Thermally Active Structures for Green Buildings - GGASHRAE · 2013. 10. 14. · o ISO 11855: 2012...

Introduction to Thermally Active Floors Designing Thermally Active Floors

Daniel Nall, FAIA, PE, LEED

Radiant Energy Seminar - 10/16/2013 1

Thermally Active Structures for Green Buildings:

Introduction and Designing the System

Daniel H. Nall, FAIA, PE, LEED Fellow, BEMP HBDP

Golden Gate Chapter, October 16, 2013

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Why Rock the BoatDisadvantages of Common HVAC Systems

• Temperature, Humidity, Ventilation all controlled by a single Sensor

• Much Energy Expended in Moving Air Around

• Energy Expended for Conditioning Areas where People Aren’t

• Poor Comfort Control due to Space and Surface Temperature Variation

Why Radiant Heating/Cooling• Avoidance of Extensive Ductwork for

Distribution of Conditioning Medium• Incorporation of the Thermal Mass of the

Structure Into the Driving Force of the Conditioning System

• Improved Human Comfort • Removal of Solar Heat Gain Directly From

Mass Without Additional Air Flow• Reduced Heat Transport Energy Using Water

Compared with Air




Radiant Heating/Cooling – Sunspace Conditioning

• Controlling the Temperature of the Building Structural Mass instead of the Air

• Dedicated Ventilation/Dehumidification System• Polyethylene Tubing Imbedded in Slab

Circulates Hot or Cool Water to Alter Slab Temperature

• Direct Removal of Absorbed Solar Heat gain from Floor Slab

Radiant Heating Cooling Issues…• Ventilation• Dehumidification • Changeover from Heating to Cooling• Condensation Avoidance• Capacity Control• Construction




Applicable Standards for Performance Testing…

• British Standards Instituteo ISO 11855: 2012 – Building environment

design. Design, dimensioning, installation and control of embedded radiant heating and cooling systems

• DINo EN 1264 -2009

Radiant Heating Floor Schematics




Radiant Heating Cooling Design Tools…• Two Dimensional Floor Heat Transfer • Shortwave Radiant Fluxes on Floor• Room Thermal Stratification • Radiant Coupling between Room Surfaces

Maria’s Radiant Floor Modeller




13

Solar Patch Projection

February 4 pm

July 4 pm

July 12 pm

14

Temperature and Velocity Distribution

5 Ft above Floor Vertical




Computational Fluid Dynamics

Pier 1: Radiant Floor, Bay Heat Exchange




IBT Headquarters:Radiant Cooling,

Displacement Ventilation

Radiant Heating/Cooling:Repsol Winter Garden -Architectural and CFD Images




Bangkok International AirportBangkok, Thailand

Bangkok International AirportBangkok, Thailand




Pier OneSan Francisco, CA

Pier OneSan Francisco, CA




Hearst Tower:Radiant Heating/Cooling Lobby Floor




Hearst Headquarters

Radiant Heating/Cooling Floor – Geometry and CFD Results

Radiant Heating/Cooling Floor - Displacement Ventilation

Hearst Headquarters




Lobby Temperature Sections






Hearst Headquarters

Chilled Water Feature

Radiant Floor Tubing




Dartmouth College McLaughlin Hall (2006)

Heating

Radiant Floor CFD Analysis

Geometry

Cooling

Heating

Dartmouth College McLaughlin Hall (2006)

Heating




The William Jefferson Clinton Presidential Center





William Jefferson Clinton Presidential Center - LEED Silver

AIR MOTION REPRESENTATION

Computational Fluid Dynamics Studies of

Museum Area -Temperature, Flow and

Ventilative Effectiveness





Syracuse University School of Management

Grand Hall

SyracuseSchool of

Management Grand Hall




Radiant Floor Tubing

Syracuse School of Management Grand Hall

Team

CFD analysis

Syracuse School of Management Grand Hall




Gaylord National Harbor Hotel

Suitland, MD


Radiant Floor Piping




CFD Analysesfor Cooling


44





45

The Newseum, Washington, DC

Thermally Active Floor and Skywalks

46

World Financial Center, Wintergarden Pavilion, New York

Thermally Active Floor and Displacement Ventilation




Radiant/Heating Cooling Guidelines

Principles of Design• The system does not provide ventilation or dehumidification. A

conditioned air system is required to provide these functions.

• The system is a low temperature difference, large active area conditioning system, so highly accurate temperature control is not required for comfort maintenance.

• A chilled floor enhances stratification, providing greater comfort where the people are. A heated floor minimizes stratification, also minimizing overheating high in the space.

• Chilled floors are most effective at removing solar heat gain as it is absorbed into the slab, reducing air flow necessary for cooling.

• System does not require quick response because direct control of building mass in the space precludes rapid change of load magnitude.

