Fundamentals of WUFI-Plus WUFI Workshop NTNU / SINTEF 2008 Simultaneous Calculation of Transient Hygrothermal Conditions of Indoor Spaces and Building Envelopes
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
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
CO2 Slide 4 Humidity
Q structure θ room Q win.. Q source Q heat Q vent. Q adjacent Zone θ adjacent Zone Slide 5
Q structure θ room Q win.. Q source Q heat Q vent. Q adjacent Zone θ adjacent Zone Slide 6
θ room Slide 7
θ room Slide 8
Q structure Slide 9
Q structure Slide 10
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
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
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
Q structure Slide 14
Q structure Slide 17
Q windows Slide 18
Q windows Slide 19
Q windows Slide 20
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
Q windows Slide 22
Q windows Slide 23
Q windows Slide 24 www.passivhaustagung.de
Q windows Slide 25 www.efficientwindows.org
Q windows U-value Slide 26
Q windows U-value U=1.6 W/m²K U=0.8 W/m²K Slide 27
Q windows Slide 28
Q windows Reduced Area Slide 29
Q windows U=1.5 W/m²K frame reduction = 0.7 U=1.5 W/m²K frame reduction = 0.5 Slide 30
Q windows Slide 31
Q windows Solar Gain Coefficient measures how well a window blocks heat from sunlight low SHGC less solar heat is transmitted Slide 32
Q windows Solar Gain Coefficient Triple-Glazed** with Low- Solar-Gain Low-E* Glass, Argon/Krypton Gas Single-Glazed with Clear Glass Slide 33
Q windows U=1.5 W/m²K SHGC = 0.6 U=1.5 W/m²K SHGC = 0.3 Slide 34
Q windows Solar Gain Coefficient Slide 35
Q windows Solar Gain Coefficient Slide 36
Q windows Solar Gain Coefficient Slide 37
Q windows U=1.5 W/m²K SHGC = 0.6 - simple U=1.5 W/m²K SHGC = 0.6 - detailed Slide 38
Q windows Slide 39
Q windows Slide 40
Influence of Shading and Cooling Systems Slide 41
Influence of Shading and Cooling Systems Case Shading criteria Cooling max. Temp. West C1 off C2 on 27 C C3 0.3 500 W/m 2 off C4 0.3 500 W/m 2 on 27 C C5 0.3 25 C off C6 0.3 250 W/m 2 off Slide 42
Influence of Shading and Cooling Systems Case Shading criteria Cooling max. Temp. C1 off C2 on 27 C C3 0.3 500 W/m 2 off C4 0.3 500 W/m 2 on 27 C C5 0.3 25 C off C6 0.3 250 W/m 2 off Slide 43
Influence of Shading and Cooling Systems Case Shading criteria Cooling max. Temp. C1 off C2 on 27 C C3 0.3 500 W/m 2 off C4 0.3 500 W/m 2 on 27 C C5 0.3 25 C off C6 0.3 250 W/m 2 off Slide 44
Q ventilation How much? Slide 45
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
Q ventilation Slide 50
ASHARE 62-2 Slide 58
ASHARE 62-2 Infiltration Credit: 10l/s per 100m² Slide 59
G structure ϕ room G source G Hum G vent. G adjacent Zone ϕ adjacent Zone Humidity Slide 60
The importance of Moisture Only and Moisture 30 air temperature average surf. temperature 30 air temperature average surf. temperature Temperature [ C] 20 10 0 Temperature [ C] 20 10 0-10 -10 100 inner 100 inner Rel. Humidity [%] 75 50 25 Rel. Humidity [%] 75 50 25 0 0 73 146 219 292 365 0 0 73 146 219 292 365 Time [d] Time [d] Slide 61
ϕ room Humidity Slide 62
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 50 60 30 25 Humidity III 70 20 IV >70 <20 Slide 63
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
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
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
C room G source G vent. CO 2 Humidity Slide 67
Normal CO2 Levels normal outside levels: 350-450 ppm acceptable levels: < 600 ppm complaints of stiffness and odors: 600-1000 ppm ASHRAE standard: 1000 ppm general drowsiness: 1000-2500 ppm adverse health effects expected: 2500-5000 ppm Humidity CO 2 maximum allowed concentration within a 8 hour working period: 5000 ppm Carbon Dioxide Standard Levels The recommendation in ASHRAE standard 62-1989 are classrooms and conference rooms 15 cfm per occupant office space and restaurants 20 cfm per occupant hospitals 25 cfm per occupant Slide 68
Slide 69 exterior e indoor i Concentration CO ppm C rate change Air h n Zone i Volume m V with CO i : : 1/, 2 3 2 S C V n C V n dt dc V e CO i CO i CO i + + =,,, 2 2 2 Humidity CO 2
Sources CO 2 Humidity Slide 70
Sources CO 2 Humidity Slide 71
Sources CO 2 Humidity Slide 72
Sources CO 2 Humidity Slide 73
Sources Moisture CO 2 Humidity Slide 74
Sources Moisture CO 2 Humidity Slide 75
Sources CO 2 S CO 2, = 17 M [ l / h] where 1Met = 58 W/m 2 CO 2 Humidity Slide 76
Ventilation Strategies 1. No 2. Temperature 3. Relative Humidity 4. C0 2 CO 2 Humidity Slide 77
Fundamentals of WUFI-Plus Simultaneous Calculation of Transient Hygrothermal Conditions of Indoor Spaces and Building Envelopes