirety is not possible – for example, we don’t always know how the shadows of trees are going to change or whether mistakes will be made during construction. However, despite all that we can fairly accurately predict how a building will behave under certain circumstances, what the room temperatures will be, how much heating it will need, etc.

And how high the winds have to be to blow off the roof?

Yes. (Pause) Of course, those kinds of things fall more within the work of another field – structures and tension. But basically that is possible.

How new is the science of simulation?

It’s about as old as computers are, but computers have become more and more powerful and now we can create simulations that a few decades ago weren’t possible. Mostly this means simulations made on supercomputers in the fields of meteorology and material physics, but regular computers can also be used to create the model of a house in full detail.

When I was looking for a university to continue my studies, I found that there were only three universities in Europe offering curricula that joined the simulation and physics aspects in a way that was interesting for me.

How different is the University of Aachen from the one in Tartu?

While everything is very much focused on theory in Tartu, here they always start with the application side. Here the first question is always what would something look like in real life.

What about what the students eat?

I would say that it is much easier to keep your belly full in Germany, because the cafeteria culture here is very strong; all the students and teachers eat at the cafeteria every day. A main course costs 2.60 – today, for example, they had chicken cordon bleu. Tuesdays are schnitzel days and Fridays are fish days.

What could Estonia learn from Germany?

There are things that actually Germans could learn from the Estonians – for example, opening hours for some state institutions are very odd and can vary from day to day. Sometimes offices will be closed for lunch, which is something unusual in Estonia.

Actually, I don’t know which way is better. I suppose it is more employee friendly in Germany. Keeping your work and private life in balance is considered to be more important here than in Estonia.

What did you want to be when you were really little?

(Sigh) Way back then… I don’t even know. I went through a lot of phases, all the simpler jobs went through my mind – one day I wanted to be a cook, then an ice skater, then a firefighter. I didn’t have one specific interest.

Later, of course, biology was very attractive for me because my parents are biologists.

What is something you dream of?

The potential of simulations to be fully used in building construction in the future.

In fact, when building a house there are so many mistakes that could show up later but can be avoided if you test things using computers first. Of course, it requires the cooperation of all involved parties – the architects, engineers, builders and owners – for things to succeed, but the potential for saving on heating energy and for increasing the comfort of the indoor climate is big.

The difference between the energy consumption of an average and a very low energy building can be tenfold, and if the price of electricity becomes even more dynamic in the future, perhaps changing from hour to hour, it could also be implemented in cutting costs.

Where would you build a house for yourself?

(Laughs) Probably somewhere in the middle of a forest in Estonia, but on a clearing that opens up towards the south, so that I could use the sun as much as possible. At the same time, the building would have to be well connected to the local electrical grid, because in a future with renewable energy sources different producers and consumers will start to balance each other more – if a building has solar panels, it can often happen that the house makes more energy than it consumes. A house that is connected to a network can share its energy with others.

Does the word “simulator” (negative connotation “faker” or “pretender”in Estonian) also mean anything in the scientific sphere of simulation?
Hmm. Not really. Although the jokes do come up, hey, you’re a simulator, faker.

How are you planning on spending your stipend?

Well, I have to live off of something. I’m not going to go and get myself something nice. If there’s anything left after eating, it will go in my laptop fund.

PC or Mac?

When it comes to building simulators, the thing is that no matter what my own preference might be, I couldn’t use anything other than Windows, because all the building construction simulators have been written for Windows. So you have to have Windows installed, even though I still mostly use Linux. In simulation sciences, like in programming generally, it is best if you can modify everything that can be modified yourself.

What would bring you back to Estonia?

It’s not a question of what would bring me back, but rather what most certainly does – family, friends, nature and challenges. Estonian society is also more open to changes. Here one person can’t change anything, but in Estonia it is possible.

You in 2030?

Hopefully by that time I’ll be back in Estonia and advanced enough that I can help others further their knowledge.

Night or day? 


Dog or cat?


Ketchup or mustard?

Mayonnaise – because Germans eat their French fries with mayo.

Favorite month?

August – the stars in Estonia.

Favorite verb?

I’m dreaming.

Ugly color?

Hmm. Are some colors dishonest? I think teal is.

Bus or train?

Train, because you can read on a train, but on a bus you get nauseous.

Fir or oak?

Oak – it is the Estonian national tree, after all.

East or west?


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