Passive house ventilation systems
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PASSIVE HOUSE VENTILATION SYSTEMS Patricia Alonso Alonso LECTURER Patricia.alonso.alonso@udc.es Department of Building Constructions Why do buildings need to be ventilated? Because we…………………………………………………….. …..…..….………………..reduce heat gain in summer ..reduce moisture and condensation in winter …………..keep people healthy and comfortable PASSIVE HOUSE VENTILATION SYSTEMS FOR DESIGN………………………………………………... INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONCLUSIONS CONVECTIVE COOLING PASSIVE HOUSE VENTILATION SYSTEMS FOR DESIGN………………………………………………... INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONCLUSIONS CONVECTIVE COOLING Thermal comfort sensation Temperature Season Temperature (ºC) Summer 23….25 Winter 21….23 Data table: temperature and thermal comfort INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Thermal comfort sensation Data table: Relative humidity and thermal comfort INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Thermal comfort sensation Velocity (m/s) Sensation Until 0,2 inappreciable 0,2 to 0,5 Nice, but air movement is perceved 0,5 to 1 Mild discomfort to severe discomfort 1 to 1,5 Unfit for human comfort >1,5 Corrective action is required Data table: Air velocity and comfort sensation. Source: Warmth feeling is reduced using air movement 1ºC less for 0,2 m/s velocity increased. Limit: 5ºC INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Comfort sensation Air quality “Sick building Symdrome” Source: (Araujo, 2009) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS PASSIVE HOUSE VENTILATION SYSTEMS INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONCLUSIONS CONVECTIVE COOLING CONCEPTS Natural ventilation without any mechanical device 1. Difference between two points “Chimmey or Stack effect” Source: (Helena Granados, 2006) The higher temperature difference , the better natural ventilation INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS 2. Decrease in pressure over extraction point “Venturi effect” Source: (Helena Granados, 2006) The higher wind velocity and little extraction gap size, the better natural ventilation. INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS 3. Dynamic pressure generated by the wind over a hole “Wind effect” The higher wind velocity, the pressure generated and difference of pressure with respect of other hole, the better of the ventilation. INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS TECHNIQUES IN BUILDINGS A. Pure natural ventilation The simplest form of ventilation is window opening (shape, side and position in relation to each other) -Direct (Effectiveness: The depth of the room should not exceed 2,5 times the room height) -Cross-ventilation (Effectiveness: The depth of the room should not exceed 5 times the room height) Cross-ventilation Direct H 2,5 or 5 H Source: (Helena Granados, 2006) INTRODUCTION CONCEPTS & TECHNIQUES Source: (Helena Granados, 2006) SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS B. Naturally forced ventilation (utilising updraught systems) (Effectiveness: air pressures decreases with increasing height. Warm air has a lower density than cold air) Reheating façade Reheating façade Reheating roof Heat chimmey extraction Wind chimmey induction Elevated atria Reheating roof Source: (Neila,2009) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Updraught systems Extraction at wet areas. Heat chimmey extraction Source: (Neila,2009) Source: (Araujo,2009) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Elevated atria Source: (Araujo, 2009) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS PASSIVE HOUSE VENTILATION SYSTEMS INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONCLUSIONS CONVECTIVE COOLING PASSIVE COOLING SYSTEMS FOR BUILDINGS Evaporative cooling Vegetation and water Air and water Radiant cooling Wet roofs Courtyards Conductive cooling Cold surfaces Underground ducts Underground constructions Convective cooling Night ventilation INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS EVAPORATIVE COOLING It is a adiabatic process The overall energy is not altered Water: To a good evaporation it is necessary to achieve a high spraying level The best: a water jet Worse: a water pond Source: (Neila, 2009) Source: (Helena Granados, 2006) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Vegetation: A tree is capable of evaporating 500 Kg of water/year every m2 of exterior surface. That means 1212MJ/m2 a year that is equivalent to a cooling power of 40W/m2 of vegetal surface Source: (Helena Granados, 2006) INTRODUCTION CONCEPTS & TECHNIQUES Source: (Neila, 2009) SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Water and vegetation: To evaporate 1 gram/s of water (it is necesary 2424 Julius/s or 2,42kW cooling power) it is reduced 2,2ºC the temperature of a m3 air Example: Alhambra de Granada Source: (Neila, 2009) Source: (Helena Granados, 2006) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Air: Popular architecture of Middle East: Wind towers “Malqaf” or windcatchers Source: (Helena Granados, 2006) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Water and air: Windcatchers with evaporative cooling effect Sample of Malqaf using Salsabil (fountain), (Hassan Fathy 1986) Section of Malqaf using Pottery Jars