Feasibility of Passive House for Public Buildings by Shivani Shah and Craig Graber, Atelier Ten, and Wendy Wan, NYC DDC

As New York City pursues greater carbon reductions, the Passive House standard (PH) offers a way to significantly accelerate energy savings in public buildings. While PH is common throughout Europe, very few buildings in NYC have achieved the standard, and those that have are private homes. This rigorous standard sets a high benchmark for energy reduction that far exceeds the current New York City Energy Conservation Code and LEED’s Energy and Atmosphere prerequisite. PH principles focus on high performance envelopes, and simple but controlled mechanical ventilation with heat recovery, so it can be applied to a range of building types and construction systems. However, with few completed examples, determining the standard’s applicability to public projects in NYC is difficult.

The New York City Department of Design and Construction (DDC) and Atelier Ten recently completed a study of three DDC projects that examines the changes in design, construction, and building operation necessary to meet the PH standard. Each project brings to light different opportunities and challenges when considering PH. The study involved modeling potential energy efficiency measures related to the building envelope, lighting, and mechanical systems, as well as the potential impact of incorporating all measures on source energy intensity and CO2 emissions. Although not exhaustive, the study does provide great insight into how PH can be employed in public projects, possible environmental benefits and limitations.

Transcript

1. Shivani Shah, LEED AP Senior Environmental Designer, Atelier Ten Craig Graber, AIA, LEED AP BD+C Senior Environmental Designer, Atelier Ten Wendy Wan, RA, LEED AP Project Director, NYC DDC - Office of Sustainable Design Feasibility of Passive House for Public Buildings A Study of Three DDC Projects
2. NYC Department of Design and Construction Location of DDC Projects
3. DDC – Office of Sustainable Design
4. Passive House • Rigorous, voluntary energy efficiency standard for buildings • Significant energy use reduction without specific construction methodology • Focus on occupant comfort Passive House, Bessancourt, France Karawitz Architecture, via GreenSource Magazine March 2011 Original Passive House, Darmstadt-Kranichstein, Germany Bott, Ridder and Westermeyer, via www.passiv.de 2010
5. PH Criteria Certification Requirements • Maximum Source Energy Use Intensity: 38.1 kBtu/ft2/yr • Maximum Annual Heating or Cooling Energy Demand: 4.75 kBtu/ft2/yr • Maximum Heating or Cooling Load: 3.17 kBtu/hr*ft2 • Building Air-tightness: ≤0.6 ACH @ 50 pascal through blower door test Performance Targets • Whole Window U-value: 0.15 Btu/hr*ft2*F • Ventilation System w/ Energy Recovery: ≥ 75% recovery efficiency with low electric consumption @ ≤ 0.765 W/CFM • Thermal-bridge Free Construction: psi (Ψ) value ≤ 0.006 Btu/hr*ft*F
6. PH in New York City Tighthouse Fabrica 718 completed 2013 951 Pacific Street Paul Castrucci Architects In-progress 174 Grand Street Loadingdock5 completed 2011 803 Knickerbocker Avenue Architecture and Energy Limited, via Daily News In-progress
7. Study of PH for Public Buildings in New York City • Applicability of PH on three recently completed DDC projects • Design and construction changes needed to achieve PH certification • Potential impact on energy use, CO2 emissions and feasibility of construction • Possible conflicts and synergies between PH and NYC building code requirements
8. Glen Oaks Branch Library Year Completed: 2013 Area: 18,000 Sq.Ft. Building Type: Library LEED Level: Gold, v2.1
9. Glen Oaks Branch Library
10. Sunrise Yards Year Completed: 2010 Area: 43,500 Sq.Ft. Building Type: DOT Maintenance Facility LEED: Platinum, v.2.1
11. Sunrise Yards
12. Weeksville Heritage Center Year Completed: 2013 Area: 23,000 Sq.Ft. Building Type: Exhibition and Educational Facilities LEED: Silver*, v2.1
13. Weeksville Heritage Center
14. Source Energy Characterization Glen Oaks Sunrise Yard Weeksville
15. Project Siting and Form • PH recommended A/V ratio: ≤ 0.21 ft2/ft3
16. Building Envelope: General Requirements • Continuous insulation with walls, floors and roofs ≥ R-38 hr*ft2*F/Btu • High performance glazing and window assemblies ≥ R-7.1 window unit ≥ R-6.7 installed • Optimum window and skylight area • Air-tightness at 0.6 ACH-50 achieved with careful detailing and installation and to be tested twice: once after installation of the air barrier and again after construction completion
17. Building Envelope: Thermal Bridging • Thermal bridges increase heat transfer across the envelope • Linear, repetitive and point thermal bridges • Thermal-bridge free design: psi (Ψ) value ≤ 0.006 Btu/hr*ft*F
18. Internal Loads: Lighting / Equipment • Daylighting as primary source of lighting • Concentrated task lighting to meet critical visual needs • Decorative lighting to contribute to ambient lighting • Lighting controls like daylight dimming, occupancy, and proximity sensors • Occupancy or photosensors to dim or turn off egress lighting • Masterswitches, capacity restrictors, and regenerative drive elevators
19. • Maximum Annual Heating or Cooling Energy Demand: 4.75 kBtu/ft2/yr • Ventilation System with energy recovery: ≥ 75% recovery efficiency • Eliminated radiant flooring in Glen Oaks and Sunrise Yards • Controls to turn off fans, VSD fans/ pumps, natural ventilation, night purge HVAC System Glen Oaks Sunrise Yard Weeksville
20. Summary of Measures and Energy Use Glen Oaks Sunrise Yard Weeksville
21. Cost Impact Glen Oaks Sunrise Yard Weeksville
22. Potential for PH in Public Buildings • PH to be considered as a project goal as early as possible o EnerPHit can be considered for major renovations of existing buildings • Project program and occupancy will affect feasibility of achieving PH certification o Public buildings that do not have high equipment usage or high ventilation requirements would be good candidates for PH certification • All projects benefit from thermal bridge-free details • Daylighting is still key to reduce internal loads