Paul Linden & Guilherme Carrilho da Graça. NaturalWorks Inc

Transcription

1 Building simulation Case Studies Paul Linden & Guilherme Carrilho da Graça NaturalWorks Inc

2 Natural Ventilation Design San Francisco Federal Office Building MORPHOSIS

3 San Francisco Federal Office Building

4 San Francisco Federal Office Building

5 San Francisco Federal Office Building Good opportunity for natural, wind driven ventilation SF has good weather Plots taken from: RWDI environmental wind study.

6 Building geometry in the naturally ventilated floors The building will be naturally cross-ventilated (C-V) in most of the floor plan in floors: The building volume with C-V measures: 107x19x52 m and starts at an elevation of 20 m.

7 C-V half floor plan isothermal simulations Cases analyzed 1-Normal full open ( ) 2-Porous full open (90%, Yarn width 0.1mm) 3-Low windows closed (0.2) 4-Half windows open on top and full open bottom CFD

8 The airflow pattern - pollutant/heat removal ability: short circuit & accumulation of pollutants S E S E D E T A I L

9 Design of the flow deflector on the lower window

10 Control system principles The control strategy groups windows together and operates them in either closed, half-open or fully-opened positions The system uses opening modes, identified by a mode number MDN, which varies from 1 (closed) to 10 (fully open) These modes are chosen to ensure uniform air distribution while limiting the maximum interior air speeds Each half of each floor is independently controlled and the control state is given by the MDN value The system responds to these variables by changing the MDN value by ±1. The time step is set at 10 minutes. Windward mostly user control Leeward building control system

11 Schematic of the aperture modes

12 The control strategy was tested using: two TMY years + a modified EnergyPlus / COMIS

13 The control strategy was tested using two TMY years + a modified EnergyPlus / COMIS

14 Children's Museum

15 Strategies to deal with overheating Night cooling. Warm night time temperatures after hot days limit the capacity to cool the building Wind-driven ventilation. Analysis shows that on warm days the prevailing wind direction is from the west (from approximately southwest to northwest). Propose that the solar chimney have an opening on the east face Control strategy that optimizes the ventilation flow. Several changes where proposed for the façade openings, including the introduction of a north facing low level opening

16 Analysis CFD to examine the wind-driven ventilation in more detail, ensuring that it provides the additional cooling required for the days when the temperature is too high The development of a control strategy (EnergyPlus) that optimizes ventilation performanceand examines the relation between system controlled and user controlled openings

17 EnergyPlus model

18 CFD Geometry

19 Supercomputer Center Performance simulation of the indoor climate control system Optimization of the shading design

20 Climate analysis.where does the wind blow during warm hours? Temperature (in red, T-70, F) Wind velocity (mph) Wind direction A c c u m u l a t e d warm hours

21 Climate analysis potential for night cooling?

22 EnergyPlus model

23 ECOTECH shading analysis initial shading optimized shading

24 Ventilation Schemes: Low (V00), Daytime (VD0), Night&Day (VDN) 300 Results Hours Smaller South Shading (SS) 0 VDN V00 VD Temperature (ºF) > Exterior Walls: Non Insulated (NI) Hours Hours Temperature (ºF) > 85 SS Base Temperature (ºF) > 85 NI Base

25 Conclusions climate has significant potential for low energy climate control systems In most spaces the use of natural cooling by single sided ventilation (both during the day and night) may provide sufficient cooling Due to the mildness of the climate, special glazing or even thermal insulation in the vertical walls may not be necessary

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