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WinDesign

WinDesign. Program to optimize the selection of windows in dwellings Inês Palma Santos, Research Assistant. September 15th, 2008. WHY TO OPTIMIZE THE WINDOWS?. “Existing buildings are responsible for over 40% of the world’s total primary energy consumption”

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WinDesign

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  1. WinDesign Program to optimize the selection of windows in dwellings Inês Palma Santos, Research Assistant September 15th, 2008

  2. WHY TO OPTIMIZE THE WINDOWS? “Existing buildings are responsible for over 40% of the world’s total primary energy consumption” (http://www.iea.org/Textbase/publications/free_new_Desc.asp?PUBS_ID=2009) 80% of world’s total primary energy consumption still comes from fossil fuels (2005)! (http://www.iea.org/Textbase/stats/graphresults.asp?COUNTRY_CODE=29) Presentation - Course 11116 - Sustainable Buildings

  3. WHY TO OPTIMIZE THE WINDOWS? (Key World Energy Statistics, 2007, International energy agency) http://www.iea.org/Textbase/nppdf/free/2007/key_stats_2007.pdf Presentation - Course 11116 - Sustainable Buildings

  4. WHY TO OPTIMIZE THE WINDOWS? Fossil fuels are limited! The process of transforming fossil fuels into useful energy leads to high emissions of C02 Need for energy savings! Need for renewable energy resources not harmful for the planet and human being! Presentation - Course 11116 - Sustainable Buildings

  5. WHY TO OPTIMIZE THE WINDOWS? How to save energy in buildings? • Better insulation of envelope (walls, roof, ground) • Lower losses through windows • Heat recovery on ventilation • Optimize daylight through windows (less artificial light consumption) • More efficient systems: ex. Appliances, Ligthing.. Presentation - Course 11116 - Sustainable Buildings

  6. WHY TO OPTIMIZE THE WINDOWS? How to use renewable energy in buildings? • Solar gains through windows • Solar heating systems • Store energy In a controlled way Presentation - Course 11116 - Sustainable Buildings

  7. WHY TO OPTIMIZE THE WINDOWS? Control solar gains through windows Lower losses through windows Optimize daylight OPTIMIZATION OF WINDOWS Presentation - Course 11116 - Sustainable Buildings

  8. HOW TO OPTIMIZE THE WINDOWS? • Select window components (glazing and frame) with better energy performance • Optimize window geometry (configuration and size) • Optimize orientations • Ex. For the South orientation the gains/losses ratio is higher than for the North orientation • Control excess of solar gains by using solar shading devices • Optimize daylight in order to reduce electrical light consumption Presentation - Course 11116 - Sustainable Buildings

  9. WINDESIGN - CONCEPT Program to optimize the selection of windows in dwellings Microsoft Excel and VBA Energy performance Indoor thermal climate Economic evaluation (Daylight not taken into account yet) User-friendly Flexible To be used by architects and engineers Design of new dwellings Renovation of old dwellings Early design phase Presentation - Course 11116 – Sustainable Buildings

  10. WINDESIGN - STRUCTURE WinDesign is organized in 4 different STEPS: STEP 1 Net energy gain of individual windows STEP 2 Seasonal energy performance of windows in dwelling STEP 3 Hourly energy performance and thermal comfort of windows in room STEP 4 Economic performance of windows 3 levels Presentation - Course 11116 – Sustainable Buildings

  11. STEP 1 Net energy gain of individual windows Presentation - Course 11116 – Sustainable Buildings

  12. STEP 1 - OVERVIEW • Output • - Net Energy Gain Input • Windowgeometry - Thermal performance of components Presentation - Course 11116 – Sustainable Buildings

  13. STEP 1 - INPUT • Window geometry (configuration and size) Presentation - Course 11116 – Sustainable Buildings

  14. STEP 1 - INPUT • Thermal performance of the window components Mullion Glazing Transom Glazing bars Sash Frame Presentation - Course 11116 – Sustainable Buildings

  15. STEP 1 - INPUT • Thermal performance of the window components Glazing • U-value [W/m2K] (thermal transmittance) • g-value [-] (total solar energy transmittance) Presentation - Course 11116 – Sustainable Buildings

  16. STEP 1 - INPUT • Thermal performance of the window components Frame/Sash • Ljoint [W/mK] (linear thermal transmittance) • width [m] Ljoint = U x w +  U - thermal transmittance of the profile [W/m²K] w – width of the profile [m]  - linear thermal transmittance due to the combined effects of glazing, spacer and profile [W/m²K] Presentation - Course 11116 – Sustainable Buildings

