Building Simulation. Where has it been? Where is it going? Curtis Pedersen Professor Emeritus University of Illinois

Transcription

1 Building Simulation Where has it been? Where is it going? Curtis Pedersen Professor Emeritus University of Illinois Outline of Talk Introduction Thermodynamics Background History of Building Simulation Simulation Today The Future 1

2 Personal Beginning of Building Simulation 1967 ASHRAE meeting in Ohio. Mitalas and Stephenson: Thermal Response Factor paper. The Beginning at the University of Illinois 2

3 Building Blocks of Building Simulation Bldg Sim First Law Carnot Clausius Obert Carnot and Clausius Carnot worked with cycles, related heat and work(1824). Clausius split cycle into parts, introduced internal energy(1850). Had inexact and exact differentials. 3

4 Obert 1960 Concepts of Thermodynamics Dedicated to the perplexed student who inquires: What are the independent variables? dq/dt-dw/dt = de/dt Q and W defined as time dependent net quantities Simulation of Buildings First Law is the Heart. Heat, Work and Energy Storage Time is the independent variable. Sun Weather Schedules Energy Storage 4

5 Why is Simulation Difficult? Many separate heat transfer processes are involved. All are small and of similar magnitude. Most inputs vary greatly with time. Building Simulation Origins Circa

6 Reference EarlyCommercialPrograms Ref:Ayres and Stamper 6

7 Simulation Program Family Tree Ref:Ayres and Stamper Family Tree Continued BLAST IBLAST DOE2 EnergyPlus 7

8 ASHRAE Activities Ref:Ayres and Stamper LaterTC 4.7 Chairs Dave Claridge Dave Claridge Chip Barnaby Chip Barnaby Chip Barnaby Robert Sonderegger Robert Sonderegger Jeff Spitler Jeff Spitler 2003-Dru Crawley 2004-Dru Crawley 2005-Les Norford 2006-Les Norford 2007-Dan Fisher 2008-Dan Fisher 2009-Phil Haves 8

9 IBPSA History All Papers are online! Have Things Changed? Tom Kusuda in 1985 IBPSA paper: 9

10 Building Simulation Today Primarily done on PCs Users generally put in too much detail Interfaces create monster simulations Users lack feel or knowledge of what is important. User Examples 10

11 State of Illinois Center, Chicago w. Randolph St. Offices in open Platforms 11

12 State of Illinois Center Designers model used DOE2 with air walls (130 zones) Reasonable temps at bottom, 95 F in governors office on 23rd floor. Had to increase air flow from 1.0 to 1.4 million CFM for stirring (3.5 to 5 ACH). Original load estimate 3000 tons, fix increased system equipment to 4300 tons. It is a single zone! Some RecentExamples from EnergyPlus Users 12

13 User Example1 (ran out of virtual memory) 1037 zones Base Surfaces Sub-surfaces. People, Lights, Equipment with Purchased Air. Only 11 Schedules! Input file was 9.3 MB. View of User Example1 13

14 Other Bad Examples User question: What is dry bulb temperature? User trying to simulate a curved surface 4437 Surfaces. Wasted Effort Ground Temperature Specification 14

15 The Future Must stick with fundamentals-get speed in other ways Doing simulation on supercomputers Using new multiprocessor PCs Cloud computing Cloud Computing Completes the Circle Mainframe CloudComputing Personal Computer Workstation 15

16 Major Future Needs User Education Green and Hybrid Designs (Fundamentals become more important) Conclusion Hope we didn t have too much Thermodynamics. There are some good and intelligent users of building simulation. Strongly support the initiative discussed this afternoon. 16

17 Thank You! Questions? Merger 17

18 Carnot Heat Engine, 1824 Cycle Q-W=0 Clausius Developed the First Law of Thermodynamics in 1850 δq-δw=de ( inexact differentials ) Two Famous Quotes from 1865: The energy of the universe is constant. The entropy of the universe tends to a maximum. 18