Achieving Net Zero Energy at Conventional Cost

Achieving Net Zero Energy at Conventional Cost
Copyright © 2017 Sterner Design, LLC IOWA NEST RESIDENCE Achieving Net Zero Energy At Conventional Cost Carl S. Sterner, Assoc. AIA, LEED AP Owner, Sterner Design LLC Director, Sol Design + Consulting 20 April 2017 Copyright © 2017 Sterner Design, LLC
Copyright © 2017 Sterner Design, LLC Topics 1.  How early analysis informed design ! 5 studies that set the design on track 2.  Monitoring ! how are we doing? 3.  Designing for a conventional budget ! 3 strategies / lessons learned 4.  Building science ! thermal + air + vapor barriers
Copyright © 2017 Sterner Design, LLC Project requirements •  ~2400 s.f. residence •  Net Zero Energy •  Underground / of the land •  Avoid conventional AC if possible •  Do all of this on a conventional budget
Copyright © 2017 Sterner Design, LLC Copyright © 2017 Sterner Design, LLC The site
Copyright © 2017 Sterner Design, LLC Copyright © 2017 Sterner Design, LLC
Copyright © 2017 Sterner Design, LLC Copyright © 2017 Sterner Design, LLC The design
Copyright © 2017 Sterner Design, LLC
Copyright © 2017 Sterner Design, LLC Copyright © 2017 Sterner Design, LLC ! FOLLOW OUR PROGRESS @ WWW.IOWANEST.COM
Copyright © 2017 Sterner Design, LLC Pre-design & Schematic Analysis 5 questions that informed design
Copyright © 2017 Sterner Design, LLC Can performance  inspire design? The question behind them all:
Copyright © 2017 Sterner Design, LLC 1.  What passive design strategies are most important?
Copyright © 2017 Sterner Design, LLC Sensitivity analysis
Copyright © 2017 Sterner Design, LLC + ! STEP-BY-STEP PROCESS @ WWW.IOWANEST.COM How was this done?
Copyright © 2017 Sterner Design, LLC Overlaying cost = “most bang for the buck”
Copyright © 2017 Sterner Design, LLC Building form?? Earth berming?? Space layout / thermal zoning?? Peak Loads! What I would do differently:
Copyright © 2017 Sterner Design, LLC A study I should’ve done: (Glazing ratio + bldg form with optimal shading)
Copyright © 2017 Sterner Design, LLC 2.  Can we avoid mechanical cooling?
Copyright © 2017 Sterner Design, LLC 6 factors that effect human comfort
Copyright © 2017 Sterner Design, LLC Strategy: Earth Berming ! air temp + radiant temp
Copyright © 2017 Sterner Design, LLC Strategy: Thermal Mass ! air temp + radiant temp
Copyright © 2017 Sterner Design, LLC Strategy: Shading ! air temp + radiant temp
Copyright © 2017 Sterner Design, LLC Strategy: Natural Ventilation + Ceiling Fans ! air movement
Copyright © 2017 Sterner Design, LLC Comfort analysis (PMV) Design case without natural ventilation = uncomfortable
Copyright © 2017 Sterner Design, LLC Not possible to get into range without dehumidification … ! STEP-BY-STEP PROCESS @ WWW.IOWANEST.COM
Copyright © 2017 Sterner Design, LLC … but comfort is personal. Clients are willing to try for no A/C. ! STEP-BY-STEP PROCESS @ WWW.IOWANEST.COM
Copyright © 2017 Sterner Design, LLC Strategy: Plan for the Future ! add dehumidification / cooling
Copyright © 2017 Sterner Design, LLC How the analysis thus far  informed the design …
Copyright © 2017 Sterner Design, LLC Construction: ICFs + exposed mass
Copyright © 2017 Sterner Design, LLC Performance Concept: Insulated mass + operable envelope
Copyright © 2017 Sterner Design, LLC Language: Planar vs Volumetric vs
Copyright © 2017 Sterner Design, LLC 3.  Which design option is best?  (And why?)
