Chair for buildings & constructional complexes

1. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY U- value, diffusion,TEDI

2. internal living environment building envelope external environment Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY energy heat materials water vapour Information • Building envelope must ensure the right energy flow that does not damage the material • building envelope must ensure the optimal living conditions inside the building by minimum energy consumption

3. katedra za stavbe in konstrukcijske elemente ZGRADBA, OKOLJE, ENERGIJA Building elements walls roofs floors working system climate particularities

4. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Considering the constructional complex taking into account U-value, vapour diffusion, heat balance • calculating the thermal transmittance (U-value) • calculating the vapour transmittance • calculating the energy balance • optimisation of a building element heat balance diffusion U-value optimisation improvements improvements improvements • using the computer program TEDI

5. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • U - value

6. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Basic physical quantities and definitions for calculating thermal transmittance • linear thermal transmittance U (W/mk) 1K 1m • U-(W/mK) specific material property: heat flow rate in one hour in steady state per square meter of material, 1m thick and by temperature difference 1K

7. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Basic physical quantities and definitions for calculating thermal transmittance • thermal conductance L (W/m2K) 1K d (m) • L=l/d • L (W/m2K) : heat flow rate in a steady state in one hour through a square meter area and 1m thickness of a material by temperature difference 1K through its thickness

8. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • thermal resistanceR=1/L=d/ l • constructional complex with several layers R=R1+R2+R3+…= S(di/ li) l1 l3 l2 R1 R2 R3 d1 d2 d3

9. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Basic physical quantities and definitions for calculating • thermal transmittance • surface thermal transmittance a (W/m2K) ai vo vi ao • adepends on: • wind speed • wind direction • position of the building element (horizontal / vertical)

10. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • thermal transmittance of the constructional complex - U value: U=1/R • thermal resistance of the constructional complex R=1/ ao +S(dj/ lj)+ 1/ ai constructionalcomplex external air surface layer inside internal air surface layer outside 1/ai 1/ao d1/ l1 d2/ l2 d3/ l3 1/ao U=S(di/ li) 1/ai U

11. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Determination of the thermal gradient through the constructional complex - graphic method • example: TI LBC T (oC) T (oC) 20 0 -20 d (m) R (m2K/W) dao d1 d2 d3 dai 1/ao d1/l1 d2/l2 d3/l3 1/ai

12. DTi=(1/ai)/Rk * (Ti-To) Tip= Ti- DTi DTj=(dj/aj)/Rk * (Ti-To) Tj= Tj-1- DTj DTo=(1/ao)/Rk * (Ti-To) Top= To+ DTo Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Determination of the thermal gradient through the constructional complex - calculation T (oC) Ti To d (m) dao d1 d2 d3 dai

13. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Heat flow rate through the building element linear density of the heat flow rate q = k * (Ti-To) [W/m2] heat flow rate Q= A * k * (Tn-Tz) [W]

14. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Dew point layer T (oC) T (oC) Ti Tl To R (m2K/W) d (m) dao d1 d2 d3 dai 1/ao d1/l1 d2/l2 d3/l3 1/ai • T of the dew point depends on inside temperature Ti and inside air humidity fi Tr=f(Ti, fi) • determination of the dew point layer • improvements: adding the vapour barrier, changing the material layers of the constructional complex or using different materials

15. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • diffusion

16. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Water vapour diffusion • This phenomenon happens when in the constructional complex moisture penetrates from layers with more moisture content in the layers with less moisture content. Water vapour diffusion is accompanied with heat flow rate; from warm to cold • Two examples for water vapour transmission • water vapour transmission through all layers of the constructional complex • condensation within the constructional complex in one or more layers • Necessary checking in case of the condensation • layers of the condensation • enlargement of the moisture content in material • possibility for complete moisture evaporation in the summer season

17. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Conditions for water vapour diffusion • Pressure difference Pi > PO • Partial water vapour pressure P [N/m2] • P= f*Ps • saturated water vapour pressure Ps [N/m2], depends on the temperature • relative humidity f=P/ Ps [%] • absolute humidity G/V [kg/m3] Pi= fi * Psi • P [N/m2] Po= fo * Pso r[m]

18. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Material properties by water vapour diffusion • Relative water vapour resistance r=d*m*(1/ dz) • m= water vapour permeability of the material (d=1m) / water vapour permeability of the air (d=1m) • d=layer thickness (m) • da =water vapour resistance of the air (1/1.6)*10-6 [kg/m2hPa] (depends on the temperature) • Density of water vapour flow q=(pi-pe)/r [kg/hm2] • P [N/m2] Pi r Po

19. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Water vapour diffusion through several layers • relative water vapour resistance of the layer ri=d*m*(1/ dz) • relative water vapour resistance of more layers Sr=r1+r2+r3+... • density of the water vapour flow through several layers q=(pi-pe)/ Sr [kg/hm2] Pi • P [N/m2] R1 R2 R3 Po r2 r3 r1 Sr

20. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Condensation by water vapour diffusion • Condensation occurs, when partial vapour pressure P’ reaches saturated vapour pressure Ps. Partial water vapour pressure P’ can not be lower than Ps; condensation does not occur. • Saturated water vapour pressure Ps depends on the temperature; it is changeable inside the building element • 3 examples of water vapour penetration • condensation does not occur inside the constructional complex p’ > ps • condensation occurs on a plane inside the building element • condensation occurs in a layer inside the building element P P P P r r r

21. P’k1 Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Condensation on the plane inside the building element Density of the water vapour flow entering the building element: Psi • P [N/m2] qm1= (pi-p’k1 ) / Sr’ Pi Density of the water vapour flow leaving the building element : qm1 qm2= (p’k1-pe ) / Sr’’ Amount of the condensed moisture : q’m= qm1- qm2 Amount of the condensed moisture in the winter period : Q’mz= q’m *24h*d Pe qm2 Increased the moisture content in the material: X’dif= Q’mz/ (dr*ro) r1 r2 r3 r [m] Sr’’ Sr’ Sr’

22. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Condensation in the layer inside the building element Density of the water vapour flow entering the building element: Psi • P [N/m2] qm1= (pi-p’k1 ) / Sr’ Pi Density of the water vapour flow leaving the building element : qm1 qm2= (p’k2-pe ) / Sr’’ Amount of the condensed moisture : q’m= qm1- qm2 Amount of the condensed moisture in the winter period : P’k1 Q’mz= q’m *24h*d qm2 P’k2 Raising the moisture content in the material: Pe X’dif= Q’mz/ (dr*ro) r [m] r1 r2 r3 X’sk= X’dif + X’r Sr’’ Sr’ Sr’

23. r1 r2 r3 Condensed moisture in the winter period q’m= (pi-p’k1 ) / Sr’- (p’k1-pe ) / Sr’’ Density of the water vapour diffusion flow by drying qm= (p’k-pi ) / Sr’+(p’k-pe ) / Sr’’ Time necessary for drying d= 1.3*Q’ mz / (qm*24h) Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Drying up the building element in the case of condensation on the plane • P [N/m2] • P [N/m2] Ps P’k1 Ps Pi Summer conditions Pe Pi P’k1 Pe r [m] r [m] r1 r2 r3 Sr’’ Sr’ Sr’

24. P’k2 P’k1 r1 r2 r3 Condensed moisture in the winter period q’m= (pi-p’k1 ) / Sr’- (p’k2-pe ) / Sr’’ Density of the water vapour diffusion flow by drying qm= (p’k1-pi ) / Sr’+(p’k2-pe ) / Sr’’ Time necessary for draining d= 1.3*Q’ mz / (qm*24h) Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Drying up in the case of condensation in the layer inside the constructional complex Ps Ps • P [N/m2] • P [N/m2] summer conditions Pi Pe Pi P’k1 P’k2 Pe r [m] r [m] r1 r2 r3 Sr’’ Sr’ Sr’

25. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • thermal inertia

26. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Thermal inertia • Is an expression denoting the resistance of the constructional element to changes in its temperature. It depends on its thermal storage and its thermal resistance. T T t t

27. Chair for buildings & constructional complexes BUILDING, ENVIRONMENT, ENERGY • Checking the thermal inertia: • calculation of temperature dumpingn • calculation time lag h h T n Ti Te t