October 16th and 17th meant two more Swegon Air Academy seminars in Poznan and Krakow. Our lecturer Mario Bodem gave very interesting presentation on “Elements of low-energy buildings in renovation and new projects – the practical solutions.” Here is the summary with the interesting points.
Mario Bodem is an architect and has many years of experiences in building passive houses all over the world. Mario gave a wonderful presentation about his practical experiences with single and multi-residential passive house buildings. He started off with an example renovation of a school to passive house level, where the building was energy efficiently renovated including the exterior design of the building, i.e. implementing colorful windows in the staircase. The renovation and new look of the school was such a success that a few weeks later the school management had chosen the colorful and inclined shaped window design as the logo of the school. And after a few months even the road had a sign with the colorful and inclined shaped window design.
Furthermore Mario talked about a larger building where they have got rid of the thermal bridges created by the structural columns placed in the façade. The solution was to “move” the columns inside by building a new exterior façade in front of the columns and therefore the columns have become part of the interior of the building. They used windows with U-value of 0.5 W/(m2.K) and there was no condensation on the inner surface of the glazing but only on the outside, as the outdoor surface become the warmer surface due to the window properties.
As EPBD is considering the implementation of nZEB as being a passive house with renewable energies by 2020, there was a super example of a sports hall in passive house standard with photovoltaic on roof which can produce 3 times more energy than the house needs. This means that we are one step closer to nZEB as the buildings can produce the energy on the surface they occupied. Mario talked about the oil prices which is even more expensive even if we get more drops in economy. Even though that we are able to make use of renewable energies, there is still not enough to cover the current consumption. Mario said: “The biggest and cheapest energy resource is energy efficiency. It is cheaper to save 1 kWh then to produce it!”
The passive house works on the principle of covering the peak heat demand for 1 m2. So if in 20 m2 room you either need two light bulbs with total of 200 W to heat up or you invite your two neighbors which gives a new interpretation of hospitability in a passive house. Usually in small passive house buildings it is necessary to use 300-400 mm of insulation, and 200-300 mm of insulation in larger buildings. It is necessary to design and build the building with no thermal bridges. There is a difference between new and old renovated passive houses where in old refurbished houses the thermal bridge cannot be avoided. The passive house windows are the important elements of the buildings and it is necessary to install them correctly and connect them to an air tight layer of the building envelope. The passive house windows need to have a spacer between glazing made from PVC or another material which is not heat conducting.
Mario said many interesting things, but the most important thing about air tightness: “Nobody feels responsible for air tightness in buildings”. The German building requirements ask n50< 3 h-1 and the passive house requirements are n50 < 0.6h-1. In reality usually it is around 0.3 h-1 which is 10 times more airtight then building legislation requires. One example on good air tightness practices is that a bundle of cables cannot be made airtight, so the solution is that each cable must be separately airtight and led separately, i.e. if you cannot put your hand in the space between the cables in wall, it is not possible to insulate and make it air tight properly. This is not a problem of workers, but problem of good planning.
The passive house needs to be equipped with low energy consuming ventilators in air handling units with the heat recovery of 75-80% or better, closer to 90%. There is a need to heat only with the air and temperature which is needed in the building, therefore the practice in passive houses is to heat and cool by just volume of the air that we need to have.
Mario has presented his latest project in St. Petersburg as an example of the passive house in the cold climate. The rather large family house is sitting on the insulation and not directly touching the ground to limit thermal bridges. In his design, Mario creates a compact structure which is more suitable for cold climate regions and he plays architecturally with parts of the garage as it doesn’t have to be insulated and it is cheaper to create. The passive house in St. Petersburg has 400 mm of insulation, 4 panes glazing in windows mainly with 0.5 W/(m2.K) and small amount of windows oriented toward north with 0.3 W/(m2.K).
In hot climate there is a need to use natural cooling if possible, and according to Mario in Poland and Germany there is no need to use active cooling if you use free night cooling. The free cooling needs to be but considered in the beginning of the project such as a passive house school where Mario has changed the fire protection areas in order to use the same air volume in classrooms opposites the hallway, i.e. the air was brought in on one side of the building to the classrooms and transported through the hallways to the other rooms. This offers a cheaper solution as the night cooling concept works well with the thermal energy and movement of the air. Apart from that the windows in school are used for ventilation and have three parts: one is fixed, second is open able and the part consisting of rain & burglar protection to vent at nights.
Mario greatly talked about one of his largest and most successful renovation of typical residential apartment building. In this project, Mario had to cope with typical problems in renovation projects such as that some windows were already replaced with not very good quality windows (1.4 W/(m2.K)). These windows are not good enough to keep them but too good to change them. There is a problem from the economic point of view and the windows are also installed in wrong position in middle of the wall. There is a need to put the outside layer in the facade insulation. In the building´s facade were installed self-regulated vents to get rid of the interior humidity towards outside. The second wooden window in the shower was closed with prefabricated PVC element with a hole for ventilation. On the roof was placed the heat pump used as extract air for very a very low cost and the ventilation ducting was placed on the exterior of existing façade and cover in total of 140 mm of insulation. The basement walls were insulated with vertical insulation in the length of 700 mm was applied on vertical walls.
Follow us and read the next article about reaction of the Polish audience to Mario´s presentation!
Photo by Petra Vladykova