Copyright © 2017 Sterner Design, LLC OPTION 1: REVEAL OPTION 2: BEACON EUI EUI Concepts
Copyright © 2017 Sterner Design, LLC OPTION 3: GLASS PAVILIONS OPTION 4: TERRACE EUI EUI Concepts
Copyright © 2017 Sterner Design, LLC OPTION 5: ROLLING HILLS Daylight Legend Energy Legend EUI Concepts
Copyright © 2017 Sterner Design, LLC Concept Comparison
Copyright © 2017 Sterner Design, LLC Concept Comparison
Copyright © 2017 Sterner Design, LLC ! STEP-BY-STEP PROCESS @ WWW.IOWANEST.COM Concept Comparison
Copyright © 2017 Sterner Design, LLC Envelope area vs EUI Glazed area vs cooling Glazed area vs EUI Envelope area vs heating What’s driving energy performance? Copyright © 2017 Sterner Design, LLC
Copyright © 2017 Sterner Design, LLC Design response
Copyright © 2017 Sterner Design, LLC 4.  What’s the best combination of strategies?
Copyright © 2017 Sterner Design, LLC ! STEP-BY-STEP PROCESS @ WWW.IOWANEST.COM
Copyright © 2017 Sterner Design, LLC Sefaira analysis was used to test m and discover the best path toward Response Curves were used to fur parameters, based on the latest ve the Sustainable Design Narrative fo The complete Sefaira analysis can apps.sefaira.com/concept/project/ single?id=30986&cid=94270&did=Copyright © 2017 Sterner Design, LLC
Copyright © 2017 Sterner Design, LLC NET ZERDRAFT SET - NOT FOR CONSTRUCTION NEST RESIDENCE // Fremont, IA TERNER DESIGN // 1555 Pullan Ave., Cincinnati, OH 45223 Copyright © 2015 Sterner Design. All rights reserved. What are the optimal envelope properties?
Copyright © 2017 Sterner Design, LLC We’ve come a long way … Energy Footprint (kBTU) Peak Space Heating Demand (ton) Energy Footprint (kBTU) Peak Space Heating Demand (ton) Code Baseline As Designed
Copyright © 2017 Sterner Design, LLC 5.  Is the glass productive?
Copyright © 2017 Sterner Design, LLC Productive glass + productive mass Typical configuration = Portions of the glass are unproductive This design = 100% of the glass is “productive” as a passive solar collector
Copyright © 2017 Sterner Design, LLC (Recognize that angle??)
Copyright © 2017 Sterner Design, LLC Direct sunlight analysis for shading optimization
Copyright © 2017 Sterner Design, LLC Is there enough daylight? Copyright © 2017 Sterner Design, LLC
Copyright © 2017 Sterner Design, LLC PRE-DESIGN: Passive strategies • Net Zero Energy feasibility CONCEPT: Comparison • Correlation SCHEMATIC / DEVELOPMENT: Envelope optimization • Shading design (direct sunlight) • Daylighting refinements Summary of studies
Copyright © 2017 Sterner Design, LLC Monitoring The proof is in the data …
Copyright © 2017 Sterner Design, LLC Data to date (January – April 2017) ! LIVE DATA @ WWW.IOWANEST.COM/MONITOR
Copyright © 2017 Sterner Design, LLC ! LIVE DATA @ WWW.IOWANEST.COM/MONITOR Remarkable stability, even though some insulation + air sealing still remains (as of April)
Copyright © 2017 Sterner Design, LLC Designing for Budget 3 strategies (AKA hard lessons)
Copyright © 2017 Sterner Design, LLC Cost comparison vs conventional house in Iowa
Copyright © 2017 Sterner Design, LLC But if you remove the green roof & custom corner lift-slide …
Copyright © 2017 Sterner Design, LLC FINISHES ! DESIGN MECHANICAL SYSTEMS ! INTEGRATIVE DESIGN ENCLOSURE ! DESIGN + MATERIALS FOUNDATION ! DESIGN PLUMBING ! DESIGN Where did the savings come from?
Copyright © 2017 Sterner Design, LLC 1.  Keep the form simple.    (DESIGN)
Copyright © 2017 Sterner Design, LLC Copyright © 2017 Sterner Design, LLC The original schematic design
Copyright © 2017 Sterner Design, LLC Copyright © 2017 Sterner Design, LLC The original schematic design = 2X over budget
Copyright © 2017 Sterner Design, LLC What drove the cost?
