Fundamentals of WUFI-Plus WUFI Workshop NTNU / SINTEF 2008

Transcription

1 Fundamentals of WUFI-Plus WUFI Workshop NTNU / SINTEF 2008 Simultaneous Calculation of Transient Hygrothermal Conditions of Indoor Spaces and Building Envelopes

2 boundary conditions Building envelope Outdoor climate Indoor climate - ventilation - moisture source - CO 2 - source - heating system - cooling system constructions material data hygrothermal conditions of the building envelope hygrothermal simulations with WUFI -Plus Indoor climate energy consumption Slide 2

3 Envelope heat transport w φ = div ) φ t ( D grad( φ δ grad( φ )) φ + p p sat moisture transport H T T t = div ( λgrad( T )) + h div δ grad( φ p ) v p sat Whole Building dθ ρ ) i c V = Ajα j ( θ j θi + QSol + Q + n V ρ c θ il dt j ( θa i ) Q& vent & & + Moisture V dc dt i = j A j gw j + n V ( ca ci ) + W IMP + W Vent Slide 3

4 CO2 Slide 4 Humidity

5 Q structure θ room Q win.. Q source Q heat Q vent. Q adjacent Zone θ adjacent Zone Slide 5

6 Q structure θ room Q win.. Q source Q heat Q vent. Q adjacent Zone θ adjacent Zone Slide 6

7 θ room Slide 7

8 θ room Slide 8

9 Q structure Slide 9

10 Q structure Slide 10

11 Q structure Q structure = A U θ structure envelope structure ( θ ) t [ ] a, e a, i Wh with A U θ θ t a, e a, i m 2 W / m K K h 2 K Area U Value Outdoor temperatur e Room temperatur e time Slide 11

12 Q structure ( θ θ ) Q structure = Astructure h s a, envelope i with A q θ θ s a, i m 2 W / m K K 2 Area heat flux inner surface temperatur e Room temperatur e From WUFI-Pro w φ = div ) φ t ( D grad( φ δ grad ( φ )) φ + p p sat Slide 12

13 Q structure ( θ θ ) Q structure = Astructure h s a, envelope i with A q θ θ s a, i m 2 W / m K K 2 Area heat flux inner surface temperatur e Room temperatur e From WUFI-Pro Slide 13

14 Q structure Slide 14

15 Q structure Slide 17

16 Q windows Slide 18

17 Q windows Slide 19

18 Q windows Slide 20

19 Q windows Q window Q Q = Q i windows = Q Q i T S, i = ( fframe Aw Uwindows a, i θa, e SHGC A w I) t ( θ ) with f frame A U θ a CoG m 2 W/m K K 2 SHGC I W / m 2 frame reduction ratio Area U Value ( whole window ) Air temperature i : indoor e : exterior Solar heat gain coefficient Solar radiation Slide 21

20 Q windows Slide 22

21 Q windows Slide 23

22 Q windows Slide 24

23 Q windows Slide 25

24 Q windows U-value Slide 26

25 Q windows U-value U=1.6 W/m²K U=0.8 W/m²K Slide 27

26 Q windows Slide 28

27 Q windows Reduced Area Slide 29

28 Q windows U=1.5 W/m²K frame reduction = 0.7 U=1.5 W/m²K frame reduction = 0.5 Slide 30

29 Q windows Slide 31

30 Q windows Solar Gain Coefficient measures how well a window blocks heat from sunlight low SHGC less solar heat is transmitted Slide 32

31 Q windows Solar Gain Coefficient Triple-Glazed** with Low- Solar-Gain Low-E* Glass, Argon/Krypton Gas Single-Glazed with Clear Glass Slide 33

32 Q windows U=1.5 W/m²K SHGC = 0.6 U=1.5 W/m²K SHGC = 0.3 Slide 34

33 Q windows Solar Gain Coefficient Slide 35

34 Q windows Solar Gain Coefficient Slide 36

35 Q windows Solar Gain Coefficient Slide 37

36 Q windows U=1.5 W/m²K SHGC = simple U=1.5 W/m²K SHGC = detailed Slide 38

37 Q windows Slide 39

38 Q windows Slide 40

39 Influence of Shading and Cooling Systems Slide 41

40 Influence of Shading and Cooling Systems Case Shading criteria Cooling max. Temp. West C1 off C2 on 27 C C W/m 2 off C W/m 2 on 27 C C C off C W/m 2 off Slide 42

