Rapid Fire

Thermal Mass CONCRETE SUSTAINABILITY HUB Mass in ICF separate from infiltration, R-value benefits High heat capacity leads to thermal lag Mass lag reduces peaks Carbon, cost, energy, equipment sizing benefits Key: Optimize use of mass in building envelope and interior

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?

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 How do we optimize the mass benefits of concrete in single family houses? What is the role of concrete in very low energy houses? –Trend in housing research (Bldg. America, BEOpt) –Trend in legislation (Greening the Codes, CA AB32) Two targets: Net Zero Energy, Passivhaus CONCRETE SUSTAINABILITY HUB

Work Through Aug 2011 Q1: How does mass shift the ‘PV Start Point”? –Christensen, et. al., 2004 CONCRETE SUSTAINABILITY HUB

Work Through Aug 2011 Q2: Does mass make a difference in a Passivhaus? –Suggestion that thermal behavior is different –Combine Q1 & Q2: Is there a “curve” that describes the optimal use of mass? Overall: Industry able to make intelligent decisions about how to promote use of concrete in very low energy houses. CONCRETE SUSTAINABILITY HUB

Alternate Slides

Chicago % Phoenix - 5.6% Greater savings in Phoenix than Chicago P REVIOUS R ESULTS [A UG 2010 M ODEL ] Updated model shows this is b/c of infiltration

Infil Rates Same R-values Different

Heating-dominated (G) in Chicago vs. Cooling- dominated in Phoenix (E)