In this article, I propose to compare different roofing solutions from the point of view of synergetic design. I have deliberately not included precise figures, as the characteristics of the materials depend on their quality, the model, the climate, the building and the installation techniques. I have also omitted petroleum-derived roofs because of the chemical pollution they cause.
Slates
strong framework required
steep slope
good watertightness
aesthetically pleasing
easy but time-consuming to install, rather difficult for roofs with complex shapes
easy to manufacture
inexpensive to manufacture
easy to maintain and renovate
moderately frequent maintenance
high durability
good acoustic insulation
poor thermal insulation
no thermal or hygrometric distortion
apparently good electromagnetic absorption
abundant only in certain regions of the world
very slow renewal (rock)
fairly easy to recycle (except for the hooks)
medium to high price
Synergy score (86%):
efficiency 5/5
accessibility 3/5
transparency 5/5
predictablity 4/5
simplicity 5/5
reversibility 4/5
contentment 4/5
Clay tiles
medium-strength framework required
medium slope
good watertightness
aesthetically pleasing
easy but time-consuming to install, very difficult for roofs with complex shapes
easy to manufacture
costly to manufacture (firing)
easy to maintain and renovate
moderately frequent maintenance
medium durability
good acoustic insulation
poor thermal insulation
no thermal or hygrometric deformation
unknown electromagnetic absorption
abundant in many places on Earth
very slow renewal (clay)
very easy to recycle
medium price
Synergy score (86 %):
efficiency 3/5
accessibility 4/5
transparency 5/5
predictablity 4/5
simplicity 5/5
reversibility 5/5
contentment 4/5
Zinc
low-strength framework required
low slope
excellent waterproofing
fairly aesthetic
quick and easy to install, even on roofs with complex shapes
difficult to manufacture
costly to manufacture
easy to maintain and renovate
rare maintenance
high durability
poor sound insulation
poor thermal insulation
medium thermal and hygrometric deformation
negative electromagnetic absorption (reflection)
scarce (industry-dependent)
very slow renewal (metal)
difficult to recycle
medium price
Synergy score (69 %):
efficiency 2/5
accessibility 2/5
transparency 4/5
predictablity 5/5
simplicity 5/5
reversibility 2/5
contentment 4/5
Corrugated sheet metal
low-strength framework required
low slope
excellent waterproofing
poor aesthetic
quick and easy to install, even on roofs with complex shapes
difficult to manufacture
costly to manufacture
easy to maintain and renovate
rare maintenance
medium durability
poor sound insulation
poor thermal insulation
medium thermal and hygrometric deformation
negative electromagnetic absorption (reflection)
scarce (industry-dependent)
very slow renewal (metal)
difficult to recycle
medium price
Synergy score (74 %):
efficiency 3/5
accessibility 3/5
transparency 4/5
predictablity 5/5
simplicity 5/5
reversibility 3/5
contentment 3/5
Thatch
medium-strength framework required
steep slope
excellent waterproofing
aesthetically pleasing
easy but time-consuming to install, the easiest for roofs with complex shapes
very easy to manufacture
very inexpensive to manufacture
fairly difficult to maintain and renovate
frequent maintenance
low durability
excellent sound insulation
excellent thermal insulation
no thermal or hygrometric deformation
unknown electromagnetic absorption
scarce but could be the most abundant
most renewable material
very easy to recycle
high price
Synergy score (91 %):
efficiency 5/5
accessibility 5/5
transparency 5/5
predictablity 4/5
simplicity 4/5
reversibility 5/5
contentment 4/5
Tavaillons (wooden roof tiles)
low-strength framework required
steep slope
good watertightness
aesthetically pleasing
easy but time-consuming to install, rather difficult for roofs with complex shapes
easy to manufacture
very inexpensive to manufacture
easy to maintain and renovate
moderately frequent maintenance
high durability
good acoustic insulation
medium thermal insulation
low thermal and hygrometric deformation
unknown electromagnetic absorption (could be slightly reflective)
not very abundant, but could be much more so
easily renewable material
very easy to recycle
medium price
Synergy score (91 %):
efficiency 5/5
accessibility 4/5
transparency 5/5
predictablity 4/5
simplicity 5/5
reversibility 5/5
contentment 4/5
Flat roofs
very strong framework required
no visible slope
low waterproofing
can be aesthetically pleasing
difficult to install
difficult to manufacture
costly to manufacture
difficult to maintain and renovate