Radiant/Heating Cooling GuidelinesPrinciples of Design• Floor is controlled to be the right temperature for a given space

condition. Floor is controlled by resetting set-point temperature

• Heating cooling changeover should be a rare event and controlled to avoid driving the floor from one mode to another

• Variable flow control (multi-zone pulsed constant flow) with constant inlet temperature (in a mode) allows inexpensive individual zone control. Constant flow with variable inlet temperature requires a pump for each zone.

• Time constant of floor temperature reset stimulus should be longer than that of the floor itself.

• Floor capacity is dependent on absorbed solar radiation. Solar radiation absorbed by non-active surfaces must be removed by alternate means.





Design Process• Calculate cooling loads with both radiant and convective

components and locate them within the room volume.

• Explicitly calculate solar heat gain patches on floor for size, location and intensity. Separate solar heat gain absorbed by windows from that transmitted through windows.

• Use two dimensional heat transfer calculations to determine temperature of solar irradiated radiant floor. Incorporate floor finish and topping slab conductances in calculation. Calculate for range of flow rates and inlet temperatures.

• Use CFD analysis with calculated radiant and convective internal heat gains and solar heat gain patches calculated above

• Configure radiant loop zoning to match pattern of solar heat gain


Radiant System Layout 1• Configure isolated radiant loop with heating and cooling heat

exchangers to minimize fouling in the tubing.

• Magnitude of space and use will determine if flow modulation is applied to individual zone loops or to manifolds for flow temperature control.

• Establish minimum zoning based upon use and solar exposure.

• Layout tubing in double serpentine pattern to minimize temperature differences across the floor.

• Locate manifolds to minimize home run distance to controlled floor area.

• Layout loops based on 300 ft. roll size. Base loop zoning size on centerline tubing spacing and homerun length.





Radiant System Layout 2• Locate floor temperature sensors to be representative of

zone.

• Use separate heat exchangers for heating and cooling or single heat exchanger with four-pipe change-over valving

• Control temperature of heat exchanger secondary outlet temperature by modulating primary flow volume.

• Allow variable flow in radiant loop with variable speed circulating pump or pressure controlled bypass.

• Compare cooling diversity flow requirements with non-diverse heating flow requirements to size pumps and heat exchangers. Max heating may take on 1.0-1.5 gpm per loop. Max cooling takes up to 2.0 gpm per loop, but is diverse because of solar patches.


Measures to Improve Comfort• Outside air system configured to provide adequate

ventilation, well distributed around the space.

• Limit temperature range of floor between 68 DegF and 80 DegF

• Limit temperature range of displacement ventilation between 66 DegF and 85 DegF

• Limit velocity through displacement diffusers to 60 fpm.

• Zone floor to accommodate solar shadowing patterns.

• Control floor to offset impact of cold surfaces on mean radiant temperature




Acknowledgements:St. Meinrad Archabbey Church Architect – Woollen Molzan Partners, Indianapolis, IN Building Services Engineers –

Roger Preston + Partners, Atlanta

Virginia Hand Callaway Center Architect ‐ Robert Lamb Hart, NYC Building Services Engineers –

Roger Preston + Partners, Atlanta and Creative Engineering Design, Atlanta

IBT Headquarters Architect – Murphy Jahn, Chicago, IL Building Services Engineers ‐

Flack + Kurtz, San Francisco, CA

Hearst Headquarters Architect – Foster and Partners, London, UK Building Services Engineers – Flack + Kurtz, NYC

Dartmouth College McLaughlin Residences Architect – Bruner Cott, Boston, MA, and Moore, Ruble, Yudell, Architects, Santa Monica, CA Building Services Engineers – Flack + Kurtz, NYC

William Jefferson Clinton Library Architect – Polshek Partners., New York, NY Building Services Engineers – Flack + Kurtz, NYC

Cromwell Architects, Engineers, Little Rock, AR

Pier 1 Architect – SMWM Architects, San Francisco, CA Building Services Engineers –

Flack + Kurtz, San Francisco, CA

Gaylord National Harbor Hotel Architect – Gensler Building Services Engineer – WSP Flack + Kurtz, NYC

Syracuse University School of Management Architect – F X Fowle, NYC Building Services Engineers – Flack + Kurtz, NYC

SAP Corporate Headquarters Architect – F X Fowle, NYC Building Services Engineers ‐ WSP Flack + Kurtz, NYC

World Financial Center Wintergarden Architect – Pelli, Clarke, Pelli Building Services Engineers ‐ WSP Flack + Kurtz, NYC

Thanks

Daniel H. Nall, FAIA, PE, LEED Fellow, HBDP, BEMPThornton Tomasetti51 Madison AvenueNew York, NY 10010

[email protected] 661 8130

Thermally Active Structures for Green Buildings - GGASHRAE · 2013. 10. 14. · o ISO 11855: 2012...

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Transcript of Thermally Active Structures for Green Buildings - GGASHRAE · 2013. 10. 14. · o ISO 11855: 2012...