  17. STEP 1 - INPUT • Thermal performance of the window components Mullions/Transoms and Glazing bars • Ljoint [W/mK] (linear thermal transmittance) • width [m] Ljoint = U x w + 2 x  Presentation - Course 11116 – Sustainable Buildings

  18. STEP 1 - OUTPUT • Net Energy Gain (heating season - reference house in Denmark) NEG = 196.42 gw – 90.36 Uw [kWh/m2] I = 196.42 kWh/m² - solar radiation calculated for the reference house during the heating season gw – total solar energy transmittance of the window [-] D = 90.36 kKh – degree hour number during the heating season Uw – thermal transmittance of the window [W/m²K] Solar gains Heat losses Presentation - Course 11116 – Sustainable Buildings

  19. STEP 1 - OVERVIEW • Output • - Net Energy Gain Input • Windowgeometry - Thermal performance of components Presentation - Course 11116 – Sustainable Buildings

  20. STEP 1 – USER INTERFACE Presentation - Course 11116 – Sustainable Buildings

  21. STEP 2 Energy consumption of the windows used in the dwelling (Seasonal calculation - ISO 13790) Presentation - Course 11116 – Sustainable Buildings

  22. STEP 2 - OVERVIEW • Output • Energy consumption of the windows • Energy consumption of the dwelling for spaceheating and cooling • Length of the heating and coolingseasons Input • Information about the dwelling • Information about the windows used in the dwelling • Different scenarios of windows Seasonal calculation ISO 13790 Presentation - Course 11116 – Sustainable Buildings

  23. STEP 2 - INPUT • Information about the dwelling • Floor area • Floor to ceiling height • Total UA-value of the envelope (excluding windows) • Heat capacity • Internal gains • Infiltration rate • Ventilation rate • Heat exchanger (efficiency, bypass?) • Heating and cooling setpoint temperatures Presentation - Course 11116 – Sustainable Buildings

  24. STEP 2 - INPUT • Information about the windows used in the dwelling • Window from STEP 1 or Uw, gw and Aw • Orientation • Shadings from horizon, overhangs and side fins • Solar shading devices Presentation - Course 11116 – Sustainable Buildings

  25. STEP 2 - INPUT • Different scenarios of windows Examples: 1) Scenario 1 - Wood profile with double glazing Scenario 2 - Fiberglass profile with triple glazing • Scenario 1 – Windows with glazing bars Scenario 2 – Windows without glazing bars 3) Scenario 1 – Flat with only south oriented windows Scenario 2 – Same flat with only north oriented windows Presentation - Course 11116 – Sustainable Buildings

  26. STEP 2 - OUTPUT • Energy consumption of the windows used in the dwelling – HEATING SEASON • For each window: - For all windows used in the dwelling: Solar gains Heat losses Presentation - Course 11116 – Sustainable Buildings

  27. STEP 2 - OUTPUT • Ei,HS – energy consumption of the window i during the heating season • Uw,i – thermal transmittance of the window i [W/m2K] • Aw,i – area of the window i [m2] • GHS – number of degree hours during the heating season [kKh] • HS,gn – dimensionless utilization factor for the heat gains during the heating season • Fsh,ob,i,HS – shading factor for external obstacles (horizon, overhangs, side fins) • Asol,i,HS – window area corrected by the window g-value and movable solar shading devices [m2] • Isol, i, HS – total solar radiation on the window i over the heating season [kWh/m2] Solar gains Heat losses Presentation - Course 11116 – Sustainable Buildings

  28. STEP 2 - OUTPUT • Ei,HS – energy consumption of the window i during the heating season • Etotal, HS – energy consumption of all windows used in the dwelling during the heating season[kWh/m2] • Af – internal floor area of the dwelling Presentation - Course 11116 – Sustainable Buildings

  29. STEP 2 - OUTPUT • Energy consumption of the windows used in the dwelling – COOLING SEASON • For each window: - For all windows used in the dwelling: Solar gains Heat losses Presentation - Course 11116 – Sustainable Buildings

  30. STEP 2 - OUTPUT • Ei,CS – energy consumption of the window i during the cooling season • Uw,i – thermal transmittance of the window i [W/m2K] • Aw,i – area of the window i [m2] • GCS – number of degree hours during the cooling season [kKh] • CS,ls – dimensionless utilization factor for the heat losses during the cooling season • Fsh,ob,i,CS – shading factor for external obstacles (horizon, overhangs, side fins) • Asol,i,CS – window area corrected by the window g-value and movable solar shading devices [m2] • Isol, i, CS – total solar radiation on the window i over the cooling season [kWh/m2] Solar gains Heat losses Presentation - Course 11116 – Sustainable Buildings

