Facade retrofit: enhancing energy performance in existing buildings

2013-11-27Buildings in the United States are responsible for over 40% of the energy used (US Department of Energy 2013a, Architecture 2030 2013a) in the country. During the life span of buildings less than 20% of energy consumption is for extraction of raw materials, materials sourcing and construction, and over 80% of the total energy consumption occurs during building operation (United Nations Environment Programme and World Resources Institute 2010). That energy, supplied by mechanical means, is wasted due to poor building performance in building facades, such as leaking windows, deficient insulation, or defects in construction. Retrofit strategies not only rescue embodied energy contained in buildings already built, but also save energy in their operational phase. ❧ A special focus of this thesis is the exploration of mid-20th century buildings. Since many of them were built with an emphasis on mechanical-conditioned spaces, they are excellent candidates for a new life reconsidering a passive approach. As the first part of the exploration, a general typology of facade retrofits is defined, examining existing cases worldwide. Building retrofits range from partial to total, presenting different combinations. Most of the existing cases of facade retrofits have been made as urgent response to facade failure mitigation. Since the cases vary in a wide range - from low-e film application in windows to whole building retrofit - this thesis typologizes these cases prior to testing through simulation modeling and in a case study. ❧ A specific case study focuses on alternative and passive energy solutions applied to an existing building in a mild climate. The building is a 12-story office building in Los Angeles area built in 1972 with a curtain wall facade. The goal of the thesis is to examine different scenarios for facade upgrading in the building using energy simulation modeling and drawing upon what was learned from the typological analysis of existing cases. Two energy software packages- eQuest and Design Builder- are explored in the case study building to evaluate selected facade solution alternatives. As the first part of the exploration, current building energy consumption and a survey of the components of the facade have been collected and transferred to the computer model. After calibrating the model, five different schemes are explored: (1) replacing existing windows for double, triple or quadruple glass, (2) adding interior and exterior insulation (3) adding overhangs and fins to fenestration, (4) re-skinning with more glazed area, and (5) attaching a double glazed skin to the existing original facade. ❧ These possibilities for the first step in the energy demand derived from facade interventions are explored in this thesis, which considers the results of the energy simulations and recorded energy consumption data. Each facade retrofit scenario is evaluated individually and combined with the most effective from each type. The thesis approach is based on the belief that building facade retrofits represent a unique opportunity to have a major impact on total energy use of existing buildings. Further research will expand this thesis results beyond the purely energy perspective