Copyright © 2017 Sterner Design, LLC 1.  # of corners 2.  # of baths + plumbing length 3. shades as “carved” elements
Copyright © 2017 Sterner Design, LLC Copyright © 2017 Sterner Design, LLC A lot of complexity here = a lot of cost
Copyright © 2017 Sterner Design, LLC Back to the drawing board …
Copyright © 2017 Sterner Design, LLC The revised schematic design
Copyright © 2017 Sterner Design, LLC Fewer corners + simpler plumbing + shading as additive
Copyright © 2017 Sterner Design, LLC % cost Original Alternative A Alternative B A Small Square footage (gross) 3,520 3,173 3,192 2,833 Sq. ft. concrete wall 19% 4,586 3,750 3,660 3,500 Sq. ft. glazing 10% 550 600 590 550 Sq. ft. green roof 10% 1,640 880 1,672 840 Sq. ft. hollow core precast 7% 2,432 2,293 2,432 2,033 Lin. ft. tunnel 5% 64 56 48 48 Sq. ft. exterior cladding 2% 3,022 3,683 2,496 2,200 Estimated cost (JH) $729,400 Estimated cost (CS) $547,592 $501,896 $524,041 $458,245 Less envelope area = less cost
Copyright © 2017 Sterner Design, LLC Less envelope area = better performance
Copyright © 2017 Sterner Design, LLC ENCLOSURE ! DESIGN + MATERIALS FOUNDATION ! DESIGN So: we have 2x the insulation and 3x the airtightness of a standard house, but spent only marginally more on the enclosure
Copyright © 2017 Sterner Design, LLC 2.  Think about labor.    (MATERIALS)
Copyright © 2017 Sterner Design, LLC Structure Insulation Air barrier ICFs = 3-in-1 solution: structure + insulation + air barrier
Copyright © 2017 Sterner Design, LLC The concrete forms a continuous air barrier Copyright © 2017 Sterner Design, LLC
Copyright © 2017 Sterner Design, LLC Copyright © 2017 Sterner Design, LLC A crew of 2 just installed •  The formwork for the concrete structure •  R-45 continuous wall insulation •  A high-quality air barrier = significant labor cost savings
Copyright © 2017 Sterner Design, LLC 3.  Use efficiency to reduce  HVAC costs.    (INTEGRATIVE DESIGN)
Copyright © 2017 Sterner Design, LLC Integrative Design in theory: Better performance at LESS cost
Copyright © 2017 Sterner Design, LLC How it worked here: Tiny heating load ! smaller, cheaper heating system Good passive design ! no A/C
Copyright © 2017 Sterner Design, LLC Designing the Enclosure Thermal, air, and vapor control
Copyright © 2017 Sterner Design, LLC 1.  Thermal control
Copyright © 2017 Sterner Design, LLC Copyright © 2017 Sterner Design, LLC Continuous insulation R-45 walls R-60 roof
Copyright © 2017 Sterner Design, LLC Window detail: Excellent windows (Zola) + Overinsulation Copyright © 2017 Sterner Design, LLC ! SEE THE DETAILS @ WWW.IOWANEST.COM
Copyright © 2017 Sterner Design, LLC 2.  Infiltration control  (air barrier)
Copyright © 2017 Sterner Design, LLC Copyright © 2017 Sterner Design, LLC Air barrier = ICF concrete core + AB membrane over roof sheathing +  good details
Copyright © 2017 Sterner Design, LLC Window detail: Siga tapes on interior  from window to plywood buck, and from buck to ICF ! SEE THE DETAILS @ WWW.IOWANEST.COM
Copyright © 2017 Sterner Design, LLC 4.  Vapor / moisture control.
Copyright © 2017 Sterner Design, LLC Why is this hard?  1. High insulation = cold surfaces  2. Cold surfaces + moisture = condensation = rot + mold = " AND, in the Midwest …
Copyright © 2017 Sterner Design, LLC Copyright © 2017 Sterner Design, LLC Summer = Cold inside, Humid outside ! Vapor drive inward
Copyright © 2017 Sterner Design, LLC Copyright © 2017 Sterner Design, LLC Winter = Cold outside, Humid inside ! Vapor drive outward
Copyright © 2017 Sterner Design, LLC The solution: •  Insulate potential condensation surfaces •  Use air barriers to keep moisture from getting into assemblies (most moisture travels via air movement, not diffusion) •  Don’t trap moisture in / let assemblies dry
Copyright © 2017 Sterner Design, LLC Strategies: •  Breathable assemblies •  Insulate sheathing" (keep above dewpoint) •  Ceiling air barrier Copyright © 2017 Sterner Design, LLC
Copyright © 2017 Sterner Design, LLC Copyright © 2017 Sterner Design, LLC To be continued … ! STAY UP-TO-DATE @ WWW.IOWANEST.COM
Copyright © 2017 Sterner Design, LLC Thank you! carl@sternerdesign.com www.sternerdesign.com www.iowanest.com

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