  31. STEP 2 - OUTPUT • Ei,CS – energy consumption of the window i during the cooling season • Etotal, CS – energy consumption of all windows used in the dwelling during the cooling season [kWh/m2] • Af – internal floor area of the dwelling Presentation - Course 11116 – Sustainable Buildings

  32. STEP 2 - OUTPUT • Energy consumption of the dwelling for space heating - Heating season: Af – internal floor area Total heat losses (transmission + ventilation) Gain utilization factor Total heat gains (solar + internal) Presentation - Course 11116 – Sustainable Buildings

  33. STEP 2 - OUTPUT • Energy consumption of the dwelling for space cooling - Cooling season: Af – internal floor area Total heat gains (solar + internal) Loss utilization factor Total heat losses (transmission + ventilation) Presentation - Course 11116 – Sustainable Buildings

  34. STEP 2 - OUTPUT • Length of the heating and cooling seasons - The lengths of the heating and cooling seasons are calculated for each individual dwelling based on the energy balance of the dwelling! • “The heating season includes all days for which the heat gains, calculated with a conventional utilization factor, gn,1, do not balance the heat transfer” (from ISO 13790) • “The cooling season includes all days for which the heat transfer, calculated with a conventional utilization factor, ls,1, do not balance the heat gains” (from ISO 13790) Presentation - Course 11116 – Sustainable Buildings

  35. STEP 2 - OVERVIEW • Output • Energy consumption of the windows • Energy consumption of the dwelling for spaceheating and cooling • Length of the heating and coolingseasons Input • Information about the dwelling • Information about the windows used in the dwelling • Different scenarios of windows Seasonal calculation ISO 13790 Presentation - Course 11116 – Sustainable Buildings

  36. STEP 2 – USER INTERFACE Presentation - Course 11116 – Sustainable Buildings

  37. STEP 2 – USER INTERFACE Presentation - Course 11116 – Sustainable Buildings

  38. STEP 2 – USER INTERFACE Presentation - Course 11116 – Sustainable Buildings

  39. STEP 3 Energy consumption and indoor thermal comfort of one room of the dwelling Hourly calculation “Simple hourly method” in ISO 13790 Presentation - Course 11116 – Sustainable Buildings

  40. STEP 3 - OVERVIEW • Output • - Roomheatingdemand • - Roomcoolingdemandornumber of hourswithoverheating Input • Information about the room Hourly calculation ”Simple hourly method” in ISO 13790 Presentation - Course 11116 – Sustainable Buildings

  41. STEP 3 - INPUT • Information about the room • Room floor area • Total UA-value of the envelope (excluding windows) • Mechanical cooling (available or not) • Venting (available or not) • Venting rate • Venting setpoint temperature - Reference temperature for indoor thermal comfort evaluation Presentation - Course 11116 – Sustainable Buildings

  42. STEP 3 - OUTPUT • Room heating demand • Room cooling demand or Number of hours with overheating Presentation - Course 11116 – Sustainable Buildings

  43. STEP 2 – ”Simple hourly method” 5 resistances - 1 capacitance model for the “Simple Hourly Method” described in ISO 13790 Presentation - Course 11116 – Sustainable Buildings

  44. STEP 3 - OVERVIEW • Output • - Roomheatingdemand • - Roomcoolingdemandornumber of hourswithoverheating Input • Information about the room Hourly calculation ”Simple hourly method” in ISO 13790 Presentation - Course 11116 – Sustainable Buildings

  45. STEP 3 – USER INTERFACE Presentation - Course 11116 – Sustainable Buildings

  46. STEP 3 – USER INTERFACE Presentation - Course 11116 – Sustainable Buildings

  47. STEP 4 Economic performance of windows Cost of conserved energy Presentation - Course 11116 – Sustainable Buildings

  48. STEP 4 - INPUT • Identify the reference scenario • Economic evaluation period • Net discount rate • Total windows cost for each scenario Presentation - Course 11116 – Sustainable Buildings

  49. STEP 4 - OUTPUT • Cost of conserved energy (compared to the reference scenario) Investment cost Net discount rate Economic evaluation period Annual energy savings Presentation - Course 11116 – Sustainable Buildings

  50. STEP 4 - OVERVIEW • Output • - Cost of conservedenergy (compared to the reference scenario) Input • Identify the reference scenario • Economic evaluation period • Net discount rate • Total windows cost for each scenario Presentation - Course 11116 – Sustainable Buildings

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