CEE 243:Week 9 Energy Simulation Challenges & Experiences from LBNL and Stanford

Transcription

1 :Week 9 Energy Simulation Challenges & Experiences from LBNL and Stanford James O Donnell Ph.D. Material Courtesy of Tobias Maile & Paul Raftery, Natasa Marazovic

2 Agenda 1. Buildings Referenced 2. Primary Issues 1. Geometry 2. HVAC 3. Schedules 4. Loads 3. Forthcoming Developments 4. Conclusions 2

3 Big Idea Understand the scope of use for Modelling, and the effort and the necessary work arounds The future direction of the domain 3

4 Buildings Referenced Ireland Mardyke Arena (University Sports Center) Environmental Research Institute (University Research Laboratory) Intel Ireland (Office Building) US Santa Rosa (Offices/Courthouse) San Diego Supercomputer (Computing Facility) San Francisco Federal Building (Office Building) Y2E2 (Offices/ Lecture Theaters/Laboratories) SCC (Jail) Europe Milan (Manufacturing Facility with Offices) Asia Tower Block Korea (Residential) 4

5 Geometry 5

6 Manual Geometry Creation One Dimensional Heat Transfer San Diego Supercomputer 6

7 Data Sources: Drawings and O&M manuals Approach: IFC Based BIM Issues encountered: Principles of Information Science not applied Solution: Manual editing of all surfaces Geometry Import 7

8 Geometry Simplifications Adjacent zones that are not physically separated must be modelled using virtual walls using Material:InfraRedTransparent Bug Identified: Outdoor wind convection coefficient changes depend on the ratio of surface area to surface perimeter. Example: 1-storey rectangular Two zoning approaches Core and 4 perimeter OR each floor as a zone Issue: Different overall convection coefficient as there are more exterior surfaces, each of which has a smaller perimeter to surface area ratio. 8

9 Geometry Simplification 2 Issues: Columns Issues Angled Walls 9

10 Curved Surfaces 10

11 Space boundaries: 1 st, 2 nd and 3 rd level Space 005 (#1415) Space 001 Space 004 Space 003 Wall 001 Space 001 Wall 010 Space 005 (#1415) Gap due to the wall-butt-print Wall 011 Space 003 Wall 012 Space 004 Wall 004 boundary Space Boundaries: 1 st Level 2 nd Level 3 rd Level Source: IAI - Implementation guideline for 2nd level space boundaries

12 Zones and Spaces Issues: Double height zones but different areas on each floor Solution Assisted the development of the ArchiCAD IFC Utility 12

13 Principles of Natural Ventilation EnergyPlus Limitations The solution Natural Ventilation 13

14 Natural Ventilation Natural Ventilation For all Office floors Issues: Measurement and Verification 14

15 HVAC 15

16 HVAC Simplifications: General No duct heat gain and loss for overhead systems No account for pressure loss in Ducts or Pipes Loop Architecture Simplifications. Inflexibility for pump banks 16

17 Plant Simplifications Boiler consumption and chiller consumption are not well modelled at low part loads. VFD losses for fans and pumps not usually accounted for Solution: Apply workaround where you add the loss to the motor loss and then change the 'motor in air fraction' parameter to discard this loss. 17

18 Air Loop Simplification: Supply Courtesy of: Tobias Maile 18

19 Air Loop Simplification: Return Only one return path allowed 19

20 Air Loop Branching Simplification: Demand Side Supply Path Courtesy of: Tobias Maile 20

21 Water Loop Simplification at SCC Thermodynamically the effect of this different configuration is negligible, however, the control strategy that the pumps are synchronized with the corresponding chiller cannot be evaluated since the link between chiller and pump gets lost in the EnergyPlus model. Courtesy of: Tobias Maile 21

22 ERI Systems Building and Systems Useful technique (Schedules): Infra-red camera at night 22

23 Hybrid System? Co-Simulation 23

24 Control Pressure Drops are not accounted for in pipe and duct systems so pressure based control is not possible. 24

25 Control Simulated Control does not match measured Courtesy of: Tobias Maile 25

26 Validation New Input Approach: System Representation Through Spreadsheet Macros Calibration requires extensive measurement: System performance to within 2% of actual Courtesy of: Paul Raftery and Andrea Costa 26

27 Internal Loads 27

28 Unusual Internal Loads Swimming Pool Main Gym Extension of Spreadsheet Macro Zoning 28

29 Forthcoming Developments 29

30 E+ GUI: Geometry 30

31 E+ GUI: HVAC 31

32 Conclusions Generic principles of simulation but are interpreted differently by each tool Major improvisation required for all buildings Pragmatic Perspective: Choose the tool that best suits your building 32

33 Questions 33