Possibilities to make good use of our school building flat roofs (implementation and alternatives)

Science Teams Activities

During the internet research, two options for the use of our flat roof turned out to be useful.

1.Greening of flat roofs

Since green roofs are considered an urban planning tool, they are sometimes publicly subsidized or even prescribed as compensation for sealed surfaces. Green roofs have a positive effect on the urban microclimate. This comes from the binding of dust and, in addition, from the temperature equalization and humidity regulation that the roofs bring about. In addition, green roofs retain water, thus relieving the burden on the sewage system during heavy rainfall events. In addition, a green flat roof forms an important urban substitute habitat for plants and animals. Building physics aspects also speak in favor of the use of green roofs. This is because the additional artificial protective layer above the actual waterproofing effectively shields the roof from the effects of weather and UV radiation. The overlying layer promotes roof waterproofing. In addition, this is an environmentally friendly and resource-saving method. Basically, there are two variants of green roofs to choose from: An extensive green roof with robust plant species such as sedum creates a flat-growing vegetation that requires little maintenance. Much more elaborate is an intensive green roof with shrubs, ornamental plants, vegetable beds or trees that literally turn the roof into a garden.

extensive greening

intensive greening

2. The flat roof as a solar power plant / with photovoltaic system.

The use of the flat roof as a location for the installation of photovoltaic or solar thermal systems also offers great ecological and economic advantages. To enable the use of the flat roof as a solar power plant, some preconditions must first be met. It is also important that the roof is not or only slightly shaded by trees or by other buildings. This prerequisite is crucial for the effectiveness of the plant. In addition, it must be ensured that the roof structure is statically capable of safely absorbing not only dead loads but also all wind and snow loads and of transmitting them permanently into the building. An important aspect in the planning of roof-integrated photovoltaic systems also concerns the functionality of the roof sealing. To ensure safe operation without damage, particular care must be taken to ensure that water drainage is not impeded.

Photovoltaic systems convert solar energy into direct current. The direct current is in turn converted into alternating current by an inverter. This electricity can then be used for personal consumption. So-called solar modules or photovoltaic modules, consisting of solar cells, are used in photovoltaic systems. Photovoltaic systems are systems for generating electricity on a small scale or for private households, while solar power plants or photovoltaic power plants are used to generate large amounts of energy.

Analysis of the actual state

The first step of our approach is the analysis of the actual state. For this, we first looked at the extensive greening of our roof.

Plant species:

Poppies
Daisies
Violets
Cornflower
Various grasses/shrubs

The green roof vegetation consists mainly of meadow flowers and various grasses. I have listed the flowers which are the most common.

In the next step, we looked at the soil composition.

Components:

1. gravel/ moss
2. extensive substrate
3. filter layer
4. drainage element
5. storage mat
6. root protection foil or root-proof roof sealing
7. roof construction – Roof drain

We also looked at the available area.

Total roof area: 8583,8 m2

Suitable for greening/solar and photovoltaic systems: approx. 4000 m2 (marked green in the first photo)

Decision between methods of use – green roof or solar or photovoltaic system?

According to the results presented above, we came to the conclusion that a green roof would make more sense. This is because greening has significantly more advantages compared to photovoltaic systems. Greening protects the roof waterproofing from the weather and extends the life of the roof. In addition, the peak temperatures in winter or summer are reduced. Another advantage is that the green roof insulates, saving electricity and heating costs. Green roofs have many more advantages (improvement of microclimate, noise protection, water circulation, etc.). This point makes the green roofs so attractive, because they offer a variety of functions.

Example graphs illustrating the functions

Thermal load of the roof waterproofing without greening. Thermal load of the roof sealing with greening. Water cycle without green roof. Water cycle with green roof.

Development Of The City Challenges

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