BauSIM Conference Seeks Energy-Saving Solutions — And Not Just for This Winter

Universities and universities of applied science will be represented along with engineering and architecture firms, the construction industry and public administration. Scientific writer Dr. Stefanie Waske spoke in advance with conference director, Prof. Dr. Conrad Völker, about the conference topics and why comfort is an issue.

How cold will it be in our homes and offices? What kinds of energy can we still afford? These are the questions on everyone’s minds at the moment. Your conference focusses on the topic from a scientific perspective. How do you, as a researcher, understand the current debates? 

In building physics and related fields, we have obviously been asking ourselves for years how we can reduce the energy consumption of our buildings and reduce CO₂ emissions. But now we are being confronted with the possibility of suddenly have little or no energy left, which is a scenario that we have encountered before. In the last weeks, we have conducted individual simulations in our department to see what would happen if, all of a sudden, there was no gas for heating. What would happen if there was suddenly no gas available for heating? How low would temperatures inside flats drop?

What were the results?

Our simulations indicated that the temperatures inside flats can drop very quickly into the single digits and that the flats can remain cold for months. This does not, of course, apply identically to every flat; insulation, use and the number of occupants (since bodies emit heat and appliances and cooking also produce heat) all play a role.

What are potential consequences for the building itself? Doesn’t mould pose a danger?

Mould growth could pose a problem, and one that can unfold relatively quickly. This affects in particular flats that bring in a lot of moisture through, for instance, cooking, hanging laundry to dry, taking showers, and poor ventilation. Ventilation is especially likely to be difficult for people when it is cold outside. If I have little or no heating available, I don’t want to make it even colder, meaning I ventilate even less. But it’s important to ventilate properly, especially is colder flats, because cold air is not as efficient at absorbing moisture which increases the risk of mould growth. The second danger posed to the building is frost issues. In cold temperatures, water in heating systems and other places freezes, expands and causes damage. Another danger is that the frost point and dew point shift inwards, which can cause structural damage.

These are all worrying scenarios.

But this crisis is also forcing us to take positive action towards reducing our CO₂ emissions. Suddenly, measures are being taken that could have actually been taken much earlier. We are now, for example, thinking about prudently reducing our heating. Many are rethinking building technology, which includes energy production or no longer lighting building at night. This not only reduces energy consumption, it also decreases light pollution. Making these reductions not is not only helpful in dealing with the current crisis — it is also something that should be maintained in the long term.

Many of the contributions to the BauSIM2022 address the topic of reducing energy consumption. Is this something new?

The conference has revolved around the simulation of energy efficiency in buildings, communities and beyond for years. At this year's conference, of course, there is a sense of urgency due to the current social situation. But the topic was just as important in the past. Our goal is not to find solutions for the upcoming winter — reducing CO₂ emissions has preoccupied is for years and will remain important in the future. Additionally, there are the ever-increasing energy prices and unwanted political dependencies due to energy supply. In this respect, it is a never-ending issue.

What are the approaches discussed most often among professionals to achieve this goal?

In the past, we looked at individual buildings. But we are moving further and further away from this. In the future, we will be looking more at neighbourhoods. It may be that one building consumes a little more energy, but that this is compensated for by a neighbouring building. If you take a look at our campus, a lot of the buildings are quite good in terms of energy efficiency. At the same time, we have buildings next to them that are UNESCO World Heritage Sites and will always consume more energy than the others. What’s important is that the neighbourhood is balanced.

We currently heat a large part of our buildings using gas and oil. This is not only politically inconvenient at the moment, it also emits high levels of CO₂. In addition to insulating buildings, we also need new technical solutions such as heat pumps, geothermal energy and hydrogen. We also need buildings and neighbourhoods to be not only energy consumers, but energy producers. Perhaps even energy storage facilities. All of these things will be discussed at the conference. The focus will be on how to calculate and simulate such ideas. You don’t want to just dive in and test things out in an actual neighbourhood; this nearly always goes south and is terribly expensive. This is why we are developing procedures such as computer simulations in our IBPSA that can be used to make calculations, among other things.

What can this be used for?

