Natural stone facades show remarkable advantages concerning energy efficiency, environmental impact, heat requirements, maintenance and production costs. EuroRoc, the internationl federation of natural stone industries, has carried out a study that compares facades of natural stone and glass.
The Frankfurt Opera Tower, with its natural stone facade, was one of the first buildings in Europe to achieve Gold Status in the LEED rating system of the US Green Building Council. The consulting company PE International was commissioned by the German Natural Stone Association (DNV) to carry out a sustainability study to assess the natural stone and glass facades about their environmental and economic performance.
According to this study, natural stone facades are more energy efficient and less expensive than glass. Over a period of 100 years, a natural stone facade has considerable ecological advantages. According to the study, natural stone facades require a lower amount of primary energy than do glass facade systems.
The actual ventilated stone facade of the Frankfurt Opera Tower has less primary energy requirements than a glass facade. The environmental impact of glass facades is 60 to 175% higher than that of a facade made of natural stone.
ECONOMIC ADVANTAGES OF NATURAL STONE
Facades of natural stone are also highly cost effective. For instance, a stone facade has a heat transfer coefficient of 0,32W/m2 compared with 1,25W/m2 for glass. The heat requirements of buildings with natural stone facades are notably lower.
The construction of natural stone facades is considerably more cost efficient than those with glass facades. Likewise the maintenance costs of natural stone facades amount to only half of the costs for maintaining glass facades. The results show clear cost advantages of natural stone facades with a window ratio of 50% over facades made entirely of glass. These differences in costs result from the lower production costs as well as the energy efficiency.