An architect explains how a passive house functions

6th April 2014

Welcome to Öhringen, ladies and gentlemen.

I wish you a pleasant stay with a lot of new impressions and interesting conversations.

Before I start with the presentation of this building, I would like to introduce myself.

My name is Volker Stegmaier. I am employed as an architect at the county of Hohenlohe. I’m representing the interests of the owner of this (new) building. Mainly, during the planning and execution time, I’ve mainly been responsible in controlling the costs, the schedule and the quality assurance in the construction work. Currently I’m busy carrying out building inspections with the contractors before the warranty of their work runs out. The warranty has been arranged for 4 years, exactly from May 2010 to 2014.

A brief historical summary

It took ten years to develop this new school. In 1999, the district council decided to create a new modern building for the domestic and agricultural school in Öhringen.

This new building was created in order to unite the different types of school and classes in only one building. Before this time, they were spread to several buildings. And some of these buildings were rented.
After a trans-European architectural competition in 2003 the winner, the architects named Broghammer-Jana-Wohlleber from Rottweil was engaged to work out the architectural planning.

Due to the financial situation the planning couldn’t be continued until the spring of 2006. The construction finally started on 14th of April 2008.

The move into the new building was scheduled for (the) Whitsun holydays 2010. Then, the school finally started in June with about 800 students and 80 teachers.

In October of the same year the official opening ceremony was held with the Eponym, the former Federal President, Mr. Richard-von-Weizsäcker. The exceptional personality and the moving words of his speech many guests from that time are still impressive in memory.

To the offered types of schools and the school system in general, the head teacher, Mr. Stiefel will certainly give further information to you.

Now let us take a closer look at the architecture of the building.

The school consists of 3 parts of buildings, each with 3 floors.
The elongated structure of the buildings was designed for climatic reasons. The wind conditions in this valley should not be influenced negatively.

We are here in the central hall between the parts A and B.
In these two parts are the classrooms for theory lessons, the science rooms (for bio, chemistry and physics), the administration and various lounges for the students.

The central hall can be used as a venue for larger events. Therefore, the movable wall can be opened in the music room to create the necessary space. A small kiosk provides the visitors and users of the building with little food (small dishes).

In the 3rd part of building (building C) are the school kitchens, the computer rooms, the workshops for metal- and wood processing and the rooms for horticulture.

All 3 parts were built in situ concrete. The raw construction is covered with Elmwood panels or plastic laminated chipboards at the walls. The floors (here) in the central hall as well as in the stairwells are covered with artificial stone (from Italy). For the remaining areas we chose very durable rubber floorings.

A few words concerning the fire safety concept of the building:
According to German law, in schools it is no longer allowed to provide the necessary (second) fire escape through the windows. For this reason, the escape stairways with direct exits to the outside are located at both ends of the parts of the building.

In case of fire the alarm can be triggered by pressing the orange button. Smoke alarm also can be triggered by the smoke detector on the ceiling. The doors in the corridors will close automatically and prevent the spread of smoke in the building.
You can find these devices at various points of the building.

The two buildings A and B are designed as a so-called “Passivhaus”:

A passive house is basically heated by solar energy (solar radiation) and by internal energy, people, lights, computers (etc.).
In order to keep this energy as long as possible in the building 4 factors are to be considered:

  1. Large memory sizes, for example by massive walls and ceilings
  2. Maximum thermal insulation of the skins
  3. Maximum density of the skins
  4. High efficiency of the ventilation system and the heat exchanger

Regarding Item # 1
Large storage mass is largely achieved by concrete walls and concrete ceilings.
concrete stores the heating energy in the building perfectly. Even in cold nights during the period of winter the indoor temperature does not fall below 19 ° Celsius. Already in the first lesson of the day the temperature will rise by the body heat of the persons again.

Regarding Item # 2
Exterior walls are made of concrete insulated by 30 cm of mineral wool. To avoid thermal bridges, the curtain wall is thermally separated / decoupled from the concrete walls. The windows are 3-fold glazing. Among the metal panels in metal facade partly there will be used vacuum insulation.

Regarding Item # 3
The windows were checked for leaks with the so-called blower-door-test. Using a ventilator the pressure drop was measured after a certain time. For the measurements, the compliance with the limit has been proofed. Such proof must be carried out strictly for the certification of the building as a Passivhaus.

Regarding item # 4
The amount of air being used during one lesson is pressed in the central hall by fresh air from the class rooms. The air is pumped from the galleries and then supplied to the ventilation system in the basement.

In a heat exchanger the available energy can be removed and eventually removed to the air outside.
A major advantage of continuous ventilation in classrooms is to prevent the increase of carbon dioxide in the air. The school conditions are thus significantly improved.

When all the components work together optimally, a maximum heating consumption of 15 kWh per m2 of the heated area and per year can be achieved.

The total cost amounts to almost 26 million Euros.

The gross Volume amounts to 42.000 cubic metres, so comparable with 42 (average) single-family homes.

Now I would like to invite you to a small trip through the construction site.

Thank you very much for your attention and I wish you a good time in the county of Hohenlohe.