Rapid Fire

▪ Objective: Understand the role of concrete portion of ICF in reducing building energy use ▪ Approach: Whole-building energy model for typical commercial and residential buildings ▪ Key findings: Small overall, but reduced peak heat transfer; mass via ICF not optimized ▪ Impact: Focus on optimized use of concrete for thermal benefit Amanda L. Webb, SMArchS Graduate Student The thermal mass benefits of concrete in Insulated Concrete Forms (ICF) With L. Norford and J. Ochsendorf

Afternoon Presentation

Residential Buildings Single Family & Multifamily Amanda Webb Feb 17, 2011 CONCRETE SUSTAINABILITY HUB

Major Model Changes CONCRETE SUSTAINABILITY HUB CategorySingle FamilyMultifamily Reference StandardBuilding America House Simulation Protocol* (IECC 2009 equiv.) DOE Benchmark Midrise Apartment EnvelopeICF – R-26 -> R-20 Attic Floor –R-60 -> R-40 (Chi) ICF with concrete interior -> ICF with wood/gyp interior Internal GainsDetailed InputNo Change Infiltration & Ventilation- No infiltration difference** - Nat vent - No HVAC Outdoor Air No Change Domestic Hot WaterDetailed DHW SystemNo Change = Most significant changes *From DOE’s National Renewable Energy Laboratory **Focus in this analysis on mass benefits of ICF

Infil rates same – focus on mass, insul. benefits R-values different

Mass portion of ICF does make a difference

Peaks reduced What if we add more concrete?

What if we expose the concrete inside?

e.g., Thermomass Better in PHX Could be better with optimized use of interior mass

Infiltration sensitivity dependent on climate

Operational energy dominates for benchmark building

Embodied energy matters more in very low energy building

Energy Model/LCA Conclusions Very solid model specifications Better contextualize our work – NREL, etc. Infiltration, R-value, and mass benefits of ICF should be considered separately Infiltration highly climate dependent; mass somewhat climate dependent Look at optimized use of mass – balance changes for low energy buildings CONCRETE SUSTAINABILITY HUB

Work Through Aug 2011 Energy benefits of concrete. Focus: low energy houses. –Analysis to find optimum curve for use of concrete in envelope, interior [Hacker 2008, Zhu 2009] –Mass vs. insulation tradeoff –Range of climates, thermal performance Comfort benefits of concrete [beyond Aug] –Control algorithm testing to understand role of concrete in comfort-based HVAC controls CONCRETE SUSTAINABILITY HUB