air-Q in action:
Kurt-Masur-Schule Leipzig - root cause analysis for temperature problems in summer

Answer Robert Pohl (engineer and committed father): High and unacceptable room temperatures are mainly found on the two upper floors on the eastern, southern and western sides of the building, as well as on the roof terrace. There are several reasons for this: 

1. The permanent overcrowding of the school building means that both upper floors have to be used simultaneously during operation, although the planning basis for the ventilation system installed only provides for the ventilation of one upper floor in use, while the unused upper floor should only be ventilated at a minimum level. In addition, there are other unfavorable room arrangements: the nursery, classroom and break rooms used by the children who are permanently present are largely located on the same upper floors and in exactly the three parts of the building that are constantly exposed to the sun. On the other hand, the teachers' rooms, school administration, secretariat, checkrooms, toilets and art or work rooms that are only used occasionally are located on the noticeably cooler north side of the building. The cool first floor houses the workroom and some of the after-school care rooms as well as the dining room, i.e. rooms that are only used temporarily. There is no openable window in the after-school kitchen.
2. There is no effective shading, which means that the building envelope in the three areas mentioned heats up despite insulation due to the high level of solar radiation. As a result, the roof terrace, for example, cannot be used during the day in the summer months due to acute health risks from heatstroke. This is exacerbated by the fact that the roller blinds arranged to shade the window fronts are automatically raised again at the slightest draught and therefore unfortunately only very rarely contribute to shading when there is virtually no wind. Unfortunately, due to their design, they then also shield any further draughts between the blind and the window, which contributes to heating.
3. Presumably, the control of the ventilation system does not work ideally within the structural possibilities. There is evidence of at least sufficient air exchange, but no cooling is noticeable, even if the temperature falls below 15°C on cold summer nights.
4. The building was architecturally designed in such a way that the ceiling heights were kept rather low. In line with a passive house, it was decided to use a technical system for the necessary ventilation rather than large, manually opened windows.
5. From an urban planning perspective, the school building is also located in a heavily sealed area of the city. This means that hot days and tropical nights are reached more quickly than on the outskirts of the city. The few roadside greenery in the form of shady trees cannot provide any noticeable cooling for the building.

‍AnswerChristiane Dubiel, Deputy Headmistress: The heat in the building persists overnight, so there is no cooling in the classrooms and corridors. These high temperatures significantly impair the concentration of the children and adults. In addition, people in the building suffer from headaches, tiredness and general malaise. Applications have already been submitted for exemption from compulsory school attendance due to the heat in the rooms. The persistent heat leads to increased stress for everyone in the building, which has a negative impact on the ability to learn and work.

‍Answerfrom Robert Pohl (engineer and committed father): Within the framework of the comprehensively and finely sliced instruction channels and distributed responsibilities, there is no viable and established way that contributes to solving these problems according to known administrative action between school management, after-school care management, LaSuB, after-school care providers, building owners and building operators as well as organizations such as health and safety, occupational health and safety, youth welfare office or accident insurance fund. The problem situation is comparatively new. In view of overcrowding, the building's high energy standard as a passive house and the increasingly significant rise in temperature levels in summer, particularly in densely built-up areas, the heating of the school building is likely to be assessed differently today than was foreseeable at the time of planning.

In addition, the city of Leipzig is still a growing city with all the associated challenges (financial and personnel capacities as well as dealing with the challenges of climate change).
Over the years, more than 20 measures for cooling or shading the building have been discussed and implemented with only limited success. And there was a lack of clarity about the potential, functionality and flexibility of the existing ventilation technology.

‍AnswerChristiane Dubiel, Deputy Headmistress: The school has had a heat working group for years, which has discussed various measures to improve the heat situation. The proposed measures include:

● Tree planting

● Shading of the roof terrace and courtyard

● Facade greening

● Regular room change of the classes

● Tours with climate architects

● Refusal of further class admissions to avoid overcrowding

● Movable air conditioning units in the classrooms

● Publicizing the issue in the borough council

● Covering the windows with film

● Discussions with architects

However, there is a lack of openness towards the topic and a lack of cooperation between the various offices, which leads to a lack of responsibility and a reduced flow of information.

Last year, the company doctor was consulted by the school's staff council. She took a stand and again asked for remedial action from various offices. As a result, the school management was asked to obtain expert opinions from the accident insurance fund and the occupational safety specialist on the subject of "heat at KMS". We are now waiting for the expert opinion from the occupational safety specialist.

