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The Need For Systems Integration with Passive Strategies
John Nelson, Architectural Energy CorporationDavid Banks, Cermak Peterka Petersen
Rob Slowinski , Architectural Energy Corporation
Learning Objectives
• Review the drivers for passive architectural strategies, and the status of the industry in regards to adoption of their principles.
• Review the principles of natural ventilation and passive conditioning.
• Present examples of how projects overcame barriers through integration.
Images by Transsolar
State of the Industry & Planet: Trends
Muir Glacier, Alaska 1941 Photo by W.O. Field Muir Glacier, Alaska 2004 Photo by B.F. Molina
Graph by Rocky Mountain Institute
Graph by American Center for Progress
Graph by 2030 ChallengeData: Energy Information Administration
State of the Industry & Planet: Trends
Paradigms• Overlook architecture’s
affect on energy use• Monolithic Temperatures• Trade offs between peak
and efficient normal operation
Photos by: James Balog
Turning Momentum
• Proof of concept• Loads of research available• 2030 Challenge
commitments• Restlessness in
professionals
Photo courtesy of NREL’s Photo Exchange
Passive Strategies: Potential & Adoption
Total US Office Building Energy Use
Source: Energy Information Administration
• Daylight• Natural Ventilation• Passive Conditioning
Heating 25%
Cooling 9%
Lighting 29%
Equipment 26%
Ventilation 5%
Other 16%
Graph courtesy of Wikipedia
Thermal Inertia
• ‘during spring and autumn, lightweight buildings may require both heating and cooling over the diurnal cycle, whereas the thermally heavy buildings can maintain comfortable internal conditions without either supplementary heating or cooling.’
– BRE Digest 454• ‘Most modern buildings are structurally heavy but thermally light.
Widespread use of carpets, floor voids, false ceilings and plasterboard wall liners, all of which effectively insulate the structure from the environment’
– BRE Digest 454• ‘Thermal storage techniques absorb heat during peak periods of
excess gain and store it until it can be discharged later.’ – CIBSE Mixed Mode Ventilation AM:13
Photo By Tom Arban
Approach of Thermal Balance
Images courtesy of Terrapin Bright Green & Rocky Mountain Magazine
Quality
Photo courtesy of World Architecture Festival
Chart by Rocky Mountain Institute
Integrated Design“Integrated design is both a process and a result”
-Michael Holtz, FAIA
Chart by Rocky Mountain Institute
Climate & Location Analysis
Image courtesy of World Architecture Festival
Testing Concepts: Modeling
• Test our strategies• Become informed to
enhance / optimize design
• Optimize glazing amount = upfront and operational savings
Push boundaries on paper first:“Only a fool views success as never having been wrong”
-Jason McLennan (Living Building Challenge creator)
Modeling by Zack Rogers
Eras & Intentions
Manitoba Hydro Headquarters, Photo by Eduard Hueber
NATURAL VENTILATION & ADAPTIVE COMFORT
Air flow from:• stack effect• winds
Related issues:• thermal mass• heat loads• expectations
How to Ventilate Naturally
Stack EffectDriven by • temperature difference• Height of column of air• gravity
WindDriven by • Wind speed• Pressure
fluctuations due to building shape and surroundings
Wind speed will overwhelm stack effect at 3-10 mph. This is most of the time.
Seasonal and diurnal wind directions
Time of day
Win
d d
ire
cti
on
Air Flow Simulations
• Nodal model/ Building Energy Sim• For the whole building• “Coupled” important if stack effect is a big part
• Computational Fluid Dynamics (CFD)• For details of a single room or building segment• Simulates a specific situation
• Boundary Layer Wind Tunnel• For outside the building• Does not predict indoor flows
Boundary-Layer Wind Tunnels
A boundary layer wind tunnel recreates the turbulent winds of the lower atmosphere in a controlled environment.
ASHRAE adaptive comfort model
Air Movement
Personal ControlOur primary objective in this project was to examine the differences between individuals with relatively high and low degrees of control in the same naturally-ventilated building… While these two groups were experiencing similar physical conditions that influenced their heat balance, we found significant differences in their subjective response … While behavioral mechanisms are certainlysignificant in allowing people to adjust their personal comfort, psychological dimensions are also relevant to the degree of thermal comfort experienced.
This emphasizes the importance of not just designing a building with a high degree of adaptive opportunity, but ensuring that all occupants have direct and easy access to those various means to control their own environment.
Operable windows were, by far, the most used control. Blinds were used about half as often as windows, and ceiling fans or desk fans were used even less.
Gail Brager, ASHRAE Transactions
Survey findings: green vs. conventional
LEED/green (n=20); rest of database (n =161)
Air quality satisfaction, by building type
INTEGRATED RESULTS: LEADING THE WAY
Integrated Results:Stanford’s Y2E2, CA
• Stack effect:4 central atria
• BAS and occupant-controlled natural ventilation
• Exposed slabs integrate with architecture
• Chilled beams well-suited for natural ventilation when systems are active
Photo by: John Nelson
Image courtesy news.stanford.edu
Integrated Results:Stanford’s Y2E2, CA
Photos by: John Nelson
Integrated Results:NREL RSF, CO
• Massing for daylight = massing for natural ventilation
• Exposed mass for passive integrated with radiant
• Radiant can use low grade heating & cooling (eg: solar thermal)
Photos courtesy of NREL’s photo exchange
Integrated Results:NREL RSF, CO
• UFAD: Office flexibility, efficient ventilation, and exposed ceilings all with one strategy
• Indirect/direct couples well with ‘open’ buildings
• Transpired solar collectors
Upper photo: John Nelson / Lower photo courtesy of NREL’s photo exchange
Integrated Results:Tulane University, New Orleans, LA• New Orleans historic
architecture with layers of shading
• Thermal zoning: designed for ‘open operation’ fall and spring
• Daylight with good shading = low solar heat gain & low internal loads
Photo courtesy of Archilovers.com
Integrated Results:Muechener Tor, Munich Germany
• 2 central stacks, 20 stories high
• No mechanical ventilation• Supply air conditioned
with geothermal ‘air to earth’ register
• Free cooling of exposed slabs and night flush is supplemented with radiant cooling from ground water
Photo courtesy of Wikipedia
Integrated Results:Unilever Headquarters, Hamburg, Germany
• Area of high winds -> double façade/hybrid ventilation
• Concerns about exhaust from harbor
• Exposed mass/radiant heating
• Large atria is ‘building’s lungs’
Photo courtesy of World Architecture Festival
Questions?
John Nelson, Architectural Energy CorporationDavid Banks, Cermak Peterka Petersen
Rob Slowinski , Architectural Energy Corporation