Sir, The new regulations for thermal efficiency may be making one problem worse, namely the overloading of flat roofs by snow.
This appears to have been the cause of the accident at the ice rink in Bad Reichenhall in Bavaria, Germany, where 15 people died ? 12 of whom were children.
Overloading of flat roofs with snow seems certain to occur more frequently in Europe since global warming is likely to bring an increase in excessive snowfalls, while the building regulations require thermal insulation to be more and more eff icient.
Large halls and similar structures are most in danger, where the new insulation standards are met and where the roof surface is very large.
The acceptable loading of an average roof is, according to statics, about a 0.5 m depth of snow, equally distributed.
Such a depth can be generated quickly and if the roof is well insulated, the snow does not melt away, creating a risk.
Well insulated roofs in areas at risk should contain an optional vent driving hot stale air beneath the roof's surface, where it would help to melt snow away.
This method would avoid the potentially risky manual clearing of the snow from the roof.
Marie Schieferstein Student of architecture Anglia Ruskin University Chelmsford Essex