City and Kommunale Immobilien Jena present report on ventilation systems in schools and daycare centers

The test report, which was commissioned by the city council at its December meeting, contains the results of a pilot test of various ventilation systems and methods that were tested at four Jena schools/daycare centers at the beginning of February.

Lord Mayor Dr. Thomas Nitzsche puts the results in context: "Making visits to schools and daycare centres as safe as possible during the coronavirus pandemic is an important concern for parents, educational staff and the city of Jena. With the report now available, we can add well-founded test results to the public discussion. The most effective ventilation models in the report are clearly also those that require a very high level of investment. We believe that the state of Thuringia has a duty to support local authorities in purchasing the appropriate equipment."

In addition to the decentralized ventilation devices, which received the best marks in the test in terms of effectiveness and sustainability, the combination of shock ventilation and continuous monitoring of the CO2 content in the rooms using a CO2 measuring device is an equally effective model. The purchase of these devices could be implemented at significantly lower cost. Air scrubbers produced a significant reduction in aerosol levels, but could only be used in combination with mechanical or free ventilation, as they do not solve the CO2 problem. The worst rating in the test comparison was given to provisional exhaust air systems based on the design plans provided by the Max Planck Institute.

Karl-Hermann Kliewe, Plant Manager of Kommunale Immobilien Jena, says of the test results: "Temporary solutions are not effective, only the integrative solution counts."

Lord Mayor Thomas Nitzsche adds: "There must be a strict hygiene regime accompanying any form of filter system in the facilities - devices do not exempt people from maintaining distances, ventilating and wearing mouth and nose protection. We had addressed the latter in particular to the state several times before the reopening of the school and daycare centers in Jena and also see this as the most effective short-term method for a sustainable reduction in indoor aerosol pollution."

The comprehensive audit report by Kommunale Immobilien Jena can be viewed via the link. The city of Jena is taking the report as an opportunity to further weigh up the selection of suitable solutions in a task force.

The results in brief:

1. Shock ventilation, supported by CO2 measuring device

• Shock ventilation in accordance with the hygiene concept of the facilities has proven to be extremely effective in all cases
• Ventilation interval supported by CO2 measuring device ensures optimized air exchange
• Advantage:
  • No structural intervention, no mechanical support
  • Measuring devices provide confidence in dealing with hygiene ventilation
  • Avoid heating costs through continuous ventilation
• Costs: 60 euros/each; 68,000 euros investment for all daycare centers, schools and rooms

2. Air washer

• Enables a significant reduction in the aerosol concentration in the air
• Can only be used in combination with mechanical and free ventilation, as CO2 content cannot be influenced
• Costs over 20 years:
  16.3 million euros

3. Decentralized ventilation units

• Most sustainable and best solution in terms of effectiveness in the test comparison
• CO2 concentrations below 800ppm
• Costs over 20 years:
  17.8 million euros incl. subsidies

4. Provisional exhaust air system similar to Max Planck Institute

• Achieved the worst result in the evaluation in terms of comparatively moderate improvement in indoor air
• Disadvantages:
  • Unsafe aerosol and particle collection through exhaust air hoods
  • Disturbing cross flows
  • Lack of building authority approval
  • Lack of acceptance
• Costs over 20 years:
  33.2 million euros (of which around €14 million electricity and heating costs)