frequent maintenance
low durability
good acoustic insulation
average thermal insulation
no thermal or hygrometric deformation
apparently good electromagnetic absorption
scarce (industry-dependent)
very slow renewal (concrete, synthetic materials)
difficult to recycle
high price (but lower number of m²)
Synergy score (51 %):
efficiency 2/5
accessibility 3/5
transparency 3/5
predictablity 3/5
simplicity 2/5
reversibility 2/5
contentment 3/5
Solar roof tiles
medium-strength framework required
medium slope
good watertightness
fairly aesthetic
difficult to install
difficult to manufacture
costly to manufacture
easy to maintain and renovate
frequent maintenance
low durability
good acoustic insulation
average thermal insulation
no thermal or hygrometric deformation
generates an apparently very weak electromagnetic field
scarce (industry-dependent)
very slow renewal (metal, synthetic materials)
very difficult to recycle
very high price (but generates electricity)
Synergy score (54 %):
efficiency 2/5
accessibility 2/5
transparency 2/5
predictablity 4/5
simplicity 4/5
reversibility 1/5
contentment 4/5
Green roof
very strong framework required
low slope or flat
low waterproofing
aesthetically pleasing
difficult to install
difficult to manufacture
costly to manufacture
difficult to maintain and renovate
frequent maintenance
medium durability
excellent acoustic insulation
excellent thermal insulation
no thermal or hygrometric deformation
apparently good electromagnetic absorption
scarce (industry-dependent because of the membrane)
variable renewal (plants are easily renewed, membrane is not)
variable difficulty to recycle (plants are easily recycled, membrane is not)
high price
Synergy score (63 %):
efficiency 3/5
accessibility 3/5
transparency 3/5
predictability 3/5
simplicity 3/5
reversibility 3/5
contentment 4/5
Conclusion
Of course, the ideal solution will depend on many other factors that I can't cover exhaustively in this article: budget, materials market, planning regulations, listed buildings, personal taste, local culture, local climate and so on.
However, I would like to highlight the two most interesting solutions in terms of synergy: thatch and wooden tiles.
Sadly, both are not widely used in industrialized countries. The difficulty of accessing materials and skills is, moreover, completely linked to the roofing market, which shuns these age-old solutions less easy to industrialize (less predictable than clay tiles, for instance) but far easier to renew.
However, if these sectors were to come back into fashion, not only would we benefit in many ways, including from a health point of view, but they would also guarantee many long-term jobs. An important point in this field, and one that concerns many other sectors, is to succeed in establishing crops (trees, cereals and other woody species) that fully include the life cycle of soils and plants. Installed locally, these new crops would avoid the need for distant imports, generally from China, and would enable us to select the varieties best suited to the local climate (especially resistant to xylophagous and fungi). It would also bring down the price of these crops, which is kind of abnormally high in many Western countries.
It is to be noted that fire is not a bigger issue with thatch, as the straws are extremely tightened (that said, fire can actually destroy quite easily any kind of roof, with possibly only slates that could be recovered afterwards and maybe some clay tiles, if they are not broken).
The possibility of wild nature to use thatch as a convenient substrate can be seen as negative or positive depending on our view on the relationship between humanity and wilderness but remains extremely relevant for the reversibility of this material.
One comment on green roofs: they seem quite useless in the countryside, but I can understand their advantages in urban contexts where there is usually a chronic lack of plants in general (except for some cities like Chisinau, in Moldova, where trees are everywhere) and therefore problems related to the quality of the air and the absorption of sunlight (high temperatures).
That said, this kind of roof seems to pose numerous infiltration problems (mainly due to plant roots and the poor quality of certain membranes) and requires extremely robust framework structures and frequent maintenance. But, if it were possible to find more ecological solutions to ensure its watertightness, and if this system could be coupled with plant-based rainwater purification to produce drinking water, the system would be much more interesting!
To be continued…