Antwort Robert Pohl (Ingenieur und engagierter Vater) : Im zweiten Obergeschoss wurden zeitgleich in zwei belegten Klassenräumen (26 Kinder + 2 Pädagogen) jeweils ein air-Q direkt neben der Tür jeweils gegenüber der nach Osten ausgerichteten Fensterfront auf einer Konsole aufgestellt, der die Raumluftparameter in der Höhe der Köpfe der sitzenden Kinder misst. Sie wurden über jeweils 2 Wochen betrieben. Herausforderung war eine möglichst gute Vergleichbarkeit der Räume zu erreichen (Ausrichtung im Gebäude) und den air-Q sicher, aber in der Nähe der Kinder und in der Nähe einer Steckdose zu positionieren.
Der air-Q kann hier eingesetzt werden, da er anhand der Leuchtdioden auch für Kinder eine interessante Rückmeldung liefert und nicht nur ein passives Gerätdarstellt. Die hochfrequente Messung aller 2 min lässt es zu, die zeitlichen Zusammenhänge zwischen den Raumluftparametern und der Raumnutzung zu erkennen, z.B. wie lang vor Unterrichtsbeginn gelüftet wurde oder ob am Nachmittag noch eine Raumnutzung erfolgte. Dennoch bleibt das zu analysierende Datenvolumen über Zeiträume von Wochen handhabbar und aussagekräftig darstellbar.
Das Limit der Nähe (<2m) zu einer Steckdose kann durch eine ausreichend dimensionierte Powerbank überwunden werden.

Answer Christiane Dubiel, Deputy Headmistress: As the air-Q records/collects the data digitally, further comparative data (e.g. measurements of outside temperatures) could be included in the analysis. In this way, we as a school have documentation of the previously only perceived issues (overheated rooms). At the same time, the air quality in the rooms could be documented based on the complex measured values.

With the written evaluation of the measurement series available, we now have a basis for further discussions. The perceptions of building users can no longer be so easily negated.

Answer Robert Pohl (engineer and committed father): With regard to the room temperature, the measurements unfortunately confirm the conditions subjectively perceived and described by pupils, teachers and parents. At a room temperature of 30°C, concentrated learning and representative performance assessment are not possible, which runs counter to the purpose of the school and the purpose of its use. Unfortunately, according to people who have been working at the school for many years, the measured temperatures are not just a temporary short-term effect but, depending on the location of the summer vacations, can have an unsustainable impact on school operations for two months and after-school care operations during the summer vacations too.
Two results are very surprising: Firstly, the air exchange is sufficiently good so that no significantly tiring CO2 concentration or an unhygienic concentration of VOCs (volatile hydrocarbons for colloquially "odors") are detected even in a full classroom. The air humidity is also not objectionable. It follows from this: The ventilation system ventilates sufficiently well, it is not necessary to open the windows permanently - which is a necessary condition for operation to the passive house standard. The subjective stress is only caused by the high temperature. Secondly, ventilation in the morning leads to a noticeable cooling effect, which, however, loses its effect almost immediately when the window is closed at the start of the school day. This leads to the following conclusion: The period of manual ventilation is too short for not only the room air but also the building structure as a whole to be cooled down.

Answer Robert Pohl (engineer and committed father): Ideally, whenever the outside temperature is lower than the room temperature (between 20 and 22°C) during the spring, summer and increasingly the fall, noticeable ventilation with outside air should be made possible. The existing ventilation system should preferably be used to avoid manual and limited cross-ventilation. Provided that staff are available, manual ventilation is possible immediately, but must not take place when pupils are present or staff are absent.

Provided the specifications are clear and the contract is awarded, optimizing the ventilation system is also a promising short-term solution, which, supplemented by perhaps two to three iteration loops over two years, also makes sense in the long term.

Answer Robert Pohl (engineer and committed father): Structural and technical measures can definitely and sustainably prevent the building from heating up. Provided the resources were available and were not lacking in other public facilities with similar or serious problems, the temperature could theoretically be set and maintained at a comfortable level by means of active cooling, for example, using the energy from the recently installed rooftop photovoltaic system with a rated output of over 90 kW. Shading through greenery also promises to provide long-term relief. However, both measures require not only a high level of investment but also knowledgeable, regular and recorded maintenance, care, servicing and repairs during operation. Against the background of constantly changing boundary conditions, such as special ventilation requirements under pandemic conditions or long periods of drought, responsibilities must also be developed at personnel level, ideally across several facilities. The advantage of this would be that it would be easier to adapt to other facilities in a more targeted manner than if each facility somehow developed its own structures according to existing possibilities and limitations.

Answer Christiane Dubiel, Deputy Headmistress: I am often asked by parents whether a less overcrowded school could alleviate the heat issue in the rooms. Unfortunately, I always have to tell parents that I can't assess this and that we can't check it in the short term, as the next first year will again consist of 5 classes.