RESIDENTIAL LIFE CYCLE ASSESSMENT MODELING: COMPARATIVE CASE STUDY OF INSULATING CONCRETE FORMS AND TRADITIONAL BUILDING MATERIALS

Innovative,sustainable construction products are emerging in response to market demands.One potential product,insulating concrete forms(ICFs),offers possible advantages in energy and environmental performance when compared with traditional construction materials.Even though ICFs are in part derived from a petroleum-based product,the benefits in the use phase outweigh the impacts of the raw material extraction and manufacturing phase.This paper quantitatively measures ICFs’performance through a comparative life cycle assessment of wall sections comprised of ICF and traditional wood-frame.The life cycle stages included raw materials extraction and manufacturing,construction,use and end of life for a 2,450 square foot house in Pittsburgh,Pennsylvania.Results showed that even though building products such as ICFs are energy intensive to produce and thus have higher environmental impacts in the raw materials extraction and manufacturing phase,the use phase dominated in the life cycle.For the use phase,the home constructed of ICFs consumed 20 percent less energy when compared to a traditional wood-frame structure.The results of the impact assessment show that ICFs have higher impacts over wood homes in most impact categories.The high impacts arise from the raw materials extraction and manufacturing phase of ICFs.But there are a number of embedded unit processes such as disposal of solid waste and transport of natural gas that contribute to this high impact and identifying the top unit process and substance contributors to the impact category is not intuitive.Selecting different unit processes or impact assessment methods will yield dissimilar results and the tradeoffs associated with every building product should be considered after studying the entire life cycle in detail.

HYGROTHERMAL PERFORMANCE ASSESSMENT OF ICF WALLS WITH DIFFERENT MOISTURE CONTROL STRATEGIES AND WALL DESIGNS

The initial high moisture content of concrete and the low vapor permeability of insu-lation layers on both sides of the concrete complicate the drying process of Insulated Concrete Forms(ICF).In order to facilitate the moisture transport and enhance the drying process,different moisture control stratcgics and wall designs can be implc-mented.The application of an air and vapor barrier is one of the most common moisture control stratcgics.In this paper,the impact of vapor permcance of an air and vapor barriers on the hygrothermal performance of an ICF wall in three differ cnt cold and wet climates is examined using a validated Hcat-Air-Moisture transfer model.The hygrothermal performance of an ICF wall assembly with different types of barriers and locations in the wall system for scveral wall designs is invcstigated.Results indicate that a smaller thickness of insulation on the outside facilitates remov-ing the moisture towards the outside and installing low permcance air/vapor barrier systems on the outside prohibits drying and drives the moisture to the inside.Our findings also show that with the proper sclection of insulation thickncss and vapor control stratcgy moisture-related problems can be avoided.