41 Influence of Shading and Cooling Systems Case Shading criteria Cooling max. Temp. C1 off C2 on 27 C C W/m 2 off C W/m 2 on 27 C C C off C W/m 2 off Slide 43

42 Influence of Shading and Cooling Systems Case Shading criteria Cooling max. Temp. C1 off C2 on 27 C C W/m 2 off C W/m 2 on 27 C C C off C W/m 2 off Slide 44

43 Q ventilation How much? Slide 45

44 Q ventilation ( ) Q ventilation cp, a a Vi n Ta, i Ta, e = ρ with c p, a J/kgK specific heat capacity of air ρ V n T i a a kg/m m 3 1/ h K 3 density of air Volume of Zone i Air change rate Air temperature i : indoor e : exterior Slide 46

45 Q ventilation Slide 50

46 ASHARE 62-2 Slide 58

47 ASHARE 62-2 Infiltration Credit: 10l/s per 100m² Slide 59

48 G structure ϕ room G source G Hum G vent. G adjacent Zone ϕ adjacent Zone Humidity Slide 60

49 The importance of Moisture Only and Moisture 30 air temperature average surf. temperature 30 air temperature average surf. temperature Temperature [ C] Temperature [ C] inner 100 inner Rel. Humidity [%] Rel. Humidity [%] Time [d] Time [d] Slide 61

50 ϕ room Humidity Slide 62

51 ϕ room Recommended criteria for the dimension of humidification/dehumidification Furthermore a limitation of the absolute humidity at 12 g/kg is recommended Category max. RH for dehumidification min. RH for humidification I II Humidity III IV >70 <20 Slide 63

52 Structure and adjacent Zones Q structure = A structure envelope g m with A g m m 2 2 kg / m h Area Moisture flux over the inner surface From WUFI-Pro H T T t = div ( ) ( λgrad( T )) + h div δ grad( φ p ) v p sat Humidity Slide 64

53 Structure and adjacent Zones Q structure = A structure envelope g m with A g m m 2 2 kg / m h Area Moisture flux over the inner surface From WUFI-Pro Humidity Slide 65

54 Ventilation ( c c ) Q ventilation = Vi n a, i a, e with V n c i a m 3 1/ h kg / m³ Volume of Zone i Air change rate Absolute MoistureContent i : indoor e : exterior Humidity Slide 66

55 C room G source G vent. CO 2 Humidity Slide 67

56 Normal CO2 Levels normal outside levels: ppm acceptable levels: < 600 ppm complaints of stiffness and odors: ppm ASHRAE standard: 1000 ppm general drowsiness: ppm adverse health effects expected: ppm Humidity CO 2 maximum allowed concentration within a 8 hour working period: 5000 ppm Carbon Dioxide Standard Levels The recommendation in ASHRAE standard are classrooms and conference rooms 15 cfm per occupant office space and restaurants 20 cfm per occupant hospitals 25 cfm per occupant Slide 68

57 Slide 69 exterior e indoor i Concentration CO ppm C rate change Air h n Zone i Volume m V with CO i : : 1/, S C V n C V n dt dc V e CO i CO i CO i + + =,,, Humidity CO 2

58 Sources CO 2 Humidity Slide 70

59 Sources CO 2 Humidity Slide 71

60 Sources CO 2 Humidity Slide 72

61 Sources CO 2 Humidity Slide 73

62 Sources Moisture CO 2 Humidity Slide 74

63 Sources Moisture CO 2 Humidity Slide 75

64 Sources CO 2 S CO 2, = 17 M [ l / h] where 1Met = 58 W/m 2 CO 2 Humidity Slide 76

65 Ventilation Strategies 1. No 2. Temperature 3. Relative Humidity 4. C0 2 CO 2 Humidity Slide 77

66 Fundamentals of WUFI-Plus Simultaneous Calculation of Transient Hygrothermal Conditions of Indoor Spaces and Building Envelopes