Different buildings with their very different constructions can be simulated taking into consideration wall structures, window proportions and the directions they face. The building technology also varies; some buildings still rely on old natural gas or oil heating systems, while others are already outfitted with heat pumps or hydrogen producing electrolysers. Most are somewhere in between.

The various uses also have to be simulated; some buildings are office spaces, others are residential. And then you have buildings such as industrial buildings or even a university — all of these are used in very different ways. We try to accommodate for all of this in our simulations. What is then simulated after creating all of these conditions is an energy balance of the building or neighbourhood. The result is then, for instance, the heating demand of a neighbourhood. And ideally this demand would be as low as possible. The remaining demand should be fulfilled with the help of renewable resources in order to reduce future CO₂ emissions.

And how do I figure into the bill as a resident?

On the one hand, you figure in as a variable in the calculation. You sometimes heat up the building by just being there and giving off heat; you also generate heat when you cook or adjust your heating. But on the other hand, you also factor into the results, meaning the heating demand, because you are the one who has to pay the heating bill. We also simulate the prevailing temperatures in the buildings; they have to be comfortable for those working or living in them. It doesn’t make any sense to make everything energy efficient if we as users suffer because of it.

You mention a key word »comfortable«. Comfort is one of the themes at BauSIM. What does this mean?

So-called thermal comfort is, according to building physicists, made up of the following six factors: The first factor is the air temperature; the second is radiant temperature; the third is the air humidity; the fourth is the flow velocity, meaning the air velocity in the room. And then there are two more personal factors: How the individual is dressed — are they wearing a suit or a pair of shorts? And the variable of metabolic activity, i.e. the human body, or how active one is at any given moment. If someone is lying down and sleeping, their metabolic activity is very low. If they are sitting at a desk and working, the metabolic activity increases. If the individual is doing physical work, like a craftsperson, or doing sport, then their heat turnover is at its highest and their body warms up in response. Each of these 6 factors influence how comfortable we find indoor climates. There are many secondary factors that also influence our comfort, such as acoustic or visual effects, gender or age.

Room acoustics are also a theme at the conference, as are health topics such as COVID-19.   

Building and room acoustics is something that we have conducted extensive research on in our department. And this is why we are including it in BauSIM for the first time. Due in part to our Acoustics Work Group and affiliated lab in our department, we have set ourselves the goal of hosting a separate conference area here and offering guided tours. We believe that acoustics play an important role in building physics and is something that should be featured at conferences. This year’s BauSIM will also include lectures on corona. In recent years, we ourselves have carried out numerous simulations and calculations, as have many other colleagues. In our case, it was all about masks and distancing in general at the beginning; we then moved on to specialising in wind instruments as well as ventilation in intensive care units. This topic has not been abandoned in the Building Physics Department and is something we will possibly be looking at more in the autumn.

The topic of ventilation continues to take centre stage...

Yes. And this conflicts with what users want when they are unable to adequately heat their homes. There will be, by the way, several presentations on user behaviours at BauSIM.

What other Bauhaus-Universität Weimar research topics can we expect at the conference?

One example is Smood. This research project involves developing neighbourhood energy consumption simulation methods together with our colleagues Prof. Guido Morgenthal and Prof. Volker Rodehorst. We first fly over the neighbourhoods using drones. These drones are outfitted with various camera systems that record neighbourhood buildings. The data collected is then fed into our simulations, which can then be used to calculate neighbourhood energy requirements. 

What are you personally most looking forward to?

I am most excited to see all my colleagues again. The last conference was held online on Graz University of Technology because of corona, of course. The most important thing is not just to sit in front of your computer and watch lectures, but to talk to one another during breaks, to check out labs and ask, »Hey, how did you did you do that? We have this or that problem« - this isn’t really possible online. And that’s a key feature of this in-person BauSIM. 

Additional information on the BauSIM2022 can be found under: www.BauSIM2022.de 

For questions, please contact Dr. -Ing. Albert Vogel from the Department of Building Physics in the Faculty of Civil Engineering by phone: +49 (0) 36 43 / 58 47 06 or via e-mail: albert.vogel[at]uni-weimar.de 

For questions about this article, contact Scientific Editor Dr. Stefanie Waske via e-mail stefanie.waske@uni-weimar.de or phone +49 (0) 36 43 / 58 11 24.