Energy Savings

Energy Savings

Worldwide, the reduction of energy consumption for cooling and ventilation installations is becoming increasingly important. The increased use of air conditioning systems, in particular, forces energy conservation strategies on the building sector (Schmidt, 2003). A new European parliament directive on the energy performance of buildings (2002/91/EC), strongly encourages the implementation of passive cooling techniques to improve indoor climatic conditions as well as the immediate micro climate.

The Institute of Physics, a project of the Architects Augustin and Frank (Berlin), is a research and office building that features several measures of sustainable architecture. The building combines sustainable water management and reduced energy consumption for cooling and ventilation. Rainwater is used to supply a façade greening system and ventilation units.

Passive and active building climatization

Impermeable surfaces like roofs and streets influence urban micro climates through radiation changes. As a result of these changes, air temperatures inside buildings also rise and lead to discomfort or increased energy consumption for climate management. A logical solution to create more comfortable air temperatures inside and outside of buildings is to green their façades and roofs, thereby „consuming“ this energy by evapotranspiration (Schmidt, 2005).

According to measurements taken at the UFA Fabrik in Berlin, extensive green roofs transfer 58% of radiation balance into evapotranspiration during the summer months. The annual average energy consumption is 81%, the resultant cooling-rates are 302 kWh/(m²*a) with a radiation balance of 372 kWh/(m²*a) (Schmidt, 2005).

A more demanding solution is a façade greening system which has a higher direct effect on the energy performance of a building than a greened roof. Green façades were implemented at the Institute with two objectives: 1) to passively climatize the building through shading and solar radiation and 2) to harness evapotranspiration to improve the micro climate inside and around the building.

Case Study Buildings and Facts

  • Building in Athens – Economy and Finance Building in Syntagma Square
  • Size – 650 sq m – half the surface of the top of the building
  • Created – July 2008
  • Saved 3600 euros a year in cooling – 9.6 %
  • Saved 2030 a year for heating – 4.4%
  • Total saving – 5630 euros a year
  • Measurements carried out by applied thermodynamics laboratory at the National Technical University of Athens (NTUA) mechanical engineering department
  • Normal roof – 55 degrees C
  • Green roof – 37 degrees C
  • Temperature difference between planted green roof and normal roof – 18 degrees centigrade

There is no denying the fact that green roofs and vertical greening systems save large sums of money, for more information please contact us.