to cool Air at Maziara Egypt by Hassan Fathy (Rosa Schiano 2007) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Water and air: Windcatchers with evaporative cooling effect Bahadori (1985) developed the Downdraught Evaporative Cool Towers as an upgrade to the traditional Malqaf & Badgir INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Water and air: Mashrabiya. Muscatese Evaporative cooling window system. Source: (Rosa Schiano 2007) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Water and air: Recent example: Spanish Pavilium. Zaragoza 2008 (Spain) Patxi Mangado Architect Based on “Botijo” effect (Porous water pot) Source: Mercadel, 2014 INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Spanish Pavilium. Zaragoza 2008 (Spain) Patxi Mangado Architect Source: (Mangado, 2009) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS RADIANT COOLING When the cooling system is reducing the quantity of energy of an environment it is named sensitive cooling. Two things we need: A bit of cold and mass enough to dump the heat and maintaining the temperature. INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Types of heat sinks to radiate: Celestial dome that covers us The ground that supports us The air that surrounds us The water Types of radiant mass at buildings Radiant slabs and ceilings Wet roofs Façade Courtyards INTRODUCTION CONCEPTS & TECHNIQUES Source: (Helena Granados, 2006) SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Wet roofs Radiant slab and ceiling Water confined in black bags and set on the roof “Roof pond” Source: (Helena Granados, 2006) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Façade: Trombe-Michel walls, (Northwest of Spain) Source: (Helena Granados, 2006) Constructive detail of a “galería” Typical galería of A Coruña (Spain) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Courtyards: Cooling effect over night radiation Outside air temperature should be 5K below the inside room temperature for at least 5 to 6 hours Source: (Helena Granados, 2006) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS CONDUCTIVE COOLING Underground buildings. Cave dwelling About nine meters underground the temperature is steady. Plan of a cave dweling at Guadix, Granada (Spain) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Cave dwelling Guadix, Granada (Spain) Ventilation chimmey of caves INTRODUCTION CONCEPTS & TECHNIQUES Typical plan of a cave SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Underground ducts Duct under the ground passing an airstream and then pushing up to the building interior. Earth pipes Example: “Canadian well” Source: (Helena Granados, 2006) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS CANADIAN WELL Typical diameter of an earth pipe is 20cm Ducts are buried between 1.5 and 3 m Ducts length are between 10 and 100 m INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS The distance between them should not be less than one metre A low velocity of 2m/s should be ensured Between temperatures 12-18ºC the earth-pipe is not usually used A Canadian well can reduce the temperature by 5 to 8°C in your house during a heat wave using virtually no electricity Source: (Eco-house system website, 2014) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Typical ventilation installation of Standard Passive house Source: (Wikipedia, 2014) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Passive house standards with heat recovery ventilation system (HVR) Source: (Araujo, 2009) INTRODUCTION CONCEPTS & TECHNIQUES Source: (Araujo, 2009) SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS Centralized ventilation Humidity sensor Spanish Building Code C.T.E. DB-HS-3 Interior Air Quality Proposed solution (Comunidad de Madrid) Night cooling is very efficient Minimum maintenance Very interesting in refubishing Individual ventilation unit Intelligent CO2 sensor Source: (Fenercom, 2014) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS CONVECTIVE COOLING Using cold mass of air. Night ventilation Example: Villa Costozza in Italy, Andrea Palladio Source: (Helena Granados, 2006) INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS PASSIVE HOUSE VENTILATION SYSTEMS INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONCLUSIONS CONVECTIVE COOLING CONCLUSIONS HOW TO PROCEED?…………………………………………….. INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS 1. We should analize very vell the environment and socioeconomical and local aspects 2. We could select different VENTILATION strategies to apply at Corte, Corsica 3. We could try to develop a diagram of how it would work 4. We could develop the solutions selected INTRODUCTION CONCEPTS & TECHNIQUES SYSTEMS EVAPORATIVE COOLING RADIANT COOLING CONDUCTIVE COOLING CONVECTIVE COOLING CONCLUSIONS For example…………………………………………………………….. Steps to analize building constructions Source: (Neila, 2004) 1. Location 2. Climate 3. Environmental conditions 4. Socioeconomic conditions 5. Formal description 6. Constructive description 7. Environmental use and bioclimatic strategies ……………the next step is your decision PASSIVE HOUSE VENTILATION SYSTEMS Thank you for your attention *All this information and images exposed are been used only for educational purposes Patricia Alonso Alonso LECTURER Patricia.alonso.alonso@udc.es Department of Building Constructions
