Energy performance of concrete buildings in five climates

This paper provides information on energy savings in mid-rise commercial buildings due to additional thermal mass and for exceeding ASHRAE 90.1-2004 thermal performance requirements in the building envelope. The results also indicate the points available for optimizing energy performance under the Energy and Atmosphere (EA) credit of LEED-NC. Five-story prototype buildings with plan dimensions of 32 by 32 m and a window-to-wall ratio of 0.40 have been modeled using the software program VisualDOE. The buildings were modeled in six cities representing the range of climates in the US. A table is included showing how results for five climates relate to similar climates in other major cities worldwide. The buildings include: precast concrete walls, curtain walls, and exterior insulation finishing system (EIFS) walls with either structural steel or reinforced concrete frame. The energy modeling shows that the effect of thermal mass in concrete framed buildings, combined with thermal improvements to the building envelopes (including walls and windows), results in energy savings up to 23% relative to the baseline steel framed EIFS buildings. This energy savings qualifies for up to four LEED-NC v2.2 points.